• Proceedings of the KIEE Conference
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• 1997.11a
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• pp.370-372
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• 1997

In this paper, magnetic fields produced by lightning return strokes were investigated and analyzed Magnetic field and its derivatives were measured with two crossed loop antennas. Frequency bandwidths of the magnetic field and its derivative measuring systems are in the range of $270\;[Hz]\;{\sim}\;2.3\;[MHz]$ and $450\;[Hz]\;{\sim}\;2.5\;[MHz]$, and their response sensitivity are 128 [mV/${\mu}T$] and 4.12 [mV/nT//${\mu}s$], respectively. Signals are digitized every 500 [ns], data are automatically recorded by transient signal analyzer(Nicolet Pro. 30) having the resolution of 12 - bit and the length of 5 kilowords, and they are registered at personal computer. Magnetic field and its derivative waveforms associated with lightning return strokes were observed since the summer of 1997 at Inha University in Inchon.

• Proceedings of the KIEE Conference
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• 1998.07e
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• pp.1650-1652
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• 1998

This paper describes characteristics of electric field waveforms associated with multiple-lightning discharges. The electric field measurment system. consists of hemi-sphere antenna 30 cm in diameter. integrator and data acquisition device. The frequency bandwidth is from 200 Hz to 1.56 MHz, and the sensitivity is 0.96 mV/V/m. The detected electric field signal is digitized every 500 ns with the resolution of 12-bit and the length of 2 kilowords and is registered at a personal computer. Also parameters of the electric fields associated with multiple-lightning discharges are ststistically analyzed.

• Proceedings of the KIEE Conference
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• 1994.07b
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• pp.1658-1660
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• 1994

This paper describes the measurement system of the magnetic field waveforms generated by lightning return strokes. The frequency bandwidth of magnetic field measurement system is from 270[Hz] to about 2.3 [MHz]. As the application experiment, the magnetic field generated by simple impulse and oscillating impulse currents, which are measured by a current transformer (Tek. AM503), is observed by the trial magnetic field measurement system. The obtained results are agreement with each other. A typical magnetic field waveform associated with lightning return strokes was recorded and presented.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2008.10a
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• pp.297-300
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• 2008

This paper described a New-Concept lightning warning system (LWS) which can measure electric field intensity on the ground level by an electric field mill (EFM) and calculate the lighting location by radiated electro-magnetic waveform. The EFM measures electric field up to 20[kV/m] with the sensitivity of 0.15[V/kV/m] and frequency bandwidth of the loop antenna was ranges from 5.2[kHz] to 1.71[MHz]. The LWS provides data on the movements of thunderclouds and the possibility of lightning return stroke.

• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1531-1532
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• 2006

Recently, the natural environment changes drastically, and the frequency of occurrence for lightning has gradually been increased. Such lightning delivers high volume of energy along the power line and communication line to the equipment in use. The high volume of energy arising from the lightning surge develops in fast velocity to destroy the facilities in power source and many other facilities in operation in sequential destruction with vast energy. In this thesis, the analysis on the change of clamping voltage characteristics by the contact resistance and lead inductance by using several case studies through the application of element for preventing the short circuit of Metal Oxide Varistor for ZnO.

• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.2135-2137
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• 2005

This paper describes the features of electric and magnetic fields produced by lightning discharges. The measuring system consists of fast electric field sensor, crossed-loop magnetic field sensors, signal processing circuit, A/D converter and data acquisition equipment with a 12bit resolution and 10[MS/s] sampling rate. The frequency bandwidth and responsitivity of the electric field measuring system were 40[Hz]${\sim}$2.6 [MHz] and 2.08 (V/m/mV) and those of the magnetic field measuring system were 400[Hz]${\sim}$1[MHz] and 2.78[nT/mV], respectively. The electric and magnetic fields produced by lightning discharges were observed, and the features and parameters of the waveforms were analyzed.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.11
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• pp.1012-1018
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• 2016

We perform a electromagnetic analysis method for indirect effects of a high-conductive structure such as an aircraft exposed by lightning, by using the finite-difference time-domain(FDTD) method. The lightning waveform used to analyze indirect effects has low frequency spectrum and high-conductive materials such as aluminum and carbon fiber composite materials have very short skin depths, and thus, it requires large memory and long computation time using conventional three dimensional FDTD analysis method. We develop an efficient electromagnetic analysis method suitable for lightning and high-conductive structures. The developed analysis method is based on two dimensional FDTD and impedance network boundary condition(INBC) algorithms and we investigate the indirect effects on the structures exposed to lightning.

• Transactions on Electrical and Electronic Materials
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• v.16 no.6
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• pp.317-322
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• 2015

The metal oxide varistor (MOV) is a major component of the surge protection devices (SPDs) currently in use. The device is judged to be faulty when fatigue caused by the continuous inflow of lightning accumulates and reaches the damage limit. In many cases, induced lightning resulting from lightning strikes flows in to the device several times per second in succession. Therefore, the frequency or the rate at which the SPD is actually exposed to stress, called a surge, is outside the range of human perception. For this reason, the protective device should be replaced if it actually approaches the end of its life even though it is not faulty at present, currently no basis exists for making the judgment of remaining lifetime. Up to now, the life of an MOV has been predicted solely based on the number of inflow surges, irrespective of the magnitude of the surge current or the amount of energy that has flowed through the device. In this study, nonlinear data that shows the damage to an MOV depending on the count of surge and the amount of input current were collected through a high-voltage test. Then, a failure prediction algorithm was proposed by preparing a look-up table using the results of the test. The proposed method was experimentally verified using an impulse surge generator

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.10
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• pp.63-68
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• 2014

This paper deals with a methodology that applies the time-varying magnetic fields produced by the cloud discharges to find the direction of thunderstorm movement. We investigated the basic performance of the magnetic field measurement system composed of multi-turn loop-type sensors, the differential amplifier and active integrator. As a result, the response characteristics of the magnetic field sensor system to sinusoidal signals was excellent. The frequency bandwidth ranges from about 1 kHz to 500 kHz, the response sensitivity was 0.16mV/nT. In addition, we proposed the algorithm that determines the direction of lightning discharges using the comparison of the output signals of right-angled loop-type magnetic field sensors. The accuracy of the direction finding of lightning discharges is fairly well within the measurement error of less than $5^{\circ}$. The magnetic field measurement system proposed in this work can be used to track the direction of thunderstorm movement.

• Journal of the Microelectronics and Packaging Society
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• v.13 no.3 s.40
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• pp.27-32
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• 2006

The occurrence frequency of lightning and surge from the weather accident is increasing recently, which the damage scale have been enlarged every year. A protection system development to solve these problems have been risen to a multinational concern field. In this paper, a novel protection system is proposed to restrain lightning and various surges which happen in electricity and communication equipment. The proposed protection system is designed to the structure to restrain the rise of the earth potential which is become to the problem of conventional protection system. The secondary damage as a result does not happen. The practicality of the developed surge protection system is proved through various accident occurrence simulator.