• 대한전기학회논문지:시스템및제어부문D
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• 제52권8호
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• pp.506-509
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• 2003

This paper describes the possibility of analyzing gait pattern from the changes of the lower leg electrical impedance. This impedance was measured by the four-electrode method. Two current electrodes were applied to the thigh, knee, and foot., and two potential electrodes were applied to the lateral, medial, and posterior position of human leg. The correlation coefficients of the joint angle and the impedance change from human leg movement was obtained using a electrogoniometer and 4ch impedance measurement system developed in this study. We found the optimal electrode position for knee and ankle joint movements based on high correlation coefficient, least interference, and maximum magnitude of impedance change. The correlation coefficients of the ankle, knee, and the hip movements were -0.913, 0.984 and 0.823, respectively. From such features of the human leg impedance, it has been made clear that different movement patterns exhibit different impedance patterns and impedance level. This system showed feasibility that lower leg movement could be easily measured by impedance measurement system with a few skin-electrodes.

• 대한전기학회논문지:시스템및제어부문D
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• 제51권8호
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• pp.374-379
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• 2002

In this study, we developed a new human arm movement detection system using electrical bio-impedance method with several skin-electrodes. The correlation coefficients of the joint angle and the impedance change from human arm movement was obtained using a goniometer and impedance measurement system developed in this study. The correlation coefficients of the wrist and the elbow movements were 0.94 and -0.99, respectively. This system was applied to control a robotic arm by converting the measured impedance to joint angle to confirm the validity of the proposed system. In conclusion, we confirmed that this system can control the robotic arm according to arm movement without any limitation of movement. This system showed possibility that upper arm movement could be easily measured by impedance measurement system with a few skin-electrodes.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 합동 추계학술대회 논문집 정보 및 제어부문
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• pp.399-402
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• 2002

In this study, we constructed a four-channel impedance measurement system including a two-channel goniometer to analyze human arm movement. Impedances and joint angles were simultaneously measured for wrist and elbow movements. As the impedance changes resulting from wrist and elbow movements depended heavily on electrode placement, we determined the optimal electrode configurations for those movements by searching for high correlation coefficients, large impedance changes, and minimum interferences in ten subjects (age: 29+6). Our optimal electrode configurations showed very strong relationships between the wrist joint angle and forearm impedance (correlation coefficient = 0.95+0.04), and between the elbow joint angle and upper arm impedance (correlation coefficient = -0.98+0.02). Although the measured impedances changes of the wrist (1.1+1.5 ohm) and elbow (-5.0+2.9 ohm) varied among individuals, the reproducibilities of wrist and elbow impedance changes of five subjects were 5.8+1.8 % and 4.6+1.4 % for the optimal electrode pairs, respectively. We propose that this optimal electrode configuration would be useful for future studies involving the measurement of accurate arm movements by impedance method.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2005년도 생물공학의 동향(XVII)
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• pp.752-753
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• 2005

• Journal of Biosystems Engineering
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• 제33권4호
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• pp.269-275
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• 2008

This study was conducted to design an impedance sensor that can measure soil water content of soils. Partial least square regression (PLSR) was applied to soil impedance data preprocessed with a smoothing method. An optimal sub-spectrum size and wavelength range were determined by comparing the coefficient of determination ($R^2$) and root mean square error (RMSE) of the PLSR models obtained using soil impedance data. various PLS analysis. Based on the PLSR analysis, it would be concluded that the optimal spectrum measurement range was $32.0{\sim}50.0\;MHz$ with the optimal sub-spectrum size of about 18.5 MHz.

• Journal of Biosystems Engineering
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• 제33권5호
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• pp.326-332
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• 2008

A respiration measurement system for vital signs was developed. Respiration signals were measured, processed, and analyzed. Four electrodes, attached on the surface of the skin, were used to monitor respiration signals by impedance pneumography. The measured signals were amplified, detrended, filtered, and transferred toan embedded module. The Kalman filter was used to remove motion artifact from the respiration signals. Experiments were conducted at stable condition and walking condition to evaluate the performance of the system. Respiration rates of five males and five females were measured and analyzed at each condition. The referenced respiration signal was determined by temperature of nose surroundings. The results showed that the respiration rates at the walking condition had more motion artifacts than the stable condition. The accuracies of the respiration measurement system with Kalman filter were found as 96% at the stable condition and 95% at the walking condition. The results showed that the Kalman filter was an effective tool to remove the motion artifact from the respiration signal.

• Agricultural and Biosystems Engineering
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• 제2권2호
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• pp.63-68
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• 2001

The objective of this study was to develop a real-time soil moisture meter using RF impedance. The impedance suchas capacitance and resistance (or conductance) was analyzed using parallel cylinder type capacitance probe(C-probe) and Q-meter (HP4342). The capacitance and conductance of soil increased as volumetric water content increased. The 5 MHz of modified Colpitts type crystal oscillator was designed to detect the capacitance change of the C-probe with moist soil. A third order polynomial regression model was proposed to describe the relationship between RF impedance and volumetric water content. The prototype real time moisture meter consisted of the C-probe, sample container, oscillator, frequency counter and related signal processing units. The calibration equation for measurement of volumetric moisture content of soil was developed and validated. The correlation coefficient and root mean square error between measured volumetric water content by oven method and predicted values by prototype moisture meter for unknown soil samples were 0.984 and 0.032$cm^3$$cm\^3$, respectively.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 학술대회 논문집 정보 및 제어부문
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• pp.197-198
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• 2008

본 논문은 Impedance plethysmography를 이용하여 당뇨병 및 동맥경화의 비침습적이고 고통없는 조기 진단을 위한 시스템 구성의 초기 단계로, 하지 동맥의 기계적 특징인 혈량 변화를 비침습적으로 측정하였다. 혈량과 혈압의 변화는 각각 Impedance plethysmograph와 mercury spbygmomanometer를 이용하여 측정되는데 탄성도는 혈량 변화값을 맥압(수축기압)의 변화량으로 나누어 계산한다. 이 논문에서는 하지 동맥의 탄성도를 비침습적으로 측정하기 위한 전초 단계로서 하지 동맥에서의 임피던스 변화만을 측정하였다. 회로는 50kHz Wien bridge 발진 회로, demodulation, 50kHz band past filter, 0.1Hz high pass filter, 20Hz low pass filter와 증폭기로 구성하였고, 생체 신호 획득 및 처리 과정을 거쳐 임피던스 변화량을 관찰하였다.

• 한국산업정보학회논문지
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• 제19권4호
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• pp.9-16
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• 2014

전극 접촉저항은 생리학적 측정에 중대한 인자이며, 전기적 임피던스 측정을 수행할 때 정확성에 제한적 요인이 될 수 있다. 생체전기임피던스 값들은 인간피부에 삽입되는 전극을 이용하여 하부 조직의 도전율과 유전율에 의해서 계산할 수 있다. 본 연구에서는 피지, 각질층, 표피층, 진피, 피하조직 및 근육층의 인체 피부의 생리적 변화를 검출하는데 주안점을 두고 있으며, 피하조직에 삽입되는 전극의 최적설계를 위해 유한요소법을 사용하였다. 이를 위해 전극의 길이(50 mm, 70 mm), 재질(금), 모양(직사각형, 둥근사각, 육각기둥) 및 깊이(22.325 mm)에 따른 전극설계의 차이를 유한요소법을 통해 피하조직 층으로부터 얻어지는 정보를 바탕으로 기하학적으로 평가하였다. 생체임피던스 실험에서 전극모양과 인가전압에 따라서 피하조직에서 생체임피던스 차이가 가장 크게 나타남을 확인하였다. 본 연구의 모의실험은 피부의 전기적 임피던스 측정과 해석에 관한 물리적 현상뿐만 아니라 다른 형태의 전극 설계에 관한 특성들을 설명할 수 있을 것이다.

• 전기학회논문지
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• 제60권9호
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• pp.1770-1776
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• 2011

In this study, a new method that can estimate ICG data from a subject's both hands to measure Cardiac Output under convenient sensor environment. With this aim, a grip-type electrode was implemented to measure ICG. To improve the accuracy of measurement, the regression equation was extracted using multiple bio-parameters and our result was compared with the thoracic ICG equipment(Physio Flow$^{(R)}$, PF104D, Manatec Biomedical, France), which is being used in clinics. The subjects consist of 26 men and 4 women(age in $22.0{\pm}3.32$). They are no cardiac disease. Parameters available for regression model were used gender, BMI, MBP, LVET, dZ/dt(max), distance between the measured electrodes, body impedance, and PTT. As a result of analyzing the ICG measurement value on thorax and both hands, the correlation with stroke volume, heart rate, and cardiac output was $R^2$=0.853, $R^2$=0.958 and $R^2$=0.899, respectively.