• 한국감성과학회:학술대회논문집
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• 한국감성과학회 2011년도 추계학술대회
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• pp.65-67
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• 2011

• 한국정밀공학회지
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• 제18권2호
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• pp.14-25
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• 2001

• 한국멀티미디어학회논문지
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• 제23권3호
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• pp.402-411
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• 2020

Power line noise in electrocardiogram signals makes it difficult to diagnose cardiovascular disease. ECG signals without power line noise are needed to increase the accuracy of diagnosis. In this paper, it is proposed DNN(Deep Neural Network) model to remove the power line noise in ECG. The proposed model is learned with noisy ECG, and clean ECG. Performance of the proposed model were performed in various environments(varying amplitude, frequency change, real-time amplitude change). The evaluation used signal-to-noise ratio and root mean square error (RMSE). The difference in evaluation metrics between the noisy ECG signals and the de-noising ECG signals can demonstrate effectiveness as the de-noising model. The proposed DNN model learning result was a decrease in RMSE 0.0224dB and a increase in signal-to-noise ratio 1.048dB. The results performed in various environments showed a decrease in RMSE 1.7672dB and a increase in signal-to-noise ratio 15.1879dB in amplitude changes, a decrease in RMSE 0.0823dB and a increase in signal-to-noise ratio 4.9287dB in frequency changes. Finally, in real-time amplitude changes, RMSE was decreased 0.3886dB and signal-to-noise ratio was increased 11.4536dB. Thus, it was shown that the proposed DNN model can de-noise power line noise in ECG.

• 한국콘텐츠학회논문지
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• 제18권2호
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• pp.370-377
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• 2018

집중도는 사용자 연구에서 중요한 감성적 반응으로 고려되고 있다. 객관적인 측정 방법으로 심장반응을 이용하여 데이터화 한다면 집중도를 감시할 수 있다. 본 연구의 목적은 상호작용을 하는 상황에서 유발되는 집중도의 차이에 따른 심장 반응의 패턴 분석을 통해 객관적이고 정량적으로 집중도를 인식하는 방법을 개발하는 것이다. 대학생 피험자 60명이 집중도 실험에 참여하였고 실험하는 동안 피실험자들의 심전도를 측정하였다. 실험은 화살로 타겟을 맞추는 게임으로 쉬운 난이도와 어려운 난이도로 구성하였다. 심전도로 부터 시간 영역 인디케이터와 주파수 영역 인디케이터를 추출하였다. 독립 표본 t검정 결과, 심전도로부터 추출한 시간 영역 인디케이터인 RRI와 SDNN, rMSSD, pNN50에서 집중도 차이에 따라 통계적으로 차이가 유의미하였다. 주파수 영역 인디케이터에서는 LF와 HF, lnLF, lnHF가 집중도 차이에 따라 통계적으로 차이가 유의미하였다. 이 중 집중도의 차이에 따라 패턴의 차이가 큰 RRI와 rMSSD, lnHF를 선정하여 통합 인디케이터를 생성하였다. 통합 인디케이터를 통해 도출한 룰베이스를 낮은 집중과 높은 집중 60개의 데이터 샘플을 통해 검증한 결과, 95%로 높은 인식 정확도를 보였다. 본 연구에서 제안한 집중도 인식 방법을 콘텐츠를 비롯한 다양한 분야에 적용하여 집중도를 높일 수 있는 컨텐츠적 요소들을 개발한다면 효율 및 흥미를 증진시킬 것이라 기대된다.

• Journal of Biosystems Engineering
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• 제33권5호
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• pp.317-325
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• 2008

The electrocardiogram (ECG) measurement system consists of I/O interface to input the ECG signals from two electrodes, FPGA (Field programmable gate arrays) module to process the signal conditioning, and real time module to control the system. The algorithms based on wavelet transform were developed to remove the noise of the ECG signals and to determine the QRS-waves. Triangular wave tests were conducted to determine the optimal factors of the wavelet filter by analyzing the SNRs (signal to noise ratios) and RMSEs (root mean square errors). The hybrid rule, soft method, and symlets of order 5 were selected as thresholding rule, thresholding method, and mother wavelet, respectively. The developed wavelet filter showed good performance to remove the noise of the triangular waves with 10.98 dB of SNR and 0.140 mV of RMSE. The ECG signals from a total of 6 subjects were measured at different measuring postures such as lying, sitting, and standing. The durations of QRS-waves, the amplitudes of R-waves, the intervals of RR-waves were analyzed by using the finite impulse response (FIR) filter and the developed wavelet filter. The wavelet filter showed good performance to determine the features of QRS-waves, but the FIR filter had some problems to detect the peaks of Q and S waves. The measuring postures affected accuracy and precision of the ECG signals. The noises of the ECG signals were increased due to the movement of the subject during measurement. The results showed that the wavelet filter was a useful tool to remove the noise of the ECG signals and to determine the features of the QRS-waves.

• 대한의용생체공학회:의공학회지
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• 제35권6호
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• pp.203-210
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• 2014

Wearable medical device has been a resurgence of interest thanks to the development of technology and propagation of smart phone in recent years. Various types of wearable devices have been introduced and available in market. Capacitive coupled electrode which measures electrocardiogram over cloth is able to be applied wearable device. In previous approaches of capacitive electrode, they need proper pressure for stable contact of the electrode to body surface. However, wearable device that gives pressure on body surface is not suitable for long-term monitoring. In this study, we proposed adhesive polyurethane-based capacitive electrode for patch-type wearable electrocardiogram (ECG) monitoring device. Self-adhesive polyurethane make the electrode and whole system be adhered to the surface of skin without any pressure. The patch-type system is consisted of analog filter, analog-to-digital converter and wireless transmission module and designed to be attached on the body as a patch. To validate the feasibility of the developed system, we measured ECG signal in stable and active state and extracted heart rate. Therefore, we observed skin response after long-term attachment for biocompatibility of the adhesive polyurethane and adhesive strength of it. The result shows the possibility of applying the developed system for ECG monitoring in real-life.

• The Korean Journal of Physiology
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• 제2권1호
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• pp.53-58
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• 1968

In order to study the electrocardiogram of small animals authors deviced a fixing apparatus in the ventral resting position of rabbit and an attaching electrodes. Normal electrocardiograms of 8 adult rabbits were studied with author's improved fixing apparatus and electrodes. Leads taken were the standard limb lead, augmented unipolar leads and the unipolar precordial leads. The total numbers of various leads were eleven altogether. Results obtained in this study may be summarized as follows: 1. The details of the methods used to record and measure the six standard frontal plane leads and the five precordial leads of the rabbit electrocardiogram in the ventral resting position were described. The fixing apparatus of rabbits in ventral position are shown in Figure 1 and the attaching electrodes are shown in Figure 2. 2. The electrocardiographic changes in ventral position were more stable than in dorsal position in each lead. 3. The analysis of the amplitude, duration and other values of various waves are shown in Table 1 and Figure 3. 4. The electrocardiogram of rabbits showed decreased heart rate in ventral position than dorsal one. 5. The mean electrical axis of QRS complex in ventral position were +44.12 degrees and in dorsal position were +25.5 degrees.

• 한국산학기술학회논문지
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• 제18권5호
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• pp.10-15
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• 2017

웨어러블 기기를 이용한 생체 신호 모니터링 어플리케이션들이 큰 관심을 끌면서 측정된 생체 신호를 무선링크를 통해 효율적으로 외부기기에 전달할 수 있는 방법에 대한 연구가 많이 이루어지고 있다. 본 논문에서는 전도성 섬유를 이용해 제작한 안테나를 옷에 부착하고 이를 심전도 센서 모듈 및 무선 통신 모듈과 결합하여 심전도 신호를 모니터링할 수 있는 시스템을 구현하는 과정에 대해 서술하였다. 사용한 전도성 섬유는 40가닥의 은도금 한 실 묶음으로 직류 선저항이 30 ohm/m 이하, 도전율이 105 S/m 이상이다. 전도성 섬유 기반 안테나를 설계하고 제작하는데 있어 3차원 전파 시뮬레이션 소프트웨어 및 자수기 소프트웨어를 이용하였으며, 제작한 안테나 시작품의 반사계수를 네트워크 분석기를 이용해 측정한 결과 지그비 2.4GHz 통신 주파수 대역에서 -10dB 이하의 우수한 안테나 임피던스 매칭 특성을 보임을 확인하였다. 해당 웨어러블 안테나를 지그비 통신 모듈, 심전도 데이터 처리 모듈 및 마이크로 프로세서로 구성한 심전도 측정 시스템에 연결하여 최대 220m 떨어진 수신기에 심전도 데이터가 실시간으로 전송됨을 시연하였다.

• 한국인터넷방송통신학회논문지
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• 제10권2호
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• pp.129-134
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• 2010

통계청에 따르면 심혈관 등의 성인병 질환으로 연 600~800명이 사망하는 것으로 나타나고, 고혈압, 동맥경화증, 심장병, 뇌졸중 등은 혈액의 흐름에 장애가 생겨 발생하는 심혈관계질환으로 오늘날 성인병의 주종을 이루고 있는 사망률이 높은 질병으로 구분된다. 또한 사망한 심혈관질환자 중 올바른 응급처치를 했더라면 생존했을 환자가 약 40%를 차지하고 있어 응급상황 발생 시 신속한 대응이 요구된다. 따라서 본 논문에서는 AdaBoost알고리즘의 weak classifier를 결합하여 strong classifier를 생성하는 방법을 통하여 효과적인 분석으로 심전도를 측정할 수 있도록 하고, 심혈관 질환자에게 발생한 응급상황을 빠른 시간 내에 관리 데스크에 전달할 수 있는 시스템을 제안하였다. 이에 따라 심전도 센서를 기반으로 측정한 데이터를 ZigBee통신으로 단말기에 전송하고 응급 상황을 판정하여 관리데스크에 긴급경보와 모니터링을 제공함으로써 신속한 의료서비스 제공이 가능하도록 하였다.

• Biomolecules & Therapeutics
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• 제1권1호
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• pp.9-19
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• 1993

DA-125, a new anthracycline antibiotic, showed antitumor activity against animal tumors and human tumors. Therefore we studied the cardiotoxic potential of DA-125 in hamsters and rats as a part of safety research, and compared it with that of doxorubicin(DXR). In acute cardiotoxicity test model used hamsters DA-125 was administered intravenously at a dose of 6, 9, 12 mg/kg, and DXR at 3 mg/kg was given. The electrocardiogram(ECG) of hamsters was recorded for 30 minutes after administration. The DA-125 caused slight ECG alterations at a dose of 6 mg/kg. At a dose of 12 mg/kg DA-125 induced moderate to remarkable changes in ECG like decrease of heart rate, widening of PR interval and 07 interval, and A-V block in 3 out of 5 animals. The severity of ECG alteration at 12 mg/kg of DA-125 was similar to that at 3mg/kg of DXR and these changes caused by DA-125 and DXR recovered within 10 minutes after injection. In chronic cardiotoxicity test model used rats, DA-125 was administered intravenously once a week for three weeks at a dose of 6, 9mg/kg and DXR was given at a dose of 6mg/kg. Electrocardiogram was recorded every week from the start of administration to 2 weeks after the last administration and the animals were sacrificed for histological heart examination at 1 week or 2 weeks after the last administration. DA-125 did not cause any abnormal changes in ECG and in histological heart examination due to administration, but DXR caused widening of ST segment, QRS complex, and QT interval from 1 week after administration and these changes were continued to necropsy. These alterations in ECG were accompanied by cardiac histological lesions such as vacuolation in myocardiac cells, interstitial edema and necrosis of myocytes. These results suggest that DA-125 is less cardiotoxic than DXR.