• 전력전자학회:학술대회논문집
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• 전력전자학회 2000년도 전력전자학술대회 논문집
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• pp.53-56
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• 2000

An Electrical equipment is the noise source which makes a noise. So the optimally designed filter should be inserted in the equipment in order to reduce the noise. The noise source impedance is varied according to the frequency It effects on the CE noise. Knowing the magnitude of its impedance and inserting an EMI filter in the equipment we can estimate the insertion loss of the filter. SO it helpful in designing the EMI filter. The measurement method of a noise source impedance is proposed and verified by experiment.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2002년도 ICCAS
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• pp.86.6-86
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• 2002

This work presents a study on development of a practical and quantitative technique for assessment of the healthy state of a structure by piezoelectric impedance-based technique associated with longitudinal wave propagation measuring method. A truss structure embedded with piezoelectric patches is investigated for a fundamental study on estimation of the looseness of bolts in the joint. In order to evaluate the minute mechanical impedance change due to loosening bolt, a harmonic longitudinal elastic wave is applied to the structure by a pair of PZT patches and their electric impedance is measured simultaneously. According to the experimental results, the change of the electric impedance of P...

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1991년도 추계학술대회
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• pp.98-100
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• 1991

We studied the characteristics of the compound electrode and found that the compound electrode provides the four-electrode method in a compact form. We developed a new method of measuring the skin impedance using simple electrodes at low frequencies. At high frequencies where the effect of internal tissue impedance is not negligible, we used the compensation method using compound electrodes since they measure the voltage right under the skin. At 50 kHz, we measured the real part of the skin impedance of less than $80\;{\Omega}$ on the thorax.

• 대한의용생체공학회:의공학회지
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• 제5권1호
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• pp.15-18
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• 1984

In this paper we developed a respiration monitor by an impedane pneumography. This technique, measuring the electrical impedance change of the lungs due to breath, provides the accurate data for the respiration trend and rates. To measure the small impedance difference we designed a special current source which was considered the electrical safety and the interference with the ECG signal.

• 전기의세계
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• 제14권1호
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• pp.26-34
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• 1965

The radiation patterns and impedance of the half wave solt on the wide side of rectangular wave guide are analyzed. The measuring methods and procedures are described. And that the experimental data of the pattern and impedance of the slot are presented which are consistent with the theoretical values. The causes of error are also considered and are believed to be tolerable for the pattern and input impedance measurements. The usefulness of the slot antenna tested are also described.

• 전기학회논문지
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• 제56권6호
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• pp.1170-1176
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• 2007

The conventional urodynamic monitoring is fulfilled by artificially filling a bladder with saline. Generally. it is difficult to evaluate the physiological functions of the storage and voiding of a bladder. With this aim, we constructed an ambulatory urodynamic monitoring (AUM) system and proposed a novel method estimating abdominal pressure by measuring bio-impedance variations. Our system was clinically evaluated for 10 patients. It turned out to be that as the intensity of the abdomen contraction increased, the amplitude of bio-impedance signal and the RMS value of EMG increased more as compared to those who observed during the rest mode. Also, we determined the optimum electrode pair for estimating the abdominal pressure using bio-impedance method and consequently compared with the conventional methods. Because impedance changes differ from a weight, a height, contractile force, volume of muscle and blood other or whatever of individuals, it was quantified in terms of impedance change, correlation coefficient and SNR Our results showed the optimum electrode pair (1,9) which could detect impedance changes due to the increase of the intensity in the abdominal pressure. The correlation coefficient and quadratic function between the RMS values of EMG and the impedance changes were 0.87 and $y=0.0014x^2+0.0620x+0.6958$, respectively. Thus, our system demonstrated that the abdominal pressure could be measured noninvasively and conveniently by simply estimating bio-impedance values. We propose that this optimum electrode configuration would be useful for the future studies involving the handy measurements of abdominal pressure with our suggested ambulatory urodynamics monitoring system.

• 대한의용생체공학회:의공학회지
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• 제13권2호
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• pp.133-140
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• 1992

Bioelectrical Impedance method for measuring human body composition is based upon the principle that the electrical conductivity of the fat-free mass (FFM) is far greater than that of the (at. Deter- mination o( impedance was nlade in 30 healthy and obese men aged $40.9{\pm}14.7$yr (mean${\pm}$SD) and 25 healthy and obese women aged $44.0{\pm}10.2$ yr. A commercial impedance body fat analyzer was used with a four electrode arrangement that introduced a painless constant current(ImA at 50 kHz) into the body. Linear relationships were found between impudence values and FFM(r=-0.786) and between weight and FFM(r=0.837). Signigicant increases in the correlation coefficients were ob served when the predicator Hta/z was regressed against FFM(r=0.912) where Ht Is height and Z Is impedance. A linear regression equation, FFM=0.586(Htf/z) +0.317(Weight) -1.674(r=0.977), was found. The correlation coefficient of % body fat between the impedance and infrared methods was 0.898. These data Indicate that the bioelectrical impedance technique is a reliable and valld approach for the estimation of human body composition. This method Is safe, noninvasivr, prouides rapld measure menu, requires little operator skill and subject cooperation, and Os portable. Finally measurement of percent body fat was made possible using both the regression equation and a developed impedance measuring device which measures impedance between wrist and ankle.

• 제어로봇시스템학회논문지
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• 제17권2호
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• pp.171-175
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• 2011

In this paper, I have developed a high-speed and high-resolution measuring device in order to check the performance of drycell. The system is developed for the drycell manufacturing plant. Measuring time is one of key factors to inference on the production speed. So the developed system is designed to generate the classified result up to 1200ea/min. In the other words, each product can be classified within 25ms. There have been many studies to estimate both state of charge as well as state of health, such as OCV (Open Circuit Voltage), SC (Short Circuit) and measuring impedance with frequency pulse. But those methods take a few second due to surface discharge. To overcome the phenomenon, I developed the method to engage the reverse current to two electrodes of battery. As a result, I could achieve to measure the indigenous capacity without the problem of surface discharge.

• 유공압시스템학회논문집
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• 제4권3호
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• pp.22-27
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• 2007

The source flow ripple and the source impedance in hydraulic pump are characteristic values showing fluid-borne vibration characteristics decisively. We cannot measure these two characteristic values directly, but can measure them by some indirect methods. One representative indirect measuring method is ISO 10767-1. The authors constructed a hardware and a software for the measuring method based on ISO 10767-1. Through the error evaluation of the measured results, accuracy of the measuring method using ISO 10767-1 was examined in detail.

• Journal of Power Electronics
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• 제16권3호
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• pp.1163-1175
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• 2016

In recent years, microgrids have been the focus of considerable attention in distributed energy distribution. Microgrids contain a large number of power electronic devices that can potentially cause negative impedance instability. Harmonic impedance is an important tool to analyze stability and power quality of microgrids. Harmonic impedance can also be used in harmonic source localization. Precise measurement of microgrid impedance and analysis of system stability with impedances are essential to increase stability. In this study, we introduce a new square wave current injection method for impedance measurement and stability analysis. First, three stability criteria based on impedance parameters are presented. Then, we present a new impedance measurement method for microgrids based on square wave current injection. By injecting an unbalanced line-to-line current between two lines of the AC system, the method determines all impedance information in the traditional synchronous reference frame d-q model. Finally, the microgrid impedances of each part and the overall microgrid are calculated to verify the measurement results. In the experiments, a simulation model of a three-phase AC microgrid is developed using PSCAD, and the AC system harmonic impedance measuring device is developed.