The Ultra-high molecular weight polyethylene (UHMWPE) is exclusivity used as the articulation component with metal or ceramic materials in artificial joint prosthesis because of its good mechanical properties. In the long term however, wear of UHMWPE causes complex problems and hence causes loosening of He prosthesis. In this study, we tried to enhance the wear property of UHMWPE by attaching a hydrophilic graft on the UHMWPE surface and by improving surface hardness without deteriorating the mechanical properties of UHMWPE. This was achieved by ion implantation and by ${\gamma}$-irradiation to the surface in acrylic acid solution and by photo-polymerization in divinylbenzen (DVB), diallysophthalate (DAIP) solution. The wear test was performed by a wear testing machine of ball-on-disk type devised by the authors. The UHMWPE with hydrophlic surface and increased surface hardness developed by above treatments showed less volumetric wear.

The purpose of this experimental investigation is to examine the influence of the catheter on local pressure changes and flow rate in an arterial branch model similar to the femoral artery of man. Effects of branch to main lumen flow rate ratios and the locations of catheter tip were found to be significant on the local pressure changes. Relatively large pressure drops due to obstruction effects may induce endothelial cell damage, which have been reported to be the primary cause of the initiation of the atherosclerosis.

Biomagnetic measurements provide superior spatial and temporal resolutions compared with the present electric measurements. We developed a SQUID system for biomagnetic applications. A magnetic field from the spontaneous ${\tau}$-rhythm activity and an auditory evoked magnetic field have been measured. And a measurement of magnetocardiogram and its field mapping have been done.

In this paper, the therapy radiation dose measurement system has been implemented by using a microcomputer after radiation was irradiated on diodes from the MM22 microtron accelerator. We have displayed 7-channel diode output values on the LCD after processing those in the 80196 MCU(Micro Computer Unit). Signal processing has been performed in the pulse mode because we can process the signal fast and use it to perform portal image by increasing a number of diode channels in the future. In order to verify the microcomputer based radiation measurement system of diodes, diode output values were compared with that of semiconductor.

This research is the basical experiment for designing kVp meter using the photo-conductive property of Amorphous Selenium. At first, we charged the surface with A re discharge method, and changed the formed surface potential voltage by x-raying on that surface. As a result the variations of the surface charge increased by the rising kVp, while maintaining a constant exposure time and mA. We become to know that we can apply the photoconductive property of Amorphous Selenium in designing kVp meter.

Small size DC motor control method for portable drug delivery system has been developed to be used for the actuator of insulins pump. The control method gives the controllabilities both in high speed(40-50 revolution per second(rps)) DC motor drive and also in low speed(0.5-1rps). In low speed mode DC motor is controlled to act like stepping motor and in high speed to optimize power consumption. To control both mode modified bang bang control is suggested. Using this method small size DC motor(spec.) speed is controlled from 0.2 rps to 50 rps. Experimental setup is developed using micro-processor(PIC16C73, Micro Chips co., USA), motor turns checking circuitry, small size DC motor for pager(SM1012, Samhong co., Korea) and gear box. Results from experiment meet need for vailable load condition which is require for portable drug delivery system.

기존의 안과 진단 및 치료 기기의 안구 고정장치는 진단 및 치료에 있어서 피검사자와 검사자에 사이에 충분한 협조가 되지 않을 경우 진단의 비효율성과 치료의 안정성등의 문제가 발생하고있다. 따라서 이러한 문제를 보완하기 위하여 SLO의 전면 세극등을 소형의 반사경으로 대치하고 표시등을 후면의 먼거리에 수직으로 배열시켜서 피검사자에게 적당한 높이의 고정등을 선택하게하여 수직방향의 안구 위치를 고정시키고 SLO(Scanning Laser Ophthalmoscope)의 좌우 회전기능으로 표적의 수평방향을 근절시킨 후에 검사자의 조작으로 원격조정되는 서보장치를 이용하여 다시 반사경을 전방향으로 미세하게 회전되게하여 정확한 위치로 안구를 이동시키게 하는 원격조정 표적 추적장치를 개발하였다. 이에 따라 피검사자는 거울에 비친 먼거리의 허상을 보게 되어 세극등을 이용한 근접주사방식의 단점인 안구의 축동, 폭주등으로 인한 환자의 눈의 피로를 최소화하면서 피검사자의 안구를 검사자가 원하는 위치로 고정시킬 수 있게 함으로써 임상실험에서 안과 진단의 정확성과 관리도를 높이고 치료의 효율성과 안전성을 증가시킬 수 있는 원격조정 추적장치로써의 성능을 확인하였다.

In this paper, we present the Computerized Polysomnographic System, which we developed for aiding manual polysomnographic diagnonis. This system is composed of four sub parts: patient information management tool, polysomno-graphic signal acquisition tool, signal analysis tool, and result-reporting tool. We calculated the parameters of sleep diagnosis, both on the sleep stage hypnogram and event lists. We developed this system on the Windows NT 4.0 and Pentium Pro 200Mhz. We are testing this system on the clinical site.

For the laryngeal function assessment, we developed a measurement system of speech sound and air flow rate. The speech sound was transduced with a standard omnidirectional condenser microphone and orally emitted air flow was measured with pneumotachometer using differential pressure transducer.

In this paper, we implemented the remote diagnosis for Pulse Diagnosis Apparatus. The system is consist with host part and slave part. 4 transfer channels are available in the system. As a result, 200Hz/channel of maximum transfer frequency is obtained.

we developed an information management system that manages various types of medical information such as text, image, sound, and laboratory data. We also developed a multimedia description system, in which medical doctors can describe his findings and interpretations with text and speech. The descriptions include the references to the data items stored in the information management systems. The communication between the description system and the information management systems is carried out using OLE/COM mechanism. The information management system was implemented by using Microsoft Open Data Base Connectivity(ODBC).

We developed a multimedia monitoring system for patients at home, equipped with video and audio-conferencing capabilities. It can also monitor biological signals in real-time with vital signs. The system has an extensible architecture to accommodate probable future needs easily.

The elevation of present medical service using advanced science contributes to offer medical examination and treatment of good quality under the subject of patient satisfaction as well as patient impression. The dental service field charging some part of public health promotion and public welfare promotion also intends to improve the dental examination and treatment quality utilizing advanced science. The object of this research is the development of dental patient education system (DPES) using multimedia of new technology. DPES can be employed for these object, harmonious operation of dental examination and treatment, treatment quality improvement, disease notice to patient under the subject of patient satisfaction and patient impression, explanation of some selective treatment course, the verification of treatment necessities and treatment validation, and the improvement of treatment effect through the oral cavity sanitation education in the sense of prevention. This research also serves the development environment, the step to collect educational document, visual information and to structure those, and the examination of DPES efficiency in clinic.

A medical image management system was implemented using WWW(world wide web) technology. The Httpd server was designed using PC with Linux operating system. The client used Netscape as its network browser. The image processing module of the client part was programmed in Java. The database was constructed with Bicom3 format images and programmed using Perl. The present technique can be used to standardize the network and user environment of PACS and teleradiology.

Currently many researches are going on a Picture Archiving and Communication System (PACS) which can handle a large number of image data very efficiently. However, the price of those systems are very expensive to a small and medium hospital. In this paper, we developed a PC based Mini-PACS at a low price with a high performance. The main components of the designed system are: Image processing and display for a diagnosis, Client/Server database management system, Multi-monitor display system, Connection through the World Wide Web with Common Gateway Interface.

Optical property of tissue is characterized by its high scattering of light. In near infrared range$(800{\sim}1200nm)$ scattering is dominant than absorption. Communication using NIR through tissue is applicable to immplantable device. In this paper, simulation of unit impulse response of light in tissue is carried out to estimate the amplitude, phaselength and phaselength deviation.

Many researchers had considered biological systems as linear systems. In many cases of biological systems, the phenomena that show the regular and periodic dynamics are considered the normal state. However, some clinical experiments reported, in some cases, the periodic signals represented the abnormal state. We assume that signals from human body system are generated from deterministic, intrinsic mechanisms and can be represented a simple equation that show nonlinear dynamics dependent on control parameters. The objective of our study is to model a nonlinear dynamics correctly from the nonlinear time series using the genetic programming method; to find a simple equation of nonlinear dynamics using collected time series and its nonlinear characteristics. We applied genetic programming to model RR interval of ECG that shows chaotic phenomena. We used 4 statistic measures and 2 fractal measures to estimate fitness of each chromosome, and could obtain good solutions of which chaotic features are similar.

This paper describes a methodology for the development of models of discrete event system(DES). The methodology is based on transformation of continuous state space into discrete one to homomorphically represent dynamics of continuous processes in discrete events. This paper proposes a formal structure which can couple DES models within a framework. The structure employs the DEVS formalism for the DES models. The proposed formal structure has been applied to develop a DEVS model for the human cardiovascular system. For this, the cardiac cycle is partitioned into a set of phases based on events identified through VisSim simulation in the CS of the electrical analog model. VisSim is the simulation tool of visual environment for developing continuous, discrete, and hybrid system models and performing dynamic simulation. For each phase, a CS of the electrical analog model for the cardiovascular system has been simulated by VisSim 2.0. To validate this model, first develop the DEVS model, then simulate the model in the DEVSIM++ environment. It has same simulation results for the data obtained from the CS simulation using VisSim. The comparison shows that the DEVS model represents dynamics of the human heart system at each phase of cardiac cycle.

The various function of the cardiovascular system(CVS) and the dynamic characteristics on each part of human body can be acquired in the electric analog circuit model. According to the performed outcome by other researchers, viscos resistance, flow inertia, and vascular compliance in the CVS are analogous to resister, inductor, and capacitor in electric circuit, so the CVS models were represented by the electric circuit models. these approaches were to propose the suitable models interest part of body and to simulate the various characteristics on the CVS. In this paper, the electric circuit model considering the characteristics of morphologic structure is represented, the parameter values of model is sotted up, and the dynamic characteristics of the the CVS is simulated using VisSim, one of the simulation tools. The observed simulation results are similar to the cardiovascular functions of nomal adults who have no heart failure. Besides, the simulation is operated to observe the pathophysiological abnomal symptoms(for example, bleeding within a certain period). The controller by baroreceptor, which is one of controllers to control the CVS, is appended in the model. and the dynamic response characteristics and the procedure to return normal state is observed in simulation when the bleeding last within a certain period.

This paper describes compensation method to evaluate arousal level in different initial arousal state. Arousal level was measured by the relationship between IRI and Nz. The value of Nz is affected by BI which is variable with initial drowsiness. we introduced a correction factor to compensate these differences.

We studied the problem of driver's low vigilance state which is related to the one reason of traffic accidents. In this paper, we developed the drowsiness warning system for a drowsy driver. To extract the eyes and mouth from the driver's facial image in real time, a computer vision method was used. The eye blink duration and yawning were used as measurement parameters of drowsiness detection. When the drowsy state of a driver was detected, the driver was refreshed by the scent generator and the alarm. Also, the driver's bio-signal was acquired and analyzed to measure the vigilance state.

In this paper, The vehicle's path construction method for motorized wheelchair's autonomous navigation in a building through analysis of a corridor image using vision system has been proposed and We detected lines of vertical axis through camera distortion parameter, which was measured by camera calibration in a corridor image. Then we got the feature points in the lines. We analyzed the distance of feature points and what is feature points. we reconstructed corridor image to vehicle's path.

The ultimate object of FES is on the recovering function of body and shape demaged from desease or injury to original state. On this study, object is recovering of gait function of the disabled who, especially, have gait disturbance. Paralyzed muscle from the central nerve disable, if peripheral nerves which be in the lower part of the harmed are activated, muscle contraction is possible. The traumatic trouble, peripheral nerves aren't connected to a central nerve but origin of peripheral nerve cells which are in the lower part of the harmed are alive, react on stimulation. We design 4-channel stimulator, being based on standard stimuli pattern. stimulator is manufactured with compact size and light weight to portable.

In this paper, we proposed the design and algorithm of force reflection joystick which control mobile robot as a rehabilitation assistance system. The disabled persons are poor at joystick control because of hand vibration and clumsiness in operating it. These problems bring tasks which concerned with operator's safety So there is required technique which prevent collision with wall or obstacles. One of these solution is force reflection joystick which disturb that robot is closed to the wall. To confirm this way, we experimented and simulated with force reflection joystick which attached torque controller.

We proposed a new system for the postural balance rehabilitation training. For the purpose, we used the virtual hiking system using virtual reality technology. We evaluated the system by measuring the parameters such as path deviation, path deviation velocity, cycling time, and head movement. From our results, we verified the usefulness of virtual reality technology in rehabilitation. Our results showed that this system was effective postural balance rehabilitation training device and might be useful as the clinical equipment.

The impaired person and the elderly who has hearing loss have been continuously increased and these people's desire for participating society as a producer has been increased also. So they strongly request the aid device which can compensate their handicap. The healing aid telephone is one of the basic aid devices that helps the hearing impaired to communicate with other people and to acquire useful information. We design the new model of the hearing aid telephone and test it's efficiency in three fields - electrical, speech perception, user test. From the result of the test we certify that the new model is better for the hearing impaired to understand the meaning of telephone speech than the old general models. We expect that the advanced healing aid telephone can be developed by the research about speech perception characteristics of the hearing impaired in engineering and clinical side.

In this study, remote articulation training system which connects the hearing disabled trainee and the speech therapist via B-ISDN is introduced. The hearing disabled does not have the hearing feedback of his own pronunciation, and the chance of watching his speech organs' movement trajectory will offer him the self-training of articulation. So the system has two purposes of self articulation training and trainer's on-line checking in remote place. We estimate the vocal tract articulatory movements from the speech signal using inverse modelling and display the movement trajectory on the sideview of human face graphically. The trajectories of trainees' articulation is displayed along with the reference trajectories, so the trainee can control his articulating to make the two trajectories overlapped. For on-line communication and ckecking training record, the system has the function of video conferencing and transferring articulatory data.

This paper describes ECG signal labeling based on Fuzzy clustering, which is necessary at automated ECG diagnosis. The NPPA(Non parametric partitioning algorithm) compares the correlations of wave forms, which tends to recognize the same wave forms as different when the wave forms have a little morphological variation. We propose to apply Fuzzy clustering to ECG QRS Complex labeling, which prevents the errors to mistake by using If-then comparision. The process is divided into two parts. The first part is a parameters extraction process from ECG signal, which is composed of filtering, QRS detection by mapping to a phase space by time delay coordinates and generation of characteristic vectors. The second is fuzzy clustering by FCM(Fuzzy c-means), which is composed of a clustering, an assessment of cluster validity and labeling.

A new type of motor-driven total artificial heart system with a moving-actuator mechanism has been developed. The prototype system consists of a brushless do motor inside of actuator, two polyurethane sacs, and peripheral devices with internal controller. In this research work, the moving-actuator type electromechanical total artificial heart was redesigned for a good anatomical fitting. For total implantation we are developing the internal controller with high reliability and stability, and automatic control algorithm in response to the physiological requirements of animal. Contents and scope of the research work on ";Development of a totally implantable artificial heart of pre-clinical stage"; is summerized below 1) Animal experiment using sheep(55-60kg) 2) Development of implantable controller 3) Automatic control algorithm 4) Improvement of biocompatibility 5) Redesign of Actuator/blood pump.

1차 년도 G-7 개발 과제로 수행된 자기 공명 진단 장치 (Magnetic Resonance Imaging System)의 개발 내용을 간략히 소개하였다. 성공적인 IT Compact 자기 공명 진단 장치의 완성을 위해 일차적으로 (1)RF (고주파), Gradient(경사 자계), Spectrometer 등의 Hard-ware 관련 MRI 핵심부분, (2) RF, Gradient, Spectrometer, Magnet 등의 각 Sub-system을 연결, 조합, 조정하여 하나의 체계적인 시스템으로 통합하고 운영하는 과정(System Integration), (3)사용자와 시스템을 연결하는 User Interface, Data Base Management, Real time 운영 SW 등과 (4)임상에 적용하여 구체적인 성능과 효용성을 확인하는 기술 등에 대하여 집중 연구하였다. 개발 방법은 (1)지난 16년간 국내에 축적 된 연구 개발 인력들을 최대한 활용하고 (2)연구 개발을 국제화 시켜 필요한 경우 부분별로 개발 인력을 해외에서 보완하고 (3)소수 정예 전문 인력 주의와 요소 기술 또는 중요 부품을 경쟁성 검토 후 필요 시 Out-sourcing 활용으로 최저의 비용으로 개발 기간을 최소화 하는 데 두었다. 개발된 1.0Tesla자기 공명 영상 장치는 미국 물리 학회에서 규격화한 Phantom및 임상 적용을 통하여 서울대 의대 연구 팀과 지속적으로 성능을 평가해 왔다. 개발된 시스템의 해상도는 $256{\times}256$ head 영상에서 1mm 이 하의 해상도를 가짐을 resolution phantom 을 통하여 확인할 수 있었고, $512{\times}512$ 영상에서 는 약 0.5 mm 의 물체를 분리 해냄으로써 외제 시스템들 보다 우수하게 평가 되었다. 차폐 경사코일의 Eddy current영향은2%이내로 촬영 시 영향은 거의 무시할 수 있었다. 또한, 개발된 영상 기법들, 즉 Multislice/Multi Echo, Oblique angle imaging, 64 Echo train을 갖는 고속 촬영 기술들이 자기 공명 장치에 장착되어 임상 적용에 문제가 없도록 하였다. 또한 20mT/m/Amp의 강력한 능동 차폐 경사 자계 코일(Active Shield Gradient Coil)을 기본 사양으로 하고, 수신단을 최대 6개로 확장토록 하여 2차년도의 초고속 촬영 기법(EPI) 및 Phased Array 코일 촬영이 가능토록 하였다. 1차 년도 개발 과제 수행 결과와 향후 개발 과제를 바탕으로 최종 목표인 국제 경쟁력이 있는 자기 공명 진단 장치 즉 기능과 영상의 질은 선진국 제품과 동일하거나 우수하되, 저가격을 구현한 상용화 제품이 완성되어, 첨단 의료기기로서 산업 구조 고도화에 기여하고 수입대체 뿐만 아니 라 수출을 통한 국익 창출과 국가의 기술을 통한 위상 제고에 기여되길 기대한다.

Bis-GMA is an important component in commercial dental restorative composites, but its hydroxy groups are considered to promote water absorption of the cured composite in a mouth. In this work, multifunctional methacrylates were prepared by blocking the hydroxy groups in bis-GMA with methacryloyl groups. Comparing to bis-GMA, new prepolymers having three methacryloyl groups (BPA-3M) and four methacryloyl groups (BPA-4M) showed much lower viscosities. Photopolymerization conversion of BPA-3M was slightly higher than that of bis-GMA. Water absorption of the photo-cured composite containing BPA-3M was measured for one month and found to be much lower than that of bis-GMA.

In this paper, we present the main research results on the 2 Tesla class - superconducting MRI magnet which we have developed. Multi section type superconducting MRI main coil and various superconducting shims were designed and fabricated for obtaining the high field homogeneity, which is requested in the MR imaging. After assembling the magnet with room temperature bore cryostat field homogenity has been measured and analyzed by NMR field mapping system. According to this, field homogeneity of 22 ppm / 30 cm dsv was confirmed.

A medical record and radiographic image transmission system has been developed using high speed communication network. The databases are designed to store and transmit the data acquired from the scanner. To maximally utilize the communication bandwidth, the medical records and radiographic images are compressed using the G3 facsimile and JPEG coding standard method respectively. TCP/IP, OOP and window based system software enables the modular design, future expandability, open system interconnectivity, and graphical user interface. In addition, the fast and easy data base access capability and diverse image manipulation functions are also implemented.

The intercommissural(AC-PC) line is automatically detected for HR and PET images. With the detected AC-PC lines from MR and PET images, fully non-iterative automatic co- registration is accomplished. It provides a new automated method for image co-registration.

In this paper, reconstruction algorithms of spiral scan imaging which has been used for ultra fast magnetic resonance imaging have been reviewed, and some simulation results using two different algorithms are reported. Since the trajectory of the spiral scan in k-space is the spiral, reconstruction of the spiral scan is not as straight forward as that used in Fourier imaging technique where the sampling points are usually on the rectangular grids. Originally the reconstruction of the spiral scan imaging was based on the convolution backprojection algorithm modified with a shift term, however, some other reconstruction techniques have also been tried by remapping sampling points from spiral trajectory to Cartesian grids. Some experimental aspects of MR spiral scan imaging will also be addressed.

An actively-shielded $r^{2}$-gradient coil has been developed for brain localized MRI or MRS. Spatial localization is very useful for spatial volume selection in MRI or MR Spectroscopy(MRS). The radial(or $R^{2}-$) gradient coil is useful in reducing the artifact or in improving the SNR by selecting the volume with less number of RF pulses. It is, however, difficult to implement the coil with a gradient intensity strong enough to use it for practical whole-body MRI system. For example, the smallest volume size for selection is just 6 cm in diameter with a 250 Ampere of current driving for a whole-body system (in case of 70-cm-diameter). In this study, an asymetric $r^{2}$-coil with a small diameter of 35 cm has been designed and implemented for brain localized MRI or MRS. An 8-rod high-pass-type birdcage RF coil has also been implemented. The coil set has been developed for 1.0 Tesla Medison MRI system and its performance has been verified experimentally.

Though the planar gradient coils, designed by the magnetic energy minimization procedure, have smaller inductance than conventional gradient coils, the planar gradient oils often suffer from their poor magnetic field linearity. Scaling the spatial frequencies of the current density function designed by the magnetic energy minimization procedure, magnetic field linearity of the planar gradient coils can be featly improved with small sacrifice of gradient coil inductance.

In this paper, we present the evaluation of signal to noise ratio(SNR) and images of Magnetic resonance imaging system which is underdevelopement. For the evaluation of such parameters, we used two different phantoms, one for SNR and image homogeneity, and the other is for the slice thickness measurement. Further, comparison with other leading MR systems may be needed for the better image quality assessment.

본 논문에서는 일반 심전도 모니터링 장비가 갖는 이동성 및 상시성의 제한을 극복하여 공중무선망을 이용한 심전도 모니터링 장치에 관한것으로서 특히, 활동중인 사람의 심전도 데이터를 공중 무선 통신망에서 제공하는 망써비스를 이용하여 원거리 모니터링 센터에서 모니터링 및 응급조치를 하는 시스템에 관한 것이다.

The Outflow facility of eye ball provides crucial informations in the diagnose of ophthalmological glaucoma. Tn this study an ophthalmic outflow facility measuring device is developed and experimentally tested. This system employs pressure sensors and linear positioning device to regulate solution reservoir height, the pressure of eye ball. The experimental result show that the system works well even in harsh environment so that it can be implemented in ophthalmic practice as well as in biomedical research.

Electrogastrography(EGG) is the technique by which gastric myoelectrical activity is recorded noninvasively, from surface electrodes on the abdominal skin. In older to know the relation between the signal of the gastric mil and the EGG signal, we measured the gastric myoelectrical activity in animals using surface electrodes and serosal electrodes, and measured the gastric contraction simultaneously using a strain gauge attached to the gastric wall we compared the signals with and without the gastric contraction.

Noninvasive multifrequency microwave radiometry using coaxial waveguide antenna has been investigated for a homogeneous and four layer human body model. The coupling between coaxial waveguide antenna and a. biological object is analyzed by use of the FDTD method to obtain the absorbed power patterns in the media. The object studied in this paper is a homogeneous and four-layered lossy medium. The specific absorption rates(SAR) distribution is calculated in each region by use of the steady-state response in FDTD method.

Computerized spirometer was developed in a form of proto type system. The system consisted of pneumotachometer, flow measurement unit, fan ventilator unit, and software program. Patient's respiratory flow signal was first converted to corresponding pressure drop signal by a screen type pneumotachometer, sensed by a differential pressure transducer, amplified and low pass filtered, and digitized at a rate of 100 Hz, then fed into a PC thru RS-232C serial port. Customized application software controls data acquisition followed by computation of test parameters. The fan ventilator unit dries and eliminates microorganism in the pneumotachometer after each test. The system performs conventional spirometic tests and manages the test results in a database for retrograde research. The proto type system was fully developed and the commercialized system is currently being built up.

[ $1.06/1.32{\mu}m$ ] dual-wavelength medical laser was developed and preliminary clinical comparisons at these two wavelengths were performed for dental application. We could develop a compact laser system 1) by lasing two wavelengths from the same Nd:YAG rod, and 2) by introducing high-voltage switching power supply modules. Experiment on gingiva of pig jaw showed higher thermal damage at $1.32{\mu}m$. Depending on particular procedures, each wavelength has its own advantages and disadvantages. For cutting, however, using conical tips rather than bare fibers provided better results with low threshold of cutting energy and less surrounding thermal damage. Appling light-absorbing dye on target area appeared to induce more damage during laser irradiation. However, histological studies showed no significant difference whether dye was applied or not.

In this paper, we suggested the combination of HMM(Hidden Markov Model) and MLP (Multi-Layer Perceptron) with GA(genetic algorithm) for a recognition of EMG signals. To describe EMG signal's dynamic properties, HMM algorithm was adapted and due to its outstanding abilities in static signal classification MLP was connected as a real processor. We also used GA( Genetic Algorithm) for improving MLP's learning rate. Experimental results showed that the suggested classifier gave higher EMG signal recognition rates with faster learning time than other one.

During the electromyographic evaluation, the presence and site of lession may be predicted by a detection of denervation potentials such as fibrllation potentials or positive sharp waves in the group of muscles. Currently, clinicians diagnose the neuropathy by detecting fibrillation potentials during EMG tests, and sometimes it is not easy to distinguish between denervation potentials and endplate spikes. The purpose of this study was to find statistically significant parameters for the quantitative distinction between denervation potentials and endplate spikes. Endplate spikes and denervation potentials from the EDB muscle of 10 patients were extracted. Also, EMG signals were classified by experienced clinicians, and were collected using a 12 bit ADC with a sampling rate of 20KHz for the duration of 400msec. In order to find statistically significant parameters, positive and negative peaks were used for analysis. As a results, standard deviation of the endplate spikes and denervation potentials showed more significant difference than others specially for the positive sharp waves. It was concluded that the results of this study could be used to develope an automated system of a EMG analysis.

In this paper, we designed a Holter analysis system using the visual programming method. It differs from the existing analysis system in that the various signal processing algorithms represented by icons were designed by GUI concept which provide unskilled user with easy and convenient analysis environment. In order to analysis ECG signal, we only select the icon representing a algorithm to be applied by mouse and arrange the selected icons upon the order to be processed on screen. As a result it provides a convenient usage and flexibility of analysis. Finally, we can find the optimal algorithm for the ambulatory ECG analysis by comparing the several results obtained from the various analysis configuration.

In this research we would like to develop an exercise ECG signal analysis algorithm using the wavelet transform, which is possible to analyze the time and the frequency simultaneously. Wavelet transform has an advantage of dividing the nonstationary signals into the high frequency and low frequency band successively. Thus, it can separates the unnecessary noises from the frequency band of QRS complex and then using the selected frequency band we could detect the QRS complex and ST segment.

In this paper, we compare three mehods to obtain PSD of HRV - FFT, AR modeling, and residual integration. Using these methods we speculate the balances of the LP and HF powers of HRV at $0^{\circ}$, $45^{\circ}$, $90^{\circ}$ tilt levels of head-up tilt table for young and healthy 24 men. R peaks are located at the highest point of QRS complex detected from modified spacial velocity algorithm. In general FFT is the most fast way to obtain PSD but PSD from FFT has too many peaks and valleies. AR PSD can show frequency of ANS activity effectively but LF component of PSD is often invisible due to interference of VLF power. The residual integration method that decomposes the AR PSD is very efficient way to extract LF component. Applying the above three methods to HRV we can visualize the trend of PSD variations along tilt levels.

This paper presents the ECG data compression using wavelet transform(WT) and adaptive fractal interpolation(AFI). The WT has the subband coding scheme. The fractal compression method represents any range of ECG signal by fractal interpolation parameters. Specially, the AFI used the adaptive range sizes and got good performance for ECG data compression. In this algorithm, the AFI is applied into the low frequency part of WT. The MIT/BIH arrhythmia data was used for evaluation. The compression rate using WT and AFI algorithm is better than the compression rate using AFI. The WT and AFI algorithm yields compression ratio as high as 21.0 without any entroy coding.

ECG data are used for the diagnostic purposes with many clinical situations, especially heart disease. In this paper, an efficient ECG data compression technique by wavelet transform and high-speed vector quantization on PMS-B algorithm is proposed. In general, ECG data compression techniques are divided into two categories: direct and transform methods. The direct data compression techniques are AZTEC, TP, CORTES, FAN and SAPA algorithms, besides the transform methods include K-L, Fourier, Walsh, and wavelet transforms. In this paper, we applied wavelet analysis to the ECG data. In particular, vector quantization on PMS-B algorithm to the wavelet coefficients in the higher frequency regions, but scalar quantized in the lower frequency regions by PCM. Finally, the quantized indices were compressed by LZW lossless entropy encoder. As the result of simulation, it turns out to get sufficient compression ratio while keeping clinically acceptable PRD.

we propose the shrinkage of wavelet coefficients and the averaging method. The wavelet analysis decomposes the measured evoked potentials into scale coefficients and wavelet coefficients as a resolution level, respectively. And in the course of synthesis of evoked potentials, the presented method shrinks the wavelet coefficients, and then reproduces the evoked potentials and lastly averages it. we measured VEP signal to simulate the presented method, and compared it with averaged signal and LMS algorithm. As a result of simulations, the proposed method gets improved VEP about 0.2-1.6db in comparison with the result of averaging method.

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 auditory 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. The experiment was devised with seven experimental conditions, which are control and six different types of auditory stimulation. Twenty subjects were used to obtain EEGs while introducing auditory stimulation. Wavelet transformation was employed to analyze the EEG signals. 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 negative and positive stimulus were found. This study could be extended to estabilish an algorithm which distinguishes psychophysiological states of the subjects exposed to the auditory stimulation.

In this paper, we present the ABR(Auditory Brainstem Response) as a clinical application. ABRs are composed of several waves or peaks. In recent years, the use of ABRs has gained popularity as one of the methods of choice in determinig hearing thresholds of newborns and infants. We introduce labeling and computational methods of peak identification in ABR.

Use of electrical stimulation for diagnosis and treatment of pyhsiolgocial impairment on the auditory system was reported by many researchers since 1800. Unfortunately, there were no standard methods or theoretical bakground for choosing stimulus conditions because of the lack of understanding on the transmission of sound through the auditory pathways. Therefore, if we could find the mechanisms of normal and abnormal functions for the system objectively, it may be possible to establish the conditions for the appropriate treatment This study was devised with three experimental conditions of electrical stimulation(0.1, 1, and 10mA) to verify the effect of electrical stimulation on the auditory system. ABRs and ECochGs were obtained from 3 Guinea Pigs before and after each stimulation, and five parameters were extracted from ABR and ECochG waveforms. The results showed that the mean differences of the first peaks of ABR, I, before and after all the stimulus conditions were significant at the significant level of p<0.05. Also, amplitude of ECochGs peak(AP) showed higher degrees of differences for the electrical stimulation than that of ABRs. Based on the results of this experiment establishment of an electrical model which characterizes the auditory system could be achieved by computer simulation. This will lead to the design of most accurate model for the real auditory system, which provide the quantitive information regarding diagnosis and treatment.

This study was peformed to characterize the physiological signal prior to develop an algorithm which quantifies EEGs evoked by tactile stimulation. The experiment was devised with four experimental conditions, which were control and two levels of pressures in tactile sensation. Twenty subjects were used to obtain EEGs while applying tactile stimulation using two types of textiles, soft towel and sand paper, to the right hand of each subject. EEGs were acquired for 20 seconds, and each trial was repeated five times randomly at the different levels of stimulus intensities. The index, $S_{n}$, was obtained by calculating the ratio of energy distribution in the time-frequency plot for each scored psychological state of the subject. The results showed that dominant aspects of the EEG signals have their maximal frequencies concentrated at a lower ranges for the resting and pleasant state, while the spectral energies were distributed to higher frequency ranges when subjects experience an unpleasant emotion.

In this paper, we tried to analyze the mental states, especially alertness or degree of concentration, by analysis of Visual Evoked Potentials. Given task to the visual stimulation, there was warning signals to enhance the alertness of the subject. With the synchronization to the stimulus, we averaged the EP waves, and estimated the power spectrums to view difference between relatively less alerted state and more alerted state. Although there was no significant difference during the waiting for the stimuli, we could find some difference during task performing.

Noninvasive monitoring of total Hemoglobin value is feasible with the use of spectroscopic measurements. As a step toward tile final goal of the development of a noninvasive monitor, the spectra$(400{\sim}800mm)$of EDTA whole blood were obtained along with reference total Hemoglobin values. Under the same condition water spectrum was generated. It was subtracted from each blood sample, and then tile first derivative of each subtracted data was taken by 'approximated first derivative algorithm' with gap (1,6,10,20nm). The correlation was obtained between total Hemoglobin and first valley wavelength of first derivative spectrum (sample number: 93).

An aorto-coronary bypass graft is frequently adopted for the interventional therapy of the diseased atherosclerotic coronary artery grafting. The bypass artery is often occluded due to restenosis and/or anastomotic neointimal fibrous hyperplasia after bypass graft. The optimal aorto-coronary bypass procedure must be studied in order to improve patency rate for the arterial bypass techniques. The objective of this study is to investigate the influences of geometric dimensions of bypass on the hemodynamics around the anastomosis in the stenosed coronary artery with aorto-coronary bypass.

The physiological systems have nonlinear complex phenomena. Expecially, the flow of capillary blood vessel has a nonlinear dynamic system. Thus, this study analyzes nonlinear characteristics of the flow of capillary blood vessel in physiological systems using chaotic tools(phase space reconstruction, correlation dimension, largest lyapunov exponent). Experimental data have been acquired from examining 10 rabbits. The results of chaotic analysis showed a decreasing largest lyapunov exponent and correlation dimension according to increasement glocose index. And we also know the chaotic behavior.

An estimation algorithm based on training of fuzzy logic system using back-propagation is proposed, in this paper, for determining cardiac output in the TAH. The proposed estimation utilizes only a motor current waveform generated from the moving actuator of the electromechanical TAH without using any extra transducers as an information source for estimation. In in vitro tests, the resultant estimation performance was acceptable to alppy the proposed algorithm to animal experiments and further clinical applications.

The removal of impulsive noise terms which occur in interventricular pressure (IVP) signals of a Korean-type total artificial heart is essential for estimation of atrial pressure change. We compared various order statistic filters and conclude that median filter with sidelength L = 1 is the most appropriate filter for IVP signals in the perspectives of operation cost, detail preserving (peak value), and waveform.

In the Total Artificial Heart (TAH) and Ventricular Assist Device (VAD), the size implanting the internal controller into human body is very serious problem. Hence, we need the size reduction of that controller for safe implantation. Using PSD302 chip for microcontroller-based applications, we could decrease the number of components in the digital control board and miniaturize the digital control board. We could replace a ROM, RAM, and a latch with that single chip, so the size of the newly developed board could be half the previous board.

We have developed a ground-isolation circuit in order to reduce the noise of the internal controller system for the total artificial heart(TAH) and ventricular assist device(VAD). Using the ground-isolation technique, we could transmit the analog target signal to other pheriperal device including IBM PC via RS232C and polygraph, with no noise. Experimental results of VAD showed that there was less impulsive noise in current signal which caused in our previous conventional system. Therefore it could be proved that implementation of isolation technique is very effective to improve the signal to noise ratios of analog signal transmission for TAH or VAD.

Pulsatile swelling behaviors and their application to drug delivery system were studied by using interpenetrating polymer networks(IPN) hydrogels constructed with poly(vinyl alcohol) and poly(acrylic acid). The PVA/PAAc IPNs hydrogels were symthesized by UV irradiation tallowed by repetitive freezing and thawing method. These hydrogels showed pH and temperature sensitive swelling behaviors. From the release experiment, the release amount of model drug incorporated into these hydrogels showed pulsatile patterns. Permeability coefficients obtained by various solutes differed in response to changes of permeation conditions.

To make correct prognoses in the area of orthodontics, dentists use cephalometric analysis methods. Currently, most of them involve two main steps: initial diagnosis and treatment establishment. Currently, dentists work manually on X-ray film to measure the cephalogmetric parameters. The work is tedious and time-consuming, and sometimes produces incorrect results. We developed an automated cephalometric analysis system, in which dentists can easily locate reference points needed for the analysis and get the results almost at the same time.

The 2-way beam simulation for the diagnostic ultrasound is performed with simplified computation by approximating the transducer and the system. The results show that the simulation program can be used as a good system design tool.

In this paper, we studied two image characteristics, similarity and smoothness, which give rise to local and global redundancy in image representation. The similarty means that any patterns in the image repeat itself anywhere in the rest of image. The smoothness means that the gray level values within a given block vary gradually rather than abruptly. In this sense, we propose a lossless medical image compression scheme which exploits both types of redundancy. This method segments the image into variable size blocks and encodes them depending on characteristics of the block. The proposed compression schemes works better than other compression schemes such as the huffman, the arithmetic, the Lempel-Ziv and the lossless scheme of JPEG.

In male reproducible health and fertility and IVF(in-vitro fertilization), semen analysis has been most important. But the traditional tools for semen analysis are subjective, imprecise, inaccurate, difficult to standardize, and difficult to reproduce mainly due to their manually oriented operations. The purpose of a morphometric analysis of sperm is to microscopically type-classify spermatozoa cytologically according to their morphology of heads. Until now, the strict criteria method has long been used in clinic to discriminate normal spermatozoa from abnormal ones. This method cannot classify the diverse groups of abnormal spermatozoa in detail and shows variations in inter-operators and intra-operator In this paper, we developed a new method of a sperm morphometric analysis using artificial neural networks which are widely used in pattern recognition and image processing.

A platform is developed for fast and effective functional mapping of human brain, which can allow semi-automatically the whole processes of an image segmentation, a fusion of MR and PET images, and 3-D rendering of volumetric data, including DICOM-based image transfers from PACS archiver within a short period of time.

Endoscopy has become a crucial diagnostic and theraputic procedure in clinical areas. Over the past three years, we have developed a computerized system to record and store clinical data pertaining to endoscopic surgery of laparascopic cholesystectomy, peviscopic endometriosis, and surgical arthroscopy. In this study, we are developed computer system, which is composed of frame grabber, sound board, VCR control board, LAN card and EDMS(endoscopic data management software). Also, computer system has controled over peripheral instruments as a color video printer, video cassette recorder, and endoscopic input/output signals(image and doctor's speech). Also, we are developed one body system of camels control unit including an endoscopic miniature camera and light source. Our system offer unsurpassed image quality in terms of resolution and color fidelity. Digital endoscopic data management system is based on open architecture and a set of widely available industry standards, namely: windows 3.1 as a operating system, TCP/IP as a network protocol and a time sequence based database that handles both an image and drctor's speech synchronized with endoscopic image.

A new design scheme of actively-shielded x,y-gradient coils for Magnetic Resonance Imaging(MRI) is proposed. An actively-shielded x-gradient coil has been designed as an example and the results are presented. In MRI, gradient coils are needed for spatial selection and position coding to obtain the position information of the NMR signal. They are usually switched on and off during imaging and the eddy current induced by the current switching usually degrades the final image quality To reduce or remove this kind of problems, the active shielding has been proposed few years ago. In this paper, a new design scheme for actively-shielded x,y-gradient coils, namely, a minimum-power design scheme using current-loop elements, has been proposed. Its utility in designing MRI gradient coils has been shown by using simulation. The design scheme seems to be useful for actively-shielded transverse gradient coils, even of non-cylindrical or of arbitrary-selected shapes.

PET 방출스캔 영상과 MRI에서 추출한 머리 표피의 경계점들의 거리를 최소화하는 방법을 사용하여 두 영상의 위치정합을 시도하였다. 위치 정합된 두영상의 동시표현을 위하여 가중정규화 방법과 interleaving 방법을 시도하였다.

To diagnose cardiac malfunctions, various imaging techniques have been applied to heart : DSA(Digital Subtracted Angiography), Doppler Ultrasound, MR Angio. But it is difficult to observe three dimensional heart motion which is the most intuitive tool for diagnosis, only by using these methods. In this research, we have suggested 4-Dimensional reconstruction scheme of heart motion images that can be acquired by ECG-gated cine MR imaging. One cardiac cycle was devided into $9\sim15$ phases and for each phase 3D reconstructed volumn heart was made. We can observe 3D volumns along the cardiac cycle, time. So the results were 4-D reconstructed data.

Electrogastrography(EGG) has been an attractive method for physiological and pathophysiological studies of the stomach and now is on the verge of becoming a new clinical tool in gastroenterology. In this study 4 channel EGG measurement system was constructed and running spectrum analysis was developed for 2D and 3D display of power spectrum with time and frequency. A wavelet multiresolution method was utilized for elimination of baseline drift and for filtering out noises.

Dental implant is increasingly used to recover the mastication function of tooth. Several types of implant were designed to give an optimal stress distribution in surrounding bony regions. In this study, six types of implant were investigated using finite element method and it was studied i) how the variation of cortical bone thickness affects the stress distribution in surrounding bony regions depending upon implant types, ii) which type gives the best characteristics in the sence of stress distribution and stability. The hybrid-type implant with cylinder and screw gave the optimum properties in view of stability and response to the variation of cortical bone thickness.

Poly(L-leucine)(PLL)/poly(ethylene oxide)(PEO)/poly (L-leucine)(PLL) block copolymers were synthsized by polymerization of L-leucine N-carboxyanhydride with diamine-terminated PEO for possibility of wound dressing which may have several advantages such as 1) increase of solubility, 2) control of biodegradation, 3) absorption of body fluid. 4) non-immunogenic effect than PLL homopolymer wound dressing aleady commercialized. Water content increased with an increase of PEO content in the block copolymer due to the hydrophilicity of PEO. Release of silver sulfadiazine(AgSD) from AgSD loaded wound dressing increased with an increase of PEO content in the block copolymer. It was found that the number of Pseudomonas aeruginosa decrease with an increase of PEO content due to the fast release of antibacterial agents with an increase of PEO content in the block copolymer.

Flexible, self-expanding metallic stent were developed using igzag wire bend and segmented polyurethane. Mechanical properties of these stents were tested using INSTRON. These stents were used for palliative treatment of mallignant esophagogastric strictures(3 case) and bawl preparation of collorectal obstruction(10 case). All stents were inserted with fluoroscopic guidance without techinal failures. According to the results, these stents are easy to insert, safe, and very effective for dilation of strictures in curved GI tract.

Debonding of cement-femoral stem interface has been suggested as a initial focus of loosening mechanism in many previous studies of cemented total hip replacement. The purpose of this study was to investigate the effect of debonding of cement-femoral stem interface to the bone-cement interface by using three-dimensional non-liner finite element analysis. Three cases of partial debonded, full debonded, full bonded cement-bone interface were modelled with partial bonding of distal 70mm from the tip of femoral stem. Each situation was studied under loading stimulating one-leg stanced gait of 68kg patient. The results showed that under partial and full debonded cement-stem interface condition the peak von Mises stress(3.1 MPa) were observed at the cement of bone-cement interface just under the calcar of proximal medial of femur, and sudden high peak stresses(3.5MPa) were developed at the distal tip of femoral stem at the lateral bone-cement interface in all 3 cases of bonding. The stresses were transfered very little to the cement of upper lateral bone-cement interface in partial and full debonded cases. Thus, once partial or full debonded cement-femoral stem interface occured, 3 times higher stress concentration were developed on the cement of proximal medial bone-cement interface than full bonded interface, and these could cause loosening of cemented total hip replacement. Clinically, preservation of more rigid cement-femoral stem interface may be important factor to prevent loosening of femoral stem.

Using FEM, we analyzed the stress changes on early osteonecrosis of femoral head as the necrotic area increases. A 3D FEM model of proximal femur was made from the CT scam data of fresh frozen adult proximal femur with the material properties from literature. The model consisted of 5994 elements and 5275 nodes. FE analyses were peformed using MSC/NASTRAN. At normal states, stress transmission is mainly along the primary compression trabeculae(PCT). Until 60% involvement of PCT with necrotic lesion, stress transmission is still along the remained PCT. When the PCT involvement is from 60% to 85%, stress transmission is along the PCT and margin of the necrotic lesion. When involvement is more than 85%, stress is mostly transferred to posterior part of femoral head.

Early this year the construction of new high voltage power lines have been forced to stop due to the demonstration of residents in Kwa-chun. According to mutual agreement between the residents and Korea Electric Power Corporation, electromagnetic field(EMF) from present power lines was measured and EMF after completion of new power lines was estimated. The results show that EMF near power lines Is relatively low, and EMFnear electric substation is quite high due to the short distance between the power lines and ground. For 4 conduction 345kV line, magnetic field decreases to 3mG at the distance of 50m from the power line.

A way of quantitatively describing the tissue architecture we have investigated when developing a computer program for malignancy grading of transitional cell bladder carcinoma. The minimum spanning trees, MST was created by connecting the center points of the nuclei in the tissue section image. These nuclei were found by thresholding the image at an automatically determined threshold followed by a connected component labeling and a watershed algorithm for separation of overlapping nuclei. Clusters were defined in the MST by thresholding the edge lengths. For these clusters geometric and densitometric features were measures. These features were compared by multivariate statistical methods to the subjective grading by the pathologists and the resulting correspondence was 85% on a material of 40 samples.

In general, the physiological systems have shown nonlinear complex phenomena. This study analyzes nonlinear characteristics of the flow of peripheral blood vessel dynamics in physiological systems using chaos theory. We performed this study by means of several quantity methods and power spectrum. The quantity methods are a phase space reconstruction and a poincare's map. And the power spectrum method is a conventional linear analysis. Experimental data have been acquired from examining 10 diabetic patients, and 10 control subjects in initial stable state. In acquisition experminetal data, we anlysized the differences of nonlinear characteristics between diabetic group and control group. The results of quality analysis methods showed the flow of peripheral blood vessel had the nonlinear and chaotic characteristics, screening a strange attractor on reconstructed phase space. In conclusion, the flow dynamics of peripheral blood vessel had a chaotic behavior of nonlinear dynamic systems, dynamic system, and differences of characteristic of nonlinear dynamic system.

Background: Recently, measure of heart rate variability and the nonlinear "complexity" of heart rate dynamics have been used as indicators of cardiovascular health. Several investigators have demonstrated that heart rate variability decreased in aging, congestive heart failure and coronary heart disease. Because hypertensive patients showed alternation of cardiovascular homeostasis, we designed this study to evaluate the effect of anesthesia in hypertensive patients with approximate entropy (ApEn). Methods: With informed consent, eighteen normotensive patients and eighteen hypertensive patients were given no premedication. ECG data were collected from 10 minutes before induction to 15 minutes after induction. Collected ECG data were stored into computer binary files. We calculated ApEn from the collected ECG data. Results: Before induction, ApEn of hypertensive patients was significantly lower than normotensive patients(p<0.05). During induction and maintain of anesthesia, there was no difference of ApEn between two groups. During induction and maintain of anesthesia, in normotensive group, ApEn was significantly lower than that of preinduction(p<0.05). And ApEn during maintain of anesthesia was lower than that of induction(p<0.05). During maintain of anesthesia, in hypertensive group, ApEn was significantly lower than that of preinduction(p<0.05). Conclusions: Before induction, ApTn of hypertensive patients is significantly lower than normotensive patients. As anesthesia was deepened, ApEn of two groups were decreased. Because the baroreflex of hypertensive patients is already decreased, decreasing of ApEn of hypertensive patients during anesthesia is less than that of normotnesive patients.

This paper describes the criterias to evaluate arousal states of subject and these are applied to contort arousal level. Correction factor was introdued to compensate under or over evaluated Nz due to the different initial basal skin impedance. These criteria and correction factor were worked well to increase the arousal level.

The purpose of this paper is to improve the P-wave detection capacity using wavelet transform. The first procedure is to remove baseline drift using the median filter. The second procedure is to cancel ECG's QRS-T complex with ECG's QRS-T complex templete to get P-wave candidate. Before we cancelled out the QRS-T complex, we estimated the best matching between templete and QRS-T complex to minimize the error. Then, Harr wavelet was used to eleminate the high frequency noise of ECG wave form cancelled the QRS-T complex. Finally, P-wave was discriminated and confirmed by threshold value. By using this method, We can got the around 95.1% P-wave detection.