• 감성과학
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• 제21권4호
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• pp.63-76
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• 2018

본 연구의 목적은 스마트 헬스케어를 위해 접촉식 직물전극의 구조가 심장활동 신호 획득에 미치는 영향을 연구하는 것이다. 본 연구에서는 심장활동 신호 측정을 위하여 전극의 크기와 구성방식을 조작한 6종의 접촉식 직물전극을 컴퓨터 자수 방식으로 구현하였고, 이를 가슴밴드에 부착하여 응용형 리드 II(modified Lead II) 방식으로 심장활동 신호를 검출하였다. 건강한 신체의 남성 4명을 대상으로 서서 정지한 자세에서 각 직물전극을 사용하여 심장활동 신호를 검출하였으며, 모든 유형의 전극에 걸쳐 4회씩 반복측정 하였다. 심장활동 신호의 수집을 위해 BIOPAC ECG100 장비를 사용하여 1 kHz로 샘플링하였으며, 검출된 원 신호를 대역통과 필터를 사용하여 필터링하였다. 직물전극의 구조에 따른 심장활동 신호 획득의 성능을 비교하기 위하여 신호의 파형과 크기를 파라미터로 하여 정성적 분석을 실시하였고, 각 전극을 통하여 획득된 심장활동 신호의 SPR(signal power ratio)을 산출함으로써 정량적 분석을 실시하였다. 산출된 SPR 값을 대상으로 하여 비모수 통계분석 방식의 차이검정과 사후검정을 실시함으로써 6개 전극의 구조에 따른 심장활동 신호 획득의 성능 차이를 구체적으로 분석하였다. 연구 결과 접촉식 직물전극의 구조에 따라 심장활동 신호의 품질에는 정성적, 정량적 측면에 걸쳐 모두 주요한 차이가 있는 것이 고찰되었다. 접촉식 직물전극의 구성 측면에 있어서는 입체전극이 평면전극에 비해 더 우수한 품질의 신호가 검출되는 것으로 나타났다. 한편 3가지 전극 크기에 따른 심장활동 신호 획득의 유의한 성능 차이는 발견되지 않았다. 이러한 결과는 심장활동 신호 획득을 위한 접촉식 직물전극 구조의 두 가지 요건 중 구성방식(평면/입체)이 웨어러블 헬스케어를 위한 심장활동 신호 획득의 성능에 주요한 영향을 미치는 것을 시사한다. 본 연구 결과를 기반으로 후속 연구에서는 직물전극이 일체형으로 통합된 의복형 플랫폼을 구현하고 성능 고도화 방안을 연구함으로써, 시공간의 제약 없이 고품질의 심장활동 모니터링이 가능한 스마트 의류 기술을 개발하고자 한다.

• 전기학회논문지
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• 제57권6호
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• pp.1102-1108
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• 2008

Wearable physiological signal monitoring systems are regarded as an important sensing unit platforms in ubiquitous/mobile healthcare application. In this paper, we suggested the modified bipolar electrodes implemented on the portable heart activity monitoring system, which minimized the distance of electrodes formed on a attachable pad. The proposed electrode configuration is useful in mobile measurement environments, but has a disadvantage of reduced amplitude of the heart action potential. In order to overcome the shortcoming of the suggested electrode configuration, we implemented the amplifying circuit to increase the signal-gain and decrease the artifacts. For evaluations, we analyzed the specificity of measured cardiography using the proposed electrodes through the comparing of heart activity monitoring system with standard clinical ECG(lead2) by pearson correlation coefficients. The result showed that the average correlation coefficient is $0.903{\pm}0.036,\;0.873{\pm}0.072$ at V3, V4 chest lead position, respectively. Thus, the modified bipolar electrode is quite suitable to monitor the electrical activity of the heart in the situation of the mobile environment, and could be considered having high similarity with standard clinical ECG.

• Journal of Electrical Engineering and Technology
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• 제9권1호
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• pp.372-377
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• 2014

Being able to monitor the heart will allow the diagnosis of heart diseases for patients during daily activities, and the detection of burden on the heart during strenuous exercise. Furthermore, with the help of U-health technology, immediate medical action can be taken, in the case of abnormal symptoms of the heart in daily life. Therefore, it appears to be necessary to develop the corresponding technology to monitor the condition of the heart daily. In this study, a novel wearable smart system was proposed, to monitor the activity of the heart in daily life, and to further evaluate the rhythm of arrhythmia. The wearable system includes three modified bipolar conductive fiber electrodes in the chest part, which can resolve the reduction problem of the magnitude of the signal, by magnifying the signal and removing the noise, to obtain high affinity and validity for medical-type usage (<0.903%). The biological signal acquisition and data lines, and the signal processing engine and communication consist of a conductive ink, and the pic18 and ANT protocol nRF24AP2, respectively. The proposed algorithm was able to detect a strong ECG, signal and r-point passing over the noise. The confidence intervals were 96 %, which could satisfy the requirement to detect arrhythmia under the unconstrained conditions.

• 한국시뮬레이션학회:학술대회논문집
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• 한국시뮬레이션학회 2004년도 춘계학술대회 논문집
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• pp.109-117
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• 2004

In this paper, we consider the aortic sinus baroreceptor, which is the most representative baroreceptor sensing the variance of pressure in the cardiovascular system, and propose heart activity control model to observe the effect of delay time in heart period and stroke volume under the regulation of baroreflex in the aortic sinus. The proposed heart activity baroreflex regulation model contains electric circuit sub-model. We constituted the time delay sub-model to observe sensitivity of heart activity baroreflex regulation model by using the variable value to represent the control signal transmission time from the output of baroreflex regulation model to efferent nerve through central nervous system. The simulation object of this model is to observe variability of the cardiovascular system by variable value in time delay sub-model. As simulation results, we observe three patterns of the cardiovascular system variability by the time delay, First, if the time delay over 2.5 second, aortic pressure and stroke volume and heart rate is observed nonperiodically and observed. Finally, if time delay under 0.1 second, then heart rate and aortic pressure-heart rate trajectory is maintained in stable state.

• Progress in Superconductivity
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• 제4권1호
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• pp.48-52
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• 2002

When applying a SQUID system for diagnosing heart disease, it is informative to obtain the source current distributions from the measured MCG (magnetocardiogram) signals since the bioelectric activity in the heart is generally represented by distributed current sources. In order to estimate the Primary current distribution in a heart, the minimum norm estimate was computed, assuming a source plane below the chest surface. In the simulation, current distributions, which were computed for the test dipoles represented well the essential feature of the test-current configurations. Source current reconstruction was performed for MCG signal of a healthy volunteer, which was recorded using a 40-channel SQUID system in a magnetically shielded room. It was found that the obtained current distribution is consistent with the electrical activity in a heart.

• 융합신호처리학회논문지
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• 제19권1호
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• pp.14-19
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• 2018

최근 건강에 대한 관심과 욕구가 크게 증가하고 있으며, 이에 따라 스마트 헬스케어 산업이 크게 주목받고 있다. 이로 인해 일상생활 중 자신의 건강 상태를 지속적으로 확인하기 위한 원격의료시스템뿐만 아니라, 최근에는 국내외 기업에서 언제 어디서나 신체의 활동 정보를 계측 할 수 있는 웨어러블 디바이스들을 지속적으로 연구개발 및 시장에 선보이고 있다. 특히, 맥파와 심전도는 일상생활 중 자신의 건강상태를 지속적으로 모니터링하기 위한 생체신호로 가장 많이 활용되고 있다. 본 연구에서는 마이크 센서를 활용한 심장의 소리 즉, 심음의 계측을 통해 심장 활동 상태 모니터링이 가능한 시스템을 구현하고자 하며, 상용 전자 청진기과 비교평가를 통해 일상생활 중 지속적인 모니터링이 가능함을 확인 하였다.

• 대한의용생체공학회:의공학회지
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• 제3권1호
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• pp.23-30
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• 1982

The regimen of physical activity of the patient with coronary artery disease requires that he should not overshoot the prescribed heart rate based on his age, health and fuctional status of the heart during his exercise. The step input of work load, however, involves a great danger of overshooting. The purpose of this study was to desigil a system that makes it passible for a subject to check the overshooting. This system shows on tile H.R-meter, the amplified and filtered heart-rate signal of the subject received by the photosensor on his earlobe, puts it in the lead coinpensational circuit where it is conpared with the reference input signal(=the presfribed heart rate). The output of the lead compensational circuit works the aull meter. By means of this null meter, the subject knows whether he is overshooting the prescribed heart rate or not. He can continue the natl meter needle at the'Zero'position through the control of the speed of pedaling of the bicycle ergometer, An experimental test, made on eight men and four women in healthy condition, showed that 91. 7% of them vlaintained the stable heart rate and that the overshooting of the desired heart rate did not exceed $\pm$2BPM. According to the result of this experiment, since the heart rate feedback controller makes it possible for the subject to take the prescribed exercise based not on the work load but on the heart rate which incidentally is inexpensive, it can be made use of as the instrument for the regimen of pflysical activity by the patient with coronary artery disease.

• 대한의용생체공학회:의공학회지
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• 제27권4호
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• pp.154-163
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• 2006

A 64-channel magnetocardiogram (MCG) system using low-noise superconducting quantum interference device (SQUID) planar gradiometers was developed for the measurements of cardiac magnetic fields generated by the heart electric activity. Owing to high flux-to-voltage transfers of double relaxation oscillation SQUID (DROS) sensors, the flux-locked loop electronics for SQUID operation could be made simpler than that of conventional DC SQUIDs, and the SQUID control was done automatically through a fiber-optic cable. The pickup coils are first-order planar gradiometers with a baseline of 4 em. The insert has 64 planar gradiometers as the sensing channels and were arranged to measure MCG field components tangential to the chest surface. When the 64-channel insert was in operation everyday, the average boil-off rate of the dewar was 3.6 Lid. The noise spectrum of the SQUID planar gradiometer system was about 5 fT$_{rms}$/$\checkmark$Hz at 100 Hz, operated inside a moderately shielded room. The MCG measurements were done at a sampling rate of 500 Hz or 1 kHz, and realtime display of MCG traces and heart rate were displayed. After the acquisition, magnetic field mapping and current mapping could be done. From the magnetic and current information, parameters for the diagnosis of myocardial ischemia were evaluated to be compared with other diagnostic methods.

• 한국위성정보통신학회논문지
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• 제9권1호
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• pp.85-89
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• 2014

심전도(electrocardiography, ECG)는 심장박동을 할 때, 발생하는 탈분극과 재분극으로 심장의 전위변화를 시간의 흐름에 따라 파형으로 표현한 것이다. 의료기관에서는 심전도신호를 이용하여 환자의 심장질환을 진단한다. 일반적으로 사람의 정상적인 심장박동수는 1분에 60-100회 이다. 만약 정상적인 심장박동 수보다 느리거나 빠르다면 부정맥이라고 한다. 본 논문에서는 심전도신호에서 R-peak를 검출하여, R-R 간격을 구하고 부정맥 중에 서맥(bradycardia)과 빈맥(tachycardia) 구간을 검출하는 알고리즘을 제안하고 모의실험을 하였다.

• 한국의류학회지
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• 제39권3호
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• pp.369-378
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• 2015

Various forms of wearable bio-signal monitoring systems have been developed recently. Acquisition of stable bio-signal data for health care purposes needs to be unconscious and continuous without hindrance to the users' daily activities. The garment type is a suitable form of a wearable bio-signal monitoring system; however, motion artifacts caused by body movement degrade the signal quality during the measurement of bio-signals. It is crucial to stabilize the electrode position to reduce motion artifacts generated when in motion. The problems with motion artifacts remain unresolved despite their significant effect on bio-signal monitoring. This research creates a foundation for the design of garment-type wearable systems for everyday use by finding a method to reduce motion artifacts through modular design. Two distinct garment-type wearable systems (tee-shirt with a motion artifact-reducing module (MARM) and tee-shirt without a MARM) were designed to compare the effects of modular design on the measurement of heart activity in terms of electrode position displacement, signal quality index value, and morphological quality. The tee-shirt with MARM showed superior properties and yielded higher quality signals than the tee-shirt without MARM. In addition, the tee-shirt with MARM showed a better repeatability of the heart activity signals. Therefore, a garment design with MARM is an efficient way to acquire stable bio-signals while in motion.