• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2010년도 춘계학술대회
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• pp.137-140
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• 2010

본 연구에서는 일상생활에서 보다 편리하게 건강모니터링을 수행하기 위해 신체에 착용 가능한 심전도 및 맥파 계측 시스템을 구현하고자 하였다. 이를 위하여 배터리로 구동 가능한 초소형의 심전도 및 맥파 측정 시스템을 구현하였으며, 계측된 생체신호의 무선전송을 위해 초저전력 무선 센서네트워크 기술을 적용한 무선 생체신호 전송시스템을 구현하였다. 무선으로 전송된 심전도 및 맥파 신호는 잡음 제거 및 심박동을 검출하기 위하여 전처리과정과 적응 가변형 문턱치를 적용하였으며, 검출된 심박동으로부터 동맥순환계의 긴장도 및 유순도의 변화를 반영하는 맥파전달시간(pulse transit time, PTT)을 계산하였다. 구현된 무선 맥파전달시간 계측시스템과 기존 상용시스템의 비교 평가를 수행함으로써 구현된 시스템의 유용성을 평가하고자 하였으며, 혈압 및 맥파전달시간의 동시계측을 통해 자세 변화에 따른 혈압의 변화 및 맥파전달시간의 변화양상을 관찰함으로써 혈압과 맥파전달시간의 관계를 추정하고자 하였다.

• 전기학회논문지
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• 제65권7호
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• pp.1252-1256
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• 2016

Internet of Things(IoT)-devices are now expanding inter-connecting networking technologies to invent healthcare monitoring system especially for assessing physiological conditions of the chronically-ill patients those with cardiovascular diseases. Hence, IoT system is expected to be utilized for home healthcare by dedicating the original usage of IoT devices to collect the biomedical data such as electrocardiogram(ECG) and photoplethysmography(PPG) signal. The aim of this work is to implement health monitoring system by integrating IoT devices with Raspberry-pi components to measure and analyze ECG and the multi-channel PPG signals. The acquired data and fiducial features from our system can be transmitted to mobile devices via wireless networking technology to support the concept of tele-monitoring services based on IoT devices.

• Journal of Multimedia Information System
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• 제8권1호
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• pp.1-10
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• 2021

Heart Rate is a crucial physiological parameter that provides basic information about the state of the human body in the cardiovascular system, as well as in medical diagnostics and fitness assessments. At present day, it has been demonstrated that facial video-based photoplethysmographic signal captured using a low-cost RGB camera is possible to retrieve remote heart rate. Traditional heart rate measurement is mostly obtained by direct contact with the human body, therefore, it can result inconvenient for long-term measurement due to the discomfort that it causes to the subject. In this paper, we propose a non-contact-based remote heart rate measuring approach of the subject which depends on the color intensity variation of the subject's facial skin. The proposed method is applied in two regions of the subject's face, forehead and cheeks. For this, three different algorithms are used to measure the heart rate. i.e., Fast Fourier Transform (FFT), Independent Component Analysis (ICA) and Principal Component Analysis (PCA). The average accuracy for the three algorithms utilizing the proposed method was 89.25% in both regions. It is also noteworthy that the FastICA algorithm showed a higher average accuracy of more than 92% in both regions. The proposed method obtained 1.94% higher average accuracy than the traditional method based on average color value.

• ETRI Journal
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• 제44권3호
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• pp.426-437
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• 2022

To understand the multilateral characteristics of human behavior and physiological markers related to physical, emotional, and environmental states, extensive lifelog data collection in a real-world environment is essential. Here, we propose a data collection method using multimodal mobile sensing and present a long-term dataset from 22 subjects and 616 days of experimental sessions. The dataset contains over 10 000 hours of data, including physiological, data such as photoplethysmography, electrodermal activity, and skin temperature in addition to the multivariate behavioral data. Furthermore, it consists of 10 372 user labels with emotional states and 590 days of sleep quality data. To demonstrate feasibility, human activity recognition was applied on the sensor data using a convolutional neural network-based deep learning model with 92.78% recognition accuracy. From the activity recognition result, we extracted the daily behavior pattern and discovered five representative models by applying spectral clustering. This demonstrates that the dataset contributed toward understanding human behavior using multimodal data accumulated throughout daily lives under natural conditions.

• 한국감성과학회:학술대회논문집
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• 한국감성과학회 2001년도 추계학술대회 논문집
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• pp.169-172
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• 2001

There are many people who suffer from simulation sickness when immersing in virtual reality. In this study, we analyzed two photoplethysmogram(PPG) parameters - a second derivative parameter and power spectral density ratios - in order to relate PPG parameters with simulation sickness. 36 young, healthy subjects were participated in the experiment, and each subject was equipped with a PPG electrode during his or her immersion. Simulation sickness section was defined as a 7 - second section which starts from the point where a subject reported simulation sickness, and normal section as a same-length section where no physical stimuli was presented to him or her. We compared the PPG parameters of the simulation sickness sections with the normal sections, - d/a ratio is believed to have lower value during vasodilation and higher value during vasoconstriction, however, we could not find much difference in the parameter between normal and simulation sickness sections. We also compared 1 to 10Hz power spectral density ratios in normal sections with in simulation sickness section, and found that 6 density ratios among them have different value. Therefore, the density ratios might be utilized as parameters to detect simulation sickness of subjects.

• Annals of Clinical Neurophysiology
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• 제25권1호
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• pp.32-37
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• 2023

Background: Type 2 diabetic mellitus (T2DM) is an emerging global pandemic which is associated with lots of co-morbidities and reported vascular dysfunctions. T2DM associated vascular dysfunctions leads to vasculopathy in the form of altered peripheral vascular dynamics. Cold stress test (CST) is a reliable sympathetic reactivity test used for assessing vascular dysfunctions. In this study we are trying to quantify vascular dysfunctions in T2DM patients non invasively by various parameters of photoplethysmography (PPG) of cold stress test. Methods: Case control study had done in referral health center AIIMS, Raipur. Parameters are recorded by finger-PPG before, during and after CST (1 min) in 2 groups, control (n = 20 healthy volunteers) and case (n = 20 diagnosed T2DM patients). Results: Due to cold stress, PPG parameter peak amplitude was significantly decreased in both healthy and T2DM groups (p <0.001 and p <0.001, respectively). However, recovery trend of amplitude was significantly slow in T2DM compared to healthy subjects. Another PPG parameter peak to peak interval was significantly higher in healthy group compared to T2DM patients. Conclusions: This study showed that T2DM patients has significant deranged pulse volume parameters like amplitude and peak to peak interval can be used to objectively quantify the vasculopathy in T2DM patients by using sympathetic reactivity to cold stress.

• 대한한의학회지
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• 제23권3호
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• pp.1-10
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• 2002

Objective: There exist gender differences in pulsatile contour waveform. Women have a greater age-related increase in left ventricular mass than do men and more likely to experience symptomatic heart failure after infarction. SDPTG (the second derivative of photoplethysmogram waveform) is a noninvasive method for evaluating the pulse wave and is correlated with age and other risk factors for atherosclerosis. We studied the effect of gender on SDPTG and made clear why the gender differences appear. Methods: To study the effects of effect factors, including height and blood pressure, on SDPTG in the fourth decade, data on height, weight, PTD (pulse transit distance), blood pressure, serum lipid levels, and SDPTG were collected in 115 laboratory healthy men and women. SDPTG is derived from double-differential processing of fingertip photoplethysmography and consists of a, b, c, and d waves in systole and an e wave in diastole; SDPTG aging index (AI) was calculated as (b-c-d-e)/a. Results: There were significant gender-related differences of SDPTG AI, height, and blood pressure. Age, height, and mean blood pressure were respectively and significantly correlated with SDPTG AI. SDPTG is dependent upon age, height, and blood pressure. Restricting analysis to SDPTG AI, age, height, and mean blood pressure, yielded that there were gender-related differences in SDPTG AI (P<0.05) which were derived from those of height (F<0.001, df=l, P=0.994). Conclusions: These new data may help to explain previous findings about age-related differences in pulsatile contour waveforms and why gender differences of SDPTG appear. The results of this study suggest that SDPTG AI, used for evaluation of biological vascular aging, should be calibrated by height as well as age and blood pressure.

• 감성과학
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• 제11권2호
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• pp.235-244
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• 2008

본 연구는 언제 어디서나 건강관리를 할 수 있는 u-health care를 위해 cuff를 사용하지 않고 손쉽게 혈압을 측정할 수 있는 기술을 개발하였다. ECG와 PPG 시그널(signal) 만을 이용하여 혈압을 실시간으로 측정할 수 있는 기존 기술은 PTT를 분석 할 때 노이즈나 진폭의 변화로 인해 Peak 추정의 오류가 자주 발생한다. 본 연구에서는 이를 해결하기 위해 적응적 peak 추정 기술을 개발하여 Peak 추정의 정확도를 향상시켰다. 이를 적용하여 측정데이터를 분석한 결과 PTT의 표준편차는 28%감소하였으며, 노이즈 탐지 성능은 18%증가하였다. 또한 PTT와 혈압간의 상관성에 대해 분석한 결과 수축기 혈압= -0.044 $\cdot$ PTT + 133.592의 상관식을 도출하였다. 도출된 상관식을 적용하여 PPG와 ECG 만으로 수축기 혈압을 연속적으로 측정할 수 있는 시스템을 구축하였다.

• 센서학회지
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• 제17권2호
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• pp.87-94
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• 2008

Blood pressure (BP), one of the most important vital signs, is used to identify an emergency state and reflects the blood flow characteristics of the cardiovascular system. The conventional noninvasive method of measuring BP is inconvenient because patients must wear a cuff on their arm and the measurement process takes time. This paper proposes an algorithm for estimating the BP using the pulse transit time (PTT) of the photoplethysmography (PPG) and pressure pulse from finger at the same time as a more convenient way to measure the BP. After recording the electrocardiogram (ECG), measuring the pressure pulse, and performing PPG, we calculated the PTT from the acquired signals. Then, we used a multiple regression analysis to measure the systolic and diastolic BP indirectly. Comparing the BP measured indirectly using the proposed algorithm and the real BP measured with a sphygmomanometer, the systolic pressure had a mean error of ${\pm}3.240$ mmHg and a standard deviation of 2.530 mmHg, while the diastolic pressure had a satisfactory result, i.e., a mean error of ${\pm}1.807$ mmHg and a standard deviation of 1.396 mmHg. These results are more superior than existing method estimating blood pressure using the one PTT and satisfy the ANSI/AAMI regulations for certifying a sphygmomanometer i.e., the measurement error should be within a mean error of ${\pm}5$ mmHg and a standard deviation of 8 mmHg. These results suggest the possibility of applying our method to a portable, long-term BP monitoring system.

• 한국콘텐츠학회논문지
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• 제13권12호
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• pp.27-37
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• 2013

축산업이 대형화 되면서 빠른 성장을 보이고 있다. 하지만 한 농가당 사육두수의 증가로 인한 위생관리부실로 경제적 손실이 전체 총 생산액의 20%인 약 2조원에 육박하고 있고, 이러한 경제적 손실을 막기 위해 축산업에 무선 센서 네트워크 기술 적용이 전 세계에서 연구되고 있다. 본 연구에서는 체온, 호흡수와 더불어 건강의 중요한 지표인 맥박의 지속적인 모니터링을 위한 측정 위치와 방법을 제안한다. 젖소의 중미동맥과 좌측 흉벽에서 맥박을 측정 할 수 있었으며, 측정 방법은 비 침습적이며 탈부착과 관리가 용이한 광 혈류측정 (Photoplethysmography, PPG) 센서를 사용하여 중미동맥과 좌측흉벽에 본 연구에서 제안한 하네스를 이용하여 측정하였다.