• Proceedings of the KOSOMBE Conference
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• v.1994 no.05
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• pp.69-71
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• 1994

1Hz에서 20Hz까지의 단속 주파수를 지닌 청각자극을 가해 얻은 EEG신호에서 자극에 따른 신호의 정성적이고 정량적인 특성을 카오스 분석방법을 통해 밝혔다. 먼저, 뇌전위 신호에 전반적으로 나타나는 일반적인 카오스 특징(fractal mechanism, 1/f frequency spectrum, positive lyapunov exponent등등)이 확인되어졌다. 유발전위에 대해서는 자극의 주파수에 따른 주기 배증을 경유한 카오스로 가는 길(route to chaos)과 2차원 pseudo-phase portrait의 뿌앙까레 단면에서의 기하학적 모양(topological property)의 변화가 관찰되어졌고, 자발전위가 포함된 유발전위에 대해서는 적절한 bases를 지닌 3차원 phase space에서 기이한 끌개(chaotic attractor)가, 유발전위의 정보를 지닌채 보여졌다. 끝으로 자극 주파수(단속 주파수와 반송 주파수) 변화와 측정이 이루어진 머리표면에서의 공간적 위치에 따른, lyapunov exponent값 변화가 의미있게 해석되어졌다. 이 결과는 무질서하게 보이는 뇌전위신호에서 주어진 청각자극에 대한 정보를 얻는 새로운 방법을 제시하게 된다.

• Proceedings of the KOSOMBE Conference
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• v.1994 no.05
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• pp.57-59
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• 1994

In this paper, we present the software part of the intelligent data processing unit (IDPU), which plays an important role in SiMACS. The software system processes ECG, EEG, EMG, blood pressure, respiration, temperature signals, and extracts some information about patient conditions. It displays the patient condition information and the signal data synchronously, and manages them together with other patient personal data in a network-based client/server environment. The software system is designed in an object-oriented paradigm, and implemented in C++ as a window-based application program.

• Journal of Biomedical Engineering Research
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• v.31 no.2
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• pp.170-175
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• 2010

A method of measuring heart rate using photoplethysmograph(PPG) signal during exercise is proposed. PPG's are composed of strong base tones and their harmonics, and the strong base tones are trackable by the adaptive notch filter (ANF) which adjusts its coefficients to minimize the output power. The proposed heart rate measurement algorithm continuously notches the frequency component with the maximum power in the measured PPG, so that the fundamental frequency corresponding to heart rate is traced. We also presents methods of detecting degeneration and impulsive noise blocks to minimize the coefficient fluctuation. Experiments were conducted using real PPG signals captured during exercise. Results showed that the proposed algorithm is capable of consistently tracking the heart rate embedded in the noisy PPG's.

• Journal of Biomedical Engineering Research
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• v.3 no.1
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• pp.35-42
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• 1982

The objective of this phantom study is to develop a digital method for improving the lateral resolution of B-scan ultrasonographic images irs medical application of ultrasound. By utilizing a discrete state-space modeling approach and Kalman-Buch method for analysis of the transducer's beam profile and the measurement and sampling noise, a stable recursive restoration of the object image was obtained for improved lateral resolution. The point spread function (PSF) was measured for the reflective signals after scanning the small pins located along the depth of interest. One major advantage of the present recursive scheme over the transform method is in its applicability for the space-variant imaging, such as in the case of the rotational movement of transducer.

• Journal of Biomedical Engineering Research
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• v.7 no.2
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• pp.169-182
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• 1986

Pulsed ultrasonic Doppler system is a useful diagnostic instrument to measure blood-flow-velocity, velocity profile, and volume-blood-flow. This system is more powerful compare with 2-dimensional B-scan tissue image. A system has been deve- loped and ii being evaluated using TMS 32010 DSP. We use this DSP for the purpose of real-time spectrum analyzer to obtain spectrogram in singlegate pulsed Doppler system and for the serial comb filter to cancel clutter and zero crossing counter to estimate Doppler mean frequency in multigate pulsed Doppler system. The Doppler shift of the backscattered signals is sensed in a phase detector. This Doppler signal corresponds to the mean velocity over a some region in space defined by the ultrasonic beam dimensions, transmitted pulse duration, and transducer ban(iwidth. Multi- gate pulsed Doppler system enable the transcutaneous and simultaneous assessment of the velocities in a number of adjacent sample volumes as a continuous function of time. A multigate pulsed Doppler system processing the information originating from presented.

• Proceedings of the KOSOMBE Conference
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• v.1994 no.12
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• pp.165-168
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• 1994

We proposed a new model of neural network, called Time Delay Counter-Propagation Neural network (TDCPN). This model is combined properly by the merits of Time Delay Neural Network (TDNN) structure and those of Counter - Propagation Neural network (CPN) learning rule, so that increase recognition rate but decrease total teaming time. And we use this model to simulate classification of EMG signals, and compare the recognition rate and teaming time with those of another neural network model. As a result of simulation, the proposed model is proved to be very effective.

• Journal of Biomedical Engineering Research
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• v.34 no.4
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• pp.204-211
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• 2013

In this paper, an algorithm for suppressing acoustic noises contained in stethoscope sound is proposed and implemented in real-time using an embedded DSP system. Sound collected by stethoscope is down-sampled and band-pass filtered, and later an NLMS adaptive filter is used to cancel the acoustic noise induced from external noise sources. Also, the unpredictable impulsive noises due to fabric friction and instantaneous tapping are detected using the SD-ROM algorithm, and suppressed using an algorithm approximating the morphology filter. The proposed algorithm was tested using signals collected with a digital stethoscope mockup, and implemented on an ARM920T-based DSP system.

• Journal of Biomedical Engineering Research
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• v.8 no.2
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• pp.151-160
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• 1987

An algorithm is suggested that truncted projection among the incomplete projections can be recovered from non-iterative extrapolation matrix by band-limited function. After the image being reconstructed from the recovered signals by non-iterative extrapolation, a known controur information and reprojection algorithm are used. It is shown that the reconstructed image using these algorithms is close to the original image. The effectiveness for these algorithms is proved by computer simulation.

• Journal of Biomedical Engineering Research
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• v.10 no.2
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• pp.185-190
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• 1989

In this paper, the discriminant analysis was performed on parameter for detection of cardiac arrythmia. The parameters used for discriminant analysis was two group. One group consist of 05 width and Heart rate, and the other Morphology and Heart Rate. For this study, we designed data acquisition system for EKG signals. The parameters pre-processed by this system was heart rate, 05 width and Morphology. And then, we analyzed the discriminancy of two group and extracted the quantity of discriminancy. The analysis results showed first that the group with morphology and heart rate is better discriminant than with 05 width and heart rate : next, that it can quantify the discriminany of each group of diseases.

• Journal of Biomedical Engineering Research
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• v.12 no.4
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• pp.303-308
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• 1991

Computer assisted cardiac mapping system has made it possible to display local activation times of the heart using a simultaneous multi-point data aquisition system, and opened an era in electrophyslology guided cardiac arrhythmia surgery especially in ventricular tachycardia. In this study, we have developed a 64 channel computerized cardiacmapping system us:ng a micro-computer for basic reasearch of electrophysiology and electrical propagation in cardiac arrhythmias. The significant tasks of this study were the simultaneous acquisition of large amount of data from 64 sites, accurate and rapid analysis, and the effective display of the analyzed data. To solve these problems, we made a 64 channel signal pre-processing board in order to amplify and fitter the raw signals. And we developed the soflu'are Yor cardiac isochronous mapping whictl is presented immediately ama computer-generated graphics. This system is expected 4o enable us to study pathophyslology of cardiac arrhythmia and to improve the results of diagnosis and surgical treatments for cardiac arrhythmia.