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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of Biomedical Engineering Research
Journal Basic Information
Journal DOI :
The Korea Society of Medical and Biological Engineering
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Volume & Issues
Volume 35, Issue 6 - Dec 2014
Volume 35, Issue 5 - Oct 2014
Volume 35, Issue 4 - Aug 2014
Volume 35, Issue 3 - Jun 2014
Volume 35, Issue 2 - Apr 2014
Volume 35, Issue 1 - Feb 2014
Selecting the target year
Unrestrained Electrocardiograph Based on Textile Electrode and Smartphone Application for Assessment of Bicycle Exercise
Hwang, L.Y. ; Shin, Y.E. ; Choi, W.H. ; Shin, T.M. ;
Journal of Biomedical Engineering Research, volume 35, issue 5, 2014, Pages 111~118
DOI : 10.9718/JBER.2014.35.5.111
As assessment of quantitative energy expenditure for effective exercise is becoming more important, many researches about the monitoring system for exercise status or result have been actively carried out. In this case, however, bicycle riders feel restrained and uncomfortable because the riders should wear a belt-type electrocardiograph or a watch-type accelerometer or GPS system during the assessment of bicycle exercise. In this study, therefore, an electrocardiograph based on textile electrode was developed for measuring ECG and calculating heart rate from the bicycle rider without feeling restraint, and smartphone application was also developed for monitoring the heart rate.
Estimation of Ventricular Assist Device Outflow with the Pressures in Air Pressure Line
Kim, Young Il ; Her, Keun ; Kang, Seong Min ; Choi, Seong Wook ;
Journal of Biomedical Engineering Research, volume 35, issue 5, 2014, Pages 119~124
DOI : 10.9718/JBER.2014.35.5.119
A Ventricular assist device (VAD) is one of the most efficient treatments to raise the survivability of the end stage heart failure patient. However, some of LVAD patients have died for the failures and improper control of LVAD. To detect critical dangers in LVAD, the monitoring methods of LVAD outflow have been requested, because it can be affected by patient`s hemodynamic states and abnormal conditions of LVAD. In the case of an external pulsatile LVAD, the air movement through the air line can be used to estimate LVAD outflow. In this study, the air movement in the air-line of the extracorporeal pulsatile LVAD was measured with a differential pressure sensor between different points. The precise estimation of air movement could be achieved by additional measurement of air pressure. In a series of in-vitro experiments, the LVAD outflow were changed according to the afterload of LVAD and the differential pressure of LVAD didn`t have close correlation with the LVAD outflow that were measured with an ultrasonic flowmeter at the same time. However, new precise estimation with the data from differential pressure and one point pressure in the air-line showed higher correlations with LVAD outflow.
The Verification of Photoplethysmography Using Green Light that Influenced by Ambient Light
Chang, K.Y. ; Ko, H.C. ; Lee, J.J. ; Yoon, Young Ro ;
Journal of Biomedical Engineering Research, volume 35, issue 5, 2014, Pages 125~131
DOI : 10.9718/JBER.2014.35.5.125
The purpose of this study is to verify the utility of reflected photoplethysmography sensor using two green light emitting diodes that influenced by ambient light. Recently it has been studied that green light emitting diode is suitable for light source of reflected photoplethysmography sensor at low temperature and high temperature. Another study showed that, green light is better for monitoring heart rate during motion than led light. However, it has a bad characteristic about ambient light noise. To verify the utility of reflected photoplethysmography sensor using green light emitting diode, this study measures the photoplethysmography signal that is distorted by ambient light and will propose a solution. This study has two parts of research method. One is measurement system that composed sensor and board. The sensor is made up PE-foam and Non-woven fabric for flexible sensor. The photoplethysmography signal is measured by measurement board that composed high-pass filter, low-pass filter and amplifier. Ambient light source is light bulb and white light emitting diode that has three steps brightness. Photoplethysmography signal is measured with lead II electrocardiography signal at the same time and it is measured at the finger and radial artery for 1 minute, 1000 Hz sampling rate. The lead II electrocardiography signal is a standard signal for heart rate and photoplethysmography signal that measured at the finger is a standard signal for waveform. The test is repeated 3 times using three sensor. The data is processed by MATLAB to verify the utility by comparing the correlation coefficient score and heart rate. The photoplethysmography sensor using two green light emitting diodes is shown better utility than using one green light emitting diode and red light emitting diode at the ambient light. The waveform and heart rate that measured by two green light emitting diodes are more identical than others. The amount of electricity used is less than red light emitting diode and error peak detectability factor is the lowest.
An Iterative Image Reconstruction Method for the Region-of-Interest CT Assisted from Exterior Projection Data
Jin, Seung Oh ; Kwon, Oh-Kyong ;
Journal of Biomedical Engineering Research, volume 35, issue 5, 2014, Pages 132~141
DOI : 10.9718/JBER.2014.35.5.132
In an ordinary CT scan, a large number of projections with full field-of-view (FFOV) are necessary to reconstruct high resolution images. However, excessive x-ray dosage is a great concern in FFOV scan. Region-of-interest (ROI) CT or sparse-view CT is considered to be a solution to reduce x-ray dosage in CT scanning, but it suffers from bright-band artifacts or streak artifacts giving contrast anomaly in the reconstructed image. In this study, we propose an image reconstruction method to eliminate the bright-band artifacts and the streak artifacts simultaneously. In addition to the ROI scan for the interior projection data with relatively high sampling rate in the view direction, we get sparse-view exterior projection data with much lower sampling rate. Then, we reconstruct images by solving a constrained total variation (TV) minimization problem for the interior projection data, which is assisted by the exterior projection data in the compressed sensing (CS) framework. For the interior image reconstruction assisted by the exterior projection data, we implemented the proposed method which enforces dual data fidelity terms and a TV term. The proposed method has effectively suppressed the bright-band artifacts around the ROI boundary and the streak artifacts in the ROI image. We expect the proposed method can be used for low-dose CT scans based on limited x-ray exposure to a small ROI in the human body.
Performance Comparison of Ray-Driven System Models in Model-Based Iterative Reconstruction for Transmission Computed Tomography
Jeong, J.E. ; Lee, S.J. ;
Journal of Biomedical Engineering Research, volume 35, issue 5, 2014, Pages 142~150
DOI : 10.9718/JBER.2014.35.5.142
The key to model-based iterative reconstruction (MBIR) algorithms for transmission computed tomography lies in the ability to accurately model the data formation process from the emitted photons produced in the transmission source to the measured photons at the detector. Therefore, accurately modeling the system matrix that accounts for the data formation process is a prerequisite for MBIR-based algorithms. In this work we compared quantitative performance of the three representative ray-driven methods for calculating the system matrix; the ray-tracing method (RTM), the distance-driven method (DDM), and the strip-area based method (SAM). We implemented the ordered-subsets separable surrogates (OS-SPS) algorithm using the three different models and performed simulation studies using a digital phantom. Our experimental results show that, in spite of the more advanced features in the SAM and DDM, the traditional RTM implemented in the OS-SPS algorithm with an edge-preserving regularizer out-performs the SAM and DDM in restoring complex edges in the underlying object. The performance of the RTM in smooth regions was also comparable to that of the SAM or DDM.
Dynamically Collimated CT Scan and Image Reconstruction of Convex Region-of-Interest
Jin, Seung Oh ; Kwon, Oh-Kyong ;
Journal of Biomedical Engineering Research, volume 35, issue 5, 2014, Pages 151~159
DOI : 10.9718/JBER.2014.35.5.151
Computed tomography (CT) is one of the most widely used medical imaging modality. However, substantial x-ray dose exposed to the human subject during the CT scan is a great concern. Region-of-interest (ROI) CT is considered to be a possible solution for its potential to reduce the x-ray dose to the human subject. In most of ROI-CT scans, the ROI is set to a circular shape whose diameter is often considerably smaller than the full field-of-view (FOV). However, an arbitrarily shaped ROI is very desirable to reduce the x-ray dose more than the circularly shaped ROI can do. We propose a new method to make a non-circular convex-shaped ROI along with the image reconstruction method. To make a ROI with an arbitrary convex shape, dynamic collimations are necessary to minimize the x-ray dose at each angle of view. In addition to the dynamic collimation, we get the ROI projection data with slightly lower sampling rate in the view direction to further reduce the x-ray dose. We reconstruct images from the ROI projection data in the compressed sensing (CS) framework assisted by the exterior projection data acquired from the pilot scan to set the ROI. To validate the proposed method, we used the experimental micro-CT projection data after truncating them to simulate the dynamic collimation. The reconstructed ROI images showed little errors as compared to the images reconstructed from the full-FOV scan data as well as little artifacts inside the ROI. We expect the proposed method can significantly reduce the x-ray dose in CT scans if the dynamic collimation is realized in real CT machines.
Accuracy Evaluation of Bi-medium Deep Body Thermometer Based on Finite Element Simulation
Sim, S.Y. ; Ryou, H.S. ; Kim, H.B. ; Jeong, J.H. ; Lee, S.J. ; Kim, S.M. ; Park, Kwang Suk ;
Journal of Biomedical Engineering Research, volume 35, issue 5, 2014, Pages 160~168
DOI : 10.9718/JBER.2014.35.5.160
Continuous body temperature monitoring is useful and essential in diverse medical procedures such as infection onset detection, therapeutic hypothermia, circadian rhythm monitoring, sleep disorder assessment, and gynecological research. However, the existing thermometers are too invasive or intrusive to be applied to long-term body temperature monitoring. In our previous study, we invented the bi-medium deep body thermometer which can noninvasively and continuously monitor deep tissue temperature. And the ratio of thermal resistances expressed as K-value should be obtained to estimate body temperature with the thermometer and it can be different under various measurement environments. Although the device was proven to be useful through preliminary simulation test and small group of human study, the experimental environment was restrictive in our previous approach. In this study, a finite element simulation was executed to obtain the K-value and evaluate the accuracy of bi-medium thermometer under various measurement environments. In addition, K-value estimation equation was developed by analyzing the influence of 5 measurement environmental factors (medium length, medium height, tissue depth, blood perfusion rate, and ambient temperature) on K-value. The results revealed that the estimation accuracy of bi-medium deep body thermometer based on computer simulation was very high (RMSE <
) in various measurement environments. Also, bi-medium deep body thermometer based on K-value estimation equation showed relatively accurate results (RMSE <
) except for one case. Although the K-value estimation technology should be improved for more accurate body temperature estimation, the results of finite element simulation showed that bi-medium deep body thermometer could accurately measure various tissue temperatures under diverse environments.
Unconstrained Estimation of Body Postures on Bed Using Polyvinylidene Fluoride Film-based Sensor
Seo, Sangwon ; Hwang, Su Hwan ; Yoon, Hee Nam ; Jung, Da Woon ; Choi, Jae Won ; Lee, Yu Jin ; Jeong, Do-Un ; Park, Kwang Suk ;
Journal of Biomedical Engineering Research, volume 35, issue 5, 2014, Pages 169~176
DOI : 10.9718/JBER.2014.35.5.169
As body postures on bed affects various sleep related diseases, it is considered as important information when monitoring sleeping in daily life. Though there have already been a few approaches to monitor body postures on bed conventionally, the development for simple and unconstrained methods is still needed to realize the long-term daily monitoring. Focusing on the fact that ballistocardiogram changes depending on the body postures on bed, we developed a novel method to estimate body posturesusing extremely simple, film-type ballistocardiogram sensor which is based on polyvinylidene fluoride(PVDF) film. With 10 subjects, we performed two experiments. One was for an estimation test to show that body postures on bed can be estimated by ballistocardiogram, and the other was for a reproducibility test to present the feasibility of ballistocardiogram based body postures monitoring. To estimate body postures on bed, we made an individual template set of body postures by designating one ballistocardiogram (BCG) sample as a template in each postures. Then, we calculated Pearson`s correlation coefficients between a sample and each templates and estimated the body posture of the sample by choosing a posture which corresponds to the most significant correlation coefficients. As a result, we estimated body postures on bed with 99.2% accuracy in average and found that the estimation using ballistocardiogram is reproducible.