• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 B
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• pp.828-830
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• 2000

This paper describes BIEM(Boundary Integral Equation Method) for computation of three dimensional electric field distribution and numerical method that an equivalent charge density is unknown variable. After computing numerically the surface charge distribution. the distribution of both potential and electric field are obtained. Finally, this numerical method is applied to the concentric sphere and the coaxial cylindrical model and numerical result is compared to the analytic solution.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 A
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• pp.169-171
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• 1996

Recently, the finite element analysis(FEM) using two dimensional magnetic permeability tensor was introduced to calculate the magnetic field considering the rotational hysteresis. We obtain the tensor matrix from the measured data using two-dimensional magnetic measuring apparatus. We calculate the induced magnetic flux density and the rotational hysteresis loss under the model with the same condition with the measuring apparatus. Therefore we show that FEM with tensor can be used to calculate the magnetic flux density and the rotational hysteresis loss in the arbitrary rotational magnetic field.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 추계학술대회 논문집 학회본부
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• pp.290-292
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• 1994

This paper presents a methodology for the electric field analysis of substation. For the electric field analysis of substation, the electrodes(substation busbars) must be represented by finite line with nonlinear charge density. In the case of dividing finite line into uniform segments, a large number of variables have to be used to obtain the accuracy within a desired tolerance. To deal with the problem, nonuniform charge arrangement modeling method is suggested. To reduce potential calculation errors, the linear charge density function is considered particularly for the segment charge model ling. If the charge arrangement is improper, the accuracy not improved regardless of increment in the number of segments. This paper proposes an optimal charge arrangement method through potential error analysis. And, the optimal charge arrangement function is formulated by a lot of simulation results.

• 새물리
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• 제68권11호
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• pp.1183-1191
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• 2018

$GaAs/Al_xGa_{1-x}As$ 다중 양자 우물들에 의한 초격자내 플라즈몬들이 다른 유전 계면과 반포물선 구속 퍼텐셜에 의한 거동을 초격자 축에 수직한 자기장과 평행한 전기장하에서 이전의 이론적 토대하에서 연구하였다. 막 위상 근사 방법을 사용하여 부 밴드 내와 부 밴드 사이의 전이가 고려된 밀도-밀도 상관함수로부터 표면과 벌크 상태의 분산 에너지를 전체 양자 우물의 평균 전기장, 자기장의 세기 및 조성비의 함수로 얻었다. 또한 여러 가지 평균 전기장, 자기장의 세기에 대한 라만 세기를 그들 상태에 대해 입사광의 에너지 함수로 얻었다.

• Journal of Electrical Engineering and Technology
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• 제10권2호
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• pp.647-652
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• 2015

A fully coupled finite element analysis (FEA) technique was developed for analyzing the discharge phenomena and dielectric liquid flow while considering surface charge density effects in dielectric flow guidance. In addition, the simulated speed of surface charge propagation was compared and verified with the experimental results shown in the literature. Recently, electrohydrodynamics (EHD) techniques have been widely applied to enhance the cooling performance of electromagnetic systems by utilizing gaseous or liquid media. The main advantage of EHD techniques is the non-contact and low-noise nature of smart control using an electric field. In some cases, flow can be achieved using only a main electric field source. The driving sources in EHD flow are ionization in the breakdown region and ionic dissociation in the sub-breakdown region. Dielectric guidance can be used to enhance the speed of discharge propagation and fluidic flow along the direction of the electric field. To analyze this EHD phenomenon, in this study, the fully coupled FEA was composed of Poisson's equation for an electric field, charge continuity equations in the form of the Nernst-Planck equation for ions, and the Navier-Stokes equation for an incompressible fluidic flow. To develop a generalized numerical technique for various EHD phenomena that considers fluidic flow effects including dielectric flow guidance, we examined the surface charge accumulation on a dielectric surface and ionization, dissociation, and recombination effects.

• 천문학회보
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• 제41권1호
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• pp.46.1-46.1
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• 2016

The formation process of a current sheet is important for solar flare from a viewpoint of a space weather prediction. We therefore derive the temporal development of the spatial and statistical distribution of electric current density distributed in a flare-producing active region to describe the formation of a current sheet. We derive time sequence distribution of electric current density by applying a nonlinear force-free approximation reconstruction to Active Region 12158 that produces an X1.6-class flare. The time sequence maps of photospheric vector magnetic field used for reconstruction are captured by a Helioseismic and Magnetic Imager (HMI) onboard Solar Dynamic Observatory (SDO) on 10th September, 2014. The spatial distribution of electric current density in NLFFF model well reproduce observed sigmoidal structure at the preflare phase, although a layer of high current density shrinks at the postflare phase. A double power-law profile of electric current density is found in statistical analysis. This may be expected to use an indicator of the occurrence of a solar flare.

• E2M - 전기 전자와 첨단 소재
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• 제10권5호
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• pp.453-460
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• 1997

In order to investigate the electrical conduction properties of polyethylene thin film for power cable with manufacturing methods, the thickness of specimen was the 30, 100[${\mu}{\textrm}{m}$] of LDPE and 200[${\mu}{\textrm}{m}$] of XLPE were manufactured. The experimental condition for conduction properties was measured until the breakdown occurs at temperature ranges from 30 to 110[$^{\circ}C$] and the electric field from 1$\times$10$^3$to 5$\times$10$^{6}$ [V/cm]. As for increase of temperature, the current density of LDPE was increased with constant ratio in low field, but changes with exponential function in high electric field. The tunnel current of pre-breakdown region is shifted toward low field as much as thermal excitation energy. At low electric field, the XLPE showed dominant electrical conduction properties by thermal excitation, and transformation of the electron was resisted by the crystal at high electric field.

• 전기학회논문지
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• 제67권4호
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• pp.554-560
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• 2018

Since Korea has a small land area, it is expected to construct the conductor return type with neutral wire in the case of ${\pm}500kV$ HVDC double bipole transmission line. Therefore, in order to apply ${\pm}500kV$ HVDC double bipole transmission line with neutral wire in Korea, it is necessary to develop technology for insulation and environmental designs. In this study, radio interference, audible noise, electric field and ion current density according to the polarity arrangement were compared and assessed in the ${\pm}500kV$ HVDC double bipole transmission line with the conductor return method. And the optimum configuration of HVDC double bipole transmission line was determined from the viewpoint of electrical environment.

• Journal of Astronomy and Space Sciences
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• 제34권4호
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• pp.251-256
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• 2017

The electric coupling between the lithosphere and the ionosphere is examined. The electric field is considered as a timevarying irregular vertical Coulomb field presumably produced on the Earth's surface before an earthquake within its epicentral zone by some micro-processes in the lithosphere. It is shown that the Fourier component of this electric field with a frequency of 500 Hz and a horizontal scale-size of 100 km produces in the nighttime ionosphere of high and middle latitudes a transverse electric field with a magnitude of ~20 mV/m if the peak value of the amplitude of this Fourier component is just 30 V/m. The time-varying vertical Coulomb field with a frequency of 500 Hz penetrates from the ground into the ionosphere by a factor of ${\sim}7{\times}10^5$ more efficient than a time independent vertical electrostatic field of the same scale size. The transverse electric field with amplitude of 20 mV/m will cause perturbations in the nighttime F region electron density through heating the F region plasma resulting in a reduction of the downward plasma flux from the protonosphere and an excitation of acoustic gravity waves.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 추계학술대회 논문집 학회본부
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• pp.354-356
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• 1997

In this paper, we study the distribution of surface charge density on polymer insulators. The electric field of polymer insulators is calculated by axisymetric 3-D FEM with dc source. And the surface charge density is calculated by electric scalar potential and boundary condition for electrostatic fields. Simulation model is the inclined type polymer insulator with a shed.