• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
• /
• 2004.05a
• /
• pp.565-569
• /
• 2004

This paper deals with the characteristics of potential rise and effective impulse impedance of deep-driven ground rods that are used in high resistivity soil or in confined places such as downtown. Also the effects of the impulse and fault currents on the deep-driven ground rods combined with different type grounding electrodes like as mesh grids and counterpoises are described. The $8/20{\mu}s$ impulse current and other wave currents with different rise times are injected into the test ground rod and the effective impedances are examined. The most effective way to obtain the fine transient impedance behaviors of deep-driven ground rods is to reduce the inductive component of grounding electrode systems combined with other ground electrodes.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
• /
• 2004.05a
• /
• pp.95-99
• /
• 2004

A systematic approach of measurement, modeling and analysis of grounding system impedance in the field of lightning protection systems is presented. The measurement and analysis of ground impedance are based on a computer aided technique. The magnitude and phase of ground impedance were measured and analyzed by the modified fall-of-potential method and the proposed computer program algerian using the waveforms of the test current and potential rise. The theoretical analysis of ground impedance were performed with the equivalent circuit models, and the theoretical results were compared with the measured data.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.25 no.8
• /
• pp.140-149
• /
• 2011

This paper deals with the impact analysis of the impedance change of 345/154[kV] power transformers on the KEPCO system's overall performance. Through the steady-state and dynamic analysis of power system, the maximum available impedance of power transformers were determined. Checking violation of short-circuit current ratings and transformer overload, parallel operation of power transformers, calculation of voltage variation ratio according to the impedance changes of power transformers are included in the steady-state analysis. In addition, transient and voltage stability analysis are also performed in the study. Available magnitudes to be able to change the impedance of the transformers in KEPCO system are finally determined in the paper.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• v.9 no.1
• /
• pp.955-958
• /
• 2005

Bioelectrical Impedance Analysis(BIA) can measure body water amount and then body fat mass. The formula is used here FFM=-4.104+0.518H+0.231W+0.130X+4.229S is used, In this work, H is height, R is resistance value, W is weight, X is reactance and S is distinction of sex.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2001.11a
• /
• pp.157-159
• /
• 2001

The molten carbonate fuel cell has conspicuous feature and high potential in being used as an energy converter of various fuel to electricity and heat. However, the MCFC which use strongly corrosive molten carbonate at 650$^{\circ}C$ have many problem. Systematic investigation on corrosion behavior of Fe/20Cr/Ti alloys has been done in (62+38)mol% (Li+K)CO$_3$ melt at 923K by using steady state polarization and electrochemical impedance spectroscopy method. And, The research and development for the solid oxide fuel cell have been promoted rapidly and extensively in recent years, because of their high efficiency and future potential. Therefore this paper describes the manufacturing method and characteristics of anode electrode for SOFC, by the way, Ni-YSZ materials are used as anode of SOFC widely. So in this experiments, we investigated the optimum content of Ni, by the impedance characteristics, overvoltage. As a result, the performance of Ni-YSZ anode(47vo1%) was bettor excellent than the others.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2002.05a
• /
• pp.184-186
• /
• 2002

In this paper, we studies EMTP analysis and characteristics of critical voltage of pulse corona and load impedance on variable electrode length. To obtain a stable pulse voltage, we designed a compact pulse generator switched MOSFET and tested their characteristics by adjusting electrode length and pulse repetition. As a result, critical voltage of pulse corona and load impedance on increasing electrode length were decreased. These results indicate we can control critical voltage of pulse corona and suppress arc discharging between two electrodes.

• Proceedings of the KIEE Conference
• /
• 2005.07c
• /
• pp.2345-2347
• /
• 2005

In this paper, impedance characteristics of overhead medium-voltage (MV) power lines is reported for power line communication (PLC) over an MV power line network. For analysis, a two-port equivalent network model of MV power lines is derived. By applying the transmission line theory, reflection behavior and impedance of power lines are investigated. For verification, impedance of power lines is measured at a test field for an MV PLC. The results show that impedance of MV power lines is between $200{\Omega}$ and $300{\Omega}$ and converges to a half of their characteristic impedance.

• Proceedings of the KIEE Conference
• /
• 2006.07c
• /
• pp.1351-1352
• /
• 2006

In this paper, the impedance properties of degraded thyristor with heat and voltage were presented. As degraded thyristor, 8 thyristors with each other different reverse blocking voltage used. Its impedance and resistance properties were measured from frequency 100Hz to 10MHz applied with bias voltage from 0V to 40V. As a result, at low frequency region, that is, at the frequency 100-10kHz, the abrupt increasement of its capacitance was confirmed. And also, at high frequency region, the capacitance peak move toward low frequency in the region of frequency 4 - 6MHz as degradation of thyristor.

• Proceedings of the KIEE Conference
• /
• 2006.07c
• /
• pp.1739-1740
• /
• 2006

병렬선재를 사용하여 권선을 제작할 경우 구성하는 초전도 선재의 임피던스의 차이에 의하여 통전전류 불균형이 발생하게 된다. 본 논문에서는 BSCCO 선재를 사용하여 제작된 병렬선재에서 전류불균형 분포에 따른 교류손실을 측정하였다. 4 가닥 병렬선재의 경우 전류 불균형이 발생한 선재에서의 교류손실이 전류 불균형이 일어나지 않을 때보다 2배 이상 증가함을 확인하였다.

• Proceedings of the KIEE Conference
• /
• 2006.07c
• /
• pp.1683-1684
• /
• 2006

본 논문에서는 Half Bridge Series Resonant Inverter 를 이용한 유도가열 시스템 설계를 하고 제작하여 구현하였다. 이러한 유도가열 시스템의 제작을 위해서는 공진탱크와 매칭 트랜스포머의 설계가 필수적이다. 따라서 이런 설계를 위해 PSpice를 이용하여 공진탱크의 입력 임피던스 Bode Plot 을 그려 분석하고 이를 바탕으로 탱크회로를 설계 하였다. 매칭 트랜스포머의 설계는 출력 Power 와 1,2 차 회로 조건에 의해 설계 되어졌다. 이렇게 설계한 유도가열 시스템을 PSpice를 이용해서 Simulation 함으로써 주파수에 따른 출력 Power 의 변화를 볼 수 있었으며, 유도가열 시스템을 실제 제작하여 구현함으로써 확인하였다.