• Title/Summary/Keyword: Discharge arc

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A study on the characteristics of arc discharge and radiated electromagnetic wave in liquid nitrogen (액체질소중에 있어서 아크방전 및 방사 전자파의 특성에 관한 연구)

  • Shin, Dong-Hwa;Park, Kwang-Seo;Ju, Jae-Hyun;Choi, Byung-Ju;Kim, Ki-Chai;Lee, Kwang-Sik;Lee, Dong-In
    • 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.

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ORGANIC POLLUTANTS DEGRADATION USING PULSELESS CORONA DISCHARGE: APPLICATION IN ULTRAPURE WATER PRODUCTION

  • Shin, Won-Tae;Sung, Nak-Chang
    • Environmental Engineering Research
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    • v.10 no.3
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    • pp.144-154
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    • 2005
  • The use of ozone gained acceptance in the production of ultrapure water because of its powerful oxidizing ability. Ozone is currently used to deactivate microorganisms and remove organic contaminants. However, interest also exists in using radical species, which arc stronger oxidants than ozone, in such processes. One means of producing radical species is by corona discharge. This work investigates the use of a novel pulseless corona-discharge system for the removal of organic substances in ultrapure water production. The method combines corona discharge with electrohydrodynamic spraying of oxygen, forming microbubbles. Experimental results show that pulseless corona discharge effectively removes organics, such as phenol and methylene blue, in deionized water. The corona-discharge method is demonstrated to be comparable to the direct use of ozone at a high-applied voltage. The results also show that a minimum applied voltage exists for operation of the corona-discharge method. In this work, the minimum applied voltage is approximately 4.5 kV. The kinetic rate or phenol degradation in the reactor is modeled. Modeling results show that the dominant species of the pulseless corona-discharge reactor are hydroxyl radical and aqueous electron. Several radical species produced in the pulseless corona-discharge process are identified experimentally. The. major species are hydroxyl radical, atomic hydrogen species, and ozone.

Operation Characteristic of Filtered Vacuum Arc Source for Amorphous Diamond Coating (비정질 다이아몬드 코팅을 위한 자장여과 아크소스의 동작 특성에 관한 연구)

  • kim, Jong-Guk;Lee, Gu-Hyeon
    • 연구논문집
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    • s.30
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    • pp.147-157
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    • 2000
  • The filtered vacuum arc source (FVAS), which is adopted by magnetic filtering methode to remove the macro-particle in vacuum arc plasma, was composed of a torus structure with bending angle of 60 degree. The radius of torus was 266 mm, the radius of plasma duct was 80 mm and the total length was 600 mm. The magnet parts were consisted of one permanent magnet, one magnetic yoke and five solenoid magnets. The plasma duct was electrically isolated from the ground so that a bias voltage could be applied. The baffles inside plasma duct were installed in order to prevent the recoil effect of macro-particles. Graphite was used as the cathode material to coat the amorphic diamond film and its diameter was 80 mm. The amorphic diamond film attracts much attention due to its excellent mechanical, optical and tribological properties suitable for wide range of applications. The effects of solenoid magnet in plasma extraction were studied by computer simulation and experiment using Taguchi's method. The source and extraction magnet affected the arc stabilization. The extraction beam current was maximized with low value of the source magnet current and high value of the filtering magnet current. Optimum deposition condition was obtained when the currents of arc discharge, source, extraction, bending, deflection and outlet magnet were 30 A, 1 A, 3 A, 5 A, and 5 A, respectively.

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A Study on the Series Arc Detection in Low-voltage Wiring Systems (저압배선계통에서 직렬아크의 검출에 관한 연구)

  • Kim, Il-Kwon;Park, Dae-Won;Choi, Su-Yeon;Park, Chan-Yong;Kim, Hwang-Kuk;Kil, Gyung-Suk
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.21 no.2
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    • pp.182-187
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    • 2008
  • This paper dealt with the detection algorithm of series arcing, which is a cause of electric fires in low-voltage wiring systems. To find the distinguished electrical features of series arc, we simulated series arcing by the arc generator specified in UL1699. An electric heater, an inverter-controlled vacuum cleaner, and a phase-controlled incandescent lamp were used as loads to generate series arcing. A high-pass filter (HPF) with the low cut-off frequency of 3 kHz at -3 dB was fabricated and applied to separate the series arc signal from the AC voltage source. The experiment showed that the high frequency signal generates randomly during series arcing, and the phase-controlled incandescent lamp produces high frequency pulses even in normal state. In this case, the magnitude, the width, and the randomness of high frequency signal should be analyzed to estimate series arcing precisely.

Synthesis of Bi-Sb-Te Thermoelectric Nanopowder by the Plasma Arc Discharge Process (플라즈마 아크 방전법에 의한 Bi-Sb-Te 나노 열전분말 제조)

  • Lee, Gil-Geun;Lee, Dong-Youl;Ha, Gook-Hyun
    • 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.

Study on the Synthesis of HoN Nanoparticles and Magnetocaloric Effect as Magnetic Refrigerant for Hydrogen Re-Liquefaction (수소재액화를 위한 자기냉매용 HoN 나노분말 합성 및 자기열량효과 연구)

  • Kim, Dongsoo;Ahn, Jongbin;Jang, Sehoon;Chung, Kookchae;Kim, Jongwoo;Choi, Chuljin
    • Journal of Hydrogen and New Energy
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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.

A Study on Combined Processes of Sliding Arc Plasma and Corona Dielectric Barrier Discharge for Improve the Efficiency Treatment of Harmful Substance (슬라이딩아크 방전과 코로나 방전의 복합공정을 통한 유해물질 처리효율 개선에 관한 연구)

  • Kwon, Woo-Taeg;Lee, Woo-Sik
    • Fire Science and Engineering
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    • v.28 no.6
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    • pp.108-113
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    • 2014
  • The combined process of Sliding Arc Plasma and corona dielectric barrier discharge process (CDBD) was used to efficiently improve harmful substance, which convert into OH radicals which have strong oxidation potential, and so have deodorization and sterilizing effects, by generating specific radicals and anion and then reacting with the moisture contained in harmful substance. As a result of experiment, even if the size of SAP reactor is reduced from 80 A to 50 A, there is no much change and therefore it is judged the size of reactor may be minimized. And it was confirmed that after the anion and ozone generated from CDBD rector react with harmful substance, a anion was reduced from 510,000 ppb to 470 ppb and ozone from 98 ppb to 22 ppb. It was also judged the stability and durability of plasma producer are excellent. Accordingly, it is considered the harmful substances which exist in indoor air quality will be efficiently improved and removed by using further plasma combined process through this study.

Fabrication of Ferromagnetic Mn-AI Alloy N anoparticles using a Plasma Arc-discharge Process (플라즈마 아크 방전법에 의한 강자성 Mn-Al 합금나노입자의 합성)

  • Lee, Jung-Goo;Li, Pu;Dong, Xing Long;Choi, Chul-Jin
    • Korean Journal of Metals and Materials
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    • v.48 no.4
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    • pp.357-362
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    • 2010
  • Ferromagnetic Mn-Al nanoparticles were prepared using a plasma arc discharge method. The influence of the process parameters on the vaporization rate, composition, particle size, and magnetic properties of the as-produced nanoparticles was investigated. The Mn content was found to be higher in the nanoparticles than in the corresponding mother materials, although the difference diminished with the reaction time. As the $H_2$ content in the reaction gas increased, both the vaporization rate and the particle size increased. With 30 at.% Mn, the average particle diameter was 35.2 nm under a pure Ar gas condition, whereas it was 95.4 nm at a Ar:$H_2$ ratio of 60:40. With the addition of a small amount of carbon, ${\varepsilon}$-phase nanoparticles were successfully synthesized. After a heat treatment in a vacuum for 30 min at $500^{\circ}C$, the nonmagnetic ${\varepsilon}$-phase was transformed into the ferromagnetic ${\tau}$-phase, and a very high coercivity of nearly 5.6 kOe was achieved.