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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 22, Issue 6 - Dec 2001
Volume 22, Issue 5 - Oct 2001
Volume 22, Issue 4 - Aug 2001
Volume 22, Issue 3 - Jun 2001
Volume 22, Issue 2 - Apr 2001
Volume 22, Issue 1 - Feb 2001
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Recognition of Thyroid Gland Cancer Cells using Fuzzy Logic and Genetic Algorithms
Journal of Biomedical Engineering Research, volume 22, issue 3, 2001, Pages 217~222
This paper proposes the new method based on fuzzy logic which recognizes between normal, and abnormal(two types of abnormal : follicular neoplastic, and papillary neoplastic) of thyroid gland cells from pre-obtained 16 feature parameters of image data. This paper applies the genetic algorithms to obtain the dominant feature parameters which have a great influence on discrimination between normal and abnormal cells. This paper shows the effectiveness of proposed method to 240 thyroid gland cells(60 normal cells, 120 follicular neoplastic cells and 60 papillary neoplastic cells) and new dominant feature parameters obtained by genetic algorithms. As a consequence of using the proposed method, average recognition rate of 88.75 % was obtained.
Performance Comparison of Reconstruction Algorithms for Fan-Beam Computerized Tomography
Journal of Biomedical Engineering Research, volume 22, issue 3, 2001, Pages 223~229
In this paper, we have compared the direct fan-beam reconstruction method with the rebinning method in terms of computation time and spatial resolution using computer simulation. As a result, the direct fan-beam method is superior to the rebinning method in the spatial resolution though the former needs longer computation time. However, if we adopt the quarter-detector-offset technique to improve the spatial resolution, the rebinning method outperforms the direct fan-beam method. The computation times have been evaluated using the fast algorithms optimized to reduce the number of interpolation calculations at the back-projection, and the spatial resolutions have been compared using the computer generated phantoms.
A Study on Segmentation of Uterine Cervical Pap-Smears Images Using Neural Networks
Journal of Biomedical Engineering Research, volume 22, issue 3, 2001, Pages 231~239
This paper proposes a region segmenting method for the Pap-smear image. The proposed method uses a pixel classifier based on neural network, which consists of four stages : preprocessing, feature extraction, region segmentation and postprocessing. In the preprocessing stage, brightness value is normalized by histogram stretching. In the feature extraction stage, total 36 features are extracted from
window. In the region segmentation stage, each pixel which is associated with 36 features, is classified into 3 groups : nucleus, cytoplasm and background. The backpropagation network is used for classification. In the postprocessing stage, the pixel, which have been rejected by the above classifier, are re-classified by the relaxation algorithm. It has been shown experimentally that the proposed method finds the nucleus region accurately and it can find the cytoplasm region too.
Power Line Noise Reductions in ABR by Properly Chosen Iteration Numbers
Journal of Biomedical Engineering Research, volume 22, issue 3, 2001, Pages 241~247
ABR(auditory brainstem response) is one of the audiometry which measures objective hearing threshold level by acquiring electric evoked potentials emanated from auditory nerve system responding to an auditory stimulation. However, the obtained potentials which are largely interfered by power line noise, have extremely low SNR, thus ensemble average algorithm is generally used. The purpose of this study was to investigate the effect of iteration number in ensemble average on the reduction of the power line noise. The power line noise was modeled to be a 60 Hz sinusoidal signal and the energy of the modeled signal was calculated when it was averaged. It was verified by simulation that the energy had the periodic zero points for each stimulation rate, and 60 Hz signal induced by the power line was applied to the developed ABR system to confirm that the period of zero energy point was the same with that of the simulation. By the properly selected iteration number, power line noise could be reduced and more reliable ABR could be acquired.
Pattern Extraction of EMG Signal of Spinal Cord Injured Patients via Multiscaled Nonlinear Processing
Journal of Biomedical Engineering Research, volume 22, issue 3, 2001, Pages 249~257
The voluntary contracted EMG signal of spinal cord injured patients is very small because the information from central nervous system is not sufficiently transmitted to
motor neuron or muscle fiber. Therefore the acquisited EMG signal from needle or surface electrodes can not be identified obvious voluntary contraction pattern by muscle movement. In this paper we propose the extraction technique of voluntary muscle contraction and relaxation pattern from EMG signal of spinal cord injured patient whose EMG signal is composed of the linear sum of mo색 unit action potentials with two noise sources, additive noise assumed to be white Gaussian noise and high frequency discharge assumed to be not motor unit action potential but impulsive noise. In order to eliminate impulsive noise and additive noise from voluntary contracted EMG signal, we use the FatBear filter which is a nonarithmetic piecewise constant filter, and multiscale nonlinear wavelet denoising processing, respectively. The proposed technique is applied to the EMG signal acquisited from transverse myelitis patients to extract voluntary muscle contraction pattern.
Estimation of Visual Evoked Potentials Using Time-Frequency Analysis
Journal of Biomedical Engineering Research, volume 22, issue 3, 2001, Pages 259~267
The visual evoked potentials(VEPs) is used to assist in the diagnosis of specific disorders associated with involvement of the sensory visual pathways. The P100 latency is an important parameter which is diagnosis of optic nerve disorders. There are characteristics of latency delay, wave distortion, amplitude deduction in abnormal subjects. It is difficult to diagnose in the case of producing peak at the P100 latency. In this paper, difference of pattern between normal VEPs and abnormal VEPs using the Choi-Williams distribution method is studied. We observed the relationship about time and spectrum. The result shown that normal VEPs had maximum spectral value at 20Hz~26.7Hz and abnormal VEPs had maximum spectral value at 16.7Hz~20Hz. Also normal VEPs spectrum is higher than abnormal VEPs spectrum.
Automatic Determination of Pacing Threshold by Surface ECG Morphology
Journal of Biomedical Engineering Research, volume 22, issue 3, 2001, Pages 269~273
Proper determination of pacing threshold is important for patient safety and pacemaker longevity. In general, cardiac muscle contractions caused by pacing pulses are verified by observing the morphology of surface ECG displayed on a monitor. In this study, a method of automatic pacing threshold determination based on morphological difference between intrinsic and paced ECGs was developed. First, characteristics of intrinsic ECG and paced ECG were analyzed in time and frequency domain and a proper discrimination parameter was extracted. Then, the automatic capture verification method based on the parameter was developed and applied to 23 pacemaker patients. The selected parameter was the area of ventricular depolarization wave during 80ms after pacing stimulus. It was found that the method was reliable and effective in identifying paced ECG and, thereby, determing a proper pacing threshold.
Analysis of Biosignal Variations caused by Epidural Anesthesia
Journal of Biomedical Engineering Research, volume 22, issue 3, 2001, Pages 275~283
This study was performed to extract and analyze the biosignals to find the relationship between the level of anesthesia and the variations of physiological parameters during epidural anesthesia. Seven male and twenty female patients(ages from 45 to 70 years old) were participated for the experiment, and ECGs, PPGs, SKTs, SCRs were obtained during anesthesia. As results, the HF/LF ratios of HRV were decreased after the injection anesthetics. For skin temperatures, values measured from the palm was reduced and the temperatures from four channels, measured from armpit through the right side of the body, were increased. SCRs were decreased for all channels after the injection of anesthetics. However the heart rate and PPGs showed no significant changes. It was concluded that the injection of anesthetics result the changes in biosignals, and it could be explained by the degree of the sympathetic and/or parasympathetic nerve activities. Results of this study could provide the valuable information for the estimation of level for the spinal and general anesthesia, and could be extended to the development of a system which could quantify the level of anesthesia.
Design of FPGA Adaptive Filter for ECG Signal Preprocessing
Journal of Biomedical Engineering Research, volume 22, issue 3, 2001, Pages 285~291
In this paper, we designed two preprocessing adaptive filter - high pass filter and notch filter - using FPGA. For minimizing the calculation load of multi-channel and high-resolution ECG system, we utilize FPGA rather than digital signal processing chip. To implement the designed filters in FPGA, we utilize FPGA design tool(Altera corporation, MAX-PLUS II) and CSE database as test data. In order to evaluate the performance in terms of processing time, we compared the designed filters with the digital filters implemented by ADSP21061(Analog Devices). As a result, the filters implemented by FPGA showed better performance than the filters based on ADSP21061. As a consequence of examination, we conclude that FPGA is a useful solution in multi-channel and high-resolution signal processing.
Development of a Musculoskeletal Model for Functional Electrical Stimulation - Noninvasive Estimation of Musculoskeletal Model Parameters at Knee Joint -
Journal of Biomedical Engineering Research, volume 22, issue 3, 2001, Pages 293~301
A patient-specific musculoskeletal model, whose parameters can be identified noninvasively, was developed for the automatic generation of patient-specific stimulation pattern in FES. The musculotendon system was modeled as a torque-generator and all the passive systems of the musculotendon working at the same joint were included in the skeletal model. Through this, it became possible that the whole model to be identified by using the experimental joint torque or the joint angle trajectories. The model parameters were grouped as recruitment of muscle fibers, passive skeletal system, static and dynamic musculotendon systems, which were identified later in sequence. The parameters in each group were successfully estimated and the maximum normalized RMS errors in all the estimation process was 8%. The model predictions with estimated parameter values were in a good agreement with the experimental results for the sinusoidal, triangular and sawlike stimulation, where the normalized RMS error was less than 17%, Above results show that the suggested musculoskeletal model and its parameter estimation method is reliable.
Effects of Temperature Change on the Current Injected MRI
Journal of Biomedical Engineering Research, volume 22, issue 3, 2001, Pages 303~309
It is well known that the electrical impedance of biological tissues is very sensitive to their temperature. In this paper, we have analyzed the effects of temperature change on the phase of magnetic resonance images obtained with external current injection. It has been found that the local phase in the current injected magnetic resonance image can be changed noticeably when local temperature change appears at a part of the tissue. At the experiments with a 0.3 Tesla MRI system, we observed the local phase changes at the phantom images when the phantom temperature was varied between 25 -45
. We think that the current injection MRI technique can be used for in-vivo monitoring of the temperature inside biiological tissues if the relation between the local temperature and phase can be quantified.