• 한국조명전기설비학회지:조명전기설비
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• 제13권2호
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• pp.178-178
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• 1999

In recent years, the electromagnetic environments are varied with the increase of power consumption and the spread of household electric appliances. Most of the interests to date have concentrated in the area of human health effects associated with exposure to power frequency electric and magnetic fields, and thus the precise measurement and analysis are required. In this paper, the measurements and analysis of the extremely low frequency(ELF) electric and magnetic fields produced by actual 22.9[kV] distribution lines were performed. The experiments have been carried out by lateral profile, and the theoretical analyses were made by use of FIELDS program for the sate of comparison with the experimental data. Electric and magnetic field intensity were strong under power distribution lines, and were inversely proportional to lateral distance. The profiles of electric and magnetic fields were M and ∩ shapes, respectively, and the measured data were good in agreement with the theoretical results. Both the electric and magnetic field intensity were increased with increasing the measurement height.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 E
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• pp.1827-1829
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• 1997

In this paper, measurement and analysis of ELF electric and magnetic fields due to a transmission line have been carried out and the power frequency field strength measuring system is designed. In order to evaluate electric and magnetic fields associated with 60 Hz electric power transmission and distribution lines, the actual survey near a transmission tower has been made and analyzed. It may be inferred from these results that the maximum electric and magnetic fields strength in the vicinity of a line tower do not exceed 3.5[kV/m] and 20[${\mu}T$]. The results of the field measurements agree with limits and guidelines recommended by various authorized international institutes.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 E
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• pp.2164-2166
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• 1999

This paper is describes the measured electric field waveform radiated by lightning discharge. We have performed measurement and analysis of the electric fields associated with stepped leaders. Electric field measurement system was composed of hemisphere electric field sensor, measurement system of a distance from lightning strokes, automatical recording system, A/D board, personal computer etc. A/D board have high sampling time, high speed data processing, 8bit of resolution. Also, measured characteristics of stepped leaders radiated by were analyzed.

• 새물리
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• 제68권11호
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• pp.1225-1230
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• 2018

Schwinger pair production of electrons and positrons in a strong electric field is a prediction of nonperturbative quantum field theory, in which the out-vacuum is superposed of multi-particle states of the in-vacuum. Solving the Dirac or Klein-Gordon equation in the background field, though a linear wave equation, and finding the pair-production rate is a difficult or nontrivial job. The phase-integral method has recently been introduced to compute the pair production in space-dependent electric fields, and a complex analysis method has been employed to calculate the pair production in time-dependent electric fields. In this paper, we apply the complex analysis method to a Sauter-type electric field and other hyperbolic-type electric fields that vanish in the past and future and show that the Stokes phenomena in pair production occur when the time-dependent frequency for a given momentum has finite simple poles (polons) with pure imaginary residues.

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 1999년도 제3회 전자장의 생체영향에 관한 워크숍
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• pp.156-164
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• 1999

This paper shows that the configuration of power transmission lines currently in place is suitable on the basis of calculated magnetic field strengths. The magnetic fields were computed for typical current distributions on power transmission lines for electric railways, which are characterized by severe load fluctuations and phase distortions. The result of the numerical analysis are compared with th ELF guidelines of magnetic fields from several case studies. The final conclusion reached in that effects of the magnetic fields near power transmission lines for electric railways are not significant enough to cause a biological safety concern.

• 대한기계학회논문집A
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• 제25권2호
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• pp.235-241
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• 2001

A crack with electrically conducting surfaces in a linear electrostrictive ceramic subjected to uniform electric fields is analyzed. Complete forms of electric fields and elastic fields for the crack are derived by using the complex function theory. The linear electromechanical theory predicts overlapping of the traction free crack surfaces. It is shown that the surfaces of the crack are contact near the crack tip. The contact zone size obtained on the basis of the linear dielectric theory for the conducting crack does not depend on the electric fields and depends on only the original crack and the material property for the linear electrostrictive ceramic.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 E
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• pp.1653-1655
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• 1998

In this paper, measurement and analysis of ELF electric and magnetic fields in the vicinity of 22.9[kV] distribution line have been performed. The height of measuring point from the earth's surface was 1[m], and the distance between the device and the operator was more than 3[m]. The experiments have been carried out by lateral profile, and we have made use of FIELDS program for the sake of comparision the experimental data with the theoretical value. Electric and magnetic fields intensity were strong under a distribution line, and were inversely proportional to lateral distance. The profiles of electric field were M shape and those of magnetic field were $\cap$ shape. Electric and magnetic fields intensity were increased with increasing the measurement height.

• 조명전기설비학회논문지
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• 제30권2호
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• pp.78-84
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• 2016

This paper is focused on the measurement and analysis of an atmospheric electric field which is caused by thunderclouds. The electric field due to thunderclouds changes very slowly. For this reason, the extremely low frequency E-field sensor needs to be used for measuring the atmospheric electric field strength. The balloon-carried E-field sensor system with the time constant of 1sec was designed and fabricated. The electric field sensor consists of $100mm{\times}100mm$ copper plate, active integrator, high pass and low pass filters and batteries. The measurements of atmospheric electric fields were made by the balloon-carried E-field sensor and radiosonde, which sends the data back to ground in real time. From the calibration experiments, the response sensitivity of the E-field sensor was 0.154mV/kV/m in the frequency range of less than 1kHz. As a result from the actual experiment of the atmospheric electric field, the electric field signals were observed from the altitude of about 2.5km. Also, as the altitude was increased, the detected electric field wave oscillated with the fluctuation of sensing plate. The proposed method seems suitable for measurements of atmospheric electric fields, because it is inexpensive, simple to use and launch.

• 소성∙가공
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• 제17권8호
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• pp.627-632
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• 2008

The cross sectional shape of intermediate die is one of important parameters to improve dimensional accuracy of final product in shaped drawing process. Until now, it has been designed by the experience or trial and error of the expert. In this study, the cross sectional shape of intermediate die for spline shape is determined by the electric fields analysis and scale factor method. The result of the electric fields analysis and scale factor method have been compared with that of the expert method. The effects of cross sectional shape on the dimensional accuracy were investigated by using FE-simulation. And then the multi-stage shaped drawing experiments were performed to verify the results of FE-simulation. As a result, the cross sectional shape from the electric fields analysis and scale factor method had the good dimensional accuracy. These two methods can be used for the method to obtain the cross sectional shape of intermediate die in shaped drawing process.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 E
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• pp.2368-2370
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• 1999

A nationwide survey for electric and magnetic fields(EMFs) near overhead transmission lines has been conducted. The median values of the electric and magnetic fields of 208 transmission lines were 0.50 kV/m and 12.6 mG, respectively. The maximum values were 3.16 kV/m and 125 mG. The measured EMFs were compared with the calculated ones. The causes of the discrepancy between measured and calculated EMFs are also discussed.