• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1998년도 추계학술대회
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• pp.183-184
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• 1998

Respiration monitoring is important in many clinical situations due to its relationship to vitality. But present commercial monitoring systems are bulky and expensive, so they are inadequate to be used for long term recording or out-patients application. We have developed a low cost, low power, handhold respiration monitoring system based on airflow measurement. Respiration flow is indirectly detected using a thermister or a themocouple sensor. Real time recording of respiration rate, abnormality detection and apnea alarming are available.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2003년도 춘계종합학술대회
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• pp.514-517
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• 2003

산소공급은 신체 요구 중 가장 기본적인 것이다. 호흡은 뇌의 연수(medulla oblongata)에 있는 호흡중추와 폐의 정상적 기능에 의해 조절된다. 즉 폐와 환경 사이의 공기 이동인 외 호흡과 헤모글로빈과 단세포 사이의 세포수준에서의 산소 이동인 내 호흡을 말한다. 성인의 호흡수는 보통 1분에 15-20회이나 연령, 운동, 기온, 심리적 변호, 질병상태, 대기의 산소 함량, 약물 투여 등에 따라 차이가 난다. 호흡측정은 대상자가 쉬고 있을 때 하는 것이 중요하다. 호흡 측정은 측정하고 있다는 사실을 대상자가 모르도록 기술적으로 해야한다. 현재 사용하는 방법은 주의를 끌지 않도록 대상자의 팔목에 손을 댄 채로 맥박을 측정한 바로 직후 계속해서 대상자의 가슴의 움직임을 관찰하면서 호흡을 측정하는 것이다. 본 논문에서 구현하고자 하는 것은 관성의 오차 및 압력의 오차에 영향을 거의 받지 않는, 그리고 반영구적으로 사용이 가능한 초음파 센서를 이용한 임베디드 환경의 호흡 량 측정기이다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2009년도 정보 및 제어 심포지움 논문집
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• pp.357-359
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• 2009

In this paper, the 2.4GHz doppler radar system consisting of the doppler radar module and a baseband module were designed to detect heartbeat and respiration signal without direct skin contact. A bio-radar system emits continuous RF signal of 2.4GHz toward human chest, and then detects the reflected signal so as to investigate cardiopulmonary activities. The heartbeat and respiration signals acquired from quadrature signal of the doppler radar system are applied to the pre-processing circuit, amplification circuit, and the offset circuit of the baseband module. ECG(electrocardiogram) and reference respiration signals are measured simultaneously to evaluate the doppler radar system. As a result, the respiration signal of doppler radar signal is detected to 1m without complex digital signal processing. The sensitivity and calculated from I/Q respiration signal were $98.29{\pm}1.79%$, $97.11{\pm}2.75%$, respectively, and positive predictivity were $98.11{\pm}1.45%$, $92.21{\pm}10.92%$, respectively. The sensitivity and positive predictivity calculated from phase and magnitude of the doppler radar were $95.17{\pm}5.33%$, $94.99{\pm}5.43%$, respectively. In this paper, we confirmed that noncontact real-time heartbeat and respiration detection using the doppler radar system has the possibility and limitation.

• 대한의용생체공학회:의공학회지
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• 제38권4호
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• pp.153-162
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• 2017

The present study proposes a system that can detect sleep-disordered breathing automatically using an air mattress and oxygen saturation. A thin air mattress was fabricated to reduce discomfort during sleep, and respiration signals were acquired. The system was configured to be synchronized with a polysomnography to receive signals simultaneously with other bio-signals. The present study has been conducted with nine adult male and female patients with sleep-disordered breathing, and sleep-disordered breathing events have been detected by applying the signals acquired from the subjects to the rule-based detection algorithm. The sensitivity and positive predictive values were found to evaluate the performance of the system, which are 91.4% and 89.7% for all events, respectively. The comparison of apnea hypopnea index(AHI) between the polysomnography and the proposed method showed squared R-value of 0.9. This study presents the possibility of detecting sleep-disordered breathing at hospitals or homes using the proposed system.

• 대한전기학회논문지:시스템및제어부문D
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• 제53권10호
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• pp.733-740
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• 2004

In this paper, an improved algorithm for the extraction of respiration signal from the electrocardiogram (ECG) is proposed. The whole system consists of two-lead electrocardiogram acquisition (lead Ⅰ and Ⅱ), baseline fluctuation elimination, R-wave detection, adjustment of sudden change in R-wave area using moving average, and optimal lead selection. In order to solve the problem of previous algorithms for the ECG-derived respiration (EDR) signal acquisition, we proposed a method for the optimal lead selection. An optimal EDR signal among the three EDR signals derived from each lead (and arctangent of their ratio) is selected by estimating the instantaneous frequency using the Hilbert transform, and then choosing the signal with minimum variation of the instantaneous frequency. The proposed algorithm was tested on 15 subjects, and we could obtain satisfactory respiration signals that shows high correlation (r>0.9) with the signal acquired from the chest-belt respiration sensor.

• Journal of electromagnetic engineering and science
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• 제3권1호
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• pp.45-49
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• 2003

Wireless life signal detecting system is implemented with using the mechanism of Doppler Effect. This system can measure the respiration and heart rates with the periodic movement of skin and muscle near the heart. The system is consisted of antenna, RF transmitter, receiver, and display part. We did use two operating frequencies at 1.9 ㎓ and 10 ㎓. Firstly, the link budget about detecting system is analyzed and the signal detected from the system is compared with electrocardiogram(ECG) of monitor which is using for patient monitoring in hospital. Secondly, the detection of vital sign is also performed according to the different distances, and including behind the wall.

• 대한의용생체공학회:의공학회지
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• 제36권2호
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• pp.48-53
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• 2015

Sudden infant death syndrome(SIDS) continues to be general cause of infant death. Also, apnea is supposed to be one of the main risk factor of SIDS. Therefore, Infant's respiratory monitoring and real-time apnea detection is very important to prevent SIDS. In this study, we proposed a non-contact home monitoring system for infant's respiration using Doppler radar in order to prevent SIDS. The respiration data were acquired from a commercialized baby simulator(Simbaby$^{TM}$) using a Doppler radar. To evaluate a performance of the proposed system, the simulator was placed in a supine and prone position and the chest belt was used simultaneously as a reference signal. As a result, correlation coefficients between respiration rates of Doppler radar and the chest belt in each position were 0.95(p < 0.001) and 0.98(p < 0.001), respectively. The averages of difference were $-0.29{\pm}5.21(mean{\pm}1.96{\cdot}$ standard deviation) in supine and $-0.12{\pm}3.05$ in prone from Bland-Altman analysis. The results indicated an excellent performance in detecting apnea with a sensitivity of 100% and a positive predictive value of 100% in each posture respectively. These results demonstrated that a proposed Doppler radar system is suitable for non-contact respiratory monitoring in order to prevent SIDS of infant.

• 전기전자학회논문지
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• 제11권1호통권20호
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• pp.24-29
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• 2007

본 연구에서 심리적으로 안정된 상태에서 맥율을 측정할 수 있는 장치를 개발하였다. 개발된 시스템은 뇌파, 호흡파, 맥동파를 검출하는 하드웨어장치와 이들 신호를 획득하고 처리하는 소프트웨어로 구성하였다. 뇌파는 전두부에서 쌍극형으로 유도하였고, 호흡은 서미스터 브리지를 이용하여 구성된 변환기를 사용하여 비강 전부에서 유도하였으며 맥동파는 귀볼에서 유도한 용적맥파를 사용하였다. 피검자의 심리적 안정된 상태의 판정은 뇌파의 스펙트럼을 이용하였다. 맥율의 결정은 원전에 따라 1호흡 당 맥동수를 사용하였다. 개발된 장치를 사용하여 맥율검출 실험을 한 결과, 뇌파의 주파수 대역별 구분, 안정된 호흡신호의 검출과 이득 조절이 되는 용적맥파의 검출이 실시간으로 가능하였다. 그리고 검출된 신호로부터 맥율을 검출할 수 있었다.

• 한국멀티미디어학회논문지
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• 제21권3호
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• pp.382-390
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• 2018

A major accident occurring on the bed is falls that occur during at times when the care of nurses or protectors is inadequate, which is fatal to patients or the elderly. In particular, Enuresis or sleepiness caused by sleep apnea increases the risk of falls. Therefore, it is very important to detect falls and sleep apnea of patients without infringing privacy in the bed to patient's safety and accident prevention. In this paper, we reviewed the technologies developed for bed monitoring and implemented a non-intrusive monitoring system. The Occupancy Sensor allows the temperature of the bed and surrounding area to be extracted to enable track of the patient's motion. The Doppler Radar detects the patient's movements at normal times and the respiration state when patients have no movement during sleeping. It is specially designed for real-time monitoring of falling and respiration during sleeping through contactless multi-sensing while solving patient's privacy problems.

• 대한의용생체공학회:의공학회지
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• 제33권1호
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• pp.39-46
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• 2012

Electrical impedance tomography(EIT) can produce functional images with conductivity distributions associated with physiological events such as cardiac and respiratory cycles. EIT has been proposed as a clinical imaging tool for the detection of stroke and breast cancer, pulmonary function monitoring, cardiac imaging and other clinical applications. However EIT still suffers from technical challenges such as the electrode interface, hardware limitations, lack of animal or human trials, and interpretation of conductivity variations in reconstructed images. We improved the KHU Mark2 EIT system by introducing an EIT electrode interface consisting of nano-web fabric electrodes and by adding a synchronized biosignal measurement system for gated conductivity imaging. ECG and respiration signals are collected to analyze the relationship between the changes in conductivity images and cardiac activity or respiration. The biosignal measurement system provides a trigger to the EIT system to commence imaging and the EIT system produces an output trigger. This EIT acquisition time trigger signal will also allow us to operate the EIT system synchronously with other clinical devices. This type of biosignal gated conductivity imaging enables capture of fast cardiac events and may also improve images and the signal-to-noise ratio (SNR) by using signal averaging methods at the same point in cardiac or respiration cycles. As an example we monitored the beat by beat cardiac-related change of conductivity in the EIT images obtained at a common state over multiple respiration cycles. We showed that the gated conductivity imaging method reveals cardiac perfusion changes in the heart region of the EIT images on a canine animal model. These changes appear to have the expected timing relationship to the ECG and ventilator settings that were used to control respiration. As EIT is radiation free and displays high timing resolution its ability to reveal perfusion changes may be of use in intensive care units for continuous monitoring of cardiopulmonary function.