• Journal of the Institute of Electronics and Information Engineers
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• v.54 no.5
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• pp.138-142
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• 2017

Photoplethysmography (PPG) is a simple and low-cost optical technique that can be used to detect blood volume changes in the microvascular bed of tissue. It is often used non-invasively to make measurements at the skin surface. In this paper, we described the implementation heart rate monitoring system using PPG sensor. Proposed system is collected data using PPG sensor and heart rate was detected using second derivative method. In order to verify the effectiveness of the proposed method, we performed the measurements of RR-intervals with a commercial medical device.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1979-1980
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• 2008

본 논문은 심혈관질환을 예방하기 위한 심박변이도 검사(HRV), 압맥파 검사(PTG), 용적맥파 검사(SDPTG), 사지혈압 검사(BPD), 맥파전달속도 검사(PWV)를 통해 심혈관의 상태를 분석하고 질병을 예방하는데 도움이 될 수 있도록 측정하고 진단 할 수 있는 심혈관 질환에 대한 통합 진단 시스템을 개발하였다. 본 논문에서 개발된 진단 시스템을 통해서 나오는 결과에 대한 소개하였다.

• Proceedings of the KIEE Conference
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• 2007.04a
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• pp.77-79
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• 2007

The purpose of this study was to suggest a new detection method for early diagnosing diabetic neuropathic foot by obtaining a ratio of toe to figer blood flow using photoplethysmography(PPG). Nerve conduction velocity (NCV) has been routinely used for diagnosing neuropathic foot, but it applies strong electric stimulus to peripheries resulting in stress and pain. The blood flow ratio of diabetic neuropathy(0.96${\pm}$0.20) was significantly higher in comoarison to normal control group(0.46${\pm}$0.15, left : p<0.05, right : p<0.05) and non-neuropathy diabetic group(0.49${\pm}$0.21, left: p<0.05. right: p<0.05).

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.1395-1396
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• 2015

본 연구의 목적은 광용적맥파 해석에 중요하게 사용되는 최대 상승기울기(maximum dV/dt) 지점 검출 알고리즘 개발로, 미분 및 필터링을 통한 전처리 과정, 극점 검출과정, 역탐색 등의 후처리 과정으로 구성되는 알고리즘을 구현하였다. 제안된 알고리즘의 성능을 평가하기 위하여 총 74,225개의 맥박파형을 사용한 검증을 수행하였으며, 동시에 측정된 심전도 QRS지점을 기준으로 최대 dV/dt 측정 위치 정확성을 판정하였다. 시뮬레이션 결과, 적응형 임계치 극점 검출 방법과 함께 사용하였을 때, 제안된 알고리즘은 기존 광용적맥파 상단, 하단극점 검출 알고리즘과 유사한 성능인 98.57%, 99.98%의 민감도와 특이도, 0.02%의 오검출율을 가지는 것으로 나타났다.

• Journal of Korea Multimedia Society
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• v.20 no.2
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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).

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2009.05a
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• pp.195-198
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• 2009

본 연구는 사용자가 경험하는 감성 이미지를 추출하여 생리신호를 통해 자동으로 분류하는 시스템을 구현하고자 한다. 본 연구에서 개발한 시스템은 이미지의 감성평가를 위하여 착용과 휴대가 간편한 PPG생체신호를 활용하였고, 생활 속의 장면들에서 감성 별 이미지를 무선으로 PC에 저장 및 분류하는 시스템을 개발하였다. 또한 이미지의 라이프 로그 정보를 제공하는 기술을 개발하였다. 본 시스템은 사용자의 경험과 이미지를 연관시켜 생활 속 정보의 경험 피드백을 하는 데에 의의가 있다.

• Journal of information and communication convergence engineering
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• v.11 no.3
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• pp.216-222
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• 2013

It is known that blood circulation in human body causes the skin tone to change concurrently with heartbeats. A number of apps have been developed to measure the heartbeat using smartphone camera; however, no any further analysis is performed. In this paper we propose an algorithm that detects heartbeats from the phone's camera and further extracts the heart rate variability (HRV). We compare the HRV extracted from the camera with the HRV extracted from the electrocardiogram. We estimated a number of commonly used HRV characteristics and compared them. Our results show that smartphone camera leads to slightly overestimated characteristics although the difference in extracted HRV signals is negligible. As a consequence we suggest that a smartphone camera can be employed in a quick heart diagnosis and diagnosis of autonomic nervous system.

• Journal of Sensor Science and Technology
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• v.25 no.1
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• pp.71-78
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• 2016

PPG signal measured by pulse oximeter can measure pulse and the oxygen saturation of arterial blood. But the PPG signal is distorted by finger movement or other movement in the body. To detect pulse from the PPG signal with motion artifact, we use band pass filter(BPF), Independent component analysis(ICA) and nonlinear autocorrelation(NAC). BPF is used to remove DC component and high frequency noise in the PPG signal with motion artifacts. ICA is used to separate pulse signal and motion artifact. However, pulse signal separated by ICA have no choice but to accompany signal distortion because pulse signal and motion artifact are not completely independent. So, we use nonlinear autocorrelation to emphasize the pure pulse signal from the distorted signal.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.8
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• pp.1514-1520
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• 2007

Currently, the signal of the human body is measured with various methods, and a noninvasive investigation of various methods is useful diagnosis method. PTT(Pulse Transit Time) which is noninvasive investigation make use of to estimate the physiological phenomena. PTT has a latent information of cardiovascular system. So we have the experiments for analysis of the relations between PTT and physiological parameters. We examine to correlate to the physiological parameters, an age and degree of paralysis on the ultrasound therapy. The 40 patients who has a such paralysis join our experiment, and we obtain the PTT data that normal condition and states after ultrasound therapy. We study that PTT after the ultrasound therapy for patients who have a paralysis was related to an age and degree of paralysis.

• Annual Conference of KIPS
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• 2015.10a
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• pp.572-574
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• 2015

최근 스마트폰 내장 카메라와 플래시를 사용하여 PPG 신호를 측정하고 생체정보를 측정하는 연구가 많이 진행되고 있다. 그러나 스마트폰 카메라를 사용하여 측정하는 PPG신호는 스마트폰 카메라와 플래시 위치에 따라 각 측정 영역의 신호의 세기가 다르다. 본 논문에서는 스마트폰 카메라와 플래시 위치에 따라 강한 PPG 신호를 가지는 ROI를 찾기 위해 비교, 분석하였다. ROI를 계산하기 위해 PPG 신호를 측정하고 ROI를 선정할 수 있는 스마트폰 애플리케이션을 개발하여 각 ROI의 PPG 신호의 편차를 계산하고 가장 최적의 영역을 실험을 통해 비교분석하였다.