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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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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 27, Issue 6 - Dec 2006
Volume 27, Issue 5 - Oct 2006
Volume 27, Issue 4 - Aug 2006
Volume 27, Issue 3 - Jun 2006
Volume 27, Issue 2 - Apr 2006
Volume 27, Issue 1 - Feb 2006
Selecting the target year
A New Method for Unconstrained Pulse Arrival Time (PAT) Measurement on a Chair
Kim Ko-Keun ; Chee Young-Joon ; Lim Yong-Gyu ; Choi Jin-Wook ; Park Kwang-Suk ;
Journal of Biomedical Engineering Research, volume 27, issue 3, 2006, Pages 83~88
A new method of measuring pulse arrival time (PAT), which is usually used for the estimation of systolic blood pressure, in an unconstrained manner using a chair, is proposed. The capacitive-coupled ECG (CC-ECG) measurement system and the air cushion with balancing tubes system were used for unconstrained PAT measurement. Firstly, the correlation between the standard PAT (S-PAT) from the photoplethysmography (PPG) and the PAT measured in an unconstrained manner (U-PAT) was evaluated. It was observed that U-PAT, which is the time delay from the R-peak of ECG to the steepest decent point of air cushion pressure wave, is significantly correlated with the S-PAT. Secondly, systolic blood pressure (SBP) measured by the radial tonometer is compared to the U-PAT. The ten-beat averaged U-PAT removed respiration effects and demonstrated a high intra-subject correlation with SBP in all participants. Finally, the tonometry SBP was estimated from these U-PAT values for one participant intermittently during half a day.
A Method to Estimate Peripheral Systolic Blood Pressure using Pulse Transit Time during Bicycle Ergometer Exercise of Healthy Korean Subjects in their Twenties
Lee Jeong-Chan ; Eo Yun-Hye ; Park Kyung-Mo ; Park Seung-Hun ;
Journal of Biomedical Engineering Research, volume 27, issue 3, 2006, Pages 89~93
A simple algorithm that can be used to estimate a healthy person's blood pressure using pulse transit time is proposed in this paper. Fifty healthy students participated in the experiment that was conducted in line with the study. The subjects were asked to exercise on several exercise levels using a bicycle ergometer. Their blood pressures during the succeeding rest period were measured. A simple method was proposed to illustrate the relationship between blood pressure and pulse transit time. The systolic blood pressures as well as the heights and weights of the subjects were regarded as the proper parameters, and a second-order regression curve was produced to estimate the subjects' blood pressures. The mean error of estimation was less than 10 mmHg, which was the mean error of manual measurement. Although our estimation model is so simple, it can be used to estimate continuous blood pressure measurement for bicycle ergometer exercise. The electrocardiograms, photoplethysmograms, and blood pressures, however, could not be measured simultaneously As such, their estimation may be slightly different from the results taken from simultaneous measurements.
Computational Analysis of Impulse Forces Affecting Coil Compaction in Cerebral Aneurysms
Cha Kyung-Se ; Balaras Elias ;
Journal of Biomedical Engineering Research, volume 27, issue 3, 2006, Pages 94~100
The effectiveness of the treatment of intracranial aneurysms with endovascular coiling depends on coil packing density, the location of aneurysm, its neck dimensions with respect to the aneurysm dome, and its size with respect to the surrounding tissue. Clinical data also suggests that the aneurysm neck size is the main predictor of aneurysm recanalization. In this study, the force impinging on the aneurysm neck in an idealized aneurysm was calculated by using a three dimensional finite volume method for the non-Newtonian incompressible laminar flow. To quantify the effect of neck size on the impingement force, calculations were performed for aneurysm neck diameters (Da) varying from 10% to 100% of the parent artery diameter (Dp). Also, maximum impingement forces were represented by a function of the ratio of the aneurysm neck to the diameter of the parent vessel. The results show that the hemodynamic forces exerted on the coil mass at the aneurysm neck due to the pulsatile blood flow are larger for wide necked aneurysms.
HMM-Based Automatic Speech Recognition using EMG Signal
Lee Ki-Seung ;
Journal of Biomedical Engineering Research, volume 27, issue 3, 2006, Pages 101~109
It has been known that there is strong relationship between human voices and the movements of the articulatory facial muscles. In this paper, we utilize this knowledge to implement an automatic speech recognition scheme which uses solely surface electromyogram (EMG) signals. The EMG signals were acquired from three articulatory facial muscles. Preliminary, 10 Korean digits were used as recognition variables. The various feature parameters including filter bank outputs, linear predictive coefficients and cepstrum coefficients were evaluated to find the appropriate parameters for EMG-based speech recognition. The sequence of the EMG signals for each word is modelled by a hidden Markov model (HMM) framework. A continuous word recognition approach was investigated in this work. Hence, the model for each word is obtained by concatenating the subword models and the embedded re-estimation techniques were employed in the training stage. The findings indicate that such a system may have a capacity to recognize speech signals with an accuracy of up to 90%, in case when mel-filter bank output was used as the feature parameters for recognition.
MRI Content-Adaptive Finite Element Mesh Generation Toolbox
Lee W.H. ; Kim T.S. ; Cho M.H. ; Lee S.Y. ;
Journal of Biomedical Engineering Research, volume 27, issue 3, 2006, Pages 110~116
Finite element method (FEM) provides several advantages over other numerical methods such as boundary element method, since it allows truly volumetric analysis and incorporation of realistic electrical conductivity values. Finite element mesh generation is the first requirement in such in FEM to represent the volumetric domain of interest with numerous finite elements accurately. However, conventional mesh generators and approaches offered by commercial packages do not generate meshes that are content-adaptive to the contents of given images. In this paper, we present software that has been implemented to generate content-adaptive finite element meshes (cMESHes) based on the contents of MR images. The software offers various computational tools for cMESH generation from multi-slice MR images. The software named as the Content-adaptive FE Mesh Generation Toolbox runs under the commercially available technical computation software called Matlab. The major routines in the toolbox include anisotropic filtering of MR images, feature map generation, content-adaptive node generation, Delaunay tessellation, and MRI segmentation for the head conductivity modeling. The presented tools should be useful to researchers who wish to generate efficient mesh models from a set of MR images. The toolbox is available upon request made to the Functional and Metabolic Imaging Center or Bio-imaging Laboratory at Kyung Hee University in Korea.
Implementation of an Ultrasound Elasticity Imaging System
Cho Gae-Young ; Yoon Ra-Young ; Park Jeong-Man ; Kwon Sung-Jae ; Ahn Young-Bok ; Bae Moo-Ho ; Jeong Mok-Kun ;
Journal of Biomedical Engineering Research, volume 27, issue 3, 2006, Pages 117~124
Recently, active research has been going on to measure the elastic modulus of human soft tissue with medical ultrasound imaging systems for the purpose of diagnosing cancers or tumors which have been difficult to detect with conventional B-mode imaging techniques. In this paper, a real-time ultrasonic elasticity imaging system is implemented in software on a Pentium processor-based ultrasonic diagnostic imaging system. Soft tissue is subjected to external vibration, and the resulting tissue displacements change the phase of received echoes, which is in turn used to estimate tissue elasticity. It was confirmed from experiment with a phantom that the implemented elasticity imaging system could differentiate between soft and hard regions, where the latter is twice harder than the former, while operating at an adequate frame rate of 20 frames/s.
Image Analysis Algorithm for the Corneal Endothelium
Kim Young-Yoon ; Kim Beop-Min ; Park Hwa-Joon ; Im Kang-Bin ; Lee Jin-Su ; Kim Dong-Youn ;
Journal of Biomedical Engineering Research, volume 27, issue 3, 2006, Pages 125~130
The number of the living endothelial cells and the shape of those are very import clinical parameters for the evaluation of the quality of cornea. In this paper, we developed the automated endothelial cell counting and shape analysis algorithm for a confocal microscope. Since, the endothelial images from the confocal microscope has a non-uniform illumination and low contrast between cell boundaries and cell bodies, it is very difficult to segment the cells from the endothelial images. To cope with these difficulties, we proposed the new two stage image processing algorithm. At first stage algorithm, we used a high-pass filter and histogram equalization to compensate the non-uniform brightness pattern and a morphological filter and a watershed method are applied to detect the boundary of cells. From this stage, we could count the number of cells in an endothelial image. At second stage algorithm, we used a Voronoi diagram method to classify the shape of cells. This cell shape analysis and the percent of hexagonal cells are very sensitive in detecting the early endothelium damage. To evaluate the performance of the proposed system, we p개cessed seven endothelial images obtained using a confocal microscope. The proposed system correctly counted 95.5% cells and classified 92.0% of hexagonal cell shapes. This result is better than any others in this research area.
Detection of Onset and Offset Time of Muscle Activity in Surface EMG using the Kalman Smoother
Lee Jung-Hoon ; Lee Hyun-Sook ; Lee Young-Hee ; Yoon Young-Ro ;
Journal of Biomedical Engineering Research, volume 27, issue 3, 2006, Pages 131~141
A visual decision by clinical experts like physical therapists is a best way to detect onset and offset time of muscle activation. The current computer-based algorithms are being researched toward similar results of clinical experts. The new algorithm in this paper has an ability to extract a trend from noisy input data. Kalman smoother is used to recognize the trend to be revealed from disorderly signals. Histogram of smoothed signals by Kalman smoother has a clear boundary to separate muscle contractions from relaxations. To verify that the Kalman smoother algorithm is reliable way to detect onset and offset time of muscle contractions, the algorithm of Robert P. Di Fabio (published in 1987) is compared with Kalman smoother. For 31 templates of subjects, an average and a standard deviation are compared. The average of errors between Di Fabio's algorithm and experts is 109 milliseconds in onset detection and 142 milliseconds in offset detection. But the average between Kalman smoother and experts is 90 and 137 milliseconds in each case. Moreover, the standard deviations of errors are 133 (onset) and 210 (offset) milliseconds in Di Fabio's one, but 48 (onset) and 55 (offset) milliseconds in Kalman smoother. As a result, the Kalman smoother is much closer to determinations of clinical experts and more reliable than Di Fabio's one.