The present study was designed to develop the functional electrical stimulation system in order to restore motor function of paralytic patients. We attempt to establish adequate stimulus parameters for the recovery of work unction in lower limb paralysis patients and to develop the electrical stimulation system, which is effective to protect foot drop in these patients. In our animal and human experiment, adequate stimulus condition for surface electrode on the lower limb were 0.2-0.3ms at the duration and 50 Hz, which contain 600Hz train pulse. This parameter has efficiently prevented the foot drop from lower limb paralysis, decreased muscle fatigue and induced powerful contraction of lower limb muscle.

In this paper, we suggested and made a classifier or qualitative and quantitative analysis in urine analysis system. Input variable number and fuzzy membership function was made from determination of standard sample, and the fuzzy rules were determined by the analysis of spectroscopic properties of pads in strip. Fuzzy classifier used in urine analysis system was evaluated or the standard samples in each items and degrees. Negative and positive response of urine test was classified in good property, but detail classification or quantitative analysis had 8% maximum error in each items. If fuzzy membership unction and generation of rule are supplemented, suggested fuzzy classifier can be applied to the clinical test.

This paper studies the arousal effects of aroma and warning sound using EDA(Electrodermal Activity:EDA), Aroma stimulus started at Nz value over 1.2. Warning sound was prepared according to the arousal evaluation and control criteria. As a result, the warning sound could be controlled the arousal level in all the mKSS state. Aroma stimulus was able to prevent drowsy more than warning sound in the mKSS 3 state(the first stage of drowsiness). Therefor, aroma stimulus was can be used for arousal control at that state. Futhermore, arousal control was shown to be more effective with presentation of both aroma and warning sounds than each presentation.

We present several biosignal measurement results and analysis algorithms or the visual stimulus from International Affective Picture System. Since human body is nonlinear dynamic system, we investigated both linear and nonlinear methods. We found that the chaos was diminished when unpleasant picture is presented relative to pleasant picture, and the alpha wave of EEG was slightly augmented in pleasant picture, but was not convincing result. These can be used as the parameter or the measurement of human sensibility.

The purpose of this study is to estimate human sensibility quantitatively under color and music stimulation and to examine the correlation between visual and auditory emotion. We measured biological signals such as EEG, ECG, skin conductance and the number of respiration in order to compare color with music sensibilities. Our result showed that red, yellow and violet color provoked active and exciting senses dominatively as dance, rock and blues music. While blue, cyan and pink color were involved in tranquil and resting emotions deeply as classic and ballade music. Our quantitative estimations of human sensibilites are useful in the design of manufactured goods.

A semiconductor microelectrode array has been successfully used in obtaining single unit recordings from medial giant nerve of clay fish, rat saphenous nerve and abdominal ganglia of aplysia. The recording device fabricated using silicon microfabrication techniques is a depth-probe type and, previously, has been mostly used to record from central nerve system of vertebrates. From invertebrates, and also from peripheral nerves of vertebrates, however, the quality of the recorded signal depends heavily on the recording conditions, such as the proximity of the electrode site to the nerve cells and the size of the neuron. We have modeled the signal to noise ratio as unctions of these parameters and compared the experimental data with the calculated values thus obtained.

A new approach to the measurement of muscle fiber conduction velocity by surface electro-myography(EMG) is developed, based upon a robust time-delay estimation algorithm. Unlike previously reported methods, it does not require the Gaussian assumption of raw EMG signal, and can be applied accurately in non-gaussian impulsive EMG signal. For ive healthy subjects the conduction velocity in the biceps brachii and vastus medialis was measured and compared with various other techniques. As a result, the average muscle fiber conduction velocity was $4.59{\pm}0.20m/s$ in case of biceps brachii and $5.67{\pm}0.33m/s$ in vastus medialis.

Posturography stands or quantitative assessment of body postural stability analysis. The present study developed a balance plate system to monitor patient's center of pressure (COP) movement and to analyze its stability. An equilateral triangular shaped plate was made of duralumin and forces were measured on the three vertices of the plate using industrial load cells. Specially designed electronic circuit picked up force signals ed into data acquisition system to calculate the cartesian coordinates of COP. COP calculation error was less than 2%. The force signals enabled to compute stability measures, which consisted of a variety of clinical parameters related to postural stability. Clinical experiments were carefully designed and performed on 40 normal subjects. The results were that 1) postural stability decreased with age and 2) the best parameters were those of posture deviation measures. A customized PC-based software package was developed to apply the present technique with a great convenience to monitoring and analyzing postural stability in an accurate and quantitative way.

This paper is a study on the hand gesture recognition using Instance-based teaming, Symbolic learning algorithms and Power Glove which supplies information on finger position, hand position and orientation. The data were carefully examined, and a few features of the data that would serve as good discriminants between signs when used with the learning algorithms were extracted. The hand gesture data collected from 5 people were applied to the teaming algorithms. In spite of the noise and accuracy constraints of the equipment used, some accuracy rates were achieved.

The purpose of this paper is to propose a method to protect the drowsiness of a driver. We measured the physiological signals, response time, and ace expression of the subjects in normal and drowsy state. Those data are used to establish the drowsiness index and fuzzy system. We employed the computer vision technology to extract and eye, track eyelids and measure the parameters related to drowsiness. These parameters were ed into the fuzzy system to decide the drowsiness level, When the drowsiness was detected, the fuzzy system generated warning signals which cons ist of sound and fragrance. Our system was available in decision of the drowsiness level and improvement of subjects' state.

In this paper, we study a signal processing method which extracts each MUAP(motor unit action potential) from EMG(Electromyogram) interference pattern or clinical diagnostic purposes. First of all, differential digital filtering is selected or eliminating the spike components of the MUAP's from the background noise. And, the algorithm identifies the spikes over the certanin threshold by template matching in frequency domain. After missing or false firing actor is cut off at the IPI(inter pulse interval) histogram, we averages the MUAP waveforms from the raw signal using the identified spikes as triggers, and Finally, measures their amplitudes, durations, and numbers of phases. Specially, We introduce algorithm performed by template matching in the frequency domain. A typical 3-s signal recorded from the biceps brachii muscle using a conventional needle electrode during a isometric contraction is used. Finally, the method decomposed five simultaneous active MUAP's from original EMG signal.

In this paper, we used Wavelet Transform to analyze EMG signals. Wavelet transform has an advantage of dividing the nonstationary signals into the high frequency and low frequency band effectively. For determining the characterized value of EMG signals, it was wavelet-transformed, absoluted, and integral-calculated. As the result, we acquired characterized value of each signals, and acknowledged the differences among them. It was concluded that the results of this study using wavelet transform could be used to powerful tool or analysis of EMG signals.

With the advent of high speed digital signal processing chips, new digital techniques have been introduced to the hearing instrument. This advanced hearing instrument circuitry has led to the need or and the development of new fitting approach. A number of different fitting approaches have been developed over the past few years, yet there has been little agreement on which approach is the "best" or most appropriate to use. However, when we develop not only new hearing aid, but also its fitting method, the intensive subject-based clinical tests are necessarily accompanied. In this paper, we present an objective method to evaluate and predict the performance of hearing aids without the help of such subject-based tests. In the hearing impairment simulation (HIS) algorithm, a sensorineural hearing impairment model is established from auditory test data of the impaired subject being simulated. Also, in the hearing impairment simulation system the abnormal loudness relationships created by recruitment was transposed to the normal dynamic span of hearing. The nonlinear behavior of the loudness recruitment is defined using hearing loss unctions generated from the measurements. The recruitment simulation is validated by an experiment with two impaired listeners, who compared processed speech in the normal ear with unprocessed speech in the impaired ear. To assess the performance, the HIS algorithm was implemented in real-time using a floating-point DSP.

In this paper, we evaluated the character of speech of hearing impaired person (HIP) who acquire his hearing loss after the youth. It is usually observed that severe HIP decreased not only speech perception but also vocalization. so there is a need for sensitive and quantitative measures or the assesment of the speech of the HIP to serve both diagnostic and prognosic purposes, 7 HIP and 12 normal hearing person(NHP) were studied with pure tone test and speaking test using word/sentence table which consists of vowel(a:), mono and two syllables and a sentence. we analyzed formant frequency, pitch, sound intensity, speech duration of HIP and NHP speech. According to the results, in the HIP's speech we find that formant frequency was shifted, first-formant prominence was reduced, the dynamic range of sound intensity was decreased, speech duration was prolonged. In the next, we expect the correlation between hearing and speech character of HIP is cleared through analysis of more acoustic parameters and precise selection of HIP group.

MR acoustic sound or noise due to gradient pulsings has been one of the problems in MRI, both in patient scanning as well as in many areas of psychiatric and neuroscience research, such as brain fMRI. Especially in brain fMRI, sound noise is one of the serious noise sources which obscures the small signals obtainable from the subtle changes occurring in oxygenation status in the cortex and blood capillaries. Therefore, we have studied the effects of acoustic or sound noise arising in fMR imaging of the auditory, motor and visual cortices. The results show that the acoustical noise effects on motor and visual responses are opposite. That is, for the motor activity, it shows an increased total motor activation while for the visual stimulation, corresponding (visual) cortical activity has diminished substantially when the subject is exposed to a loud acoustic sound. Although the current observations are preliminary and require more experimental confirmation, it appears that the observed acoustic-noise effects on brain unctions, such as in the motor and visual cortices, are new observations and could have significant consequences in data observation and interpretation in future fMRI studies.

In this paper we present new sound spectral analysis methods or prosthetic heart valve sounds. Phonocardiograms(PCG) of prosthetic heart valve were analyzed in order to derive frequency domain feature suitable or the classification of the valve state. The fast orthogonal search method and MUSIC (MUltiple SIgnal Classification) method are described or finding the significant frequencies in PCG. The fast orthogonal search method is effective with short data records and cope with noisy, missing and unequally-spaced data. MUSIC method's key to the performance is the division of the information in the autocorrelation matrix or the data matrix into two vector subspaces, one a signal subspace and the other a noise subspace.

In this paper, a body-worn type digital hearing aid (DHA) based on a dedicated DSP chip is developed. A fitting software running on a PC supported by the Win95 OS is also developed. The fitting protocol is based on the NAL-R procedure applied to eight frequency bands, but it is designed to support a curvilinear fitting to cope with the nonlinear perception of hearing-impaired listeners. Preliminary subjective tests regarding the speech intelligibility and perceived quality revealed that the new DHA could be of benefit to hearing aid users.

To provide ameliorated aided environment to hearing impaired listeners, background noise reduction techniques are investigated as a front-end of conventional hearing aids, and their effects are tested in a subjective manner. Several speech enhancement schemes were implemented and preference tests or normal listeners are performed to select the best possible scheme or hearing impaired listeners. Results indicated that SDT scores without the speech enhancement scheme drop more sharply as SNR decreases than those with the speech enhancement techniques. SDT scores obtained or hearing impaired listeners with hearing aids showed large variability. However, all impaired listeners preferred noise suppressed sounds to unsuppressed ones.

Electrical stimulation has been used or diagnosis and treatment of impairment on the auditory system. Unfortunately, there were no standard methods or theoretical background or choosing stimulus conditions because of the lack of understanding on the current propagation through the auditory pathways. Nine guniea pigs, experimental group(A) and control group(B), were used for the experiment. ABR and ECochG were obtained under our experimental conditions, before tinnitus and 1, 6, 12 hours after tinnitus induction using salicylate. Electrical stimulations were applied to the group A, and the changes on ABR/ECochG's correlation coefficients were observed. Results showed that an electrical stimulation brings ABR waveform back to the normal states well in the group A compare to the group B, which proved the effectiveness of the stimulation. Based on the results of this experiment, establishment of an electrical model which provide the quantitative information regarding diagnosis and treatment of tinnitus could be achievied.

In this paper, pseudo-random ternary sequence (PRTS) was used to investigate the cardiovascular and respiratory responses to hypoxia and hypercapnia. The actual input or this study was the changes in inhaled oxygen and carbon dioxide concentrations. It is hard to randomly change the concentration within a given breath. Since PRTS has almost the same statistical properties as Gaussian white noise, plus it is physically realizable, PRTS is used for this study. Using PRTS and Volterra kernels by Gram-Schmidt orthogonalization procedure, the cardiovascular and respiratory responses to hypoxia and hypercapnia were analyzed.

In this paper, several nonlinear system identification theories and the application of these methods to the physiological system are reviewed by extracting significant results from the literature. Methods based on unctional series expansion, parameter estimation, block-oriented models are included. However, there is still considerable debate about the advantages and disadvantages of each approach. This is true primarily because each method has limitations on the types of assumption and interpretation, types of nonlinear elements, etc. This means that user must select an appropriate method and the selection will depend on the problem under investigation.

A neural spike sorting technique has been developed that also has the capability of template learning. A system of software has been written that first obtains the templates by learning, and then performs the sorting of the spikes into single units. The spike sorting can be done in real time. The template learning consists of spike detection based on the discrete Haar transform (DHT), feature extraction by clustering of spike amplitude and duration, classification based on rms error, and fabrication of templates. The developed algorithms can be implemented into real time systems using digital signal processors.

In this paper, we developed a portable electrical ventilator that could be controlled by the microcontroller. Control algorithm of motor drive t programmed with ASM96 assembly language software. We evaluated the system by measuring the parameters such as motor speed, feedback gain and overall specification.

The Hydrodynamic performance of the trileaflet polymer prosthetic valves depends on the design of the leaflet and the physical properties of the leaflet membrane. In order to study the effect of leaflet membrane elasticity on the hemodynamic performance of trileaflet prosthetic valve, leaflet membranes are manufactured using two different polymers - Biospan and Tecoflex SG-93A. The hemodynamic performance parameters are measured under steady and physiological pulsatile flow, and compared with monoleaflet polymer valve(floating valve) and bileaflet mechanical valve(St. Jude Medical valve). Well designed trileaflet valve shows the lowest mean pressure drop among the tested valves. The trileaflet valves with Biospan membrane show lower pressure drop and back low comparing to those with Tecoflex membrane. More elastic membrane may provide wide opening area during systole and close membrane ree edge contact during diastole. Durability of trileaflet valves are also tested in vitro. Trileaflet valves with non-uniform membrane thickness ail within 17 days because of stress concentration. Trileaflet polymer valves with uniform membrane thickness perform well over 55 days without failure.

In this paper we detected the thrombosis formation by spectral analysis and neural network. Using microphone and amplifier, we measured the sound from the mechanical valve which is attached to the pneumatic ventricular assist device. The sound was sampled by A/D converter and the periodogram is the main algorithm or obtaining spectrum. We made the valvular thrombosis models using pellethane and silicon and they are thrombosis model on the disk, around the sewing ring and fibrous tissue growth across the orifice of valve. The spectrum of normal and 5 kinds of thrombotic valve were obtained and primary and secondary peak appeared in each spectrum waveform. So to distinguish the secondary peak of normal and thrombotic valve quantatively, 3 layer back propagation neural network.

Intel's 80C196KD has been applied at the moving-actuator type total artificial heart ( MA-TAH ) from about early 1990th at our laboratory and it fulfilled its role successively. But the increased need of higher performance brought the other-type of the CPU, and the new challenge of ASIC to the application to the MA-TAH accelerated its need. So the new concept of the utilization of the DSP based CPU to the motor control was surveyed and analyzed deeply or about ew months and the results were introduced and summarized in this paper.

It is needless to say that the hemodynamic variables estimation is a very important study or the artificial heart. Even though its importance there have not been satisfactory results which can be applied to the real-world situations. In this paper, we propose a practical afterload model ( AoP, PAP) which can be applied to the real-world situation.

In the development of the totally implantable artificial heart (TAH), the information of the preload condition is important to ind appropriate condition or the automatic control of the heart. Our TAH configuration consists of two artificial ventricles, and brushless DC motor within actuator. The pressure between ventricles could indicate the preload condition during the TAH operation. If we can measure accurately inspite of the noise induced from TAH and environmental condition. We suggested integrating a feedback loop to remove an unexpected DC drift. NPI 19-series Nova sensor was used which could measure pressure in gas and liquid. This method and sensor enabled us to develop the pressure transducer compact so (that) the systems can be implanted with TAH into patient. This system has been verified in vitro and in vivo test. This results showed that the output waveform of this system was stable irrespective of animal condition.

The human chromosome analysis is widely used to diagnose genetic disease and various congenital anomalies. Many researches on automated chromosome karyotype analysis has been carried out, some of which produced commercial systems. However, there still remains much room or improving the accuracy of chromosome classification. In this paper, We propose an optimal pattern classifier by neural network to improve the accuracy of chromosome classification. The proposed pattern classifier was built up of multi-step multi-layer neural network(MMANN). We reconstructed chromosome image to improve the chromosome classification accuracy and extracted three morphological features parameters such as centromeric index(C.I.), relative length ratio(R.L.), and relative area ratio(R.A.). This Parameters employed as input in neural network by preprocessing twenty human chromosome images. The experiment results show that the chromosome classification error is reduced much more than that of the other classification methods.

In this study, in order to improve visualization and enhance the ability of the surgeon to perform delicate endoscopic surgery, three dimensional endoscopic system is designed. These 3D systems have our features of stereoendoscopic image processing: real time image capture and retrieve; presentation of left and right image on a single monitor; separable processing of the left and right eye images; coding of the 3D endoscopic video. For 3D endoscopic video coding, three approaches are presented based on interlaced picture structure, side-field format structure, and simulcast technique. Experimental results and performances comparisons are presented and analyzed or these approaches. Digital video coding techniques are presented or 3D endoscopic video sequences by means of an MPEG-2 video coding.

This paper presents the development of depth extraction algorithm or the 3D Endoscopic Data using a stereo matching method and depth calculation. The purpose of other's algorithms is to reconstruct 3D object surface and make depth map, but a one of this paper is to measure exact depth information on the base of [cm] from camera to object. For this, we carried out camera calibration.

Computerized densitometry was developed or the quantitative measurement of diffuse retinal nerve fiber layer (RNFL) atrophy and intra- and inter-operator reliability and clinical validity of this system were evaluated. Vertical diameter, center of the optic disc, and peripapillary circles which had radii of 1.5 and 2.5 times that of the optic disc were user-interactively determined in digitized RNFL photograph and density profile along each circle was measured and normalized. The areas under the normalized density profiles of the superior and the inferior segments in both circle were used or the study of RNFL. To determine the variability and correspondence in the measurements of density variations, 21 RNFL photographs of glaucoma patients which showed varying degrees of atrophy underwent computerized densitometry by two operators on two separate occasions. Coefficient of variation in the densitometric measurements was $1.2{\sim}5.4%$. Intra- and inter-operator reliabilities were excellent. The correlations between the densitometric values and mean deviations of Humphrey C30-2 visual field showed statistical significance. Computerized densitometry of RNFL photographs was useful in the objective and quantitative assessment of diffuse RNFL atrophy.

The proposed tracking algorithm approaches geometrical method or position, direction, width of vessel. This algorithm using continuity of vessel in spatial coordinates used to determine direction of the center point, after estimating boundary point in dynamic region. Therefore the tracking of vessel's contour is tracked contour as direction of entire contour in coronary artery. This algorithm is automatically processed by DIP as a compared with conventional method, because searching area varies adaptively to allocate searching region from extracted information at past. And ML estimation expressed robust method or angiography as evaluating sample values after preprocessing.

By their rapid and periodic actions, the cilia of the human respiratory tract play an important role in clearing inhaled noxious particles. Based on the automated image-processing technique, we studied ciliary beat frequency (CBF) objectively and quantitatively. Microscopic ciliary images were transformed into digitized gray ones through an image-grabber, and from these we extracted signals or CBF. By means of a FFT, maximum peak frequencies were detected as CBFs in each partitioned block or the entire digitized field. With these CBFs, we composed distribution maps visualiy showing the spatial distribution of CBFs. Through distribution maps of CBF, the whole aspects of CBF changes or cells and the difference of CBF of neighboring cells can be easily measured and detected. Histogram statistics calculated from the user-defined polygonal window can show the local dominant frequency presumed to be the CBF of a cell or a crust the region includes.

In this paper, a two-dimensional electron beam dose calculational algorithm implented for use in a two-dimensional radiation therapy planning system is described. The 2-D electron beam calculations have been in use clinically for a few decades. Our algorithm uses Age-diffusion model based int the Boltzman Transport Equation. Our implementation provides convenient user interface associated with electron beam therapy planning and displays radiation dose distribution according to different electron energy on patient images.

The treatment setup of patients during irradiation is an important aspect in relation to the success of radiotherapy. Imaging with the treatment beam is a widely used method or verification of the radiation field position relative to the target area, prior to or during irradiation. In this paper, Real time digital radiography system was implemented or verification of local error between simulation plan and radiation therapy machine. Portal image can be acquired by CCD camera, image board and pentium PC after therapy Radiation was converted into light by a metal/fluorescent Screen. The resulting image quality is comparable to film, so the imaging system represents a promising alternative to film as a method of verifying patient positioning in radiotherapy. Edge detection and field size measurement were also implemented and detected automatically for verification of treatment position. Field edge was added to the original image or checking the anatomical treatment verification by therapy technicians. By means of therapy efficiency improvement and decrease of Radiation side effects with these techniques, Exact Radiation treatments are expected.

The purpose of this study is the development of PBL(problem-based learning) system using visual C++5.0 as a window-based application program. A patient who complains of weight loss was used in PBL case. Initial frame is made by dialog-based in MFC(microsoft foundation class). Also, sample medical images are composed of ultra-sound, chest PA, Thyroid scan, otherwise. we will make this program as CD-ROM and the internet application or computer assisted learning and continuous medical education.

Outline contour is detected firstly to simulate dose distribution in radiation therapy planning system. In this paper, we developed automatic contour detection system using temporal and spatial relationships of image sequences. The low level image analysis involves the use of directional gradient edge operators and Laplacian operator. The High level portion of algorithm uses a knowledge-based strategy that incorporates fuzzy resoning method.

In this paper, We developed a radiation therapy planning system using photon beams. Firstly We accomplished simulation on the regular field. Then it has been modified step by step to handle the irregular field, wedge filter, and inhomogeneous field. This system is equipped with useful user interface and database. This system is implemented in Visual C++ as a window-based application program.

In this paper, we present the Tele-consulting system of radiology, which uses the communication network as asymetric satellite data communication system. The asymetric satellite data communication system uses receive-only satellite links or data delivery and PSTN(Public Switched Telephone Network) modem or N-ISDN(Integrate Services Digital Network) for communication. The satellite communication linking shows the very high-speed performance than 28.8kbps modem linking. The satellite linking is 5 - 10 times aster than the modem linking. Consequently, we get the conclusion that our system is suitable or tele-radiology and telemedicine.

Small PACS based on a personal computer or CR has initially been designed to improve the performance of cost-effective PACS implementation. In that system, Wavelet compression scheme is newly adopted to store images hierarchically to storage unit, and retrieve and display images progressively or display workstation. In this compression method, image is decomposed into subclasses of image by wavelet transform, and then the subclasses of image are vector quantized using a multiresolution codebook.

The purpose of this study are changing wired medical instrument's terminal into wireless and implementing BSS of Wireless Local Area Network. the wireless terminal using frequency hopping spread spectrum in ISM band transfers patients medical information data such as ECG data, Patient Disease Indication Message to AP(or Server) and it also performs that as a response of transmission request in server. we made Clinet-Server network structure support only BSS service and patient's terminal controlled by polling in server. Wireless Terminal will guarantee mobility and give doctors real time monitoring capability in office.

This paper proposes a new medical information management system to be used or small to medium sized clinics and hospitals. The system is designed to process, analyze and manage each patient's clinical record using database technique. The structure of the database was determined and implemented through careful and rigorous study of medical practices in Korea and, therefore, reflects the needs of information management in Korean medical community. Furthermore, a sophisticated inference engine that can deduce possible disease from the result of medical examination is added to the system to provide doctors with a guideline in medical diagnoses.

In this paper, we present a 3D reconstruction method of color volume data or a computerized human atlas. Binary volume rendering which takes the advantages of shear-warp factorization and new normal vector calculation method visualizes 3D organs in real time. Various manipulations such as rotation, multiple object rendering, removal, and transparency effect improve the usefulness and comprehensiveness of the computerized atlas.

With the recent advance of Web and its associated technologies, information sharing on distribute computing environments has gained a great amount of attention from many researchers in many application areas, such as medicine, engineering, and business. One basic requirement of distributed medical consultation systems is that geographically dispersed, disparate participants are allowed to exchange information readily with each other. Such software also needs to be supported on a broad range of computer platforms to increase the software's accessibility. In this paper, the development of world-wide-web based medical consultation system or radiology imaging is addressed to provide the platform independence and great accessibility. The system supports sharing of 3-dimensional objects. We use VRML (Virtual Reality Modeling Language), which is the de-facto standard in 3-D modeling on the Web. 3-D objects are reconstructed from CT or MRI volume data using a VRML format, which can be viewed and manipulated easily in Web-browsers with a VRML plug-in. A Marching cubes method is used in the transformation of scanned volume data set to polygonal surfaces of VRML. A decimation algorithm is adopted to reduce the number of meshes in the resulting VRML file. 3-D volume data are often very large-sized, and hence loading the data on PC level computers requires a significant reduction of the size of the data, while minimizing the loss of the original shape information. This is also important to decrease network delays. A prototype system has been implemented (http://netopia.snu.ac.kr/-cyber/). and several sessions of experiments are carried out.

The stereostatic surgery becomes a important part of neurosurgery. The conventional style of stereostatic system uses a input method of film digitizing. It is time consuming and laborious. In this paper, we presented a system that can manage digital images from medical imaging machine to surgery assisting program. CT images were transferred in DICOM format to a surgery assisting computer in a operation room through PACS. The streotatic surgery assisting program processed the digital images and calculated the parameters that were required in steostatic surgery. The assisting program were developed that can detect the reference points automatically, transform CT coordinate to frame coordinate and calculate the RM (Riechert-Mundinger) frame. This system were applied to clinical cases in Seoul National Univ. Hospital. The two advantages of this system were revealed. The processing time from imaging to surgery parameters were much aster than conventional system. The surgery accuracy were more mininute as the digitizing error were reduced. This system were a good application of connecting imaging machines to clinical treatment system through PACS.

In this study, three-dimensional inite element model was developed and analyzed or DAI using ABAQUS. To verify the developed FE model, simulated results were compared to experimental results of human cadaver by Nahum et. al. (1977). The effect of acceleration pattern and accelerating duration time or DAI was analyzed by means of maximum shear stress and pressure distribution. DAI was favored or angular acceleration rather than linear acceleration, and occured in brain stem, pons and midbrain easily as accelerating duration time was increased.

In this paper, we designed a myocaldial ischemia model based on L-R dynamic model including hyperkalemia and anoxia. Using the model, we simulated the effects of ionic concentration $[K^+]_o$ and intracellular $[ATP]_i$ on action potential in single cardiac cell. Also we evaluated this model by comparing the simulated results with that of other researches. In luther research, we are going to consider the effect of acidosis quantitatively.

회귀에 기인하는 부정맥의 발생 기전 분석을 위해 심장 전도 계통의 변경된 Hidden Markov Model을 세우고 모의 실험을 하였다. 먼저, 심근의 탈분극 시간과 전도 속도, 탈분극의 자율성(autonomicity)을 매개 변수로 한 모의 실험을 통해 시간적인 심장 진도와 피에 따른 심전도 결과를 얻었다. 결과는 연속된 심전도 파형과 그 발생 시간이었다. 매개변수는 율동의 속도, 각 파형간의 간격, 이상 파형의 발생 빈도등을 결정한다. 정상 동율격 및 심실상성/심실성 정맥, 심방/심실 조기 박동등을 모의 실험할 수 있는 매개변수의 세트를 구하였다. 다음으로 Hidden Markov Model의 확률적 추정 방법을 응용하여 심전도 결과를 가지고 최적 확률의 심장 전도 경로를 추정하였다. 변경된 추정 방법을 이용하여, 모의 실험한 전도경로와 추정한 경로가 유사함을 확인하였다.

In this paper, we designed an ART(Adaptive Resonance Theory) network based on LPC(Linear Prediction Coefficient) for classification of PVB (Premature Ventricular Beat: PVC, LBBB, RBBB). The procedure of proposed system consists of the error calculation, feature generation and processing of the ART network. The error is calculated after processing by linear prediction algorithm and the features of ART network or classification are obtained from the binary ata determined by threshold method. In conclusion, ART network has good performance in classification of PVB.

Apnea refers to episode of apnea (or not breathing) lasting more than 10 seconds that occur while sleeping. These episodes, whitch can occur hundreds of times per night, may transiently awaken resulting in fragmentation of sleep. Although the precise cause of Sudden Infant Death Syndrome(SIDS) are still unclear, there is evidence to suggest that hypoxaemia may be a contributory actor. Transcutaneous oxygen monitor can be used, but it is very difficult to use or baby stayed at home. In this reason, monitors whitch is easy or deal with are reqiured. In 1972, Steinschieder reported that two of the five infants noted to have apnea lasting or more than 20 seconds later died of SIDS episode, he also suggested that home monitoring or neonates should be used or managing apnea at home. Transthoracic electrical impedance technique is used or acquiring respiration waveform and detecting episode of apnea state. Transthoracic electrical impedance measurements have been made from the human trunk over the frequency range 9.6KHz to 614KHz. We conclude that application of impedance technique or detecting apnea state is proper or neonates.

Snakes is an active contour model or representing image contours. To detect chest boundary on thoracic MRI sequences, we proposed a method based on modified greedy algorithm. Because thoracic MRI sequences have a spatial correlation, we added energy term related with spatial correlation to Snakes energy formulation. A measure of shape similarity called the BMD was used to evaluate the accuracy of the algorithm. The average BMD value or the modified algorithm's result is higher than greedy algorithm's.

Operative interventions for the management of osteonecrosis of the femoral head (ONFH) include core drilling, with or without vascularized fibular bone grafting. Nevertheless, their clinical results have not been consistently satisfactory. Recently, a new surgical procedure that incorporates cementation with polymethylmethacrylate (PMMA) after core drilling has been tried clinically. In this study, a biomechanical analysis using a finite element method(FEM) was undertaken to evaluate surgical methods and their underlying surgical parameter. Our finite element models included five types. They were (1) normal model (Type I), (2) necrotic model (Type II), (3) core decompressed model (Type III). (4) fibular bone grafted model (Type IV), and (5) cemented with PMMA model (Type V). The geometric dimensions of the femur were based on digitized CT-scan data of a normal person. Various physiological loading conditions and surgical penetration depths by the core were used as mechanical variables to study their biomechanical contributions in stress transfer within the femoral head region. In addition. the peak von Mises stress(PVMS) within the necrotic cancellous bone of the femoral head was obtained. The fibular bone grafted method and cementation method provided optimal stress transfer behaviors. Here. substantial increase in the low stress level was observed when the penetration depth was extended to 0mm and 5mm from the subchondral region. Moreover, significant decrease in PVMS due to surgery was observed in the fibular bone grafted method and the cementation method when the penetration depths were extended up to 0 and 5mm from the subchondral region. The drop in PVMS was greater during toe-off than during heel-strike (57% vs. 28% in Type IV and 49% vs. 22% in Type V). Both the vascularized fibular bone grafting method (Type IV) and the new PMMA technique (Type V) appear to be very effective in providing good stress transfer and reducing the peak Von-Mises stress within the necrotic region. Overall results show that fibular bone grafting and cementation methods are quite similar. In light of above results, the new cementation method appears to be a promising surgical alternative or the treatment of ONFH. The use of PMMA for the core can be less prone to surgical complication as opposed to preparation of fibular bone graft and can achieve more immediate fixation between the core and the surrounding region.

ABA-type block copolymers composed of poly(L-leucine)(PLL) as the A component and poly(ethylene glycol)(PEG) as the B component were synthesized by ring-opening polymerization of L-leucine N-carboxyanhydride initiated by primary amino group located at both ends of PEG chain. A silver sulfadiazine(AgSD)-impregnated wound dressing of sponge-type was prepared by the lyophilization method. Morphological structure of this wound dressing obtained by scanning electron microscopy(SEM) was composed of a dense skin layer and a macroporous inner sponge layer. Equilibrium water content(EWC) of wound dressing was above 10%. It increased with an increased of PEO content in the block copolymer due to the hydrophilicity of PEO. AgSD release from AgSD- impregnated wound dressing in PBS buffer(pH=7.4) was dependent on PEG composition in the block copolymer. Therefore, EWC and release of AgSD can be control by PEG composition. Antibacterial capacity of AgSD-impregnated wound dressing was examined in agar plate against Pseudmonas aeruginosa and Stapplococus aruous. Cytotoxicity of the wound dressing was evaluated by studing mouse skin fibroblast(L929). From the behavior of antimicrobial releasing and the investigation of the suppression of bacterial proliferation, it was supposed that the wound dressing containing antibiotics could protect the wound surfaces from bacterial invasion to suppress the bacterial proliferation effectively. In cytotoxicity observation, cellular damage was reduced by the control led released of AgSD from the LEL sponge matrix of AgSD-medicated wound dressing. In vivo test, granulous tissue formation and wound contraction or the AgSD and DHEA impregnated wound dressing were aster than any other groups.

The essence of meridian collateral and acupoints is an overall physiologic unction with the level of multiple unctional states. However it is a pity that until present, so in this paper described about some experimental results of physical reactions of meridian and acupoints. In order to verify meridian pathway and channel theory of energy in body. It is suppose that substance of meridian is pathway channel of the meridian materials. In basic examination, It was analyzed spectrum of reflection waves after beat or continuos vibrate to meridian point and non-meridian point meridian line and non-meridian line. The characteristics of reflection waves similar to flow channel in hydrodynamic. So it be able to suggest that the meridian is pathway and channel in body.

Three dimensional numerical model based on the finite element method(FEM) were developed to predict the mechanical behavior of hip implants. The purpose of this study is to investigate the stress distribution of two types of cementless total hip replacement femoral component -a straight stem and a curved stem, and to compare their effect on the stress shielding between two types by three dimensional finite element method. The authors analyzed von Mises stress in the cortex & stem and compared the stress between the straight and the curved stem. In comparison of stresses between two different design of femoral stem, there was 25% more decrease of stress in straight stem than curved stem in the medial cortex at proximal region. The straight stem had consistently much lower stresses than the curved stem throughout the whole medial cortex with maximum 70% reduction of stress. However, there was little change in stress between nature and 2 implanted femur throughout the lateral cortex. Stress of femoral stem was much higher in the straight stem than the curved stem up to 60%. The straight stem had more chance of stress shielding and a risk of fatigue fracture of the stem compared with the curved stem in noncement hip arthroplasty. In design of femoral stem still we have to consider to develop design to distribute more even stress on the proximal medial cortex.

In this study, swing phase dynamic simulation of above-knee prosthesis is performed. The prosthesis consists of a single axis knee mechanism and pneumatic cylinder. The numerical modelling of the prosthesis is analyzed in two dimensions. The governing equation of thermodynamical pneumatic cylinder model is applied to construct the control of lower limb during swing phase. Knee flexion angle with respect to the orifice diameter of the pneumatic cylinder is produced. This analysis will be very useful to the design of pneumatic cylinder in prosthesis.

Noninvasive multifrequency microwave radiometry using coaxial waveguide antenna has been investigated for a homogeneous and our layer human body model. We derived finite-difference time-domain(FDTD) algorithm and equation of MUR and generalized perfectly matched layer(GPML) absorbing boundary conditions(ABCs) in cylindrical coordination. The coupling between coaxial waveguide antenna and a biological object was analyzed by use of the FDTD method using MUR and GPML ABCs to obtain the absorbed power patterns in the media. The specific absorption rates(SAR) distribution which was corresponding to the temperature distribution was calculated in each region by use of the steady-state response in FDTD method. The SAR patterns of FDTD method using MUR ABCs was compared with those of FDTD method using GPML ABCs.

A simple bio-feedback system was developed to monitor and to analyze patient's postural balance. Two load celIs were used to measure the weight of each side. A specially designed electronic circuit was made to pick up the weight signals and to feed into the data acquisition system. Clinical trials were also made on 20-30 year-old normal subjects and nine hemiplegia patients who had the potential instability in weight bearing. A Microsoft window-based software collected and analyzed the postural balance data. Normal subjects showed only 5% deviations of their body weight. However, hemipegic patients had significant weight shifts toward the healthy limb. With the present system, patients can also exercise their balance and weight bearing. The present system should be of convenience to monitor in real-time and analyze the postural balance control of hemiplegic patients.

Human cervical spine has to protect the neural components and vascular structures. Also, it must have the flexibility afforded by an extensive range of motion to integrate the head with the body and environment. Because of these two-sided features, human cervical spine has very complicated shapes and their injury mechanisms are not fully understood yet. We have developed analytical model of human CS by using the finite element method. The model has been verified with in vivo and in vitro experimental results. From the qualitative analysis of simulation results, we were able to explain some of the fundamental mechanisms of neck pain. Further more, this FE model of human CS can be used as an analytical tool or biomechanical design of the clinical device and safety restraints.

A new quadrature RF coil is designed for Breast MR Imaging. Quadrature RF coils for MRI have been useful to improve the signal-to-noise ratio (SNR) by "$\sqrt{2}$" using two orthogonal RF coils in combination. A modified Breast Quadrature coil is designed. It is a modified type of the high-pass birdcage coil. To reduce the field distortion, by using current feeding, the field pattern is optimized to achieve a quadrature circularly-polarized field pattern. The coil has been implemented for receive-only mode, and tested by phantom imaging. The experimental results show the utility of the proposed RF coil.

In the magnetic resonance imaging, the fast spin echo imaging technique is a widely used clinical imaging method, since its scanning time is much shorter than the conventional spin echo imaging and it gives the almost same image quality. However, the fast spin echo technique has two times longer imaging time or the dual echo acquisition which can obtain a spin density image and a $T_2$-weighted image simultaneously. To overcome such a drawback, this paper proposes a new fast dual echo imaging technique which can give the same quality images at the single echo imaging time. The proposed technique reduces the imaging time by overlapping most of echo train data for each image reconstruction. In order to verify its validity and usability the human head experimental results which were obtained at the 0.3T permanent MRI system are presented.

In-vivo and in-vitro NMR Microscopy has been performed to investigate the histological and/or pathological difference between the normal and the abnormal skin layers. The acquired images in the present study were able to provide the information of both the relaxation changes and the histological changes due to skin abnormality. The present study is also intended to show the possibility of NMR Microscopy application to both the noninvasive investigation of skin pathology and the helpful use in the development of cosmetics.

This study was purposed to observe the advantages obtained from iridodiagnostics and automatic iridoscope or oriental medical doctors. In order to study the iridodiagnostics, 5 case-researches were made as the first step. The results were obtained as follows. 1. First of all, the formation of darkening area must be paid attentionally with toxic spot and lacunain relation to the interpretation of present illness. 2. The theoretical concepts about structure in iridodiagnostics and oriental medicine were same. 3. The constitutional type of iridodiagnostics played a important role in concluding the nature and background of symptoms. 4. Most of iris signs reflected the histological changes of body structure equally, and successive study about the difference of visceral scheme between iridology and Oriental Medicine would be needed in the future.

The ECG-NIBP patient monitor consist of Noninvasive Blood Pressure(NIBP) module that have micro controller inside. This module transfer data by serial communication to the main processor. This system apply the fuzzy inflating method to reduce the blood pressure measuring time, and moving artifact removing algorithm, several parameters used or more accurate measurement. The ECG monitor use the Digital Signal Processor(DSP) or digital filtering, peak detection, heart rate calculation. This system also offer convenient user interface by rotary key, menu bar. With 7" CRT display, auxiliary TFT LCD display adapted to display information on wide screen.

This paper presents a CAD (Computer-Aided Diagnosis) system or detection of breast cancer, which is composed of personal computer, X-ray film scanner, high resolution display and application softwares. There are three major algorithms implemented in the application software. The irst algorithm is the adaptive enhancement of the digitized X-ray mammograms based on the first derivative and the local statistics. The second one is to detect the clustered microcalcifications by using the statistical texture analysis, and the third one is the classification of the clustered microcalcifications as malignant or benign by using the shape analysis. These algorithms were verified by real experiments.

In this study, we investigated the circardian rhythm of complexity of cardiac dynamics in humans. Dynamic 24-hour electrocardiographic recordings were obtained from 30 healthy ambulant subjects aged 41 to 50 years. or each recordings, normalized low frequency (0.04-0.1 hertz) and high frequency (>0.15 hertz) component are calculated. our different indexes obtained from separate algorithms of nonlinear dynamics - approximate entropy, correlation dimension, Lyapunov exponent and fractal dimension - were calculated. During early morning, low frequency component rose rapidly with concomitant withdrawl of high frequency component. All the our indexes of nonlinear dynamics showed remarkably same circardian rhythm: an early morning dip preceded by a steep decline during late night, a gradual recovery during evening and a peak around midnight. These data indicate that the simultansous losses of all of the our different mechanisms of nonlinear control of heart rate during early morning, concomitent with the surge of symapathetic activity and reduction of vagal activity, may contribute to the increased incidence of cardiovascular events during morning hours.

To develop the supplementary heart valve which could reduce the complications of prosthetic heart valve, in vitro experiments were performed to analyze the movement of the supplementary valves. The autologous pericardium was attached to deficient portion of the porcine valve which was dissected completely and partially. The instantaneous motion of the leaflet was pictured by the 35mm camera and the pressure drop through the valve and cardiac output were measured in mock circulatory system. The durability of the valves were tested in severe hemodynamic conditions.

The adhesion of activated and normal platelets to fibrinogen requires the receptor binding site of GPIIb/IIIa. These recognition sites exists in the A ${\alpha}$ chain(RGDS at 572-575 and RGDF at 95-98) and the carboxy-terminal of ${\gamma}$ chain (HHLGGAKQAGDV at 400-411) of fibrinogen. In this study, we developed RGDF-immobilized surface to detect the unctional state of platelet. RGDF-immobilized surface was prepared on the glass using photolithographic technology. Platelet adhesion to RGDF-immobilized surface was observed by staining platelets with mepacrine using a fluorescence microscope using mepacrine. Using the RGDF peptide of fragment E, we observed that the platelets pretreated with PGE1 interacted incompletely with RGDF-immobilized surface, whereas ADP activated platelets interacted with the surface extensively. These results show that the distinct selectivity of RGDF-immobilized micro-patterned surface can be used to detect the unctional state of platelets.

Dental implant has been increasingly used to recover the masticatory unction of tooth. It has been well known that the success of dental implant is heavily dependent on initial stability and long-term osseointegration due to optimal stress distribution in the surrounding bones. The role of periodontal ligament, removed during operation, is to absorb impact force and to distribute them to alveolar bone. or this reason, the study for artificial periodontal ligament has become an important issue in this field. In this study, chitosan was coated on dental implant or the purpose of replacing the role of intact periodontal ligament. The results by experiment and FEM analysis showed : I) Initial stability of dental implant was significantly increased(35%) when the implant was coated with chitosan. II) The coated implant showed higher impact absorption, more even stress distribution and lower stress magnitude under impact force than uncoated implant. Accordingly, the micro-fracture of the surrounding bones due to impact force would be lessened by chitosan coating on dental implant.

A new type of stent was invented using a Nitinol wire. The hoop strength of the new stent was found to be 2 times larger than that of the Cragg or Memotherm stents. However, the longitudinal flexibility of the new stent was inferior to both the Cragg and Memotherm stents. This new stent seems to be useful or the treatment of stenosis with straight configuration, but need to be improved or use in tortuous stenotic region. The stent was applied to the patients with esophargeal stenosis and showed a good result.

In this study, we designed a vascular occlusion device based on the principle that slowing blood flow would induce thrombosis. Tungsten, stainless steel and platinum were tested for finding a good embolic metallic coil. The primary coil and the second coil were done with heat treatment or different time. The pitch distance and the shape retention capability of second coil were characterized by SEM. To increase thrombogenicity, we tried to treat different proteins on steel coils: thrombin, gelatin and both gelatin and thrombin. To verify protein materials treated on coils, the surface of coil treated with different proteins were characterized using Laser Raman Spectrophotometer. After observation of embolic coils, the peptides bonds on theirs' surface were found. In order to compare the thrombogenicity of different embolic agents, we measured whole blood clotting time.

For medical students and doctors, knowledge of the 3-dimensional (3D) structure of the heart is very important in diagnosis and treatment of the heart diseases. 2-dimensional (2D) tools (e.g. anatomy book) or classical 3D tools (e.g. plastic model) are not sufficient or understanding the complex structures of the heart. Moreover, it is not always guaranteed to dissect the heart of cadaver when it is necessary. To overcome this problem, virtual dissection systems of the heart have been developed. But these systems are not satisfactory since they are made of radiographs; they are not true 3D images; they can not be used to dissect freely; or they can only be operated on the workstation. It is also necessary to make the dissection systems incorporating the various races and tribes because of the organ's difference according to race and tribe. This study was intended to make the 3D image of the heart from a Korean cadaver, and to establish a virtual dissection system of the heart with a personal computer. The procedures or manufacturing this system were as follows. 1. The heart from a Korean adult cadaver was embedded with gelatin solution, and serially cross-sectioned at 1mm-thickness on a meat slicer. Pictures or 153 cross-sectioned specimens were inputted into the computer using a digital camera ($756{\times}504$ resolution, true color). 2. The alignment system was established by means of the language of IDL, and applied to align 2D images of the heart. In each of 2D images, closed curves lining clean and dirty blood pathways were drawn manually on the CorelDRAW program. 3. Using the language of IDL, the 3D image and the virtual dissection system of the heart were constructed. The virtual dissection system of the heart allowed or ree rotation, any-directional sectioning, and selected visualization of the heart's structure. This system is expected to become more advanced, and to be used widely through Internet or CD-title as an educational tool for medical students and doctors.

Bayesian MAP-EM approaches have been quite useful or tomographic reconstruction in that they can stabilize the instability of well-known ML-EM approaches, and can incorporate a priori information on the underlying emission object. However, MAP reconstruction algorithms with expressive priors often suffer from the optimization problem when their objective unctions are nonquadratic. In our previous work [1], we showed that the use of deterministic annealing method greatly reduces computational burden or optimization and provides a good solution or nonquadratic objective unctions. Here, we further investigate the convergence of the deterministic annealing algorithm; our experimental results show that, while the solutions obtained by a simple quenching algorithm depend on the initial conditions, the estimates converged via deterministic annealing algorithm are consistent under various initial conditions.

We are developing a small gamma camera or imaging malignant breast tumors. The small scintillation camera system consists of NaI(Tl) crystal ($60\;{\times}\;60\;{\times}\;6\;mm^3$) coupled to position sensitive photomultiplier tube (PSPMT), nuclear instrument module (NIM), analog to digital converter (ADC), and personal computer. High quality flood source image and hole mask image were obtained using the gamma camera developed in this study. Breast phantom containing $2{\sim}7\;mm$ diameter spheres was successfully imaged with parallel hole collimator. The obtained image displayed accurate activity distribution over the imaging field of view. Linearity and uniformity correction algorithms are being developed. It is believed that the developed small gamma camera could be useful or detection of malignant breast cancer.

Socket pressure distributions with gait analyses of a transfemoral and a transtibial prostheses were measured in order to assess an optimal socket fitting and unction. Ankle joint was aligned by the neutral and the dorsi/plantar flexed positions. Compared to dorsi and plantar flexed positions of ankle joint, cadence and walking speed increased with the neutral ankle joint alignment. Other gait parameters were close to the normative data with the neutral ankle joint alignment. For the transfemoral amputee, dorsiflexed alignment of the ankle joint created high pressure on the lateral aspect of the socket, on the other hand, plantarflexed alignment resulted in increased pressure on the medial aspect of the socket. For the transtibial amputee, dorsiflexed alignment of the ankle resulted in high pressure on the antero-lateral aspect of the socket during mid-stance, but plantarflexion of the ankle joint showed slight increases in pressure at the same location in the socket. The present study clearly demonstrated that malalignment of a prosthesis results in localized increasing pressure within the socket. Proper alignment of the prosthesis is required in order to acquire an appropriate socket-limb interface as well as the proper gait.

Pulsed Er:YAG and $CO_2$ lasers induced temperature rise of tissue are studied using axisymmetric, two-dimensional, and transient Pennes' bio-heat equation or the implications of skin resurfacing. Model results indicate that Er:YAG laser induced temperature has much higher but more shallow distribution in tissue than that of the $CO_2$ laser because of its higher absorption coefficient. The increase of repetition rate does not affect the temperature rise too much because these laser modalities have much shorter heat diffusion time than the temporal length of each off-pulse. This model works as a tool to understand the photothermal effect in the laser-tissue interaction.

This study was performed to understand the exogenous-water-drop induced thermomechanical effect on the tooth in the free-running Er:YAG laser mode for the proper use of water as a laser energy absorber and coolant in dentistry. The ree-running Er:YAG laser was used in the dental hard tissue ablation study. A Microjet system was employed to dispense precise water drops. Ablation rate, recoil momentum, and temperature rise in the pulp cavity were measured with and without an exogenous water drop on the tooth surface. Exogenous water enhanced ablation rate in the thick tooth in which the ablation rate on the dry surface does not increase linearly but shows plateau. Optimal exogenous water volume was shifted from 2 nl to 4 nl as the laser energy was increased from 48 mJ to 145 mJ. The magnitude of the recoil momentum was increased as the volume of exogenous water increased. The results of this study suggest that we must pay attention to the recoil momentum or recoil pressure study or the optimal and safe usage of water in the dental treatment because these mechanical effects depend on the volume of exogenous water on the tooth surface.

Plasma luminescence spectroscopy was used or precise ablation of bone tissue during ultrashort pulse laser (USPL) micro-spinal surgery. Strong contrast of the luminescence spectra between bone marrow and spinal cord provided the real time feedback control so that only bone tissue can be selectively ablated while preserving the spinal cord.

A cryotherapy system using the low temperature air was developed. The developed cryotherapy system had superior low temperature characteristics and many safety devices. For a clinical evaluation, skin and intra-articular temperatures of the knee joint were measured during and after the cryotherapy. After 5-minute therapy, skin and intra-articular temperature decreased by $23.3{\pm}4.7(^{\circ}C)$ and $4.1{\pm}1.0(^{\circ}C)$ respectively. A 5-minute cryotherapy therapy is good enough to maintain low intra-articular temperatures or 2-3 hours.

Human pulse represents the physical characteristics of heart and cardiovascular system. Therefore, malfunctions and errors of heart and cardiovascular system can be determined by using an automatic diagnosis system that can detect the pulse signal. Not only will the computerised system preclude the possibilities of observational errors by giving an accurate measurement with great stability, but minimize the possibilities of misinterpretation by using an automated diagnostic logic. A new combinational fiber-optic sensor, which has a detecting part and a transmitting part was used to acquire radial pulse signal noninvasively. The development of P-5 transducer makes it possible to obtain more effective detection and obvious display of pulse signals in the aspect of reliability. Using P-5 transducer in the field of plethysomography and MAC- JIN, one of our diagnoses in Korean traditional medicine, it is expected that we can ontain quantitative and valuable information or the diagnosis of human pulses.

It is important to find a accurate root canal length or successful endodontic therapy. By X-ray method takes a long time and difficult in a curved canal. After developed electronic apex locator has allowed to measure the root canal length with easy, in a short time also in a curved canal. But most electronic apex locators have the disadvantage which is too short reading or sometimes the measurement itself becomes impossible if there are electrolytes in the canal. To overcome this drawback, impedance ratio method has been developed. In this study, we have developed frequency dependent electronic apex locator to minimize the interference of electrolytes. And based on that also some error in clinic use, we added the other method. Difference of two signals which are used in calculation of impedance ratio was can be represent the status of root canal fluid. As a result, using impedance ratio method and auto-calibration by voltage difference method can reduce the measurement error.

Electrogastrogaphy(EGG) is the technique by which gastric myoelectrical activity is recorded noninvasively, from electrodes on the abdominal skin. Despite many attempts made over the decades, the clinical application of the EGG signal has not improved to the identification of waveform characteristics using comparison of EGG signal to be detected other EGG system. Cutaneous measurements of EGG are yet to be standardized in methods of detection and analysis. This may be responsible in part for some of the variability in the results. Thus, we develope EGG system composed of amplifiers, analysis methods, patient database or standardization. we introduce configurations of EGG system and their functions. Several important EGG parameters are introduced, including the dominant frequency and power of the EGG, the relative, period EGG-dominant frequency and power, the instability coefficient of EGG-dominant frequency and power, standard deviation, the percentage of running spectrum activity of gastric slow waves.

In this paper, we have designed a portable patient monitor that monitors both ECG and NIBP(Non-Invasive Blood Pressure) for a patient who is bring moved around inside a hospital. System hardware consists of the one-chip microcomputer(80c251), A/D converter, ROM, RAM, LCD diplsy, two channel ECG module and NIBP module. NIBP module was calibrated to the values found in NIBP analyzer. ECG module detects QRS complex and compute heart rate. NIBP module measures the blood pressure by oscilometric method.

This paper describes the design guideline, methodology and general specification of the developed 12 channel interpretive electrocardiograph. The developed 12 channel electrocardiograph consists of main module, patient module, DSP module, interface module, power/battery module, TFT color LCD and thermal recorder. The control panel of the system has full keyboard, rotate/push button, function key and unctional indicators. The graphic user interface program conveniently allows user to record, setup, store, manage ECGs. A variety of system configurations give it ability to make user favorable environment. This system also has a resting adult's ECG analysis program. The developed system and program will be continusely evolved using a database of clinically correlated ECGs.

The left ventricular relaxation rate is used as a golden standard which describes the left ventricular diastolic unction. So far, to get the rate of relaxation one should calculate the data after full recording, that is, off-line method. Therefore one cannot get the rate of relaxation in real-time while changing loading condition or infusing drug. But real time monitoring of the relaxation rate is necessary while changing loading condition or infusing drug to control the mechanics of heart and to get more information. We propose a new criterion to get the left ventricular relaxation rate and a real time algorithm. By comparison, it was turned out that our criterion outperforms others criterion.

The oxygen saturation of blood can be measured by sensing the difference absorption in optical spectra of Hb and $HbO_2$, as the well known previous study. [1] In this study we developed the noninvasive tissue reflectance oximeter(TRO) using three kinds of LEDs which produce a peak spectral emission at a wavelength of 565, 660 and 940nm. And we tested the unction of the TR oximeter by comparing the output signals measured on normal tissue to measured on low oxygenated tissue. The results showed that oxygen saturation of blood and biological tissue can be monitored from the separation arrangement light source and detector.

Electrical impedance plethysmography is still be one of the simplest and most convenient methods or non-invasive measurement of blood low, but it has the weak point can not do real-time measurement because of using chart-record or processing after receiving data from analog plethysmography through A/D converter. In this study. we developed hardware system composed of analog part which include auto-balancing circuit and calibration register and digital part which include 80C196KC, keypad, and LCD. we studied the algorithms or extracting parameter to calculate blood low and implemented it using general purpose micro controller.

This study is the basic research on esophageal balloon dialation with automatic detection of the pressure change in the balloon and analysis using personal computer. In conventional method, the esophageal stricture is cured by surgically. Recently, balloon dialation method has been proposed and is popularized. In balloon dialation, detecting esophageal rupture is very important. When using radiological investigation, the leak of contrast medium is very dangerous. In proposed method, the detection of esopageal rupture can be peformed by detecting and analyze the pressure change of dialation balloon. Experimental system is composed of balloon catheter, pressure pump, pressure sensor, A/D converter and PC.

One of the main techniques or diagnosing heart disease is by examining the electrocardiogram(ECG). Many studies on detecting the QRS complex, P, and T waves have been performed because meaningful information is contained in these parameters. However, the earlier detecting techniques can not effectively extract those parameters from the ECG that is severely contaminated by noise source such 60Hz powerline interference, motion artifact and baseline drift. in this paper, we performed the extracting parameters from and recovering the ECG signal using wavelet transform that has recently been applying to various fields.

In our research, we will extract diagnostic parameters by LPC method and wavelet transform. Then, we will design artificial neural network which is based on RBF that can express input features in terms of fuzzy. Because PVC(Premature Ventricular Contraction) has possibility to cause heart attack, the detection of PVC is a very significant problem. To deal with this problem, LPC method which gives different coefficients or different morphologies and wavelet transform which has superior localization nature of time-frequency, are used to extract effective parameters or classification of normal and PVC. Because RBF network can allocate an input feature to the membership degree of each category, total system will be more flexible.

HRV(heart rate variability) is the time series data of R-R interval time duration based on ECGs. Power spectral analysis of HRV has recently been used to define the activity of ANS(autonomic nervous system). In this study, 14 rats were divided into two groups, sympathectomy and vagotomy. During the experiments, ECGs of rats were collected three times at each experimental conditions or the duration of 5 minutes, where sampling frequency was set at 2KHz. After the application of the Berger's Serires algorithm to ECG raw data, power spectrum of HRV was obtained via FFT. Results showed that HF/LF were increased or the sympathectomy group and decreased or the vagotomy group. It implies that the variations in HF/LF components could be used or the ANS function classification.

In this paper, the method is proposed, which enables us to assess baroreflex sensitivity noninvasively through the closed-loop feedback model between RR fluctuation and arterial blood pressure fluctuation, which are obtained in blood low signals. The proposed indexes of baroreflex sensitivity, $BRS_{LF}$ and $BRS_{HF}$, are calculated by the modulus(or gain) of the transfer unction between two fluctuations above in LF band and HF band, where the coherence is more than 0.5. To evaluate the performance of the proposed method, it is applied to blood low signals obtained from subjects at tilt angles of $0^{\circ},\;45^{\circ},\;90^{\circ}$ and $0^{\circ}$ successively. In result, it is concluded that the proposed method enables us to assess baroreflex sensitivity noninvasively.

It has been reported that sudden cardiac death and ventricular tachycardia occur after treatment of tetralogy of fallot(TOF). It is regarded that ventricular arrythmia is the main source or the sudden cardiac death, but it is not verified. It is likely that TOF has effect on the heart rate variability because of the ventricular arrythmia. We study how complex and periodic heart rate dynamics change in the normal children (n=13) and TOF children (n=13) throughout 24 hours. We recorded 24-hour holter ECG, and segmented each ECG data into 1 hour length. We analyze each HR time series, and quantify the overall complexity of each HR time series by its correlation dimension. We also calculate the power spectrum of HR, and obtain low-frequency component (0.03-0.15Hz) and high-frequency component (0.15-0.4Hz). We compare the results between normal and TOF groups throughout 24 hours. TOF group have lower correlation dimension ($4.055{\pm}0.4134$ vs. $4.9310{\pm}0.2054$, p<0.05) than the normal group, even though there are no significant differences in the low($0.9864{\pm}0.5598$ vs. $1.5560{\pm}0.8325$, p<0.05) and high($1.1168{\pm}0.1.1448$ vs. $0.9271{\pm}0.6528$, p<0.05) frequency components. It can be concluded that HR time series of TOF group are more regular than that of normal group, and that correlation dimension reveals a nonlinear characteristics of HR time series which is not determined in the frequency domain.

We are exposed to the various external stimuli input from the environment, which cause emotional changes based on the characteristics of the stimuli. Unfortunately, there are no quantitative results on relationship between human sensibility and the characteristics of physiological signals. The objective of this study was to quantify EEG signals evoked by visual stimulation based on the assumption that the analysis of the variability on the characteristics of the EEG waveform may provide the significant information regarding changes in psychological states of the subject. Seven university students were participated in this study. The experiment was devised with eleven experimental conditions, which are control and ten different types of visual stimulation based on IAPS (International Affective Picture Systems). Wavelet transformation was employed to analyze the EEG signals. Most positive and negative emotional response were compared in pairs. The results showed that the reconstructed signals at the decomposition level revealed the different energy value on the EEG signals. Also, general patterns of EEG signals in rest state compare with positive and negative stimulus were found. This study could be extended to establish an algorithm which distinguishes psychophysiological states of the subjects exposed to the visual stimulation.

In this paper, we present the elimination of ECG artifact from the polysomnographic EEG and EOG. The idea of this method is that the ECG synchronized EEG segment is detected from ECG and regard samples of that segment a missing signal. After this, we used two interpolation methods to recover the missing segment. One is the Lagrange Polynomial Interpolation Method and the other is the Least Square Error AR Interpolation method. We tested those methods by applying to simulated signals. AR methods works well enough to reject the artifact about 10% of the main artifact level. We practically applied to real EEG and EOG signals. We also developed the algorithm to detect whether the artifact level is high or not. If the artifact level is high, then the interpolations are applied.

In this study, ECG was recorded during sleep patients with obstructive sleep apnea. We detecte(heart rate variability) signal from the ECG wa QRS detection algorithm. And we observed HRV by the power spectrum density using autoregr modeling. The experimental results were analysis sleep stage 1, sleep stage 2, sleep stage 3, sleep s sleep stage REM. In experimental result, the PSD with obstructive sleep apnea patients was distributed low frequency band except sleep step 4. These effect means that the sympathetic nervous system affected the sleep stage 1, 2, REM and the parasympathetic nervous system affected the sleep stage 3, 4 with obstructive sleep apnea patients.

Recently, many studies have shown clinically the detection of proximal arterial stenosis through evaluation of a Doppler waveform alternation, the so-called pulsus tardus and parvus, that often occurs distal to the stenosis. However the cause of the tardus-parvus phenomenon remains obscure. To analyze its cause, we modeled the blood-flow circuit as simple electrical circuit. This shows that pulsus tardus-parvus effect is caused as a result of high-frequency waveform component attenuation from low-pass filtering by capacitance(complience of the poststenotic vessel wall) and resistance(stenosis). As a result, the degree of pulsus tardus-parvus increased as the complience of the poststenotic segment of vessel increased, as well as increasing stenosis.

We have analyzed the fluorescence image obtaining from green fluorescence protein (GFP). In order to monitor the fluorescence of specific gene, we used the amyloid precursor protein promoter which has been known to act as a major role in the development of Alzheimer's disease. The promoter from - 3.0 kb to + 100 base pair was inserted into the gene expression monitoring GFP vector purchased from Clontech. This construct was transfected into the PC 12 and fibroblast cells and the fluorescence image was captured by two kinds of methods. One is using cheaper CCD camera and other is SIT-CCD camera. or the higher sensitivity of the fluorescence image, we developed the multiple image grabbing program. As a results, the fluorescence image by conventional CCD camera have the similar sensitivity compared with that of the SIT-camera by applying the multiple image grabbing programs. By this system. it will be possible to construct the fluorescence monitoring system with lower cost. And gene expression in real time by fluorescence image will be possible without changing the fluorescence images.

A technique or the preparation of porous polyurethane vascular prostheses was investigated. Small-diameter vessels are not in general clinical use due to their limited long-term biocompatibility and low patency rates in experimental trial. These limits are mainly due to the failure of mechanical unction of the vascular grafts. This failure has been suggested to result partially from compliance mismatch. The long-term patency is considered to depend critically on the properties of the material and the fabrication process of the graft. So the control of pores is very important and main points to develop a available vascular grafts. Two-kind polymer sheets was compared. One was the porous PU-sheet made at room temperature by the solvent/non-solvent exchange. And the other was the porous PU-sheet which was fabricated by thermal phase transition and solvent-/non-solvent exchange using the thermal controller. The polymer sheets had a uniform pore size and pore occupation. According to the result of the above experiments, polyurethane solution was injected into a mold designed or U-type tube. The average pore size and pore occupation were easily changed by changing polyurethane concentration, freezing temperature, and methods. This technique can give a proper pore size ($10{\sim}45\;{\mu}m$) or tissue in growth, and suitable compliances or matching with arteries and veins. Besides, the fabrication of more complicated shaped vessels such as the U-type vascular grafts is easily controlled by using the fixed mold. this method might give a desired compliant graft or artificial implantation with the presently valid medical polymers.

Antifibrinolytic effect of lumbrokinase in mice, in vivo, was studied. Liquid phase lumbrokinse from Lumbricus rubellus was purified by column chromatography method. Lumbrokinase was orally inserted to mice. Although oral dosage of lumbrokinase, to investigate whether lumbrokinase in mice causes antifibrinolytic effect, we have concentration of lumbrokinase varied, and detection of antifibrinolytic effect was carried out using a FDP (fibrin degradation product) test and euglobulin fibrinolytic activity test. FDP test and euglobulin fibrinolytic activity test were compared the data of PBS ingestion. control with lumbrokinase ingestion. As a result, FDP was increased in 7.8mg, 26mg lumbrokinase concentrations after 25 hours succeeding oral prescription of lumbrokinase, and decreased after 49 hours, but 7.8mg lumbrokinase ingestion more increased than 26mg. Also, FDP of PBS ingestion control and 1.3mg lumbrokinase ingestion were not been observed nothing. Euglobulin fibrinolytic activity of PBS ingestion control and 1.3mg lumbrokinase ingestion were not been observed any clear zone after 8, 25, 48 hours, and 7.8mg and 26mg were observed the most largest clear zone after 25 hours and decreased after 48 hours. However, antifibrinolytic effect of oral prescription of lumbrokinase in mice was observed. Now we need to determine an efficient amount of lumbrokinase for antifibrinolytic effect.

Three-dimensional finite element analyses were used to compare the stress distribution and the stability of the fixation among seven different tibial components and to investigate the effect due to implant materials in total knee arthroplasty. The components included an intact tibia(Type I), Cemented Cobalt-Chromium tibial tray implanted with a PMMA cemented Co-Cr stem(Type II), Cemented Co-Cr tibial tray with a uncemented Co-Cr stem(Type III), Cemented Ultra High Molecular Weight Polyethylene (UHMWPE) tibial tray with a cemented UHMWPE stem (Type IV), Cemented UHMWPE tray with a uncemented UHMWPE stem(Type V), Cemented Co-Cr tray without a stem(Type VI), and Cemented UHMWPE tray without a stem(Type VII). Uncemented components were assumed to have complete bony in growth and a rigid state of fixation between component and bone. The interface between bone/cement/component of cemented components was also assumed to be fully bonded. Bi-condylar forces were applied. The results indicated that Uncemented stem components provided lower bone stress shielding and stress concentration. The UHMWPE tray and stem component showed better agreement with the intact tibia than the Co-Cr Alloy tray and stem components. If the implant tray can be fixed firmed without a stem, Cemented PE tray without a stem(Type VII) may be recommended to give the best characteristics in the sense of stress distribution and stability.

The general pattern of adaptation in the appendicular skeleton with aging is that the subperiosteal apposition of bone occur along with endosteal absorption. This remodeling of diaphysis to a cylinder of larger diameter is hypothesized to serve a mechanical compensatory unction by increasing the moment of inertia as the cortex thins with aging. These findings is only true of the diaphysis of long bone. Measuring the area and inertia at each section of femur, the age-related change of proximal emur and diaphysis is observed. After screening by physical and radiological examination, 200 normal Korean adults divided 5 groups in both male and female based on age. Twenty persons were in each group. One femur in each person was analyzed using CT images. femur scanned with 60 to 80 slices and this images were digitized. Then 2-D images were reconstructed into 3-D images. Using the nonlinear method, normalization and interpolation technique, 7 locations of interest (trochanteric area: 1, 2 subtrochanteric area: 3, 4, isthmic area: 5, 6, 7) were determined. On the each cross section at each location, the area (total, cortical and medullary) and 5 inertia of moment were measured. The results were analyzed statistically. With aging, significant area change occurred mainly in diaphysis and female. In trochanteric area, no significant change was noted. With aging, total and medullary area were increased, but cortical area was not changed. In diaphysis, lateral bendingresistanceincreasedsignificantly. No inertia change was noted in trochanteric area. Anteroposterior bending resistance was constant with aging. In more than age 60, total area and medullary area were larger than that of others. Lateral bending resistance was higher especially in diaphysis. In diaphysis, with aging, the decreased properties is compensated with the increased lateral bending resistance by geometric remodeling. In trochanteric area, no compensation occur. With aging, especially in more than age 60, the higher rate of trochanteric fracture is expected.

In this paper, we present the design strategy of the assistive communication system to be able to communicate or the mute and speech disorder under the restricted circumstances. To be used conveniently in daily life, first, a specific domain should be set according to circumstance, and second, proper words in each domain should be selected according to physical, mental ability of user. As the design process of this system should be reflected by the abilities of user, each word is represented as symbols, transparently. The sentences are compounded from symbols. Compounded sentences are showed on display in letters, and synthesized naturally in voice in order to be understood easy.

In this paper, we proposes a bending actuator using shape memory alloy coil-type springs. By the heating of two shape memory alloy coil-type springs sequentially, the bending and stretching motion of the actuator is possible. We measure the bending angle and repeated bending motion with the various currents. Furthermore, we control the bending angle of the 1 directional bending actuator with sensors. The performance of the actuator has been characterized or the possible application for catheter.

This is to investigate the physical properties of the commercially available Soft, Thomas, Minerva, and Philadelphia cervical braces which are widely used in orthopedics, neurosurgery, and rehabilitation medicine clinics as assisting devices or physical stabilization of cervical vertebrates, to use as a basic data or designing new type brace. Tensile strengths were observed by universal mechanical measuring device and Thomas brace required the highest stress to break by tensile stress. Durabilities against continuous frictional forces were also determined, and Minerva brace demonstrated the longest frictional time until being perforated. and Thomas/minerva braces are superior to the other braces in the effect of the material property on the skin tissue, as the animal test. According to these results, polyethylene is recommendable as a frame and preparation of pores in the material is favorable to provide ventilation to skin.

In this paper, we proposed force reflection method using joystick or controlling rehabilitation assisting mobile robot. We defined reflected orce equation as two terms. One is distance between mobile robot and obstacle, the other is speed of rehabilitation assisting robot. And we found the each gain value which guarantees stable navigation of robot. And we experimented simulation with simulation program supporting virtual 2-D map. Through the experiments, we confirmed force reflection algorithm is efficient when controlling rehabilitation assisting robot.

The objective of this study is to propose a finite element based design of the dental implant replacing unction and shape of natural teeth. For this, geometric actors were varied to investigate stress distribution of the alveolar bone around dental implant. In this study, the results were obtained based on the theory of linear elastic, with geometrically axisymmetric assumption. Geometric actors determining implant shape are ranged as 0.2mm-0.6mm, 0.04mm-0.1mm, 0.46mm-0.84mm or height of thread, radius of curvature of thread, and pitch, respectively. The stresses in the alveolar bone caused by biting force playa major role in determining implant stability. Especially, the stress concentration in the cortical bone causes bone resorption and finally makes the implant unstable. Therefore, the stress distributions were investigated on the side of the alveolar bone focusing on the area of cortical bone. The maximum von Mises stress was found to increase up to 6% as the height of thread increases, while its value was to decrease to 19% when the radius of curvature increase within the assigned ranges. For the variation of pitch, the larger size of pitch results in greater maximum von Mises stress when the length of the implant under consideration is fixed. The existence of the neck below the shoulder did not affect the stress distribution in the region of alveolar bone. However, the stresses on the side of the implant near the neck were found to be different by 20% approximately. Therefore, the neck can provide the stability of the implant against continuing biting movement. As a conclusion, the finite element based study shows a potential in designing the dental implant systematically.

Magnetic Resonance Spectroscopic Imaging is a methodology combining the imaging and spectroscopy. It can provide the spectrum of each areas of image so that one can easily compare the spectrum of one position to another position of the image. In this study, we developed pulse sequence or the spectroscopic imaging method, RF wave forms or the saturation of water signal, computer simulations to validate our method, and confirmed the methodology with phantom experiment. Then we applied the spectroscopic method to human subject and identified a few important metabolites in in vivo. To develope a water saturating RF waveform, we used Shinnar-Le-Roux algorithm and obtained maximum phase RF waveform. With this RF pulse, it could suppress the water signal to 1:1000. The magnet is shimmed to under 1.0ppm with auto-shimming technique. The saturation bandwidth is 80Hz(2ppm). The water and fat seperation is 3.3ppm(about 140Hz at 1 Tesla magnet), the bandwidth is enough to resolve the difference. But we are more concerned about the narrow window in between the two peaks, in which the small quantity of metabolites reside. We performed the computer simulation and phantom experiments in 8*8 matrix form and showed good agreement in the image and spectrum. Finally we applied spectroscopic imaging to the brain of human subject. Only the lipid signal was shown in the periphery region which agrees with the at distribution in human head surface area. The spectrum inside the brain shows the important metabolites such as NAA, Cr/PCr, Choline. We here have shown the spectroscopic imaging which is normally done above 1.5 Tesla machine can be performed in the 1 Tesla Magnetic Resonance Imaging Unit.

X-Ray Angiography has been gold standard or imaging of blood flow. However, patients have to take many risks such as catheterization procedure, iodine contrast agent and ionizing X-rays. MR Angiography has been suggested as a substitute for its non-hazard to patient. But the resolution and contrast was inferior to that of X-ray Angiography. Recently the resolution and the contrast have been much improved due to the development of fast imaging technique.

In this paper, we visualized 3-dimensional volume of heart using volume method by thresholding in EBT slices data. Volume rendering is the method that acquire the color by casting a pixel ray to volume data. The gray level of heart region is so high that we decide heart region by thresholding method. When a pixel ray is cast to volume data, the region that is higher than threshold value becomes heart region. We effectively rendered the heart volume and showed the 3-dimensional heart volume.

The quantitative comparison of brain architecture across different subjects requires a common coordinate system, with respect to which the spatial variability of features form different individuals can be expressed. We have developed and implemented an image warping technique which is based on an elastic body deformation. The resulting 2D deformation map can be used to quantify anatomic differences between subjects. The technique's accuracy is tested, by warping 2D magnetic resonance images of age seventies into Talairach atlas.

This paper presents a modified geometric active contour model or edge detection and segmentation of computed tomography(CT) scan images. The method is based on the level setup approach developed by Osher and Sethian and the modeling of propagation fronts with curvature dependent speeds by Malladi. Based on above algorithms, the geometric active contour is obtained through a particular level set of hypersurface lowing along its gradient force and curvature force. This technique retains the attractive feature which is topological and geometric flexibility of the contour in recovering objects with complex shapes and unknown topologies. But there are limitations in this algorithm which are being not able to separate the object with weak difference from neighbor object. So we use speed limitation filter to overcome those problems. We apply a 2D model to various synthetic cases and the three cases of real CT scan images in order to segment objects with complicated shapes and topologies. From the results, the presented model confirms that it attracts very naturally and efficiently to the desired feature of CT scan images.

3D medical image reconstruction techniques are useful to figure out complex 3D structure from the set of 2D sections but their implementations are difficult due to processor's limitation and their computational complexity. In this paper, we propose a new speed optimization technique or accelerating the volume rendering algorithm. In addition, the whole procedure or reconstructing the medical images are constructed by using Visual C++ 5.0 under PC environment. They include classification, shading and ray-casting.

Acoustic or sound noise due to gradient pulsing has been one of the problems in MRI, both in patient scanning as well as in many areas of psychiatric and neuroscience research, such as unctional MRI (fMRI). Our recent observations in MRI or the visual and motor cortex show very different results with sound noise in comparison with the results obtained without sound noise. Although a number of ideas has been suggested in the literature about the possible elimination or reduction of sound noise, progress has been slow due to the basic role of gradient pulsing in MR imaging. Therefore, we report on some typical behavior of sound noise observed from MRI scanners and the analyses of their characteristics. Data are obtained both from a commercial MRI scanner (GE Signa 1.5-T EPI system).

A new approach to silent MR imaging using a rotating DC gradient has been explored and experimentally studied. As is known, acoustic or sound noise has been one of the major problems in handling patients, mainly due to the fast gradient pulsings in interaction with the main magnetic field. The sound noise is also proportionally louder as the magnetic field strength becomes larger. In this article, we have described a new imaging technique using a mechanically rotating DC gradient coil as an approach toward silent MR imaging, i.e., a mechanically rotated DC gradient effectively replaces both the phase encoding as well as the readout gradient pulsings and data obtained in this manner provides a set of project ion data which later can be used or the projection reconstructionorwithsomeinterpolation techniques one can also perform conventional 2-D FFT (Fast Fourier Transform) image reconstruction. We found, with this new technique, that the sound noise intensity compared with the conventional imaging technique, such as spin echo sequence, is reduced down to -20.7 dB or about 117.5 times. The experimental pulse sequence and its principle are described and images obtained by the new silent MR imaging technique are reported.

In this paper, we propose the method that reduce the grating lobe in the ultrasound synthetic focusing images. synthetic focusing images have more larger and closer grating lobe than conventional phased array images and more lower signal to noise ratio. so, we represent the method that reduce the grating lobe by using multi element receive focusing. experimental results are showed that the proposed multi element receiving method reduce the grating lobe and increase the signal to noise ratio.

In this paper, several bandwidth sampling methods were compared in which contains "multi-order sampling", which was proposed or envelope detections in RF ultrasonic signals by a computer simulation and on experiment quadrature sampling method. The second-order sampling method were compared with it. As a conclusion, a multi-order sampling method, especially 5th order sampling method showed quite good envelope detection property. This means that more economical and quite good performance digital beamforming system can be built by adopting this new bandwidth sampling method.

In a conventional digital beamformer received signal were sampled at least Nyquist rate of its maximum frequency. But it is wide band signal and its coherent sum must be obtained, the sampling clock of about $8f_o$ and $16f_o$ is necessary or high quality images. This paper described how image qualities are varied according to sampling clock. Mainly, we compared the SDF(Sampled Delay Focusing) that had maximum precision of $8f_o$ with $16f_o$ sampling system and analyze its characteristics.

fMRI, functional MRI introduced recently appears based on the gradient echo technique which is sensitive to the field inhomogeneity developed due to the local susceptibility changes of blood oxygenation and deoxygenation. Common to all the gradient echo techniques is that the signal due to the susceptibility effects is generally decreased with increasing inhomogeneity due to the $T2^*$ effect or conventionally known as blood oxygenation level dependent (BOLD) effect. It is, also found that the BOLD sensitivity is also dependent on the imaging modes, namely whether the imaging is in axial, or coronal or sagittal mode as well as the directions of the vessels against the main magnetic field. We have, therefore, launched a systematic study of imaging mode dependent signal change or BOLD sensitivity as well as the signal changes due to the tilting angle of the imaging planes. Study has been made or both TRFGE sequence and CGE sequence to compare the distinctions of the each mode since each technique has different sensitivity against susceptibility effect. Method of computation and both the computer simulations and their corresponding experimental results are presented.

Myocardial blood low (MBF) in human can be noninvasively quantified using dynamic N-13 ammonia PET and two-compartment tracer kinetic model. In this study, factor analysis was used to extract the "pure" blood-pool time-activity curves (TACs) and to generate actor images. ive human N-13 ammonia PET dynamic studies were obtained. Three actors and their corresponding actor images were extracted rom each study. The accuracy of MBF estimated by the actor analysis (FA/FA MBF) was examined by comparing to the values estimated using the conventional ROI method (ROI/ROI MBF). MBF obtained by the actor analysis linearly correlated with MBF obtained by the ROI method (slope=0.98, r=0.91). Input unctions obtained by the two methods agreed well. In conclusion, MBF can be measured accurately and noninvasively with dynamic N-13 ammonia PET imaging and actor analysis. This method is simple and acurate and can measure MBF without blood sampling, ROI drawing nor spillover correction.

The two dimnesional echocardiography is widely used to evaluate regional wall motion abnormaility, because of its abilities to depict left ventricluar wall motion. A new method, color kinesis is a technology or echocardiographic assessment of left ventricular wall motion. In this paper, we proposed a algorithm or color kinesis which is based on acoustic quantification and automatically detects endocardial motion during systole on a frame-by-frame basis. The echocardiograms were obtained in the short-axis views in normal subjects. Automated edge detection and endocardial contour tracing algorithm was applied to each frames, quantitative analysis based on segmentation was performed, and pre-defined color overlays superimposed on the gray scale images. Segmental analysis of color kinesis provided automated, quantitative diagnosis of regional wall motion abnormality.

In this study, we proposed an application of wavelet transform or analysis of ultrasound echo signals to improve troubles of convenianced methods such as SDM, SSM. We examined method using wavelet transform to prove again our proposal which we have proposed prior time. At first, we made phantoms by adding 0.01, 0.015, 0.02, 0.025, 0.03, 0.035, 0.04, 0.045, 0.05($g/cm^3$) on constant quantity of distilled water and agar, and collected echo signals. We used SDM(spectral difference method) and WTM(wavelet transform method) as signal processing method. To compare with WTM, SDM was used. In WTM, we selected detail signals of level 3 of Daubechies 16, and got derivative, calculated area of it. Next, we calculated slopes. In SDM, it was 0.0308 and in WTM, it was 0.5248. As a result, we knew that we could know that the values using WTM showed more detailed than those using SDM. So we could concluded wavelet transform is very useful and powerful in ultrasound tissue characterization.

The virtual surgical trial of TAH is very important in some points as follows. The chests of patients who is under heart-disease are various types of undefine form. It is hard to say that there exist the standard shape of TAH and the position to surgern. So, the virtual surgery system is very important in realizing TAH surgery of human. We have implemented virtual surgery system of TAH that supporting multi volume fitting trial. We have acquired CT images of patients with DICOM format. Each organ of patients was segmented in 2-dimensional CT images. 3-dimensional objects were made with marching cube algorithm and save as file in VRML format. Virtual fitting trial was performed on Cosmo-World; a VRML editor. The collision points of TAH with other organs were well observed. And the best position and angles were determined and saved or each case. We believed that this virtual surgery will be helpful in TAH surgery and TAH customizing.

Making physical models of human body is not only time-consuming but also very expensive since they are usually hand-made. This problem is doubled with implant fabrication because an implant is almost always custom-made. Recently, RP is emerging as an alternative, and many RP applications are proposed in the medical field. The major advantage of this approach is due to a significant reduction of both time and cost required or the production. However, the technology is not much in practical use yet, especially in Korea. In this paper, we provide a method of generating STL files that are the standard format to RP machines. The original data are obtained from two-dimensional slices of MRI/CT machine. Example bone models have been produced using a commercially available RP machine, and the results are presented.