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생체 정보 감시 장치를 위한 광변조 기법의 PPG 신호처리
이한욱,이주원,정원근,김성후,이건기,Lee, Han-Wook,Lee, Ju-Won,Jeong, Won-Geun,Kim, Seong-Hoo,Lee, Gun-Ki 대한의용생체공학회 2009 의공학회지 Vol.30 No.6
The development of technology has led to ubiquitous health care service, which enables many patients to receive medical services anytime and anywhere. For the ubiquitous health care environment, real-time measurement of biomedical signals is very important, and the medical instruments must be small and portable or wearable. So, such devices have been developed to measure biomedical signals. In this study, we develop the biomedical monitoring device which is sensing the PPG signal, one of the useful signal in the field of ubiquitous healthcare. We design a watch-like biomedical signal monitoring system without a finger probe to prevent the user's inconvenience. This system obtains the PPG from the radial artery using a sensor in the wrist band. But, new device developed in this paper is easy to get the motion artifacts. So, we proposed new algorithm removing the motion artifacts from the PPG signal. The method detects motion artifacts by changing the degree of brightness of the light source. If the brightness of the light source is reduced, the PPG pulses will disappear. When the PPG pulses have disappeared completely, the remaining signal is not the signal that results from the changing blood flow. We believe that this signal is the motion artifact and call it the noise reference signal. The motion artifacts are removed by subtracting the noise reference signal from the input signal. We apply this algorithm to the system, so we can stabilize the biomedical monitoring system we designed.
이한욱,이건기,Lee, Hanwook,Lee, Gunki 대한의용생체공학회 2016 의공학회지 Vol.37 No.1
The biomedical information (heart rate, HRV, $SpO_2$ etc) from the Photoplethysmography (PPG) signal section can be estimated without the motion artifacts if the PPG signal section in the motion artifacts is detected accurately. But the PPG signal is easily exposed to the motion artifacts by the decrease of the medical instrument size and applying as portable or wearable. Besides, it is difficult to completely eliminate the motion artifacts from the PPG signal without distortion and ensure reliability as well. In this paper, the method was suggested to determine the motion artifacts or not on the PPG signal of the section divided into intervals of constant length. By comparing the spectrum of each section, it can be determined whether the motion artifacts are or not after obtaining the spectrum of each section by the Goertzel algorithm. Moreover, an amount of computation while maintaining a high detection rate can be reduced by using the Goertzel algorithm.
Pulsed-UV 시스템을 이용한 염소계 유기화합물 및 화약류 제거에 관한 연구
이한욱,한종훈,윤여민,이종열,허남국,Lee, Han-Uk,Han, Jonghun,Yoon, Yeomin,Lee, Jongyeol,Her, Namguk 한국지하수토양환경학회 2013 지하수토양환경 Vol.18 No.1
This study was conducted in order to evaluate the removal process for long-term contamination sources including chlorinated hydrocarbons (TCE and PCE) and explosive compounds (TNT, RDX, and HMX) in underground water using a pulsed-UV system. Crystallized cells containing the contaminants were placed 10, 20, and 40 cm away from a lamp that emits pulsed-UV rays in order to examine how the removal efficiency is influenced by the distance between the source of the light and the compounds. Chlorinated hydrocarbons were completely removed in 30 minutes with a distance of 10 cm, while PCE was completely removed even with a distance of 20 cm. In the case of explosive compounds, removal efficiencies slightly varied depending on the compounds. The majority of the compounds were perfectly removed with a contact time of 10 minutes. In particular, for RDX, the results showed that complete removal was obtained within one minute, regardless of the distance from the UV source. The amount of light energy is in inverse proportion to the distance, and thus the energy reaching the compounds severely diminishes as the distance increases. Therefore, the removal efficiency decreased with increasing distance in the system.
기체상 질소산화물을 포함한 2012~2014년도 대한민국 질소수지 연구
이한욱,어세연,박재우,Lee, Hanuk,Oa, Seyeon,Park, Jae-Woo 한국지하수토양환경학회 2017 지하수토양환경 Vol.22 No.4
This study estimated the nitrogen budget, including gaseous nitrogen oxides ($NO_x$), of South Korea in 2012~2014. The nitrogen budget was classified into three categories: agricultural and livestock, forest, and city. To estimate the nitrogen budget, several input and output parameters were investigated, including deposition, fixation, irrigation, chemical fertilizer use, compost, fuel, denitrification, volatilization, runoff, crop uptake, leaching, and $NO_x$ emissions. The annual nitrogen inputs from 2012 to 2014 were 6,202,828, 6,137,708, and 6,022,379 ton/yr, respectively. The corresponding annual nitrogen outputs were 1,393,763, 1,380,406, and 1,360,819 ton/yr, respectively, signifying a slight decrease from 2012 to 2014. $NO_x$ was the parameter contributing to the nitrogen budget to the greatest extent. The annual ratios of $NO_x$ emissions by vehicles, power plants, and businesses were 0.31, 0.31, and 0.30 in 2012, 2013, and 2014, respectively. A change in government policy that prohibited the disposal of livestock manure and sewage sludge in the ocean from 2012 affected nitrogen budget profile. As a result, the ocean disposal ratio completely diminished, which differs from previous studies.
PPG신호의 동잡음 제거를 위한 2-D 이동평균필터 설계
이한욱(Han-Wook Lee),이주원(Ju-Won Lee),정원근(Won-Geun Jung),장준영(Jun-Young Jang),김영일(Young-Il Kim),이건기(Gun-Ki Lee) 대한전자공학회 2007 대한전자공학회 학술대회 Vol.2007 No.7
The accuracy of the Heart rate or SPO2 using the photoplethysmography(PPG), is influenced by how the noise is removed well, especially motion artifact. However, it is difficult to remove the motion artifacts from measured the PPG signal because the frequency bands of the two signals overlap each other. In this paper, the motion artifacts can be reduced by the proposed method we named two dimension moving average filter utilizing the quasi-periodicity of the PPG signals.
U-헬스케어 시스템을 위한 개선된 PMAF 기반의 PPG 신호의 동잡음 제거
이한욱(Hanwook Lee),이주원(Juwon Lee),정원근(Wongeun Jeong),전재철(Jaechul Jun),이건기(Gunki Lee) 대한전자공학회 2008 電子工學會論文誌-SC (System and control) Vol.45 No.5
유비쿼터스 헬스케어 환경의 실현을 위해 실시간의 생체 정보 모니터링은 매우 중요한 요소이다. 이러한 생체 정보 모니터링을 위한 장치는 대부분 PPG 신호를 얻어 피측정자의 상태 모니터링에 활용하고 있다. PPG 신호를 얻기 위해서는 핑거프로브를 손가락에 착용해야 하기 때문에 일상생활을 하기에 불편할 뿐만 아니라, 핑거 프로브 착용자의 움직임에 의한 동잡음으로 인하여 정확한 PPG신호를 얻기가 매우 힘들다. 본 논문에서는 핑거프로브를 없앤 U-헬스케어를 위한 손목형 생체 정보모니터링 시스템을 개발하고, 생체 정보 모니터링 시스템의 감시 요소 중 하나인 PPG 신호의 동잡음 제거를 위해 새로운 알고리즘을 제안한다. 개발한 시스템은 핑거프로브를 없앤 대신 밴드스트립에 LED와 포토센서를 장착하여 손목의 동맥혈관의 혈류 변화량으로부터 PPG를 얻도록 설계하였다. 그러나 밴드스트립에 위치한 센서는 핑거프로브에 위치한 센서에 비해 많은 동잡음에 노출되어 있으므로, 그 동잡음들을 제거하기 위하여 최근 제기된 PPG 신호의 유사 주기성을 이용한 PMAF(Periodic Moving Average Filter) 방법을 개선한 새로운 동잡음 제거 방법을 제안한다. The real-time biomedical signal monitoring is a very important factor to realize the ubiquitous healthcare environment. Most of these devices for monitoring the biomedical information get the PPG signal from the user, and these signals are utilized for monitoring their health. It is inconvenient to get the PPG because the user should wear the finger probe with his finger for measuring the PPG signal. Also it is difficult to get the PPG correctly, because of the motion artifacts from the movement of the user. In this paper, we develop the watch type biomedical signal monitoring system without the finger probe, and propose the new algorithm for reducing the motion artifacts from the PPG signal. We designed the system which gets the PPG from the sensor on the wrist band strip. As compared with the finger probe type, this system we proposed is more affected by the motion artifacts. So to filter this motion artifacts, we propose the new method; the improved PMAF(Periodic Moving Average Filter) method.
U-Health를 위한 휴대형 생체신호 측정 시스템 설계
이한욱(Lee, Han-Wook),김성후(Kim, Sung-Hoo),정원근(Jeong, Won-Geun),이주원(Lee, Ju-Won),장두봉(Jang, Doo-Bong),이건기(Lee, Gun-Ki) 한국정보전자통신기술학회 2008 한국정보전자통신기술학회논문지 Vol.1 No.2
U-Health란 ubiquitous Health 의 약자로서 궁극적인 목표는 "삶의 질 향상 추구"에 있으며, 이를 현실화시키기 위하여 정보통신 기술의 향상과 네트워크의 구축 등 IT 인프라의 보편화를 바탕으로 언제 어디서나 무의식적으로 보건의료의 혜택을 누릴 수 있도록 보장하는 것이다. 이에 발맞추어 본 논문에서는 기존 모듈에 사용되었던 손가락에 끼워 사용하는 Probe 대신 적외선센서를 통한 무자각적 측정환경 조성과 TFT-LCD를 이용하여 모듈 자체 디스플레이 기능을 구현, 직접 제작한 Zigbee 통신 모듈을 적용하여 소형화와 휴대성을 강조한 U-Healthcare 기반의 휴대형 생체신호 측정 단말기를 설계 및 구현하였다. U-Health is abbreviated from ubiquitous Health. Its final aim is "to improve the quality of life. To realize it, it is needed to generalize IT infrastructure such as the development of information-technology and construction of network. It is guaranteed to get medical care benefits unconsciously every time and everywhere based on this system. In this study, the environment of unconscious measurement was set up through ultra-violet instead of the existing Probe to wear with finger to follow this. TFT-LCD was included into module for display. U-Healthcare focused on the minimization and portable characteristic through the designed Zigbee communication module. Handled healthcare device was developed based on the U-Healthcare.