• Journal of Advanced Navigation Technology
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• v.13 no.6
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• pp.926-932
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• 2009

The whole-body massager among healthcare devices is under being popularized in a large scale as times goes by. It is critical to measure, analyze and judge the stress relaxsation trend from HRV signal using PPG in case of massager operation with such relaxsation device for removing stress of human being. There may be artifact in HRV measured signal because the measured object is under shaking with that massager in this case. We present the methodology to remove such artifact from those measured HRV signal, and then measure and analyze the desired HRV successfully in this paper.

• Journal of the Ergonomics Society of Korea
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• v.29 no.1
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• pp.113-120
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• 2010

This research is to evaluate the arousal level by using cardiovascular response. PPG was used in this study as one of the method of measuring it rather than ECG (Electrocardiography) for the purpose of solving ergonomic problem of sensing. The participants were in the age group of 20 (mean=24, standard deviation=1.25): five men and five women. Each experiment composed with four identical sets. First, a black screen was displayed for 30 second rest. Then, the prepared 6 pair images were randomly presented for 10 second stimulation and for 30 second non-stimulation. PPG was measured on the earlobes of experimenters at 200Hz sampling frequency. PPG amplitude, PPI(Pulse to Pulse Interval), and PRV(Pulse Rate Variability) were analyzed according to arousal level. T-test was performed to compare between the PPG variables of rest and relaxation, rest and arousal, and relaxation and arousal. Relative to the rest state, PPG amplitude decreased in relaxed state and increased in aroused state. Relative to the rest state, PPI decreased in both emotional states. However, more significant decline was observed in aroused state. PRV's LF and HF were used in the form of LF/HF to compare between the relaxed and the aroused state. Therefore, PPG signal showed significant differences between relaxed and aroused state. In conclusion, evaluation of human arousal level used in the PPG analysis demonstrated that PPG has better usability and comforter measurement than ECG and is clearly an alternative method of measuring arousal level.

• Proceedings of the Korean Society of Computer Information Conference
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• 2013.01a
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• pp.281-282
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• 2013

맥박을 측정하는 방법 중 하나인 PPG(photoplethysmography) 센서는 설계가 비교적 간편하며 사용이 편한 장점이 있지만, 움직임으로 인한 동잡음에 취약하다는 단점이 있다. 본 논문에서는 동잡음으로 인한 센서와 손가락 사이의 밀착되는 압력의 변화를 측정하여 왜곡된 신호를 보상하였다. PPG센서와 손가락 사이의 압력을 측정하기 위하여 FSR(force sensing resistor)센서를 이용하여 측정하였으며, 측정된 압력과 왜곡된 PPG 신호 비교를 통해 왜곡된 PPG신호와 FSR센서에서 얻은 압력 사이의 연관성을 확인하였고, 신호처리를 통하여 왜곡된 신호를 보상 시켰다. 이와 같은 방법으로 PPG신호를 보상하게 된다면 웨어러블한 환경에서의 적용뿐만 아니라 헬스케어로 응용이 가능할 것으로 보인다.

• Journal of Industrial Technology
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• v.26 no.A
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• pp.89-93
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• 2006

Pulse oximetry, which monitors non-invasively the oxygen saturation in blood, is influenced by patient's respiration, movement or a factor of an environment. Specially, it's difficult to measure a PPG (Photoplethsmography) signal from the moving patient because of the motion artifact. Accordingly, it is required to extract the pure PPG signal from the PPG signal to measure oxygen saturation. In this paper, we propose an adaptive noise canceller to improve the performance of motion artifact removal. Then we design a hardware system for real time monitoring of the oxygen saturation. The proposed algorithm estimates the slope of transition rate between two different wavelength signals.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.52 no.10
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• pp.598-605
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• 2003

In this paper, we propose the method that separates PPG signal and motion artifact signal from two input signals using new independent component analysis algorithm in time domain. In order to eliminate the large level artifact efficiently, block interleaving. lowpass time filtering and innovation processing technique were applied in ICA preprocessing, and FastICA algorithm were applicable. Experiments are made with the numerical simulation and the real PPG signal including four kinds of motion artifact pattern. Our results show that ICA can effectively detect, separate and remove motion artifact in input signals. Then from the separated signals we restore the original PPG signal and propose a new method which computes SpO$_2$ using ICA mixing matrix.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.4
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• pp.986-991
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• 2014

The PPG signal used in mobile-healthcare and telemedicine system is including the various motion artifact that is signal generated from patient's movements. Recently, although the various methods to remove motion artifacts have been suggested, the performances of these methods are still not satisfactory. Therefore, this s study suggested the novel method based on the Kalman filter and adaptive filter to remove motion artifacts, and we used various motion artifacts to analyze the performance of the proposed method. In the results of experiments, the signal-to-noise ratio of proposed method showed good performace that was 4.8 times of moving average filter.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.4
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• pp.917-924
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• 2015

In this study, we study that the video attributes captured by built-in camera in smart-phone can effect on the quality of PPG signal. The conditions of video attributes were composed of the bitrate, the resolution, the flash. As each condition, we measured a change in the red value of the video image and calculated a PPI(Pulse to Pulse Interval) for extracting the pulse wave signal. 20 subjects participated in the experiment and this experiment was carried out 18 tasks. The PPG signal was measured simultaneously for two minutes with the PPG sensor in the middle finger and Smart-phone in the forefinger of the right hand. By proceeding the correlation analysis, we obtained the highest correlation condition(83%, p=0.01), which the resolution was $640{\times}480$, bitrate was 5000kbps, flash was on. As a result, this study will be a useful guide for quality of signals in the pulse signal measurement system using built-in camera in smart-phone.

• The Journal of the Korea institute of electronic communication sciences
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• v.6 no.6
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• pp.981-986
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• 2011

In this paper, the module for measuring SpO2 and PPG(Photo Plethysmo Graphy) signal of human body and the module for wireless communication of these bio-signals to PC were developed. The program was developed to display transmitted SpO2 and PPG signal by various type data and graph without information loss during a emergency transfer. This system can be utilized as appropriate for remote medical care and a new market is expected, to be created according to revision of medical law.

• Proceedings of the Korean Society of Computer Information Conference
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• 2012.07a
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• pp.225-226
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• 2012

본 논문에서는 손목과 손가락에서의 광전용적맥파(photoplethysmography:PPG)를 이용한 맥파 동시 측정에 있어서 두 신호의 peak간의 시간차와 혈압과의 관계를 비교하였다. 이를 통하여 연속적인 혈압측정방법에 대해 측정 가능성을 발견하였다. 본 논문에서는 적외선을 이용한 반사형 PPG 측정 시스템을 사용하였으며 손목과 손가락에서 동시에 측정한 신호를 측정된 혈압과 비교하였다. 이를 통하여 혈압에 따라 손목과 손가락의 PPG신호 peak간의 시간차에 일정한 변화가 있음을 발견하였고 이를 통하여 손목과 손가락사이의 PPG 신호만으로 연속혈압측정이 가능하다는 결론을 얻었다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2016.06a
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• pp.278-279
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• 2016

최근 웨어러블 장치의 개발로 인하여 다양하게 생체 신호를 측정하는 방법이 많아지고 있다. 이와 관련하여 대표적으로 측정하는 신호가 PPG(plethysmography) 신호이다. PPG 신호를 이용하여 맥박수, 혈박출량, SPo2 등의 값들을 추정할 수 있다. 그러나 웨어러블 장치의 특성상 동적잡음이 많이 발생하게 된다. 동적잡음을 제거하기 위한 방법들은 가속도 센서를 사용하는 방법, 칼만필터(Kalman filter)를 이용하는 방법 등 다양한 방법들이 존재한다. 그러나 여전히 범용으로 사용하기에는 한계가 있다. 본 논문은 Neural Network를 사용하여 개인별로 PPG 신호를 학습하여 PPG 신호의 이상 유무를 판단하고 이전 신호의 평균 맥박수를 사용하여 효과적으로 PPG 신호의 정확한 맥박수를 검출하는 알고리듬을 제안한다.