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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 19, Issue 6 - Dec 1998
Volume 19, Issue 5 - Oct 1998
Volume 19, Issue 4 - Aug 1998
Volume 19, Issue 3 - Jun 1998
Volume 19, Issue 2 - Apr 1998
Volume 19, Issue 1 - Feb 1998
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A Study on a Multiresolution Filtering Algorithm based on a Physical Model of SPECT Lesion Detectability
Kim, Jeong-Hui ; Kim, Gwang-Ik ;
Journal of Biomedical Engineering Research, volume 19, issue 6, 1998, Pages 551~562
Amultiresolution filtering algorithm based on the physical SPECT lesion detachability provides and optimal solution for SPECT reconstruction problem. Related to the previous study, we estimated the SPECT lesion detection capability by m minimum detectable lesion sizes (MDLSs), and generated m reconstruction filters which are designed to maximize the smoothing effect at a fixed MDLS-dependent resolution level
. The proposed multiresolution filtering algorithm used a coarse-to-fine approach for the m-level resolution filter images obtained from these m filters for a given projection image. First, the local homogeneity is determined for every pixel of the filter images, by comparing the local variance value computed in a window centered at the pixel and the mode determined from the distribution of the local variances. Based on the local homogeneity, the pixels declared as homogeneous are chosen from the filter image of the lowest resolution, and for the other pixels the same process is repeated for the higher resolution filter images. For the non-homogeneous pixels after this pixels after this repetition process ends, the pixel values of the highest resolution filter image are substituted. From the results of the simulated experiments, the proposed multiresolution filtering algorithm showed a strong smoothing effect in the homogeneous regions and a significant resolution improvement near the edge regions of the projection images, and so produced good adaptability effects in the reconstructed images.
Computer Simulation for Effects of Scintillator and Parallel Hole Collimator on Gamma Probe Imaging
Bong, Jeong-Gyun ; Kim, Hui-Jung ; Lee, Jong-Du ; Gwon, Su-Il ;
Journal of Biomedical Engineering Research, volume 19, issue 6, 1998, Pages 563~570
The purpose of this study was to investigate the effects of scintillator and collimator parameters that tradeoff between system sensitivity and spatial resolution. The parameters simulated using Monte Carlo program were scintillator thickness, colimator hole shape, septal thickness, and hole length. The results show that the sensitivity increases exponentially upto about 1 cm of scintillator thickness as the thickness increases. However the sensitivity is almost constant when the scintiallator is thicker than about 1 cm. The simulation of collimator hole shape shows that the hexagonal hole gives the best spatial resolution for the same system sensitivity. The system statical resolution is improved, as both collimator septal thickness and hole length increase, however that system sensitivity is rapidly decreased. In conclusion, The optimization of scintillator and collimator parameters using monte carlo simulation may be useful to develop a high-resolution miniature gamma probe.
A Study on the Generation of Ultrasonic Binary Image for Image Segmentation
Choe, Heung-Ho ; Yuk, In-Su ;
Journal of Biomedical Engineering Research, volume 19, issue 6, 1998, Pages 571~575
One of the most significant features of diagnostic ultrasonic instruments is to provide real time information of the soft tissues movements. Echocardiogram has been widely used for diagnosis of heart diseases since it is able to show real time images of heart valves and walls. However, the currently used ultrasonic images are deteriorated due to presence of speckle noises and image dropout. Therefore, it is very important to develop a new technique which can enhance ultrasonic images. In this study, a technique which extracts enhanced binary images in echocardiograms was proposed. For this purpose, a digital moving image file was made from analog echocardiogram, then it was stored as 8-bit gray-level for each frame. For an efficient image processing, the region containing the heat septum and tricuspid valve was selected as the region of interest(ROI). Image enhancement filters and morphology filters were used to reduce speckle noises in the images. The proposed procedure in this paper resulted in binary images with enhanced contour compared to those form the conventional threshold technique and original image processing technique which can be further implemented for the quantitative analysis of the left ventricular wall motion in echocardiogram by easy detection of the heart wall contours.
A Detection System of Drowsy Driving using Computer Vision Method
Kim, Nam-Gyun ; Kim, Beop-Jung ; Park, Sang-Su ; Yu, Chung-Gi ;
Journal of Biomedical Engineering Research, volume 19, issue 6, 1998, Pages 577~584
The purpose of this paper is to detect the drowsiness of a driver suing the computer vision technology. We could extract an eye of a driver from dynamic image got through an infrared LED and a CCD camera. Also we could have tracking the extracted eye at real time and measuring all eye blinks. The subjects in drowsy state showed longer blink duration than those in normal state. And blink frames per constant time was found more in the drowsy subjects' image processing results than in the normal subjects'
Using Bayesian Approaches to Reduce Truncation Artifact in Magnetic Resonance Imaging
Lee, Su-Jin ;
Journal of Biomedical Engineering Research, volume 19, issue 6, 1998, Pages 585~593
In Fourier magnetic resonance imaging (MRI), the number of phase encoded signals is often reduced to minimize the duration of the studies and maintain adequate signal-to-noise ratio. However, this results in the well-known truncation artifact, whose effect manifests itself as blurring and ringing in the image domain. In this paper, we propose a new regularization method in the context of a Bayesian framework to reduce truncation artifact. Since the truncation artifact appears in t도 phase direction only, the use of conventional piecewise-smoothness constraints with symmetric neighbors may result in the loss of small details and soft edge structures in the read direction. Here, we propose more elaborate forms of constraints than the conventional piecewise-smoothness constraints, which can capture actual spatial information about the MR images. Our experimental results indicate that the proposed method not only reduces the truncation artifact, but also improves tissue regularity and boundary definition without oversmoothing soft edge regions.
Development of a Frequency Dependent Type Apex Locator with Automatic Compensation
Kim, Deok-Won ; Nam, Gi-Chang ; Kim, Yeong-Ju ; Lee, Seung-Jong ;
Journal of Biomedical Engineering Research, volume 19, issue 6, 1998, Pages 595~602
Among the apex locators, the frequency dependent type is more accurate and convenient to use than others, But the accuracy of the apex locator is still influenced by the presence of various electrolytes used in root canal treatments. In this study, we have developed a frequency dependent electronic apex locator minimizing the influence of the electrolytes on the measurement of root canal lengths. It was also confirmed that two frequencies of 500Hz and 100kHz are optimal for the measuring impedance compare with commercial product used(400Hz and 8kHz)a and there were no differences in accuracy among the three different types of the waveforms; sinusoidal, triangular, and rectangular waves(p>0.05). Impedance ratio of the two different frequencies represents the position of the file in root canal, and the voltage difference of two signals represents the status of the fluid in the root canal. As a result of compensation using the voltage differences, the errors were decreased on the average from +0.54mm to +0.18mm in
solution (p<0.01), and from -0.33mm to -0.01mm in NaOCl solution(p<0.01). The accuracies based on
and NaOCl solutions were improved with the automatic compensation from 71.1% and 91.1% to 82.2% and 100% respectively.
Analysis of the Diffuse Axonal Injury of the Human Brain using Finite Element Model
Kim, Yeong-Eun ; Nam, Dae-Hun ;
Journal of Biomedical Engineering Research, volume 19, issue 6, 1998, Pages 603~609
To anlyze the diffuse axonal injury of the human brain, 3-D finite element models of the adult, two and three years child were developed. Triangular type acceleration which had its maximum value 200g was applied to investigate the effects of acceleration direction and duration time. The pattern of high shear stress generated at the brain stem, pones and midbrain was similar to the pattern of DAI seen in the clinical observation, especially high maximum shear stress was detected in the brain stem of the six year old child model under flexional acceleration. As the duration of acceleration increased generated pressure and maximum shear stress also increased. For the children's model relatively small pressure was generated regardless of the acceleration direction and continued much longer compared with adult's model. From this analysis maximum shear stress was revealed more proper indicator to predict DAI compared to HIC in case of angular acceleration loading.
Analysis of the Vibratory Characteristic of the Adult's and Baby's Brain Model
Kim, Yeong-Eun ; Yu, Jin-Hwan ;
Journal of Biomedical Engineering Research, volume 19, issue 6, 1998, Pages 611~616
Using three dimensional finite element model of the human brain, vibratory characteristics of the human brain according to vibratory direction was analyzed. From this analysis 9, 14Hz and 2, 3Hz natural frequencies were calculated for adult's and baby's brain model respectively. Regardless of the vibratory direction relatively high shear stress, pressure and von Mises stress variation except acceleration were detected in the baby brain model. At each natural frequencies, adult's model showed relatively high stress level in the region of lower limb control area compared with upper limb control area at 14Hz natural frequency.
The Development of a Cryotherapy System
Kim, Yeong-Ho ; Yang, Gil-Tae ; Jang, Yun-Hui ; Park, Si-Bok ; Ryu, Jin-Sang ;
Journal of Biomedical Engineering Research, volume 19, issue 6, 1998, Pages 617~622
A cryotherapy system using cold air was developed. The developed system had superior low-temperature characteristics with various flow rates and nozzle sizes, and used R-404A, as a coolant, which has no destructive effects of Ozone layers. Flow rates and the treatment time can be easily altered during the operation. In addition, and alarm system was designed for the overload, overheat, and over-charge of the machine. For clinical applications, skin temperatures, intra-articular temperatures of the knee joint and intra-muscluar temperatures of the gluteal muscles were measured during and after the cryotherapy. After a 5-minute therapy, skin and intra-articular temperatures decreased by
, respectively. A 5-minute cryotherapy was good enough to maintain low intra-articular temperatures for 2-3 hours. Resting intra-muscular temperatures in 2, 4, and 6cm deep in the gluteal muscle were
, respectively (p<0.05). Lowest temperatures in 2, 4, and 6cm depth were
, respectively (p<0.05). Temperatures after a 2-hour cold air application on the skin and in the muscle in dept도 of 2, 4, and 6cm were
respectively (p<0.05). Temperatures on the skin and in the muscle significantly decreased after 2 hours, compared with before cold air application (p<0.05). The intra-muscular temperature was changed more slowly than the skin temperature, and the deeper the muscle, the lesser temperature changes. The effect of a 5-minute cold air application lasts up to 2 hours, and it seems that the rebound-rise of the temperature dut to the reactive vasodilatation does not occur in the gluteal muscle.
Amplification and Howling Suppression of Telephonic Speech for the Hearing-Impaired Person
Lee, Sang-Min ;
Journal of Biomedical Engineering Research, volume 19, issue 6, 1998, Pages 623~629
To provide sufficient sound to the hearing-impaired person(HIP) who have many difficulty in communication with others using general telephone, big amplification is needed. But big amplification can occur howling as a side effect. In this study we developed the new technique of big amplification without howling, manufactured and estimated the new hearing aid telephone. Telephone speech is divided to three frequency band, amplified respectively and fitted to HIP's hearing ability. The telephone speech frequency is monitored by counter in time domain. The counter transfers the sinusoidal sound to rectangular wave using comparator and counts the number of rectangular wave in a certain time period, that is frequency, to monitor the howling. Telephone have microphone and speaker, which are fitted in a rigid structure and frequency band of telephone sound is limited, so howling occurs in the limited frequency band. If the counter notices that howling conditions happen, microprocessor decreases quickly the gain of the related frequency band. The result of test of our new hearing aid telephone showed that we can amplifiy the sound as much as 40dB, which is meaningful level to many HIP, and make HIP increase their perception ability from 20% to 60.8% in 1 syllable test and from 28.9% to 78% in 2 syllable test.