• 한국산학기술학회논문지
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• 제18권5호
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• pp.10-15
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• 2017

웨어러블 기기를 이용한 생체 신호 모니터링 어플리케이션들이 큰 관심을 끌면서 측정된 생체 신호를 무선링크를 통해 효율적으로 외부기기에 전달할 수 있는 방법에 대한 연구가 많이 이루어지고 있다. 본 논문에서는 전도성 섬유를 이용해 제작한 안테나를 옷에 부착하고 이를 심전도 센서 모듈 및 무선 통신 모듈과 결합하여 심전도 신호를 모니터링할 수 있는 시스템을 구현하는 과정에 대해 서술하였다. 사용한 전도성 섬유는 40가닥의 은도금 한 실 묶음으로 직류 선저항이 30 ohm/m 이하, 도전율이 105 S/m 이상이다. 전도성 섬유 기반 안테나를 설계하고 제작하는데 있어 3차원 전파 시뮬레이션 소프트웨어 및 자수기 소프트웨어를 이용하였으며, 제작한 안테나 시작품의 반사계수를 네트워크 분석기를 이용해 측정한 결과 지그비 2.4GHz 통신 주파수 대역에서 -10dB 이하의 우수한 안테나 임피던스 매칭 특성을 보임을 확인하였다. 해당 웨어러블 안테나를 지그비 통신 모듈, 심전도 데이터 처리 모듈 및 마이크로 프로세서로 구성한 심전도 측정 시스템에 연결하여 최대 220m 떨어진 수신기에 심전도 데이터가 실시간으로 전송됨을 시연하였다.

• 한국전자통신학회논문지
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• 제7권3호
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• pp.671-677
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• 2012

수면 중에 부정기적으로 발생하는 인체 이상유형을 모니터링하기 위한 블랙박스 프로그램을 구현하였다. 인체 블랙박스 시스템은 생체 신호를 계측하는 센서와 알람, 전등, 네트워크 카메라와 같은 보조 장치 및 신호를 모니터링 하는 컴퓨터로 구성되어 있다. 신체 이상 증상의 원인을 정확하게 규명하기 위하여 PPG, EOG, EEG, 호흡센서, 온도센서, G-센서 및 마이크로폰과 같은 다양한 센서를 이용하였다. 이상 증상이 발생하면 시스템은 치료에 활용할 수 있는 정보를 제공하기 위해서 환자의 상태를 기록한다. 신체 이상유형을 감지하게 위하여 적절한 센서 위치를 선정한다. 측정 데이터의 유형별 정상 범위에 근거하여, 신체 이상유형을 구별하기 위한 신호 수준을 선정하였다. 이상 신호가 계측되면 전등 및 알람, 네트워크 카메라가 동시에 작동하고, 센서 신호 및 비디오 데이터가 저장된다.

• 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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• 제5권2호
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• pp.167-172
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• 1984

In the present study, we developed a nuclear stethoscope interfaced with a personal computer (APPLE- II) and evaluated it's performances as compared with the gamma camera. This single-probe, ECG-gated system has been used for displaying the left ventricular time-activity curves, the peak ejection time and its rate, the peak filling time and its rate, and the R-R interval distribution. The radioactivity was measured at every 10msec around the ventricular region, where the activity curves shows the maximal peak to peak variations. The background activity was measured around the lung area showing its counts approximately 50% of the end-diastolic count with minimal variations. The average time-activity curves of 100 beats were used for analysis in the equilibrium study after intravenous injection of 15-20mCi of Tc. The ejection fractions measured by the nuclear stethoscope(Y) were compared with those measured by gamma camera(X) in 47 patients with various heart diseases. The correlation coefficient between two measurements was 0.766 with a relation of Y=1.04 x-8.48. Also, the high reproducibility was obtained for the same patient. Also, the high reproducibility was obtained for the same patient. From this study, we conclude that this device is useful for continuous monitoring in the intensive care unit, as it is portable, compact, and inexpensive.

• 대한핵의학회지
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• 제9권1호
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• pp.21-29
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• 1975

Radioimmunoassay for the measurement of plasma renin activity (PRA) was performed in 43 normal Koreans and 45 patients with essential hypertension. Plasma samples were drawn in supine position in the morning and after upright posture for 4 hours. Urinary sodium excretion rates were measured in the concurrent 24 hour urine samples, as an index of their sodium balance. The results were as follows: 1. There was an inverse correlation between 24hr sodium excretion and PRA. The normal values of PRA in supine position ranged from 1.0 to 7.0 ng/ml/hr. when 24 hour sodium excretion were between 50 to 150 mEq. PRA in elderly tended to be low. 2. When stimulated by 4 hour upright posture, PRA increased by 2.6 times from the baseline value. 3. Of the 45 patients with essential hypertension, PRA was low in 10 cases (22.2%), normal in 28 cases (62.2%), and high in 7 cases (15.6%). 4. In the normal and high renin groups, who tended to be younger in ages, mean diastolic blood pressure and BUN were higher than in low renin group. Though hypertensive retinopathy and left ventricular hypertrophy in ECG were more prevalent in the former, no significant differences were noted as in the case of serum cholesterol. 5. There were 8 cases of cardiovascular complications (7 with cerebral vascular accident, 1 with myocardial infarction); 3 in low renin group (30%), 2 in normal renin (7.1%) and 3 in high renin group (42.9%). This figure indicated higher rate of cardiovascular complications in high renin groups, and lower rate in normal renin group. But the incidence of the complication was not significantly low in low renin group.

• 한국컴퓨터정보학회논문지
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• 제24권10호
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• pp.175-182
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• 2019

이 연구는 경찰관에게 실시한 기본인명소생술 훈련의 효과를 증명하기 위해 실시되었고, 연구대상자는 K 경찰관 중 10명의 실험군과 10명의 대조군으로, 교육프로그램은 60분 이론과 30분 실습을 포함하였다. 기본인명소생술 술기 측정은 미국심장협회에서 제시한 응급 심혈관 치료의 가이드라인을 따랐다. 결과는 다음과 같다. 실험군에서 현장확인기술, 1차 평가수행기술 및 기본인명소생술 능력(심장압박, 인공호흡, 의학적 평가)이 대조군에 비하여 높게 나타났다. 결론적으로, 이 연구결과는 시뮬레이션 교육프로그램이 전통적인 이론실습강의보다 경찰관의 임상술기능력을 향상시키는데 효과적이라는 것을 증명하였다. 그러므로 시뮬레이션 교육프로그램을 심정지 응급치료에 대한 교육프로그램으로 적용하는 것을 제안한다.

• 대한의용생체공학회:의공학회지
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• 제40권1호
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• pp.32-37
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• 2019

In this study, we designed a blending algorithm for rate adaptive pacing for cardiac pacemaker. Generally, rate adaptive pacing (RAP) is applied to patients whose heart rate does not rise during exercise for chronotropic incompetence (CI) patient. It is very important to develop an algorithm for RAP that can be properly applied to CI patients. In order to design an RAP algorithm we used dual sensors. Firstly, we designed a bio-signal measurement system based on the dual sensors, which are accelerometer and respiratory system. Secondly, we conducted treadmill test for the simulation experiment while using 3-lead ECG as reference. Finally, we designed a blending algorithm based on activation state of the dual sensors. The proposed blending algorithm was subdivided into three sections based on the accelerometer signal, which are rapidly increased section (W1), hardly changed section (W2), and decreased section (W3). Each weight is set aside for each section. To evaluate this algorithm, ten healthy adult males were participated. The correlation and Root Mean Square Error between the proposed algorithm and the reference were compared, and shown to be r=0.88 and 2.82 bpm, respectively. These results show that the proposed blending algorithm of dual sensors enables proper tracking of the heart rate during exercise. Also, it shows the possibility that the proposed blending algorithm can be applied to improve quality of life of the chronotropic incompetence patient.

• 대한인간공학회:학술대회논문집
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• 대한인간공학회 1996년도 추계학술대회논문집
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• pp.47-55
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• 1996

This study developed a comprehensive and easily applicable nuclear reactor control system evaluation method using reactor operators behavioral and mental workload database. A proposed control panel design cycle consists of the 5 steps: (1) finding out inconvenient, erroneous, and mentally stressful factors for the proposed design through evaluative experiments, (2) drafting improved design alternatives considering detective factors found out in the step (1), (3) comparative experiements for the design alternatives, (4) selecting a best design alternative, (5) returning to the step (1) and repeating the design cycle. Reactor operators behavioral and mental workload database collected from evaluative experiments in the step (1) and comparative experiments in the step (3) of the design cycle have a key roll in finding out defective factors and yielding the criteria for selection of the proposed reactor control systems. The behavioral database was designed to include the major informations about reactor operators' control behaviors: beginning time of operations, involved displays, classification of observational behaviors, dehaviors, decisions, involved control devices, classification of control behaviors, communications, emotional status, opinions for man-machine interface, and system event log. The database for mental workload scored from various physiological variables-EEG, EOG, ECG, and respir- ation pattern-was developed to indicate the most stressful situation during reactor control operations and to give hints for defective design factors. An experimental test for the evaluation method applied to the Compact Nuclear Simulator (CNS) installed in Korea Atomic Energy Research Institute (KAERI) suggested that some defective design factors of analog indicators should be improved and that automatization of power control to a target level would give relaxation to the subject operators in stressful situation.

• 한국융합학회논문지
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• 제11권7호
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• pp.35-40
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• 2020

최근 초소형 생체신호를 측정할 수 있는 스마트 워치 등의 장비들이 출시됨에 따라, 체성분, 혈압, 심박동수, 산소포화도 등 다양한 정보를 쉽게 얻을 수 있다. 그러나 사용자에게 신뢰를 얻지 못하는 부분이 바로 정확성이다. 이러한 생체신호는 외부 환경에 대해 민감하며, 대상자 신체 내부의 조건에 따라 변동값이 크다. 특히 혈압 측정은 아직 신체 내부의 조건들의 처리에 따라 결과값이 다르다. 따라서 실험에서는 PPG 알고리즘에서 혈관 상태를 정의하는 인자를 특정값으로 처리하고 PPG를 분석하였으며, PTT 측정에 있어서 최고점 80%, 100%의 두 지점 PTT 측정값이 SBP와 DBP에 미치는 영향을 분석하였다. 또한 정확도를 높이기 위한 방안 중 하나를 제시하고자 하였다. 연구결과 PPG 최고점 80%에서 측정값 PTT값이 100%에서 측정한 값보다 SBP, DBP 혈압추정에 효과적이며, 변화율 혈압추정의 회귀분석에서 SBP(80%)의 결정계수가 0.6946, DBP(100%)는 0.547로 나타났다. 결론적으로 ECG와 PPG를 통해 PTT를 측정할 경우 PPG 80% 지점의 측정값이 혈압추정의 정확도를 향상시킬 수 있다.

• 대한한의진단학회지
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• 제10권2호
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• pp.88-103
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• 2006

Objectives : We performed this study to search the best time for HRV measuring and which index has the validity in a short term measuring. Methods : At first, three examiner measured electrocardiogram(ECG) of 5 people(4 male + 1 female) for 20 minutes in two times. and we devided ten regions (0-5, 5-10, 10-15, 15-20, 0-10, 0-15, 0-20, 5-15, 10-20, 5-20 minutes). After that we finded the HRV index for each regions. To evaluate the validity, we used Gage Repeatability and Reproducibility Study by MINITAB(ver. 13.20). If the '%Study Var' is under 30 and 'Number of Distinct Categories' is over 4, we could tell it has validity(repeatability and reproducibility). Results : 1) The region and HRV index has repeatability and reproducibility, was HF index in 10-15 minutes. The HF index in 15-20 minutes gained 27.41(%Study Var) and 5(Number of Distinct Categories). 2) The HF index in 10-15 minutes has the better reproducibility than repeatability. The value of measurement is under the control. There is consistency among the examiner. The distribution of measurement is not large. There is no interaction between examiner and each people. 3) The HF index in 10-15, 0-10, 0-15, 0-20, 10-20 minutes was not enough to gain the repeatability and reproducibility. But it had some meanings ; %Study Var, Number of Distinct Categories is 32.68, 4 for 10-15 minutes, 34.43, 4 for 0-10 minutes, 34.44, 4 for 0-15 minutes, 33.56, 4 for 0-20 minutes, 32.07, 4 for 10-20 minutes. Conclusions : This study shows the best index of measuring HRV is the HF index in 15-20 minutes. So, from now on we should measure the HRV for 20 minutes and extract the HF index in 15-20 minutes. It must be the standard for HRV measuring.