• The Transactions of the Korean Institute of Electrical Engineers B
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• v.54 no.11
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• pp.527-532
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• 2005

During the last ten years the new interruption techniques, which use the arc energy itself to increase the pressure inside a chamber by the PTFE nozzle ablation, have displaced the puffer circuit breakers due to reduced driving forces and better maintainability. In this paper, we have investigated the thermal flow characteristics inside a thermal puffer type gas circuit breaker by solving the Wavier-Stokes equations coupled with Maxwell's equations for considering all instabilities effects such as turbulence and Lorentz forces by transient arc plasmas. These relative inexpensive computer simulations might help the engineer research and design the new interrupter in order to downscale and uprating the GIS integral.

• Tribology and Lubricants
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• v.25 no.3
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• pp.157-162
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• 2009

In this paper, the hydrodynamic pressure and minimum oil film thickness of a pin bush bearing for a connecting rod have been analyzed as functions of the number of oil grooves and an arc length of oil grooves. The lubrication characteristic of a pin bush is governed by oil groove design factors, which are considered in this study. The most influential design parameter is a number of oil grooves, which is three oil grooves with an arc length of oil groove, 1/6($60^{\circ}$). This means that oil groove with a long arc length of a pin bush does not contribute to the hydrodynamic pressure development. Thus the optimal design of a pin bush is necessary with an increased number of oil grooves and a reduced arc length.

• Proceedings of the KIEE Conference
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• 2001.04a
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• pp.44-46
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• 2001

This paper describes the use of the PHOENICS CFD package for the simulation of the high-current period of the arcing process in a hybrid rotating arc/auto expansion by interrupter. The operating principle of this device depends on rapid arc rotation due to the magnetic field created by the fault current through a coil which is mounted on contacts and also relies on the principle of thermal expansion created by arc energy in extinguishing chamber and finally causes pressure rise in expansion volume. This paper is divided into three main sections. The first gives a brief overview of the interrupter. The second section gives a full description of the methods used in the calculation. The final section presents some sample results for the hybrid interrupter.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.05a
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• pp.68-73
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• 2000

An arc model based on the N-S equations modified by adding an energy source term to take account of the arc is developed and solved using Taylor-Galerkin FEM. The numerical method is applied to the simulation of the interruption process of a puffer type GCB. Moving boundary conditions of the arc chamber during operation is taken into account. The thermal interruption capability of an actual puffer type GCB will be predicted and compared with that of the measured result.

• Journal of the Korean Society of Propulsion Engineers
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• v.11 no.6
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• pp.1-8
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• 2007

The objective of the present work is to characterize design parameters of solid propellant ignitor for composite, double base, and nitramine propellants using arc image furnace. Arc image furnace and fiber optics surface reflectometer were used to measure ignition delay time and reflected optical energy of several compositions of composite, double base and nitramine base rocket propellant at different pressure levels each other. The order of ignitability was double base > composite> nitramine propellants at initial pressure of over 75 psia. The highest ignition energy was needed to ignite nitramine propellant, however, the ignition delay time decreased abruptly as the pressure increased up to the range of $75{\sim}400$ psia. The absorbtion of radiation energy could be increased by the addition of small amount of opacifiers as carbon black, ZrC, WC and burning catalyst.

• Journal of Advanced Marine Engineering and Technology
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• v.37 no.6
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• pp.589-595
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• 2013

This paper was to study the effect to Yongrak phenomenon of I groove submerged arc welding depending on the plasma cutting surface characteristics, and how to reduce the causes and characteristics Yongrak phenomenon. Shipbuilding and marine structures is designed to use the thick plates and welded by high current to obtain deep penetration. Yongrak phenomenon has been occurred frequently depending on the quality of cutting surface and it makes degrade of the welding quality and modification of the welding. As a result, it was confirmed that I Groove plasma cutting characteristics get bevel form of 2 to 4 degrees to one side direction from the vertical position with Yongrak phenomenon. This is the main reason of Yongrak phenomenon in butt joint welding and 4 degree reverse bevel on the upper surface of base metal by submerged arc welding brought the effect of significant reduction of Yongrak phenomenon.

• Resources Recycling
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• v.24 no.3
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• pp.27-33
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• 2015

EAFD (Electric Arc Furnace Dust) is considered as pernicious pollutant, assigned hazardous waste. Since this dust is a by-product of industry, it contains valuable metals such as Fe, Zn, Ni, Cu which can be turned into resources by recycling process. In this study, hydrometallurgical process was applied to recover Zn from Electric Arc Furnace Dusts. The result showed 95% Zn recovery at 3M $H_2SO_4$, Solids/Liquid ratio 1:2 and aeration of 1.8L/min for 2hr. However there was 80% Zn recovery at lower $H_2SO_4$ concentration apply for pilot scale plant.

• Journal of the Korean Society for Railway
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• v.13 no.1
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• pp.37-43
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• 2010

Catenary (Overhead Contact Lines) and Pantograph are used to transmit electrical energy to electric railways. An Arc occurs by unstable contact between catenary and pantograph during electric railways operation, which causes malfunctioning or even an accident. Therefore, to prevent a arc or electric contact loss are required arc detection systems with catenary maintenance capability. This paper describes developing of catenary arc detection system using photo detector in order to detect arc incidence in a indirect way. This developed system can also achieve Video-recordings and environmental conditions such as wire voltage/current, pantograph height, speed, position of electric railways, and temperature/humidity. This system have been evaluated at the section that bounds for dongdaegu from seoul. From the experimental results, the occurrence of arc and intensity of arc are mainly effected by wire voltage/current, pantograph height and speed of electric railways.

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.1391-1393
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• 2002

There arc some problems on storage batteries which are called Secondary Battery, such as long charging time, limited cycle life, low coulomb efficiency and inaccurate residual power meter. To solve those problems, a complex system of capacitors and Super Capacitors of increased energy density. Though the capacitors alone arc not capable of delivering stable output, the accompanied circuits compensate the various characteristics all through the charge-and discharge-cycle. This paper deals with Energy Storage System with Super Capacitor for PV System Discussed in this paper are, explains the accompanied circuits of Super Capacitor which is compared with the Second Batteries.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.190-193
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• 2001

ZnO varistors have been widely used to protect power system and electronic system against overvoltages based on their excellent nonlinearity. In order to increase their protection capability, the fracture and protection technologies of arresters have to study according to their applications, namely ImA DC voltage, leakage currents, impulse residual voltages, withstanding capability to impulse surge, and energy absorption capability. ZnO varistors which have nonlinear current-voltage characteristic name a number of failure mechanism when ZnO elements absorb surge energies. Failure mode by thermal stress and Pin hole are among the most common failure mechanism at the high current surge current. In this study, the fracture mechaism of power arresters are introduced and protection technologies are researched. In particular the effect of thermal stress by surge currents to ZnO elements and methods against arc surge energy through withstand structure design of arrester are discussed.