• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.1981-1983
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• 2000

In this paper, the arc resistance of INPIStron is presented. It is need to the design of Pulsed power system and simulation on the circuit of pulsed power system with INPIStron switch. It is also possible to use this parameter to the part of discharge characteristics of Xenon lamp and the device with electrical discharge.

• 한국전산유체공학회:학술대회논문집
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• 2010.05a
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• pp.201-207
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• 2010

In this study, we calculated arc discharges happened in high-voltage circuit breakers for understanding the complex physics and the probability of thermal breakdown. The four main parts of arc model for this virtual-reality are radiation, PTFE abaltion, Cu evaporation and turbulence. Among these important parts the turbulence model can be critical to the reliability of computation results during high-current period because the plasma flow is affected by high eat energy and mass momentum. Two kinds of turbulence model, zero-equation model and two-equation model, are applied for these calculations and are compared with the measured pressure data inside a chamber.

• Proceedings of the KSR Conference
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• 2011.05a
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• pp.98-100
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• 2011

High speed Train Systems are the energy supplied system via the pantograph through which the voltage and the current supplied by the catenary wire flow. The arc discharges generate owing to the contact loss between the catenary and the pantograph, and the electromagnetic fields radiate. There are many different phenomena between the static charges and the moving charges in view of the radiated electromagnetic fields. To calculate the electromagnetic filed about the moving charges, it is necessary to adapt Lorentz transformation. Actually, the particle which moves near the speed of light has the relativisitic phenomena. In addition, it is necessary to predict the electromagnetic field because the radiated electromagnetic field takes effect on the near electronic devices and the human beings. In this paper, we model the arc discharge into the dipole antenna model, adapt Lorentz transformation to the case that the electric railway cars move, and calculate the radiated electromagnetic field. By the calculation, we take the basis upon the electromagnetic prediction, and apply to the future research.

• Proceedings of the KIEE Conference
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• 1997.07e
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• pp.1669-1671
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• 1997

Liquid nitrogen has many adventages. It is cheaper than other cooling medium. It is easy to obtain high purity. It's utilized with easy. In future, liquid nitrogen is able to be accepted cooling medium for the superconducting and cryogenic applicated equipments. Cryogenic liquid may be atmospheric pressure state because thermoinsulation is ineffective, airtight decreasing by long time using and bubble occured by flowing current. If it is to be atmospheric pressure state, the electrical insulation strength is dropped and processed partial discharge, finally breakdown. Processing of breakdown has anticipated by measuring radiated-electromagnetic wave which is happened in time of breakdown. There is a measurement of radiated electromagnetic wave as a method that proceeding breakdown is anticipated. In this paper, radiated electromagnetic wave was measured in arc discharge by above conditions as a basic experiment.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.8
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• pp.49-54
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• 2015

Molded Circucit Breaker(MCCB) is a most widely used device to protect loads from the over-current in low power level distribution system. When the MCCB interrupts the over-current, the arc discharge occurred between fixed contact and moving contact to create hot gas. By the Lorentz force due to arc current, the occurred arc is bent to the grids. The grids extend and cool and divide it for arc extinguish. In the majority cases, the MCCB protects loads by interrupting the over-current successfully but in some cases the re-ignition is occurred by hot-gas created during process of interruption. The re-ignition arises when the recovery voltage(RV) is more higher than the recovery strength between contacts and it leads to interruption fault. Therefore to find out the dielectric recovery characteristics of protecting device has a great importance for preventing interruption fault. In this paper, we studies measurement method of the dielectric recovery characteristics considering inherent attribute of the MCCB. To measure the dielectric recovery characteristic of MCCB, we makes an experiment circuit for applying the over-current and the randomly recovery voltage. The measurement methode to find out the dielectric recovery voltage of the MCCB was established and the result was based on experiment results.

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.814-816
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• 2002

Because there is a strong interaction between the arc discharge and their surroundings, it is not easy to predict the characteristics of industrial arc plasma systems such as gas circuit breakers. The design procedure of these systems is still largely based on trial and error, although the situation is rapidly improving because of the available computational power at a cost in which is still coming down. The desire to predict the behavior of arc plasma systems, thus optimizing and reducing the develpment cost, has been the motivation of these arc researches. In this paper. we have simulated the switching operation of a gas circuit breaker during high current area using a computational fluid dynamics considered the electric field analysis, the radiation model and the effeects of turbulence.

• Journal of Powder Materials
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• v.15 no.5
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• pp.352-358
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• 2008

The present study focused on the synthesis of a bismuth-antimony-tellurium-based thermoelectric nanopowders using plasma arc discharge process. The chemical composition, phase structure, particle size of the synthesized powders under various synthesis conditions were analyzed using XRF, XRD and SEM. The powders as synthesized were sintered by the plasma activated sintering. The thermoelectric properties of sintered body were analyzed by measuring Seebeck coefficient, specific electric resistivity and thermal conductivity. The chemical composition of the synthesized Bi-Sb-Te-based powders approached that of the raw material with an increasing DC current of the are plasma. The synthesized Bi-Sb-Te-based powder consist of a mixed phase structure of the $Bi_{0.5}Sb_{1.5}Te_{3}$, $Bi_{2}Te_{3}$ and $Sb_{2}Te_{3}$ phases. This powder has homogeneous mixing state of two different particles in an average particle size; about 100nm and about 500nm. The figure of merit of the sintered body of the synthesized 18.75 wt.%Bi-24.68 wt.%Sb-56.57 wt.%Te nanopowder showed higher value than one of the sintered body of the mechanically milled 12.64 wt.%Bi-29.47 wt.%Sb-57.89 wt.%Te powder.

• Transactions of the Korean hydrogen and new energy society
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• v.25 no.6
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• pp.594-601
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• 2014

Rare-earth (RE) nitrides can be used as magnetocaloric materials in low temperature. They exhibit ferromagnetism and have Curie temperature in the region from 6 to 70 K. In this study, Holmium nitride (HoN) nano particles were prepared through plasma arc discharge technique and their magnetocaloric properties were studied. Nitrogen gas ($N_2$) was employed as an active element for arc discharge between two electrodes maintained at a constant current. Also, it played an important role not only as a reducing agent but also as an inevitable source of excited nitrogen molecules and nitrogen ions for the formation of HoN phase. Partial pressure of $N_2$ was systematically varied from 0 to 28,000 Pa in order to obtain single phase of HoN with minimal impurities. Magnetic entropy change (${\Delta}S_m$) was calculated with data set measured by PPMS (Physical Property Measurement System). The as-synthesized HoN particles have shown a magnetic entropy change ${\Delta}S_m$) of 27.5 J/kgK in applied field of 50,000 Oe at 14.2 K thereby demonstrating its ability to be applied as an effective magnetic refrigerant towards the re-liquefaction of hydrogen.

• Smart Media Journal
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• v.9 no.1
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• pp.38-44
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• 2020

Due to the high dependence on electric energy, electric fires make up a significant portion of fires in Korea. Electric arcs by short circuits or poor contact cause three of four electrical fires. An electric arc is a discharge phenomenon of electrical current between the insulators, which instantaneously produces high temperature. In order to reduce the fire due to electric arc, this study aims to predict the electric arc risk. We collected arc data from the arc detectors and converted into graphs based on temporal arc data. We used machine learning for training converted graph with different number of temporal arc data. To measure the performance of the learning model, we use the test data. In the results, when the number of temporal arc data was 20, the prediction rate was high as 86%.

• Proceedings of the KWS Conference
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• 2009.11a
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• pp.235-238
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• 2009

To study the relationship between spark ignition and the gap in the nano-scale region, the electric potential was applied to between a Pt-Ir tip and a gold substrate. The tip was sharpened by electro-chemical etching process in the solution of $CaCl_2;H_2O$ and acetone. The radius of tip was measured to be around 200nm and attached to the scanning probe microscope to control the gap between the tip and the substrate. The electric potential of 10V to 80V was applied to initialize the spark. The gaps and the current profile were measured to analyze the characteristics of spark ignition. A spark sustaining time was measured to be between 50ns and 200ns depending on the applied electric potential and the gap between the electrodes. The continuous electric discharge was successfully sustained up to 1 second of spark or arc time. The developed process can be applicable to the micro-scale fabrication of automotive sensors as a similar concept of GTAW.