• 대한전기학회논문지:시스템및제어부문D
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• 제50권5호
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• pp.241-246
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• 2001

The conventional stethoscope can not store its stethoscopic sounds. Therefor a doctor diagnoses a patient with instantaneous stethoscopic sounds at that time, and he can not remember the state of the patient's stethoscopic sounds on the next. This prevent accurate and objective diagnosis. If the electronic stethoscope, which can store the stethoscopic sound, is developed, the auscultation will be greatly improved. This study describes an amplifier for electronic stethoscope system that can extract heart sounds of fetus as well as adult and alow us hear and record the sounds. Using the developed stethoscopic amplifier, clean heart sounds of fetus and adult can be heard in noisy environment, such as a consultation room of a university hospital, a laboratory of a university. Surprisingly, the heart sound of a 22-week fetus was heard through the developed electronic stethoscope. Pitch detection experiments using the detected heart sounds showed that the signal represents distinct periodicity. It can be expected that the developed electronic stethoscope can substitute for conventional stethoscopes and if proper analysis method for the stethoscopic signal is developed, a good electronic stethoscope system can be produced.

• 전기학회논문지
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• 제63권7호
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• pp.945-949
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• 2014

In cardiac magnetic resonance imaging (CMRI), heart and respiratory motions are one of main obstacles in obtaining diagnostic quality of images. To synchronize CMRI to the physiological motions, ECG and respiratory gatings are commonly used. In this paper multi-biological signal (ECG, respiratory, and SPO2) based smart trigger system is proposed. By using multi-biological signal, the proposed system is robust to the induced noise such as eddy current when gradient pulsing is continuously applied during the examination. Digital conversion of the multi-biological signal makes the system flexible in implementing smart and intelligent algorithm to detect cardiac and respiratory motion and to reject arrhythmia of the heart. The digital data is used for real-time trigger, as well as signal display, and data storage which may be used for retrospective signal processing.

• 반도체디스플레이기술학회지
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• 제23권2호
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• pp.33-37
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• 2024

Recently, wearable virtual reality devices are widely used. These instruments include a 3-axis accelerometer. User's heart rate information in virtual reality contents can be useful for measuring user experience. In this paper, we propose a method to measure the heart rate through a 3-axis accelerometer based on the principle of ballistocardiography without additional sensors. The angular velocity was successively measured in a time series by the 3-axis accelerometer mounted to the head. The frequency of the maximum magnitude is determined as the heart rate through frequency transform and band pass filtering of the time series signal. For verification, the heart rate calculated from photoplethysmography sensors acquired at the same time was compared as ground-truth. In the virtual reality, the user's heart rate information can be extracted without additional heart rate sensor, and the emotional state and fatigue can be measured.

• 대한전자공학회논문지SD
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• 제46권1호
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• pp.59-67
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• 2009

본 논문에서 생체신호의 적응잡음을 제거하기 위해 개선된 비적적응필터(IMADF) 알고리즘을 제안한다. IMADF 구조는 DPCM과 Sign 알고리즘을 사용한 MADF에 1차 예측 필터를 사용한다. 그때 생체신호를 시험하기 위해서 MCG(심자도)에 기반한 심장팬텀 모델을 사용하고 신호를 분석한다. 심장팬텀의 기능들은 다극점 전류원으로부터 만들어진다. 이것은 인간의 심장과 똑같은 기능을 수행하는 역할을 한다 실험결과 IMADF 알고리즘은 곱셈동작이 없고 덧셈동작만 MADF 알고리즘보다 2개 더 늘어났으나, 훨씬 안전한 수렴특성을 나타냈고, 계산상을 복잡성도 줄이는 결과를 얻었다.

• 대한방사선기술학회지:방사선기술과학
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• 제40권2호
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• pp.197-203
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• 2017

본 연구는 흉부영상에서 심장저부 음영 관심영역(Region of Interest; ROI)의 신호대잡음비(Signal to Noise Ratio; SNR)를 Post processing에서의 이퀄라이제이션 기법으로 측정 평가하였다. 연구대상은 대학병원에서 흉부검사를 실시한 환자 87명이다. 측정방법은 ImageJ 프로그램을 사용하여 표본의 인구사회학적 특성, 영상별 흉부영상의 SNR평균값, 95% 신뢰구간 값, SNR평균차이 값 등을 분석하였다. 이때 SPSS Statistics21 통계프로그램으로 ANOVA 분석을 하였으며, 95%(p < 0.05)에서 유의한 것으로 판단하였다. 영상별 분석결과의 SNR은 Original chest image, Original chest image heart shadow, Equalization chest image, Equalization chest image heart shadow순으로 높은 값을 나타냈다(p < 0.001). 결론적으로, 본 연구에서는 흉부영상의 평활화 시 심장저부 음영의 정량화한 평가결과를 보조적인 수단으로 활용할 수 있을 것으로 사료된다.

• 전자공학회논문지B
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• 제31B권2호
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• pp.80-87
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• 1994

Fetal monitoring is a routine procedure to obtain a record of physiologic functions during pregnancy and labor. It is required to determine fetal heart frequency accurately. There are various types of fetal heart rate(FHR) determination and the most frequently applied method is transabdominal Doppler ultrasound. However, in the case of weak or noise corrupted Doppler ultrasound signals, conventional peak detections and the autocorrelation function method have many difficulties to determine FHR precisely. Also the autocorrelation function is effected by threshold level and window size. To solve these problems, the high resolution pitch determination algorinthm is introduced to detect FHR from Doppler ultrasound signals. This scheme digitally processes Doppler ultrasound signal for digital rectification, envelope detection, decimation and correlation calculation of two interconnected segments and then FHR is determined by its maximal value. Even in the case of a greatly smeared noise signal, this algorithm is able to search FHR more accurately than autocorrelation function by means of compensating FHR with a constant correlation threshold. This algorithm is simulated by 386-MATLAB on PC 486/DX and verified that it is superior to the autocorrelation function method.

• 한국멀티미디어학회논문지
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• 제20권2호
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• pp.234-243
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• 2017

With the development of smartphone technologies enable photoplethysmogram (PPG) acquisition by camera and heart rate (HR) measurement. This papers presents improved algorithm to extract HR from PPG signal recorded by smartphone camera and to develop real-time PPG signal processing Android application. 400 video samples recorded by Samsung smartphone camera are imported as input data for further processing and evaluating algorithm on MATLAB. An optimized algorithm is developed and tested on Android platform with different kind of Samsung smartphones. To assess algorithm's performance, medical device Beurer BC08 is used as reference. According to related works, accuracy parameters includes 90% number of samples that has relative errors less than 5%, Person correlation (r) more than 0.9, and standard estimated error (SEE) less than 5 beats-per-minutes (bpm).

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1997년도 추계학술대회
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• pp.75-78
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• 1997

In this paper we present new sound spectral analysis methods or prosthetic heart valve sounds. Phonocardiograms(PCG) of prosthetic heart valve were analyzed in order to derive frequency domain feature suitable or the classification of the valve state. The fast orthogonal search method and MUSIC (MUltiple SIgnal Classification) method are described or finding the significant frequencies in PCG. The fast orthogonal search method is effective with short data records and cope with noisy, missing and unequally-spaced data. MUSIC method's key to the performance is the division of the information in the autocorrelation matrix or the data matrix into two vector subspaces, one a signal subspace and the other a noise subspace.

• 대한전기학회논문지:시스템및제어부문D
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• 제52권9호
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• pp.547-553
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• 2003

In this paper, we designed the PC-based analyzer of the power spectral density that could estimate the heart rate variability from time series data of R-R interval. The power spectral density estimated that it applied the autoregressive model to the measured electrocardiogram during a short period. Also, the characteristics of the designed analyzer are that it could process of the signal filtering, the generation and recomposition of time series and the feature extraction at the same time. Especially the analyzer reconstructed which applied the lowpass filter of the time series composed by the linear interpolation so as to enhance the signal-to-noise feature. We could estimate the power spectral density that confirmed a variety of power peak with low frequency range and high frequency rang of autonomic nerve by the heart rate variability.

• 대한전기학회논문지:시스템및제어부문D
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• 제50권11호
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• pp.550-556
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• 2001

The computerized cardiac analysis system, which acquires and analyzes the electrical activation signal propagating along the surface of the heart, is indispensible equipment for the open heart surgery and electrical cardiac study. In this paper, the design requirement and the electrical circuit analysis are performed to construct the multi-channel cardiac activation pre-amplifier necessary for a signal conditioning circuit. The general 64 channel configuration is expanded into 128 channels to enhance the spatial resolution on the mapped surface of the heart. The 128 channels pre-amplifier consists of input circuit, differential amplifier, right leg driven circuit and isolation part. It has distinct features; high voltage protection, leakage current limitation, isolation and the maximization of common mode rejection ratio with respect to the half-cell potential difference due to different electrode materials. The final pre-amplifier circuit is assembled with 8 boards, each of which composing of 16 channels.