• Journal of Advanced Navigation Technology
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• v.19 no.5
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• pp.395-402
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• 2015

This paper introduces the design details and test procedures of the lightning induced transient protection device for protecting the damage caused by indirect lightning strike on the computer mounted on the aircraft. Lightning induced surge voltage is bring a malfunction or damage to the aircraft electrical and electronic equipment, that is referred to indirect effects of lightning. In order to protect the electronic equipment on aircraft from the indirect effects of lightning, that is achieved by analyzing the effect on aircraft from lightning and protect design for each devices. In this paper, we introduce an indirect lightning strike level decisions, the protection circuit design method according to the chosen level through the RTCA DO-160G Section 22 category analysis and selection was performed in order to protect the damage caused by indirect lightning strikes in the protected equipment. In addition, we show the indirect lightning effects verification test performed to validate the designed protection circuits.

• Journal of Advanced Navigation Technology
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• v.21 no.5
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• pp.459-465
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• 2017

In this paper, we introduce the design consideration of the lightning induced transient protection circuit for the indirect lightning strike on the avionics equipment. The lightning induced surge voltage, which is so-called as indirect effects of lightning, may cause a functional failure or physical damage to the electrical and electronic equipment of aircraft. In order to protect the electrical and electronic equipment of aircraft from the indirect effects of lightning, we should analyze the effect of lightning strike on aircraft and consider applying protection design for each avionics device. However, lightning induced transient protection circuits can have unintended consequences because parasitic inductance elements are exist in PCB and TVS diodes. In this paper, we introduce the design method of the protection circuit considering the parasitic inductance of the protection circuit. In addition, we show the result of verification test performed to validate the protection circuits for indirect effects of lightning.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.12
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• pp.1071-1086
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• 2016

The safety of aircraft can be threatened by environmental factors, such as icing, turbulence, and lightning strike. Due to its adverse effects on aircraft structure and electronic components of aircraft, lightning strike is one of the biggest hazards on aircraft safety. Lightning strike can inject high voltage electric current to the aircraft, which may generate strong magnetic field and extreme hot spots, leading to severe damage of structure or other equipment in aircraft. In this work, mechanism of lightning strike and associated direct and indirect effects of lightning on aircraft were studied. First, on the basis of aircraft lightning regulations provided by Aerospace Recommended Practice (ARP), we considered different lightning waveform and zones of an aircraft. A coupled thermal-electrical computational model of ABAQUS was then used for simulating flow of heat and electric current caused by a lightning strike. A study on fuel tank, with and without lightning protection system, was also conducted using the computational model. Finally, electric current flow on two full scale airframes was analyzed using the EMA3D code.

• Journal of the Korean earth science society
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• v.31 no.4
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• pp.335-347
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• 2010

The statistical characteristics of Cloud-to-Ground (CG) lightning data, observed by the total lightning detection system (TLDS) of KMA during the recent seven years (2002-2008), have been analyzed. Lightning frequency shows a strong interannual, seasonal and diurnal variations without regard to the polarity. The 74% and 0.6% of the total lightning occurred during the summer and winter, respectively. And it has a bimodal diurnal variation with two peaks (dawn: 0500-0700 LST, mid-afternoon: 1500-1600 LST). The ratio of positive flashes to negative ones also has a strong seasonal variation with the maximum and minimum during winter (62.5%) and summer (7.3%), respectively. Unlike the lightning frequency, the lightning intensity of negative flashes shows a weak interannual, seasonal and diurnal variations. However, the lightning intensity of positive flashes exhibits an inverse seasonal variation to that of lightning frequency, with the minimum and maximum during summer and winter, respectively. The lightning density is greatly higher in the western inland areas and the West/South Sea than in the eastern part and the East Sea. In general, the lightning intensity is stronger in the ocean, especially in the East Sea than in the inland area, regardless of the polarity.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2013.04a
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• pp.66-66
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• 2013

최근 기후변화로 전국 평균 뇌전일수의 증가와 기상이변 현상에 따라 그동안 심각성을 느끼지 못했던 낙뢰로 인한 산불 발생 빈도가 높아지고 있는 실정이다. 2012년 봄철 산불조심기간 종료 후 42건의 산불 중 절반인 21건이 낙뢰로 인한 산불이 발생하였으며, 특히 경북 영양군 석보면에서 일어난 낙뢰 산불은 2012년 발생한 산불 중 두 번째로 큰 피해 면적(4.5ha)으로 나타났다. 낙뢰는 예측이 불가능한 데다 산 정상부 부근에서 주로 발생해 접근하기 어렵고 헬기 운항도 쉽지 않아 진화에 어려움을 겪고 있다. 따라서 본 연구에서는 최근 22년(1990~2012년)간 연도별 낙뢰산불 발생현황과 원인을 분석하여 산불피해저감을 위한 기초자료를 제공하고자 한다.

• Proceedings of the KIEE Conference
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• 2005.07a
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• pp.621-623
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• 2005

산업이 고도화되고 전력수요가 증가함에 따라 전력의 안정적인 공급에 대한 국민들의 요구가 점점 증가하고 있다. 그러나 전력을 수송하는 대부분의 송전선로는 가공 송선선로로서 낙뢰에 의한 고장에 노출되어 있어 한전에서는 이를 최소화하려는 노력을 하고 있다. 현재 한전에서는 년간 100km당 1건 이내로 낙뢰에 의한 고장을 제한하는 것을 목표치로 설계하여 운영하고 있으나 낙뢰에 의한 고장을 더욱 감소시키기 위하여 각종 내뢰 시책을 시행하고 있다. 이를 위해서는 근본적으로 낙뢰에 의한 송전선로의 고장을 가능한한 정확하게 예측하는 것이 중요하며, 본 논문에서는 낙뢰 고장 예측 계산을 위해 중요한 요소인 차폐실패 고장률 계산 알고리즘을 검토하고자 한다.

• Atmosphere
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• v.20 no.4
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• pp.467-482
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• 2010

In this study, characteristics of various stability indexes (SI) and environmental parameters (EP) for the lightning are analysed by using 5 upper air observatories (Osan, Gwangju, Jeju, Pohang, and Baengnyeongdo) for the years 2002-2006 over South Korea. The analysed SI and EP are the lifted index, K-index, Showalter stability index, total precipitable water, mixing ratio, wind shear and temperature of lifting condensation level. The lightning data occurred on the range of -2 hr~+1 hr and within 100 km based on the launch time of rawinsonde and observing location are selected. In general, summer averaged temperature and mixing ratio of lower troposphere for the lightning cases are higher about 1 K and $1{\sim}2gkg^{-1}$ than no lightning cases, respectively. The Box-Whisker plot shows that the range of various SI and EP values for lightning and no lightning cases are well separated but overlapping of SI and EP values between lightning and no lightning are not a little. The optimized threshold values for the detection of lightning are determined objectively based on the highest Heidke skill socre (HSS), which is the most favorable validation parameter for the rare event, such as lightning, by using the simulation of SI and EP threshold values. Although the HSS is not high (0.15~0.30) and the number and values of selected SI and EP are dependent on geographic location, the new threshold values can be used as a supplementary tool for the detection or forecast of lightning over South Korea.

• Journal of Aerospace System Engineering
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• v.13 no.6
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• pp.60-69
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• 2019

Companies around the world are actively developing Personal Air Vehicle (PAV) to solve the serious social problem of traffic jams. Airworthiness certification for PAV is required, since it is a manned vehicle. As with aircraft, the critical threat to the safe operation of PAV is lightning strike with strong thermal load and magnetic fields. Lightning certification issue also remains important for PAV, since there are still insufficient development of PAV-related lightning certification technologies, guidelines, and requirements. In this study, the SAE Aerospace Recommended Practice (ARP), an international standard certification guideline recognized by the Federal Aviation Administration (FAA), was analyzed. In addition, the guideline of lightning certification was applied to a PAV. The impact of lightning on PAV was also analyzed through computational software. Finally, the basis for the establishment of the PAV lightning certification guidance was presented.

• Journal of Aerospace System Engineering
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• v.14 no.spc
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• pp.49-55
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• 2020

The average probability of a lightning strike to transport aircraft operating in airline service has been estimated to be approximately one strike in every year (or one strike per 1,000 through 20,000 flight hours). The important thing is not the probability of a lightning strike to aircraft, but the fact that aircraft is struck by lightning. Therefore, lightning protection design for aircraft should be qualified and compliance with airworthiness standards related to lightning protection must be substantiated in the process of certification. In this paper, I studied means of compliance for lightning protection through analysis of some test cases, including the KC-100 airplane that firstly obtained civil type certificate in Korea. Based on this paper, it will be also necessary to study on the effect of lightning for space launch vehicles.

• Journal of Aerospace System Engineering
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• v.17 no.6
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• pp.35-45
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• 2023

In this paper, we analyze the influence of indirect lightning strikes based on the structure of shielded cables used in an aircraft and propose a cable structure to enhance shielding effectiveness. Cables in an aircraft account for the largest proportion among components and play a crucial role in connecting aircraft frames and electronic devices; thus, making them highly influential. In particular, indirect lightning strike noise can lead to malfunctions and cause damage in aircraft electronic equipment, making the utilization of shielded cables essential for mitigating damage caused by indirect lightning strike noise. We conducted an analysis of the impact of indirect lightning strikes on aircraft shielded cables considering factors, such as the presence of shielding layers, core, and insulation in the cable structure. Furthermore, we validated our findings through simulations and experiments by applying the internationally recognized standard for indirect lightning, RTCA DO-160G Sec. 22.