• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 A
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• pp.452-454
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• 2001

This paper described the calculation results of lightning flashover rate on the 345kV and 154kV transmission system of KEPCO. The back-flashover rate and shielding failure rate was calculated by FLASH(lightning flashover rate calculation program from IEEE) and KEPRI's own program which is based on the EGM(Electro Geometrical Model) method. The estimated lightning flashover late of 345kV transmission system of double circuit was 1.0 flash per 100km-year, and the lightning flashover rate of 154kV transmission line was 2.0 flash Per 100km-year approximately.

• 기술사
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• 제31권4호
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• pp.64-68
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• 1998

According to some statistics, about 13,000 passenger aircrafts are daily flying over the globe and these aircrafts are struck by a lightning flash at least once a year. But so far we have never heard lightning injured any passengers and crew members got shocked by lightning. The aircraft, lightning and the sky are inseparably related to each other. Accordingly, the aircraft and lightning are also inseparably related to each other. They say lightning is easily attracted to metals and these aircrafts are incidentally made of metal. Aircraft become statically and electrically charged when flying because of the friction with air. A lot of research and investigation to protect aircraft from the influence of lightening have been made since the early days. The following descriptions outline researches and investigations on how aircraft and ships get aways from lightning flashes during the flight or the sail. (Research and Investigation on Aircraft and Ships Get Aways from Lightning Flash)

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제49권12호
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• pp.685-690
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• 2000

Multiple-lightning impulse currents are a general feature of the lightning ground f=flash. It is therefore necessary for lightning arresters used in power systems to be estimated by applying not only a single-lightning impulse current but also a multiple-lightning impulse currents. This paper presents the effects of multiple-lightning impulse currents on deterioration of ZnO arrester blocks. The multiple-lightning impulse generator which can produce quadruple 8/20$[\mus]$ 5[kA] with separation time of 30~120[ms] is designed and fabricated. The total energy applied to the arrester block at each impulse is about 1,200[J]. In experiment, various parameters such as leakage current component, reference voltage, and temperature are measured with the number of applied impulse current. Also, micro-structure changes of the ZnO blocks after applying the single and the multiple-lightning impulse currents of 200 times are compared. The experimental results indicate that the types of arrester blocks are more vulnerable to deterioration or damage by multiple-lightning impulse currents.

• 한국지구과학회지
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• 제30권2호
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• pp.210-222
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• 2009

최근(2002-2006) 발생한 낙뢰의 빈도, 강도, 지속시간 및 낙뢰율의 시 공간적 특성을 분석하였다. 빈도는 경년변동이 크게 나타났으며, 여름과 겨울에 각각 전체 낙뢰의 75%, 0.6%가 발생하였다. 정극성 낙뢰는 우기(6-9월)에 부극성 낙뢰의 0.15 비율로 발생했으나 동계에는 그 비율이 증가하여 2월경에 부극성 낙뢰의 0.98까지 증가하였다. 낙뢰 지속시간은 여름에 집중되는 계절변동이 크게 나타났으나 낙뢰율의 변동은 이에 비해 작았다. 낙뢰는 새벽(2시, 5-7시)과 오후 중반(15시)에 두 번의 최대 빈도가 나타났으며 5시경에는 낙뢰강도가 강하였으나, 15시를 전후로 하는 오후 중반에는 낙뢰 강도가 약했다. 낙뢰밀도는 남한 서부 내륙 및 서 남해상에 높으며, 영동 및 동해지역은 낮았다. 충남 및 전북지역에서 0.4 이상으로 높게 나타났는데, 구름내 방전일 가능성이 있어 해석의 주의를 요한다. 낙뢰 밀도가 높은 서부내륙에서는 우기 낙뢰 지속시간이 연 평균 15-25시간으로 나타났으나, 서해상에서는 낙뢰 발생 시의 집중도가 높고 강도가 강하였다. 대부분의 내륙에서는 오후 중반에서 저녁 사이에 낙뢰 발생 빈도가 최대였으나 산악 및 해안, 중서부 지역은 각각 오전과 새벽에 최대로 발생하였다.

• 한국항공우주학회지
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• 제31권9호
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• pp.110-120
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• 2003

고공을 운항하는 항공기는 대기중의 자연현상에 의해 낙뢰에 노출되게 된다. 낙뢰 피해는 개발초기에는 목재 항공기의 절연파괴에 의한 손상과 화재등이 있었으며 알루미늄의 보급으로 전금속체 항공기가 개발되었지만 연료탱크의 화재 문제라든지 낙뢰 사고는 계속 발생하였다. 이에 NACA에서는 1938년 문제를 제기하고, 인공 낙뢰에 대한 연구를 시작하였다. 이어 FAA에서는 낙뢰보호에 대한 인증을 위해 감항기준을 제정하고 SAE에 낙뢰에 대한 항공기의 보호를 위한 시험대책 연구를 의뢰하여 낙뢰를 모사한 시험 전류, 전약 파형을 제시하여 항공기의 낙뢰보호, 인증에 활용하고 있다. 이 글에서는 낙뢰의 메커니즘 분석을 통한 항공기에 대한 낙뢰의 영향을 제시하고 특히 항공기 안전사고의 중요한 요인으로 대두되고 있는 항공기에 대한 낙뢰의 직접영향에 대한 사례를 분석하고 인증기준과 시험 전류 및 전압파형, 낙뢰 피격부위를 열거하여 개발항공기 및 비행체에 대한 인증에 활용되도록 하였다.

• 한국환경과학회지
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• 제31권7호
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• pp.543-553
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• 2022

The latest aerospace technology is important for the stable flight of a launch vehicle, but weather conditions on the day of launch are also one of the essential factors for successful launch campaign. If a launch vehicle is directly struck while preparing to take off from the launch pad on the day of launch or the electronic device are damaged by induced current during flight of the launch vehicle, this means launch failure and can lead to enormous national loss. Therefore, for a successful launch campaign, it is necessary to analyze the lightning detection characteristics of the Naro Space Center. In this study, the seasonal factors of the lightning that occurred over the Naro Space Center from 2003 to 2017, the influence of the polarity, and the correlation with the lightning intensity was confirmed. As a result, there was a high probability of intensive occurrence of multiple lightning strikes in summer, and a high proportion of positive (+) lightning strikes in winter. Lastly, in the distribution of the number of lightning strikes, an average of 2.0 to 2.5 negative (-) lightning strikes occurs in the coastal regions of the South and West Seas when one flash happens.

• Journal of Electrical Engineering and Technology
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• 제11권3호
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• pp.602-608
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• 2016

Because of the random characteristics of lightning, the Monte Carlo method is applied to estimate the flashover rate due to lightning, however, the simulations using previous methods are difficult to both beginner and expert in power corporations. Therefore, this paper proposes the new and easy method to simulate the flashover rate by connection of electromagnetic transients program (EMTP) and MATLAB. The magnitude of a lightning strike is based on a curve measured in the field, while the classification of direct and indirect lightning depends on the striking distance. In a Korean distribution system, the flashover rate induced by lightning is simulated using proposed method. Simulations of the footing resistance according to the existence of an overhead ground wire (OHGW) are performed and the simulation results are discussed. The simulation results are compared with findings obtained with the IEEE Flash 2.0 program.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2002년도 Proceedings of International Symposium on Remote Sensing
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• pp.366-366
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• 2002

Cloud-to ground lightning and total precipitation over Korean peninsula during the summer monsoon season are studied extensively with a special emphasis on the characteristics of convective precipitation. Ten years (1988-1997) lightning and rainfall data and a temporal and spatial scale of one month and 10$^2$ km$^2$ respectively are used to calculate the monthly number of CG lightning flash count. Monsoonal convective activity is higher over the west coast with maxima at two different regions, one in the northern part which increases nortwestward and the other is at the middle west coast of Korea increasing towards the west coast. East coast represents the minimum value of monsoonal convective activity. In the east coast of Korean peninsula, particularly in the region east of Tae-back mountain, the value of Rain yield, (which is defined as the ratio of total precipitation to CG flash count over a common area), is maximum with an average value of 3$\times$10$^{8}$ kg fl$^{-1}$, while the minimum value of rain yield is occurred in the west of Tae-back mountain, with an average value of 0.8$\times$10$^{8}$ kg fl$^{-1}$. Results show in the west coast stations, nearly 82% of the total rainfall is convective in nature, at the middle of the peninsula 53% of the total rain is convective while in the east coast stations 46% contribution from the convective rain is seen. Kanghwa receives the maximum convective rain while at Ulsan the convective rain is minimum. Correlation coefficient between the total precipitation and CG lightning during the summer monsoon season is 0.54.

• Journal of Electrical Engineering and Technology
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• 제11권1호
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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.

• 한국지구과학회지
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• 제24권3호
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• pp.181-189
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• 2003

이 연구는 일본 중서부 지방에서 1996년 겨울철에 발생한 뇌우의 관측 자료를 분석한 것이다. 관측기간 중 35 회의 뇌우가 발생하였으며 발생된 뇌 방전 수는 4426개였다. 관측된 뇌 방전 수를 뇌 방전 종별로 구분하여 그 발생비율을 구하였고, 뇌 방전의 종류와 기압배치와의 관계도 분석하였다. 그 결과 구름 뇌 방전의 비율은 약 78%이었으며, 양극성 낙뢰가 42.3%로 나타났다. 동계의 낙뢰활동은 미약하나 0${\sim}$5시에 가장 강하였다. 또한, 낙뢰는 북서 계절풍이 강한 경우에 활발하게 발생되고 있음을 알 수 있었다. 다중뇌와 다지점 낙뢰의 분석결과 평균 다중도는 1.4이고, 평균 다지점 낙뢰는 1.2로 나타났다.