• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 하계종합학술대회 논문집(5)
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• pp.218-221
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• 2000

The electronystagmography(ENG) means to measure and record CRP(Corneal-Retinal Potential) whenever the eyeball is moved by using a skin electrode stuck to the hi-temporal and the difference of CRP. Both the horizontal and vertical movement are known according to the position of the stuck skin electrode. In this paper, the variable time-constances to record the eyeball signal of the conventional EOG(Electro-Oculograph) Amplifier is chosen. The shorter the time-constance is, the worse the distortion of a signal is. But the unbalanced impedance of the electrode stuck on the hi-temporal is reduced. Also, the longer the time-constance is, the less the distortion of it signal is. But it is sensitive to the change of base line according to the unbalanced impedance. In order to solve these problems, an DC-Amplifier, the distortion of the eyeball signal is globally used. By solving unbalanced impedance problem of EOG amplifier, the distortion ratio of EOG amplifier is improved.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 C
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• pp.1778-1780
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• 1996

In this paper, we describe the partial discharge measurement with measuring impedance to have two wide frequency band transformers(filters) in the oil-paper and air insulation. The measuring impedance consists of high and low limiting frequency transformers. This measuring impedance could be measured the partial discharge current wave. We have the results that the amplitude partial discharge pulse ratio of low limiting frequency tranformer to high limiting frequency one is varied in the condition(in oil-paper insulation and air) to generate partial discharge.

• 한국농공학회지
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• 제40권6호
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• pp.79-88
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• 1998

This study was conducted to measure the moisture content of soil using RF impedance in the range of 1 to 30MHz. Considering the water potential flow in the soils, two types of sensor such as parallel cylinder and perpendicular plate type were fabricated and tested. The capacitance and resistance of sonsors for soil samples having moisture content range of 2 to 27% were measured by Q-meter (HP4342). The higher soil moisture content was and the larger soil bulk density was, the more the capacitance of sensors increased. To eliminate the effect of bulk density on measuring soil moisture content using RF impedance, two kinds of model having the density independent functions such as the ratio of capacitance change to conductance change and weight of water and dry soils respectively were developed and estimated by regression analysis.

• 한국전자파학회논문지
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• 제11권5호
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• pp.738-747
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• 2000

본 논문에서 낮은 주파수 영역에서는 약 결합된 meander line은 근사적으로 단일 전송선으로 취급할 수 있음을 증명하였다. 이 때 meander line의 특성 impedance는 이 meander line에서 coupling을 무시할 때 단일전송선의 특성 impedance와 같으며, 반면 이것의 등가길이는 coupling없이 계산된 길이에 비해서는 수축되는 것을 보았다. 얻어진 해석적 결과는 회로 simulation 결과와 비교되었으며 또한 EM simulation 결과와 비교결과 결과식은 약 결합시에는 잘 일치하는 것을 알 수 있었다.

• ETRI Journal
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• 제37권3호
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• pp.637-645
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• 2015

Common-mode noise (CMN) is an unresolved problem in wireless capsule endoscopy (WCE) systems. In a WCE system, CMN originates from various electric currents found within the human body or external interference sources and causes critical demodulation performance degradation. The differential operation, a typical method for the removal of CMN rejection, can remove CMN by subtracting two signals simultaneously received by two reception sensors attached to a human body. However, when there is impedance mismatching between the two reception sensors, the differential operation method cannot completely remove CMN. Therefore, to overcome this problem, we propose an enhanced CMN rejection method. The proposed method performs not only subtraction but also addition between two received signals. Then a CMN ratio can be estimated by sufficient accumulation of division operation outcomes between the subtraction and addition outputs during the guard period. Finally, we can reject the residual CMN by combining the subtraction and addition outputs.

• Journal of electromagnetic engineering and science
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• 제18권2호
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• pp.101-107
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• 2018

The impedance bandwidth and radiation characteristics of an aperture-coupled microstrip line-fed patch antenna (ACMPA) with a high permittivity (${\varepsilon}_r=10$) feed substrate suitable for integration with a monolithic microwave integrated circuit (MMIC) are investigated for various feed substrate thicknesses through an experiment and computer simulation. The impedance bandwidth of an ACMPA with a high permittivity feed substrate increases as the feed substrate thickness decreases. Furthermore, the front-to-back ratio of an ACMPA with a high permittivity feed substrate increases and the cross-polarization level decreases as the feed substrate thickness decreases. As the impedance bandwidth of an ACMPA with a high permittivity feed substrate increases and its radiation characteristics improve as the feed substrate thickness decreases, the ACMPA configuration becomes suitable for integration with an MMIC.

• 드라이브 ㆍ 컨트롤
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• 제13권3호
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• pp.8-14
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• 2016

This study describes the effect of the critical pressure ratio of a control valve on the performance of an air spring system composed of an air spring, auxiliary chamber, control valve and mass in order to suggest a more efficient design for an air spring system. The critical pressure ratio of the control valve is assumed to have a fixed value, but the critical pressure ratio of the control valve is known to have various values between 0.05 and 0.6, and the effect of the variation of the critical pressure ratio on the performance of the air spring system has not yet been reported. The analysis derives nonlinear and linear governing equations of the air spring system, including the critical pressure ratio of the control valve. This simulation study is presented to show that the impedance and transmissibility characteristics of the air spring system change due to variations in the critical pressure ratio of the control valve as well as its sonic conductance. As a result, the critical pressure ratio of the control valve should be maintained as large as possible to improve the vibration isolation characteristics of the air spring system.

• Corrosion Science and Technology
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• 제13권1호
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• pp.15-19
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• 2014

Recently, anti-fouling paints which does not include the poison components such as tin(Sn), copper(Cu) have been increasingly developed in order to inhibit the environmental contamination of the sea water. Moreover, the wear ratios of these anti-fouling paints are very important problem to prolong their life time in economical point of view. In this study, five types of anti-fouling paints as self polishing type were investigated on the relationship between their polarization characteristics and wear ratios. It was verified that there was apparently a good relationship between the wear ratio and polarization characteristics, for example, the wear ratio increased with increasing the impedance ratio, and increased or decreased with the corrosion potential shifting in the negative or positive direction respectively. In addition, the wear ratio decreased with decreasing the corrosion current density. Consequently, it is suggested that we can qualitatively expect the wear ratio by only measuring the polarization characteristics. Therefore, before the examination of the wear ratio was actually carried out in the field, the evaluation of polarization property in the laboratory may give a available reference data for their developments.

• 한국소음진동공학회논문집
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• 제21권11호
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• pp.1059-1066
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• 2011

The micro-perforated panel absorber(MPPA) is one of promising noise control elements because of its applicability to extreme environments where general porous materials cannot be used. Since the MPPA is inherently non-porous sound absorber, it can be a good candidate of acoustic protection system of a space launcher. The overall sound pressure level inside payload fairings of commercial launch vehicles is so high(around 140 dB OASPL) that the conventional linear impedance model cannot be directly applied to the design of the acoustic protection systems. In this paper an acoustic impedance models of a micro-perforated panel absorber at high sound pressure environment were reviewed and the use of the impedance on the practical design of MPPAs was addressed. The variation of absorption characteristics of MPPA was discussed according to the design parameters, e.g., perforation ratio, the minute hole diameter, the thickness of MPP and the incident sound pressure level.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제49권1호
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• pp.30-35
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• 2000

The pulsed plasma wire-plate reactor was analyzed on the basis of experiment, EMTP simulation and modelling method. Though the reactor has a non-linear impedance characteristics, we demonstrate that the reactor impedance can be approximately analyzed with the measured initial capacitance and average resistive component of flat zone. Using this modelling method, the influence of the reactor capacitance on the impedance matching between pulse generator and reactor can be investigated. From this, we found that the energy of 95% was delivered form pulse generator to reactor at the ratio of $C_r/C_p\cong 0.3,\; where\; C_p\; is\; pulse\; generator\; capacitance, C_r$ is reactor capacitance.