• The Korean Journal of Physiology
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• v.24 no.2
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• pp.249-260
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• 1990

Maximal cardiac output and oxygen uptake $(VO_{2max})$ were measured during treadmill exercise for seven top-class marathoners and nine non-athletes using impedance cardiograph developed by one of the authors (DW Kim). Results of this study are summarized as belows. 1) New shoes with sponge and silicon rubber attached to the soles were developed to reduce motion artifact during treadmill exercise. Ensemble everaging techneque with the developed shoes was also used to improve the measurement of stroke volume using impedance cardiography. 2) Maximal cardiac output of the athletes, 14.98 L/min, was significantly higher than that of the non-athletes, 13.46 L/min. As maximal heart rate of the marathoners is lower than that of non-athletes, stroke volume of the former is significantly larger than that of the latter. 3) $VO_{2max}$ of the marathoners, 59.38 ml/kg/min, was higher than that of the non-athletes, 40.22 ml/kg/min. At the anaerobic threshold. $VO_{2max}$ of the former was 62.3% of $VO_{2max}$ and this was significantly higher than that of the non-athletes, 57.2%, This results indicates that the marathoners have higher aerobic capacity than the non-athletes. 4) The marathoners showed larger $VO_2$ than the non-athletes at the same cardiac output, indicating that a-v $O_2$ of the former is higher than that of the latter. 5) Maximal systolic pressure of the marathoners was higher than that of the non-athletes, and so was maximal rate-pressure products. These results indicate that heart oxygen consumption rate $(hVO_2)$ of the marathoner is higher than that of the non-athletes is mainly due to higher stroke volume. And higher oxygen consumption of the marathoners is due to higher stroke volume. And higher oxygen consumption of the marathoners is due to their larger a-v $O_2$. The marathoners show both higher threshold and $VO_{2max}$. Especially, measurement of cardiac output during treadmill exercise by improved impedance cardiography is expected to contribute in study of cardiac function of athletes.

• 전기의세계
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• v.37 no.7
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• pp.81-86
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• 1988

임피던스 혈량 측정법(impedance plethysmography)은 인체의 어느 특정부위에서의 혈량의 변화를 환자에게 전혀 고통을 주지않고(noninvasive) 안전하고 간편하게 측정하는 방법으로서, 특히 심장의 빅동량(stroke volume)를 측정하는 분야를 임피던스 카디오그라피(impedance cardiography)라고 한다. 혈량 측정법은 인체의 어느 부위에서 박동하는 혈량은 그 부위로 유입되는 혈량과 유출하는 혈량의 차이 만큼 유발한다는데 근거를 두고 있다. 한편 심전도는 주로 심장의 전기적인 면을 측정하는 반면 임피던스 카디오그라피는 박동량과 심장 근육의 수축능력(contractility)등 심장의 기계적인 면을 측정할 수 있다.

• Proceedings of the KOSOMBE Conference
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• v.1993 no.11
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• pp.60-62
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• 1993

• Journal of the Korean Institute of Telematics and Electronics
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• v.27 no.3
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• pp.54-62
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• 1990

The thermodiluton is a standard method to measure cardiac output in clinical medicine. However it has many disadvantages such as expensive instrument and measurement, limited number of measurement, pain, safety problem, and side-effect due to insertion of catheter into heart. Electrical Impedance Cardiography has no such disadvantages and that it can continuously monitor stroke volume, contractility of cardiac muscle, and systolic time interval (STI) as well as cardiac output. While this impedance technique has been widely used and vigorously studied adroad, it is not introduced yet in Korea. Thus an Impedance Cardiograph has been developed in order to introduce this new technique. Its accuracy also has been verified by simultaneous measurement of cardiac output with the thermodilution technique. Finally changes of cardiac function during exercise were also measured.

• Proceedings of the KIEE Conference
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• 1988.07a
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• pp.727-730
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• 1988

In this paper, cardiac parameters and relationship between stroke volume and impedance change were explained, and an impedance cardiograph was designed and constructed, and its accuracy was verified by experiment. Useful cardiac parameters such as stroke volume and contractility of cardiac muscle were measured noninvasively. The reproducibility of the instrument was measured to be better(less than 10%) than that of clinical standard method such as thermodilution. Hence impedance cardiography was found to be better technique for monitoring stroke volume and contractility of patients for pre and post operation, and pharmacological studies.

• Proceedings of the KOSOMBE Conference
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• v.1993 no.11
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• pp.183-186
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• 1993

We have developed a bioimpedance measurement system for impedance cardiography and pneumography. The system injects 50kHz, $200mA_{p-p}$ curreng into the thorax and measures the voltage changes using body surface electrodes. We used the four-electrode method for tile measurement of cardiac singnals and two-electrode method for respiratory signals. We developed a Microsoft Windows program for the acquisition, display, storage, and processing of impedance signals.

• Journal of Biomedical Engineering Research
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• v.10 no.3
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• pp.309-316
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• 1989

In this paper, the patient monitor consisting of amplifier, scan converter, A/D converter, CRT amplifier, and micro-controller part was developed. This patient monitor measures the patient's 4 states in the hospital such as electro-cardiography, respiration, blood pressure, and temperature. The control and processing methods based on micro-processor employ the flexibility, extensibility and economy over other conventional system. The followings are incorporated in this system. First, record the heart rate trends for 1 and 4 hours respectively. Second, measures the respiration by impedance pneumography. Third, measures the blood pressure with auto-zero balance. Fourth, linesrize the temperatures by bridge method.

• Proceedings of the KIEE Conference
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• 1987.07b
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• pp.1288-1291
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• 1987

An finite element code has been developed to calculate current flowing through an 8-node trilinear cubic element from the calculated potentials on the eight node. This code was implemented to the three-dimensional thoracic model for impedance cardiography to find the total currents in the z-direction flowing through the layers which are parallel to x-y plane. The accuracy of the total current was estimated from its variation among the layers. It was found that the accuracy of the total currents in the layers was less than 0.6%.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.05a
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• pp.503-506
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• 2001

There are four factors for patient monitoring : electrocardiography, blood pressure, temperature and respiration. While there are a lot of studies of E.C.C (electro-cardiography) monitoring system in the world, the studies of Respiratory system are not enough and leave much to be desired in the country. In this paper, we developed a respiratory system with the electrical impedance change of the lungs depending on the breath. Using the same electrode, we can monitor E.C.C and Respiration simultaneously, so we can monitor a patient's no-breathing state due to the central nerve paralysis in the emergency room easily. In this monitoring system, the analog part was made separated from the digital part for reducing power source noise and protecting patient from electric shock. The analog part consists of the several parts a high-frequency sine-wave generator, all amplifier for amplifying any impedance change signal, an analog processing part for rectifying and filtering. And the digital parts consists of three parts an AD convertor for converting analog signal to digital signal, digital filter, and a digital part for digital signal processing. This system's merits are using the same electrode with E.C.C and developing the multiple patient monitoring system easily.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.9
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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.