• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.21 no.10
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• pp.40-45
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• 2007

Lightning warning system plays an important role in protecting human life and other facilities from lightning return strokes. This paper dealt with lightning positioning algorithms and circuits as a main function of lightning warning system, which monitor movements and activities of thunderclouds. Electric field component produced by lightning discharge is detected by the configuration of a whip antenna and a narrow-band resonance amplifier with center frequency of 300[kHz]. Measurement circuit of magnetic field waveform consists of a crossed-loop coil and an integral amplifier, and its frequency bandwidth is ranges from 5[kHz] to 1.2[MHz]. The polarity of lightning discharge is discriminated by electric field component. After-fixing the polarity, we can calculate the direction and distance of lightning discharge by the peak and the zero-cross time of magnetic field waveform.

• Journal of Electrical Engineering and Technology
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• v.11 no.1
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• pp.184-191
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• 2016

In recent years, there are a number of studies that have been carried out to explore the alternative for Mineral Oil (MO) as dielectric insulating fluid in transformers due to the increasing tight regulation on safety and environment. Vegetable oils have been identified as suitable candidate since it is biodegradable, non-toxic and high flash/fire points which ensure more in-service safety. Among the types of vegetable oils considered for transformers application are Palm Oil (PO) and Coconut Oil (CO). This paper presents an experimental study on the lightning breakdown voltages of PO and CO under non-uniform electric field based on needle-sphere electrodes configuration at 3 small gap distances. The type of PO used in this study is Refined Bleached and Deodorized Palm Oil (RBDPO) Olein. The main focus of this study is to examine the lightning breakdown performance of RBDPO and CO under different test conditions and assess its suitability as dielectric insulating fluid in transformers. The effect of voltage polarities (positive and negative) and testing methods (rising-voltage, up-and-down and multiple-voltage) were investigated. The data obtained from all tests were analysed by Weibull distribution in order to determine the withstand voltages for each type of oils. It was found that the breakdown voltages of RBDPO and CO are comparable with MO under positive lightning impulse. Under negative lightning impulse, the breakdown voltage of MO is slightly higher than RBDPO and CO. There is no significant effect of testing methods and voltage polarities on lightning breakdown voltages of RBDPO and CO. Based on the statistical analysis, it is found that the breakdown voltages of RBDPO and CO at 1% probability are slightly lower than MO.

• Proceedings of the KIEE Conference
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• 2001.07c
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• pp.1658-1660
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• 2001

Because the overhead transmission lines are exposed to the outdoor weather, the faults of the transmission lines are due to natural conditions, and among these faults, the outage rate by lightning is about 50%. The lightning causes the damage of power system equipments, the shut down of electricity and the electro-magnetic interference. Therefore, the pertinent insulation design is important, not only to decrease the damage of the facility itself but also to increase the reliability of electric power system. For these reasons, we have to obtain and accumulate the lightning current parameters for the basic lightning research. This paper describes the statistical distribution of lightning current parameters and the IKL map.

• Journal of Aerospace System Engineering
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• v.10 no.2
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• pp.41-45
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• 2016

Statistical data show that a large aircraft(transport category) is struck by lightning once a year or once per 1,000 ~ 20,000 flight time. The protection design for lightning must be applied to the aircraft because an aircraft is developed on condition that it is absolutely struck by lightning. For the proper protection design, we need to understand direct effect and indirect effect of lightning. This paper described the direct effect of lightning on aircraft's structures and systems.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.1
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• pp.71-78
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• 2008

In this paper, The voltage waveshapes and the lightning parameters such as peak voltage, rise time, decay time and steepness of the front wave were statistically anal zed from the lightning-induced voltages measured on subscriber telecommunication line by lightning. Induced voltage measurement system to measure and collect the lightning-induced voltages in several regions of Korea was developed and installed in several sites. The distributions of lightning-induced voltages for Tears, regions and seasons were analyzed.

• Proceedings of the KIEE Conference
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• 1998.07e
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• pp.1571-1573
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• 1998

To study the basic research of the lightning parameter for power system operation. LPATS(Lightning Position and Tracking System) has been introduced since 1995 in KEPCO. We have developed the lightning parameter analysis program. We obtained the various statistical distribution of lightning current parameters from 1995 by this program. In this paper, we describe LPATS system configuration. the algorithm of the program and the statistical distribution of lightning current parameters from 1996 to 1997.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.1193-1198
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• 2004

This paper describes the lightning protection system for railway signaling equipments installed at subway car depots in Seoul metropolitan Rapid Transit Cooperation. Several measures for improving lightning protection performance are adopted; newly organized grounding system for neutral line of power system, rolling method to minimize damages induced by direct lightning strike, new measures to reduce voltage differences between the signaling equipments and the ground, and improvement of grounding system. The proposed system has greatly reduced the grounding resistance and also the voltage difference between the signaling equipments and the ground, and has prevented the accident related with lightning surges since it was installed. The proposed approach can be viewed as a useful alternative of dealing with lightning protection for railway signaling equipments.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.53 no.8
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• pp.454-460
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• 2004

The effects of surge arresters for protection of transmission systems against direct lightning strokes have already been reviewed using Electromagnetic Transients Program(EMTP). Distribution lines are spanned in much larger area than transmission lines, and therefore, are more susceptible to lightning strokes. We have modelled the 22.9kV underground distribution cable systems that have arresters and grounding wires. And this paper analyzes the overvoltages on underground distribution cable systems when direct lightning strokes strike on the overhead grounding wire using EMTP. Then we investigated that (1) the effects of lightning stroke according to underground distribution cable length (2) voltages at the riser pole and at the cable terminal according to installation of arrester. This study will provide insulation coordination methods for reasonable systems design in 22.9kV underground distribution cable systems.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.140-143
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• 2000

The primary function of ZnO lightning arrester is to protect transmission and distribution equipment from overvoltages and to absorb electrical energy resulting from lightning or switching surges and form temporary overvoltage. However, ZnO lightning arrester are known to exhibit an increases in resistive current with time, the rate of increase being exacerbated with increasing applied voltage and ambient temperature. So, it is important to the leakage current measurement of ZnO lightning arrester. In addition, since the resistive leakage current caused by deterioration of ZnO lightning arrester mainly caused an increase of the third harmonic component, thereby it is possible the arrester degradation diagnosis by measuring the third harmonic component in the total leakage current. The leakage current and third harmonic component are measured and used to investigate the degradation diagnosis of ZnO element of arrester. Also the SEM photography is used to investigate the change of crystal structure of ZnO element with degradation.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2001.11a
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• pp.73-76
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• 2001

This paper dives the current status of lightning damages in apartments obtained by questionnaire and analysis the cause of ligntning damages. As a result, the apartments experienced lightning damages are assumed about 5[%] lot total apartments and the lightning surges invaded on power line are identified as the main cause of lightning damages in apartments.