• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.9
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• pp.1374-1379
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• 2012

Urban rail transit tends to global grounding system in order to control ground potential rise and potential differences between electric equipments. In addition, global grounding system can discharge the large capacity surge current to the ground safely. Since some railway electric equipments are installed all section of line, the global grounding system connected with the connecting grounding wire is more effectively. However, if the fault occurred in the connecting grounding wire area, some dangerous voltage is generated. So, the installation of additional grounding rod will be required. In this study, the global grounding system is simulated using CDEGS program to analyze the divergence spacing of additional ground rod depending on dangerous electric potential characteristics. Grounding net of the each station is modelled in depending on the size of the platform, and the spacing of the connecting grounding rod are compared 50m, 100m, 250m and 400m. Simulation results considering of earth resistivity and underground condition of the connecting grounding wire, spacing of the connecting grounding rod is that less than 250m to spacing of the ground rod was appropriately confirmed.

• Journal of Power System Engineering
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• v.3 no.4
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• pp.57-62
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• 1999

The microaccelerometer using a tunnelling current effect concept has the potential of high performance, although it requires slightly complex signal-processing circuit for servo-system. The paddle of micro accelerometer is pulled to have the gap width of about 2nm which almost allows the flow tunnelling current. This paper demonstrates at capacitor of microaccelerometer the use of the coupled thermo-electric analysis for voltage, current, heat flux and Joule heating then tunnelling current flows. Two electrodes are applied to the microaccelerometer producing a unform difference of temperature gradient and electric potential between the paddle and the substrate.

• Journal of the Korean Society of Visualization
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• v.4 no.1
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• pp.31-40
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• 2006

In this study a newly designed electro-osmotic micro-mixer is proposed. This study is composed of a channel and metal electrodes attached locally on the side wall surface ultimately to control the mixing effect. To obtain the flow patterns, numerical computation was performed by using a commercial code, CFD-ACE. The fluid-flow solutions are the cast into studying the characteristics of stirring in terms of the mixing index. It was shown that the local control of the electric potential can indeed contribute to the enhancement of mixing effect.

• Journal of Power System Engineering
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• v.11 no.3
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• pp.41-46
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• 2007

The microstructure and electrochemical analysis of welds of electric resistance welding(ERW) pipe were investigated. The direction of metal flow line in HAZ of ERW pipe shifted to the inner(or outer) surface of pipe by plastic deformation during welding. The lowest heat input welds of ERW pipe was showed crack by liquid penetrant testing. Accelerated corrosion test by constant current density of 20mA/$cm^{2}$ developed groove at the welds of ERW pipe and the measured grooving factors were about $1.2{\sim}1.5$. Corrosion potential of base metal obtained by cyclic polarization in artificial sea water(3.5wt.% NaCl solution) was 100mV higher than that of weld metal of ERW pipe.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.09a
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• pp.203-206
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• 2004

To analysis the electrokinetic phenomena in the ground dependent on the way of applied electric power, such as constant current and constant voltage, the governing equations are derived considering advection, diffusion, ionmigration, and then they were formulated using by finite difference method. The developed program is verified by comparing the tested and predicted results reported in present papers. The results indicate that the slightly small electrical potential is predicted for constant current and for constant voltage pH near to the cathode was small than the test results. But the other predictions including the final suction, pH of electrolyte and cumulative flow are similar to the test results and predictions.

• Journal of Electrical Engineering and Technology
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• v.9 no.1
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• pp.247-253
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• 2014

In this paper, a new two dimensional (2D) analytical modeling and simulation for a Dual Material Double Gate tunnel field effect transistor (DMDG TFET) is proposed. The Parabolic approximation technique is used to solve the 2-D Poisson equation with suitable boundary conditions and analytical expressions for surface potential and electric field are derived. This electric field distribution is further used to calculate the tunnelling generation rate and thus we numerically extract the tunnelling current. The results show a significant improvement in on-current characteristics while short channel effects are greatly reduced. Effectiveness of the proposed model has been confirmed by comparing the analytical results with the TCAD simulation results.

• Journal of Korean Society for Quality Management
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• v.13 no.1
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• pp.26-30
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• 1985

In the light of the properties of colloids, in the surface of disperse phase and dispersion, there exist specific characters such as adsorption or electric double layer, which seems to play important roles in determining the physiochemical properties in the dyeing system. Nylon, wool and silk, the typical amphoteric fibers were dyed with Acid dye and various combinations were prepared by combining pH, temperature and dye concentration, in order to generate flowing electric potential which were measured by microviolt meter and specific conductivity meter. The results were transformed to Zeta potential by Helmholtz-Smoluchowski formular and to surface electric charge density by Suzawa formular, surface dye amount, and effective surface area of fibers, and these data were statistically analysed by principle component analysis.

• Structural Engineering and Mechanics
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• v.53 no.6
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• pp.1167-1182
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• 2015

In this study, the stresses and electric potential redistributions of a cylinder made from functionally graded piezoelectric material (FGPM) are investigated. All the mechanical, thermal and piezoelectric properties are modeled as power-law distribution of volume fraction. Using the coupled electro-thermo-mechanical relations, strain-displacement relations, Maxwell and equilibrium equations are obtained including the time dependent creep strains. Creep strains are time, temperature and stress dependent, the closed form solution cannot be found for this constitutive differential equation. A semi-analytical method in conjunction with the Mendelson method of successive approximation is therefore proposed for this analysis. Similar to the radial stress histories, electric potentials increase with time, because the latter is induced by the former during creep deformation of the cylinder, justifying industrial application of such a material as efficient actuators and sensors.

• Proceedings of the KIEE Conference
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• 1994.11a
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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.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.11
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• pp.2229-2235
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• 2009

In this paper, each specimen blended at weight proportions of 80% HDPE to 20% EVA, 70% HDPE to 30% EVA, 60% HDPE to 40% EVA, and 50% HDPE to 50% EVA was manufactured respectively. The insulation performances of the proposed insulator were compared with conventional XLPE, main insulating material of CV cable on the basis of the investigation results of DC insulation performances. From the space charge density, electric field and potential profiles with raising DC voltage and time variation in HE82, distortion of electric field distribution was improved. As EVA mixed into the bulks acts as nucleation in crystallization process of HDPE, the size of spherulites became decreased and finally formed continuous network structure. Ultimately, it resulted from extinction of space charge in the interfacial region of spherulites.