• Journal of Power Electronics
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• v.4 no.4
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• pp.256-260
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• 2004

A new communication system is suggested using a single-phase full-bridge inverter with high efficiency ferrite core for power line communication (PLC). The conventional system has a decreasing signal voltage problem due to internal resistance. The proposed system has almost zero internal impedance and replaces a linear amplifier.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1700-1701
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• 2007

DC Arc Fault Current is an electric discharge which is occurred in two opposite electrode. In this paper, DC arc detection device is designed for the display of DC arc fault current which is occurred in the local electric network with DC Power. This DC arc is one of the main causes of electric fire. Arc fault in electrical network has the characteristics of low current, high impedance and low frequency. DC Arc current detection device is designed for the display of arc fault current which has the modified arc characteristics.

• Journal of Industrial Technology
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• v.21 no.A
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• pp.207-211
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• 2001

For the power line communication, we studied its characteristic impedance, noise characteristics, loss characteristics and the coupling circuit between the communication MODEM and power lines. As the results of the experiments, we concluded that the power line impedance in a house varied in the wide range because the electric systems generate the current and voltage hamornic noises.

• Proceedings of the KSR Conference
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• 2000.05a
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• pp.116-122
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• 2000

This paper presents a simulation method with constant power model for the train load. In power system simulation loads could be modeled as a constant power, constant current, constant Impedance or a function of voltage and frequency. At this time, however, representing a train load as the function is difficult because of the lack of data. Therefore as a first step, simulation method with a constant power model fer a train is studied, and the test result is compared with the simulation result using the constant Impedance model.

• Proceedings of the KIEE Conference
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• summer
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• pp.1403-1405
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• 2004

The method proposed by Carson contains indefinite complex integral which simulates earth return current. Although the Carson solution is proposed with power series, the solution is limited and valid at special range of frequency. We proposed a simplified Carson solution by modelling earth current path analytical method using ground transmission line return current. In this paper, we studied on trying to find the equivalent distance for earth current return path.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2007.11a
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• pp.26-26
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• 2007

To attest zinc electrodeposition mechanism, electric circuit models for zinc electro reaction on Pt electrode are analyzed from the a.c. impedance data. Electrochemical reactions of zinc deposition are composed of the three electrochemical reactions on the cathode layer and of the induced electrode layers.

• Proceedings of the Korea Society of Information Technology Applications Conference
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• 2005.11a
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• pp.215-218
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• 2005

We have investigated on the development of 2-2 piezocomposites that have better piezoelectric activity and lower acoustic impedance than those of conventional piezoceramics. In this study, we have investigated the piezoelectric and acoustic properties of 2-2 piezocomposites sensor which were fabricated using dice-and-fill technique for the different volume fraction of PZT. The resonance characteristics measured by an impedance analyzer were similar to the analysis of finite element method. The resonance characteristics and the electromechanical coupling factor were the best when the volume fraction PZT was 0.6. It also showed the highest result from the standpoint of sensitivity, bandwidth and ring-down property and so on at the same condition. The specific characteristics shows that the 2-2 piezocomposites turned out to be superior to the ultrasonic sensor composed by single phase PZT.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.10
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• pp.1265-1270
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• 2018

One of the ways to improve the stability of power facilities used in power systems is to use power surge arresters and to protect against transient overvoltages and surges in normal operation. Also it is important to reduce the impact of lightning strikes because lightning can create overvoltage in the grid of the wind turbine and affect power quality. So This paper analyzes the effects of overvoltage and adjacent turbines due to single strike and multi strike to ground impedance changes when the surge arrester is deteriorated in a wind power farm.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.272-273
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• 2015

This paper analyze scenario of feeder wire fault that occurs in the AC feeding system considering train position. The fault location of AC feeding system is calculated by measuring impedance. However, in this way, estimation error can be occurred because of tie connection, boosting current, etc. Therefore, it's hard to find fault location, so that it is required to detailed circuit analysis according to fault location. We analyze the short circuit impedance values with respect to feeder wire fault according to a train position. In this paper, PSCAD is used for modeling and analysis of AC railway feeding system.

• Proceedings of the Membrane Society of Korea Conference
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• 1994.10a
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• pp.17-19
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• 1994

고분자 분리막의 구조가 투과율에 미치는 영향에 대해서는 지금까지 많은 연구가 행하여져 왔지만, 분자구조가 투과경로에 미치는 영향에 대한 연구는 아직 미미하며, black box approach만으로는 투과경로를 기술하기 어렵다. Impedance spectrowcopy는 막에 alternating electric field를 가해줌으로써 얻어지는 전류와 전압의 상관관계를 이용하여, 막내의 전해질의 투과에 대한 정보를 얻어내는 기기로써, dielectric loss spectra를 분석하면 투과물의 투과경로에 대한 정보도 얻을 수 있다. 전해질을 포함한 막의 dielectric loss ($\varepsilon"$) spectra는 다음의 식과 같이 두 부분으로 나뉘어 진다. $\varepsilon" = \varepsilon_{ac}" + \varepsilon_{dc}"$ (1) $\varepsilon_{dc}"$는 막을 통한 이온의 투과에 관계된 항이며, $\varepsilon_{ac}"$는 강한 dipole의 relaxation에 의해 나타나는 항이다. $\varepsilon_{dc}"$는 다음의 실험식에 의해 잘 기술되어진다. $\varepsilon_{dc}" = A\omega^{-n}$ 0