• 전자공학회논문지CI
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• 제46권6호
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• pp.18-26
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• 2009

본 논문에서는 심전도 기반의 u헬스케어시스템을 위한 다용도 신호추출 방법을 제안한다. 심전도 기반의 u헬스케어시스템 구현을 위해서는 심장질환 진단을 위한 QRS파형의 추출기술이 필수적이다. 또한, 보안성 및 편의성을 위하여 u헬스케어시스템에서 ECG신호와 같은 생체신호에서 직접 사용자의 신원을 확인할 수 있는 생체인식기능을 보유하고 있다면 매우 유용하다. 이를 위해서 본 논문에서는, 리드II 파형으로부터 QRS파형을 추출하고, 또한 상대적으로 노화 및 질환에 따른 변동에 강건한 리드III 파형으로부터 생체인식을 위한 신호추출법을 제안한다. 리드II 파형으로부터 QRS신호추출성능을 검증하기 위해 MIT-BIH 데이터베이스의 심전도신호가 사용되었고 99.36%의 정확도 및 99.68%의 민감도성능을 보였다. 또한 생체인식용 신호추출성능평가를 위해서는 다양한 측정환경을 고려하기 위해 음주, 흡연 및 운동 직후 리드III파형이 측정되었고 99.92%의 정확도 및 99.97%의 민감도 성능을 보였다.

• 한국의류학회지
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• 제33권10호
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• pp.1665-1672
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• 2009

This study examines the comfort of outdoorwear by electrocardiogram (ECG) and electroencephalogram (EEG) analyses. An experiment that consisted of rest (30 min), exercise (30 min), and recovery (20 min) periods was administered in a climate chamber with 10 healthy male participants. Two kinds of outdoorwear made of 100% cotton fabrics ('Control') and specially engineered fabrics having the feature of quick sweat absorbency and high speed drying fabric ('Functional') are evaluated in the experiment. ECG and EEG signals were obtained during the rest and recovery periods for the two outdoorwear conditions. The ECG analysis identified a smaller decrement of high frequency (HF) power for the 'Functional' when compared with the 'Control' during the recovery period. Next, the EEG analysis showed that the relative band powers of slow $\alpha$ and mid $\alpha$ increased for the 'Functional' while they decreased for the 'Control' and that the ratio of $\alpha$ power to high $\beta$ power was higher for the 'Functional'. The evaluation results indicate that the participants could remain relaxed more with less stress while wearing the functional outdoorwear that demonstrated the positive effects on autonomic nervous system (ANS) activities. The present study is significant in regard that use of ECG and EEG for the assessment of wear comfort is the first in the field of clothing and textile.

• 대한의용생체공학회:의공학회지
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• 제27권6호
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• pp.370-375
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• 2006

The purpose of this work is to predict the systolic blood pressure (BP) during exercise from pulse transit time (PTT) for warning of possible danger. PTT was calculated as the time between R-peak of ECG and the peak of differential photoplethysmograph (PPG). For the PTT-BP model, we used regress equations from previous studies and 3 kinds of new models combining linear and nonlinear regress equation. The model parameters were estimated with the data measured under low to middle intensity exercise, and then was tested with the data measured under high intensity exercise. Predicted BP values after high intensity exercise were compared with those measured by cuff-type sphygmomanometer. The results showed that the error between measured and predicted values were acceptable for the monitoring BP. We tested PTT-BP models 1 month after the identification without further calibration. Models could predict the BP and the errors between measured and predicted BP were about 5mmHg. The suggested system is expected to be helpful in recognizing any danger during exercise.

• 융합신호처리학회논문지
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• 제21권1호
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• pp.49-54
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• 2020

심혈관질환은 전 세계 주요 사망 원인으로 다양한 원인에 의해 발생한다. 심혈관질환의 가장 높은 위험인자는 고혈압으로 뚜렷한 증상이 없지만 방치할 경우 여러 합병증을 유발한다. 고혈압을 치료하기 위하여 약물치료와 규칙적 운동을 진행해야한다. 고혈압 환자의 경우 과도한 신체 활동 시 심장에 큰 무리가 발생해 심혈관질환으로 이어질 수 있다. 따라서 적정 강도로 운동을 진행할 수 있는 PTT 계측을 통한 운동 강도 모니터링 시스템이 요구된다. 본 연구에서는 심전도와 맥파 계측을 통해 PTT를 산출하여 운동 강도에 따른 PTT 변화 모니터링 시스템을 구현하였다. 구현된 시스템은 심전도의 R-peak와 맥파의 P-peak를 미분하여 peak간의 시간차를 이용하여 PTT를 산출한다. 운동 강도에 따른 PTT 변화 모니터링을 위하여 달리기 실험을 진행하였다. 실험결과 저강도는 0.313s, 중강도는 0.220s, 고강도는 0.188s의 PTT가 측정되었으며, 운동 강도가 증가함에 따라 PTT는 감소하는 것을 확인하였다.

• 전기학회논문지
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• 제56권12호
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• pp.2265-2267
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• 2007

The purpose of this work is to compare the local fitting and global fitting approaches while applying regression model to the PTT-BP data for the prediction of exercise blood pressures. We used linear and nonlinear regression models to represent the PTT-BP relationship during exercise. PTT-BP data were acquired both under resting state and also after cycling exercise with several load conditions. PTT was calculated as the time between R-peak of ECG and the peak of differential photo-plethysmogram. For the identification of the regression models, we used local fitting which used only the resting state data and global fitting which used the whole region of data including exercise BP. The results showed that the global fitting was superior to the local fitting in terms of the coefficient of determination and the RMS (root mean square) error between the experimental and estimated BP. The nonlinear regression model which used global fitting showed slightly better performance than the linear one (no significant difference). We confirmed that the wide-range of data is required for the regression model to appropriately predict the exercise BP.

• Journal of Electrical Engineering and Technology
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• 제3권4호
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• pp.576-583
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• 2008

In this study, we attempt to design a real-time autonomic nervous system(ANS) evaluation system usable during exercise using heart instantaneous frequency(HIF). Although heart rate variability(HRV) is considered to be a representative signal widely used ANS evaluation system, the R-peak detection process must be included to obtain an HRV signal, which involves a high sampling frequency and interpolation process. In particular, it cannot accurately evaluate the ANS using HRV signals during exercise because it is difficult to detect the R-peak of electrocardiogram(ECG) signals with exposure to many noises during exercise. Therefore, in this study, we develop the ground for a system that can analyze an ANS in real-time by using the HIF signal circumventing the problem of the HRV signal during exercise. First, we compare the HRV and HIF signals in order to prove that the HIF signal is more efficient for ANS analysis than HRV signals during exercise. Further, we performed real-time ANS analysis using HIF and confirmed that the exerciser's ANS variation experiences massive surges at points of acceleration and deceleration of the treadmill(similar to HRV).

• 한국정보통신학회논문지
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• 제18권8호
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• pp.2008-2016
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• 2014

최근 건강관리 및 심장질환 관리 등에 대한 관심이 증가하면서 유비쿼터스 헬스케어 서비스와 관련 기기에 대한 개발이 활발히 이루어지고 있다. 본 논문에서는 패치형 심전도 측정기기와 연동된 스마트폰으로 구성된 모바일 헬스케어 시스템을 개발하였다. 본 시스템은 실시간으로 심전도, 맥박, 스트레스 지수를 모니터링하고 저장 및 전송하는 기능과 심박 수에 따른 건강관리 기능 등을 제공한다. 이처럼 웨어러블 생체신호 측정 장치와 연동된 모바일 헬스케어 시스템을 통해 생체 신호를 지속적으로 모니터링함으로써 사용자는 만성질환을 예방하고 꾸준히 건강을 유지할 수 있다. 본 논문에서는 실제 플랫폼에 탑재되어 구현된 결과를 보여준다.

• 대한의생명과학회지
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• 제27권2호
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• pp.88-94
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• 2021

A whole-body compression garment (WBCG) is mainly used for cosmetic purpose in Korea. Another case for wearing the WBCG would be while exercising because it allows the body to move easily. But physiological effects of wearing WBCG to the body have not been known much. To investigate whether wearing WBCG would be helpful for conducting exercises, we measured physiological criteria, which could be influenced by the compression, such as cardiovascular and pulmonary function. Twelve female college students participated in this experiment. Increase of blood pressure was monitored in all of the participants when they wore a WBCG just for 10 minutes. Pulmonary function that requires skeletal muscle contraction was decreased by wearing a WBCG. Blood pressure measured after conducting exercise became even lower when wearing a WBCG than non-wearing. Interestingly, heart pulse remained lower when wearing a WBCG than non-wearing during the whole relaxing period after the exercise. Electrocardiogram (ECG) analyses showed that such lower heart rate largely depended on extension of QT time. For that reason, physiological efficiency index (PEI) was higher for wearing WBCG. These results indicate wearing WBCG could enhance exercise efficiency by lowering heart pulse.

• 전기학회논문지
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• 제67권12호
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• pp.1690-1698
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• 2018

Recent advances in ICT technology have transformed many of our daily lives and attracted a lot of attention to personal health. Heart beat measurement that reflects cardiac activities has been used in various fields such as exercise evaluation and psychological state evaluation for a long time, but its utilization method is limited due to its differentiation from clinical electrocardiogram. Therefore, in this study, we could observe the change of the measured signal according to the change of the distance and the position of the measuring electrodes which are non-standard electrode configuration. Based on the electric dipole model of the heart, correlation with clinical electrocardiogram could be confirmed by synthesizing multiple surface potentials measured with a shorter electrode distance than standard one. From the electromagnetic point of view, the distance between the measuring electrodes corresponds to the distance that the electric potential by the cardiac electric dipole moves, and the electric potential measured at the body surface is proportional to the moving distance of the electric potential. Therefore, it is preferable to make the distance between electrodes as long as possible, and to position the measuring electrode close to the ventricle rather than the atrium. In addition, it was found that standard electrocardiographic waveforms could be synthesized by using arithmetic sum of multiple measuring electrodes due to the relationship of electrical dipole vectors, which is obtained by dividing and positioning a plurality of measuring electrodes on a reference electrode line, such as Lead-I, Lead-II direction. Also, we obtained a significant Pearson correlation coefficient ($r=0.9113{\pm}0.0169$) as a result of synthetic experiments on four subjects.

• 대한핵의학회지
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• 제33권1호
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• pp.40-48
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• 1999

목적: 운동부하 심전도검사에 나타나는 ST-분절의 하강은 운동부하의 정도에 영향을 받는다. 그러나 운동부하의 정도가 운동부하 심근관류영상의 관동맥 질환 진단능에 미치는 영향은 보고자마다 달라 아직도 논란이 되고있다. 본 연구는 운동부하의 정도가 심근관류 영상의 관상동맥 질환 진단능에 미치는 영향을 규명하고자 시행하였다. 대상 및 방법: 111명(남자 73명, 여자 38명, 평균연령: 56세)의 안정된 환자를 대상으로 운동부하검사와 함께 Tc-99m MIBI를 이용한 심근관류 스캔을 실시하고 3개월 이내에 관상동맥촬영술을 실시하였다. 운동부하의 정도는 운동시 최대 예측 심박수의 85%에 도달했는가를 기준으로 하고, 운동심전도 소견을 첨가하여 4군으로 구분하고 각각의 군에서의 진단능을 비교하였다. 결과: 1) Tc-99m MIBI 심근관류스캔의 예민도와 특이도는 심전도검사의 소견이나 심박수의 증가정도에 따른 차이는 없었다. 2) 운동부하 Tc-99m MIBI SPECT의 예민도는 87%, 특이도는 79%였고 전례를 대상으로 한 경우 운동부하 심전도는 예민도 55%, 특이도 74%로서 예민도는 SPECT가 운동부하 심전도보다 유의하게 높았으며 특이도는 유의한 차이는 없었으나 SPECT가 더 높은 경향을 보였다. 3) 최대 예측 심박수의 85% 이상의 운동량에 도달한 경우의 관동맥 질환 진단 예민도는 85% 이하의 운동량에 도달한 군과 유사하였다(88% vs 87%, p=NS). 4) 운동부하 정도가 적었으나 조기에 심전도 검사상 양성 소견을 보인 경우에는 다혈관 질환에서 개개 혈관의 협착 진단능은 낮은 경향을 나타내었다. 결론: 이상의 결과로 볼 때 운동부하 Tc-99m MIBI 심근관류 스캔의 관동맥 협착 진단능은 운동부하 심전도검사보다 높았고, 답차를 이용한 증상 제한적 운동부하검사에서 심박동수의 증가로 평가란 운동 정도가 운동 목표량에 도달하지 않아도 진단능이 감소되지 않음을 알 수 있었다.