• Journal of Sensor Science and Technology
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• v.10 no.4
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• pp.250-258
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• 2001

In this study, a lightning warning system (LWS) which can predict a lightning return stroke is developed, and the LWS is based on the measurement of electric field intensity at the ground level. The LWS consist of a rotation-type field mill as an electric field sensor, an impedance changer, a two-stage amplifier, and a microprocessor unit. From the calibration experiment, the frequency bandwidth and the maximum resolution of the LWS are $DC{\sim}200\;[Hz]$ and 73 [V/m], respectively. Also, the LWS can measure the electric field strength caused by a thunderstorm up to 18.7 [kV/m] at the ground. To ensure the sensing ability of the developed LWS in an actual situation, computer simulation using thundercloud models was carried out, and the result showed that the LWS can monitor the movement of thunderclouds within 6 [km] from the observation site.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.588-595
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• 2008

Recently, it is caused by environment change that is increased the number of lightning occurrence and the strength of lightning current is coming to be strong little by little. The performance of grounding system depends on how to construct. Specially the common grounding systems which uses the buried earth cable must be constructed by very well qualities because it is difficult to measure earth resistance and to manage the buried earth cable. Common grounding systems and independence grounding systems could be composed different. Against railway signalling equipment which like this is used from the environment lower part which is various it presents a standard grounding systems, and very it is hard job. We will present improvement through this paper that review grounding systems configuration condition of railway signalling equipment.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.3
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• pp.459-466
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• 2022

Switching surges are a common type of phenomenon that occur on any sort of power system network. These are more pronounced on long transmission lines and in high voltage converter stations. At AC/DC hybrid transmission lines, the insulation coordination of such lines is mainly dictated by the peak level of switching surges, the most dangerous of which include three phase line energization and AC/DC converter station. The power system structure consist of AC/DC hybrid transmission lines which is combination of AC 765kV and ±500kV HVDC 1 bipole system for contingency analysis. The power system under study and its components are simulated using EMTDC software package, the effects of the various AC/DC mixing power lines are reviewed. The developed models of EMTDC conversion lines based on combination of AC/DC system are simulated and the characteristics of switching surge over-voltage from its results are discussed.

• The Journal of the Korea institute of electronic communication sciences
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• v.10 no.8
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• pp.927-934
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• 2015

In this paper, in order to prevent impulse surge PoE(Power Over Ethernet) communications error caused by natural phenomenon in industrial sites, countermeasure design of impulse surge of PoE communications equipment is suggested by designing dual impulse surge protection circuit. In order to analyze characteristic of impulse surge noise signal, surge generating device which meet international standard IEC 61000-4-5 is invented. And this device shows that surge signal is weakened by designing dual PoE power supply protection circuit by connecting surge generating device to the PoE data transfer line.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.8
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• pp.14-20
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• 2009

In this paper, the time-varying failure rate to consider climate effect was extracted. Even if the same kind of equipments is estimated for extracting the time-varying failure rate, the failure rates could be different depending on external effect such as climate. With the consequence, the failure rate extracted to consider the climate effect is necessary for using the failure rate on the optimal investment plan or asset management, To consider the characteristic of climate effects(Classified into 5 categories, heavy rain, thunderbolt, strong wind, tidal waves, no character), the survey of officers charging the operation of equipment in KEPCO branch office was done. With this consequence, this paper suggest the failure rate extraction method to consider the climate effect analyzed by the survey.

• Proceedings of the KIPE Conference
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• 2014.11a
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• pp.64-65
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• 2014

신재생에너지원의 급속한 보급, 고신뢰 및 고효율 전원망에 대한 고객의 요구, 디지털부하의 급증 등 기술적 사회적 환경의 변화에 따라 직류배전망에 대한 관심이 높아지고 있다. 이에 따라 직류배전망의 안전성에 대한 문제도 지속적으로 제기되고 있다. 특히 지락, 단락사고, 절연고장, 낙뢰, 아크, 전식 등으로부터 인체 감전과 기기의 소손, 정지 또는 오동작이 발생될 수 있으며 이로 인해 심각한 문제를 야기될 수 있다. 국제표준 IEC 60364에서는 전기설비에 따른 접지시스템을 TT, TN 및 IT접지의 3가지로 분류하고 있다. TN접지방식은 전원선과 설비외함의 노출 도전부를 보호도체를 사용하여 공통으로 접지하는 계통을 말한다. 따라서, 전원선이 외함에 접촉되거나 인체의 감전에 의한 누전사고가 발생하였을 때 전원선 전체를 통하여 흐르는 전류의 차이를 검출함으로서 사고전류의 검출이 즉각 이루어 질 수 있다. 교류계통에서는 영상전류검출기에 의하여 누설전류의 검출이 가능하지만 직류계통에서는 영상전류검출기를 사용할 수 없으므로 새로운 방식의 누전검출장치의 개발이 요구된다. 또한 감전 사고는 인체의 사고와 설비의 사고 두 가지로 구별되며, 효율적인 전력운영과 안전을 위하여 두가지 사고에 대해 통합적으로 구분 동작이 가능한 누설전류 검출기 개발이 요구된다. 본 연구에서는 TN접지계통에서 직류누설전류 검출이 가능한 홀 센서(HCT)를 사용하여 인체 및 설비의 누설전류 패턴에 따라 구분 동작이 가능한 직류용 누설전류 검출기 개발에 관한 연구를 수행하였다.

• Proceedings of the KIEE Conference
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• summer
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• pp.584-586
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• 2004

This paper deals with the development of on-line fault and lightning stroke section locating system for branched overhead transmission line. The section locating algorithm of this system i3 by analyzing the distribution pattern of current flowing through the overhead ground wire. It composes of three parts; current sensors, local remote terminal unit(RTU) and analysis program at surveillance tenter. Double Rogowski coil sensor having integrating amplifier was designed as current sensor. In order for current pattern analysis, the transmitted waves from each sensor wert synchronized by GPS tim c clock in RTU. While, lightning stroke location are judged only by polarity information of lightning currents. This design has a benefit in simplicity of signal processing unit of RTU.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.4
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• pp.724-730
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• 2006

The earth resistance is a essential basic factor of the performance of the earth. The earth enables system to be operated in a stable way not only against thunderbolts, unexpected transitional currents, the inflow of voltages and electric noises but also protect human life from electric shocks. In a domestic case, there is a technique criterion about earth technique but it falls short of reality since the content is very limitted, which causes a lot of problems to establish communications facilities. This paper gives the results through actual measurement or the earth resistance as reffered date in a way to improve these problems.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.5
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• pp.65-70
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• 2015

Lightning is one of hazards affecting the rapid-transit railway system. There are two effects, which are direct lightning surge to electric car line and induced lightning surge. Protection methods for the direct lightning surge are studied with various occasions, however, study of induced lightning surge is insufficient in spite of a large or small effects. In this paper, it is analysed the way that serge voltage is induced to electric car line by lightning strikes. By modeling the propagation process and the coupling phenomenon of electromagnetic wave produced by lightning strikes, it is achieved to make integrative circuit model combined with existing electric car model. The study is conducted into three different waveform of electromagnetic wave produced by lightning; rectangular wave, double exponential distribution wave, triangle wave. It is also simulated that the inducing serge is coupled to electric car line in an arbitrary location. The simulation results in that, when rapidly changing rectangular wave is supplied, maximum power is induced to electric car line.

• Korean Journal of Remote Sensing
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• v.34 no.3
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• pp.465-480
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• 2018

On 20 January 2017, the fresh snow cover which is more than 20 cm, accompaning with lightning occurred over Yeongdong coastal region for the first 3-hour of the heavy snowfall event. This study analyzed sounding observations in the heavy snow period which were including the measurements of wind profiler, radiometer and rawinsonde. The features examined from the vertical wind and temperature data at the two adjacent stations, Bukgangneung and Gangneung-Wonju National University, are summarized as follows: 1) The strong (30-40 kts) north-east winds were observed in the level from 2 to 6 km. The Strong atmospheric instability was found from 4 to 6 km, in which the lapse rate of temperature was about $-18^{\circ}C\;km^{-1}$. These features indicate that the deep convective cloud develops up to the height of 6 km in the heavy snowfall period, which is shown in the satellite infrared images. 2) The cooling was observed in the level below 1 km. At this time, the surface air temperature at Bukgangneung station decreased by $4^{\circ}C$. The narrow cooling zone estimated from AWS and buoy data was located in east-west direction. These are the features observed in the cold front of extratropical cyclone. The distributions of radar echo and lightning also show the same shape in east-west direction. Therefore, the results indicate that the Yeongdong thundersnow event was the combined precipitation system of deep convective cloud and cold frontal precipitation.