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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
Journal of Biomedical Engineering Research
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Journal DOI :
The Korea Society of Medical and Biological Engineering
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Volume & Issues
Volume 30, Issue 6 - Dec 2009
Volume 30, Issue 5 - Oct 2009
Volume 30, Issue 4 - Aug 2009
Volume 30, Issue 3 - Jun 2009
Volume 30, Issue 2 - Apr 2009
Volume 30, Issue 1 - Feb 2009
Selecting the target year
Dynamic Flow Lithography Technologies
Chung, Su-Eun ; Park, Wook ; Kwon, Sung-Hoon ;
Journal of Biomedical Engineering Research, volume 30, issue 6, 2009, Pages 453~460
In this review paper, concepts in optofluidics are applied to an advanced manufacturing technology based on self-assembled microparts. The "optical" aspect of optofluidics will be described in the context of photolithography, and the "fluidic" aspect will be discussed in the context of self-assembly. First, optofluidic maskless lithography will be introduced as a dynamic fabrication method to generate microparticles in microfluidic channels. Next, the history and application of optofluidic lithography will be presented.
Chemical Shift Artifact Correction in MREIT
Minhas, Atul S. ; Kim, Young-Tae ; Jeong, Woo-Chul ; Kim, Hyung-Joong ; Lee, Soo-Yeol ; Woo, Eung-Je ;
Journal of Biomedical Engineering Research, volume 30, issue 6, 2009, Pages 461~468
Magnetic resonance electrical impedance tomography (MREIT) enables us to perform high-resolution conductivity imaging of an electrically conducting object. Injecting low-frequency current through a pair of surface electrodes, we measure an induced magnetic flux density using an MRI scanner and this requires a sophisticated MR phase imaging method. Applying a conductivity image reconstruction algorithm to measured magnetic flux density data subject to multiple injection currents, we can produce multi-slice cross-sectional conductivity images. When there exists a local region of fat, the well-known chemical shift phenomenon produces misalignments of pixels in MR images. This may result in artifacts in magnetic flux density image and consequently in conductivity image. In this paper, we investigate chemical shift artifact correction in MREIT based on the well-known three-point Dixon technique. The major difference is in the fact that we must focus on the phase image in MREIT. Using three Dixon data sets, we explain how to calculate a magnetic flux density image without chemical shift artifact. We test the correction method through imaging experiments of a cheese phantom and postmortem canine head. Experimental results clearly show that the method effectively eliminates artifacts related with the chemical shift phenomenon in a reconstructed conductivity image.
Development of a Non-invasive Ultrasonic Measurement System for tissue elasticity
Lee, G.J. ; Choi, W.H. ; Yu, J.W. ; Seo, J.B. ; Choi, S.H. ; Shin, T.M. ;
Journal of Biomedical Engineering Research, volume 30, issue 6, 2009, Pages 469~475
Diseases caused by indurate tissues of the internal organs are liver cirrhosis and abdominal sclerosis. The cause of chronic gastro-intestinal disease is a digestive system disorder and a defecation disorder. They impede peristaltic movement and digestive system with the symptom that indurate tissues. The purpose of the present study was to determine the disease grade quantitatively by measuring an indurated standard of tissues and organs. For the measurement of elasticity, we designed the system that measure the displacement of the substance and approved pressure using ultrasound transducer. For verification of developed system, we compared elasticity as results of experiment between the developed system and public elasticity measurement machine at individual plastic phantoms made by plastic hardener and softener. Elasticity of the plastic phantoms is averagely 0.007MPa lower measured by developed system than Micro-indenter, and less than 10% errors. Comparing with economical value and accuracy between developed system and Micro-indenter, the system is significant of measurement for tissue elasticity. Thus, it is possible to measure a elasticity at human tissue and organ. A chronic gastro-disease as well as grade could be decided objective validity using this system.
A Ring Artifact Correction Method for a Flat-panel Detector Based Micro-CT System
Kim, Gyu-Won ; Lee, Soo-Yeol ; Cho, Min-Hyoung ;
Journal of Biomedical Engineering Research, volume 30, issue 6, 2009, Pages 476~481
The most troublesome artifacts in micro computed tomography (micro-CT) are ring artifacts. The ring artifacts are caused by non-uniform sensitivity and defective pixels of the x-ray detector. These ring artifacts seriously degrade the quality of CT images. In flat-panel detector based micro-CT systems, the ring artifacts are hardly removed by conventional correction methods of digital radiography, because very small difference of detector pixel signals may make severe ring artifacts. This paper presents a novel method to remove ring artifacts in flat-panel detector based micro-CT systems. First, the bad lines of a sinogram which are caused by defective pixels of the detector are identified, and then, they are corrected using a cubic spline interpolation technique. Finally, a ring artifacts free image is reconstructed from the corrected projections. We applied the method to various kinds of objects and found that the image qualities were much improved.
Computer Simulation of the Transanal Endoscopic Microsurgery for the Improvement of Optimal Operation Range
Kim, Hyung-Tae ; Kim, Kwang-Gi ; Sohn, Dae-Kyung ; Kim, Hyun-Ho ; Nam, Kyoung-Won ;
Journal of Biomedical Engineering Research, volume 30, issue 6, 2009, Pages 482~488
Conventional devices for transanal endoscopic microsurgery that are currently used clinically for intestine or rectal cancer patients have 40 mm external diameter of rectoscope tube - induces anal damage and long-term postoperative pain for small-sized patients. In this paper, we designed rectum and rectoscope models and calculated the changing trends of operation area of the surgical tools in accordance with the step-by-step variation of design parameters of the rectoscope tube - external diameter, axial length, and distal angle. Using the results of computer simulation, we suggested an optimal set of design parameters that minimizes external diameter of the rectoscope tube and at the same time, maintains similar operation area of the surgical tools compared with commercialized devices (
). The results of the simulation showed that the optimal design parameters were 35 mm external diameter, 100 mm axial length, and
distal angle of the rectoscope tube. This result can be applied to the development of endoscopic microsurgery device that can minimize side effects to the intestine or rectal cancer patients.
Development of a Respiration Sensor Using Plastic Optical Fiber
Yoo, Wook-Jae ; Baek, Ji-Yun ; Cho, Dong-Hyun ; Jang, Kyoung-Won ; Seo, Jeong-Ki ; Heo, Ji-Yeon ; Lee, Bong-Soo ; Cho, Young-Ho ; Park, Byung-Gi ; Moon, Joo-Hyun ;
Journal of Biomedical Engineering Research, volume 30, issue 6, 2009, Pages 489~494
In this study, we fabricated a plastic optical fiber based sensor which can monitor the respiration of a patient. The circumference changes of the abdomen were measured using a mirror, a light source and optical detectors because the circumferences of the abdomen could be varied with respiration. The intensity of the reflected lights were measured according to the changes of distance between mirror and plastic optical fiber connected to a light source and a photodiode-amplifier system using a Y-coupler. The respiration signals of fiber-optic sensor system were compared with those of the respiratory and temperature transducers of the
system. It is expected that a fiber-optic respiration sensor could be developed for real time respiration monitoring during MRI procedure based on this study.
Study on the Characteristic of Dynamic Postural Control during Horizontal Translation of Support Surface
Oh, G.Y. ; Piao, Y.J. ; Kwon, T.K. ; Kim, N.G. ;
Journal of Biomedical Engineering Research, volume 30, issue 6, 2009, Pages 495~502
This paper investigated the effects of dynamic postural control for maintaining upright standing on a support surface during continuous sinusoidal horizontal translation in anterior-posterior direction. 15 healthy young subjects participated in this experiment. The analysis of body movement was analyzed using Ariel Performance Analysis System. Motion pattern was analyzed by seven markers on subject's body. Position of markers were head, chest, hip, right knee, left knee, right ankle and left ankle. Seven different frequencies of support surface were employed ; 0.1, 0.25, 0.5, 0.75, 1, 1.5 and 2Hz at 2cm of moving path of motionbase. The experiments were performed dynamic postural reponses at the condition of eye open. The results showed that median frequency of the knee, ankle were increased in all frequency bands. Following the frequency of perturbation increased, postural control strategy was changed from ankle strategy to combined strategy. The experiment results could be applied to the dynamic postural training for the elderly and the rehabilitation training for the patients to improving the ability of postural control.
Light Modulation based on PPG Signal Processing for Biomedical Signal Monitoring Device
Lee, Han-Wook ; Lee, Ju-Won ; Jeong, Won-Geun ; Kim, Seong-Hoo ; Lee, Gun-Ki ;
Journal of Biomedical Engineering Research, volume 30, issue 6, 2009, Pages 503~509
The development of technology has led to ubiquitous health care service, which enables many patients to receive medical services anytime and anywhere. For the ubiquitous health care environment, real-time measurement of biomedical signals is very important, and the medical instruments must be small and portable or wearable. So, such devices have been developed to measure biomedical signals. In this study, we develop the biomedical monitoring device which is sensing the PPG signal, one of the useful signal in the field of ubiquitous healthcare. We design a watch-like biomedical signal monitoring system without a finger probe to prevent the user's inconvenience. This system obtains the PPG from the radial artery using a sensor in the wrist band. But, new device developed in this paper is easy to get the motion artifacts. So, we proposed new algorithm removing the motion artifacts from the PPG signal. The method detects motion artifacts by changing the degree of brightness of the light source. If the brightness of the light source is reduced, the PPG pulses will disappear. When the PPG pulses have disappeared completely, the remaining signal is not the signal that results from the changing blood flow. We believe that this signal is the motion artifact and call it the noise reference signal. The motion artifacts are removed by subtracting the noise reference signal from the input signal. We apply this algorithm to the system, so we can stabilize the biomedical monitoring system we designed.
Development of Blood Pressure Estimation Algorithm Using Variable Characteristic Ratios on Oscillometric Method
Shin, Joon ;
Journal of Biomedical Engineering Research, volume 30, issue 6, 2009, Pages 510~515
In this paper, variable characteristic ratio algorithm based on oscillometric method is proposed to enhance the accuracy of blood pressure measurement. We combined the slope-based approach and fuzzy inference technique to change the characteristic ratios of height-based method. The proposed algorithm was assessed on 255 measurements from 85 subjects and compared with the conventional height-based algorithm. The testing results showed that the developed algorithm achieved an overall grade A for both systolic and diastolic blood pressures according to the BHS protocol. And, mean standard deviation between the observers and the developed algorithm were 5.71mmHg and 6.29mmHg for systolic and diastolic pressures respectively, which also fulfilled the AAMI criteria. In conclusion, this algorithm was successfully developed and recommended for further clinical trials with the wider adult population.
Determination of filtering condition and threshold for detection of Gait-Cycles under Various Gait Speeds and Walkway Slopes
Kwon, Yu-Ri ; Kim, Ji-Won ; Lee, Jae-Ho ; Tack, Gye-Rae ; Eom, Gwang-Moon ;
Journal of Biomedical Engineering Research, volume 30, issue 6, 2009, Pages 516~520
The purpose of this study is to determine optimal filtering condition and threshold for the detection of gait-cycles for various walkway slopes as well as gait velocities. Ten young healthy subjects with accelerometer system on thigh and ankle walked on a treadmill at 9 conditions (three speeds and three slopes) for 5 minutes. Two direction signals, i.e. anterior-posterior (AP) and superior-inferior (SI) directions, of each sensor (four sensor orientations) were used to detect specific events of gait cycle. Variation of the threshold (from -1G to 1G) and lowpass cutoff frequency (fc) were applied to the event detection and their performance was evaluated according to the error index (EI), which was defined as the combination of the accuracy and false positive rate. Optimal fc and threshold were determined for each slope in terms of the EI. The optimal fc, threshold and their corresponding EI depended much on the walkway slope so that their coefficients of variation (CV) ranged 19~120%. When all data for 3 slopes were used in the identification of optimal conditions for each sensor, the best error indices for all sensor orientations were comparable ranging 1.43~1.76%, but the optimal fc and threshold depended much on the sensor position. The result indicates that the gait-cycle detection robust to walkway slope is possible by threshold method with well-defined filtering condition and threshold.
Evaluation of Postural Stability according to characteristics of Electrical Stimulation on the ankle muscles
Lee, S.Y. ; Yu, M. ; Kim, N.G. ; Kim, D.W. ;
Journal of Biomedical Engineering Research, volume 30, issue 6, 2009, Pages 521~528
This study is about to evaluation of postural stability according to characteristics of electrical stimulation on the ankle muscles. We measured body sway(center of pressure, COP) when various parameters of electrical stimulation was applied to ankle muscles in stable and unstable posture. Subjects consisted of 10 young adults, and electrical stimulation was delivered on right and left of tibialis anterior and Achilles tendon. The body sway was measured during electrical stimulation of three duty cycle and frequencies in stable posture and three amplitudes of sensory threshold in unstable posture. Consequently, the COP Shift is higher during electrical stimulation of 1/30(duty ratio) and 100Hz(frequency) in stable posture. In unstable posture, 100% amplitude of sensory threshold induced postural stability. These findings are important for the rehabilitation system of postural stability and the use of electrical stimulation as somatosensory information.
A Study on Acoustic Masking Effect by Frame-Based Formant Enhancement
Jeon, Yu-Yong ; Kim, Kyu-Sung ; Lee, Sang-Min ;
Journal of Biomedical Engineering Research, volume 30, issue 6, 2009, Pages 529~534
One of the characteristics of the hearing impaired is that their frequency selectivity is poorer than that of the normal hearing. To compensate this, formant enhancement algorithms and spectral contrast enhancement algorithms have been developed. However in some cases, these algorithms fail to improve the frequency selectivity of the hearing impaired. One of the reasons is the acoustic masking among enhanced formants. In this study, we tried to enhance the formants based on the individual masking characteristic of each subject. The masking characteristic used in this study was minimum level difference (MLD) between the first formant to the second formant while acoustic masking was occurred. If the level difference between the two formants in each frame is larger than the MLD, the gain of the first formant was decreased to reduce the acoustic masking that occurred among formants. As a result of the speech discrimination test, using formant enhanced speeches, speech discrimination score (SDS) of the speeches having differently enhanced formants was significantly superior to SDS of the speeches having equally enhanced formants. It means that suppression of the acoustic masking among formants improve frequency selectivity of the hearing impaired.