• 한국연소학회:학술대회논문집
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• 한국연소학회 2006년도 제32회 KOSCO SYMPOSIUM 논문집
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• pp.144-148
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• 2006

Characteristics of a plasma reactor for partial oxidation of methane, especially focused on the role and effectiveness of plasma chemistry, is investigated. Partial oxidation of methane is investigated using a rotating arc which is a three dimensional version of a typical glidingarc. The rotating arc has both the characteristics of equilibrium and non-equilibrium plasma. Non-equilibrium characteristics of the rotating gliding arc can be increased by rotating an elongated arc string attached at both the tip of inner electrode and the edge of outer electrode. In this way, plasma chemistry can be enhanced and hydrogen selectivity can reach almost 100% that is much higher than thermal equilibrium condition. As a result, the present study enables the strategic approach of the plasma reforming process by means of appropriate reactor design to maximize plasma effect and resulting in maximized reaction efficiency.

• 한국추진공학회지
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• 제22권5호
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• pp.115-124
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• 2018

전북대학교 고온플라즈마응용연구센터에서는 지구 재진입 및 고온재료의 열부하 평가를 위해 0.4 MW 급 아크가열플라즈마 풍동을 이용한 내열재료의 삭마 거동 등을 연구해 오고 있다. 아크가열 플라즈마 풍동은 고엔탈피 플라즈마를 발생시켜 다양한 고열부하의 극한 환경을 만들어 낸다. 이를 위해서는 플라즈마 토치내에 공기유량과 입력전류 등을 조절하여 다양한 열유속을 형성한다. 본 연구는 0.4 MW 아크가열 플라즈마 풍동의 다양한 방전 특성에 대해 조사하였다.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2020년도 가을 학술논문 발표대회
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• pp.52-53
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• 2020

The thermal spray coating process is being used to protect the metals and alloys from wear, abrasion, fatigue, tribology, and corrosion failure. Therefore, in the present study, Al and Zn was deposited by plasma arc thermal spray process onto the steel substrate and their performance was assessed. The bond adhesion result shows that Al coating has higher value attributed to compact, dense, and less porous compared to Zn coating which contain defects/pores and uneven morphology assessed by scanning electron microscopy (SEM). Electrochemical results show that the Al coating exhibited higher impedance value compared to Zn in artificial ocean water solution at prolonged exposure periods. However, both coatings show the increment in polarization resistance with exposure periods which reveal that porosity of coatings is filled by the corrosion products.

• 한국연소학회지
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• 제10권4호
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• pp.24-32
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• 2005

Various types of plasma source applied in $CH_4$ decomposition process are compared. DBD by pulse and AC power, spark by pulse and AC power, rotating arc and hollow cathode plasma are chosen to be compared. The results show that $CH_4$ conversion per given unit power is relatively high in hollow cathode plasma and rotating arc that induces rather high temperature condition and that is why both thermal dehydration and plasma induced decomposition contribute for the overall process. In case of DBD wherein high temperature electron and low temperature gas molecule coexist, the process shows low conversion rate, for in rather low temperature condition the contribution of thermal dehydration is lowered. Selectivity of $C_2H_6$ and $C_2H_2$ is shown to be a good parameter of the relative contribution of plasma chemistry in the overall process. From the results we concluded that required condition of plasma source for a cost effective and high yield $CH_4$ decomposition is to have characteristics of both thermal plasma and non thermal plasma in which temperature is high above a certain threshold state for thermal dehydration and electron induced collision is maximized in the same breath.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2002년도 학술대회지
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• pp.365-368
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• 2002

The design of industrial arc plasma systems is still largely based on trial and error although the situation is rapidly improving because of the available computational power at a cost which is still fast coming down. The desire to predict the behavior of arc plasma system, thus reducing the development cost, has been the motivation of arc research. To interrupt fault current, the most enormous duty of a circuit breaker, is achieved by separating two contacts in a interruption medium, $SF_{6}$ gas or air etc., and arc plasma is inevitably established between the contacts. The arc must be controlled and interrupted at an appropriate current zero. In order to analyze arc behavior in $SF_{6}$ gas circuit breakers, a numerical calculation method combined with flow field and electromagnetic field has been developed. The method has been applied to model arc generated in the Aachen nozzle and compared the results with the experimental results. Next, we have simulated the unsteady flow characteristics to be induced by arcing of AC cycle, and conformed that the method can predict arc behavior in account of thermal transport to $SF_{6}$ gas around the arc, such as increase of arc voltage near current zero and dependency of arc radius on arc current to maintain constant arc current density.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2005년도 추계 학술대회논문집
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• pp.311-317
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• 2005

It has been the most progressive interruption technique to use the ablation gas from the surface of PTFE nozzle driven by arc plasma during switching process in $SF_6$ gas circuit breakers. This advanced interruption technique can reduce the required mechanical energy to compress and blow the gas for extinguishing the arc plasma between the electrodes due to using the ablation effect instead. In order to consider the phenomena during calculation of switching process, it is required to confirm the principles of ablation from PTFE nozzle as well as of arc plasma during switching process. In this study, we have calculated the switching process considered the ablation of PTFE nozzle driven by arc plasma using multidisciplinary simulation technique and compared the results with the data without the ablation effect. More $50\%$ difference of pressure rise inside expansion chamber has been found from the results and it should be indispensable for this type of computational work to consider and include the ablation effect of PTFE nozzle. Further study on turbulence and radiation will be followed.

• Journal of Welding and Joining
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• 제5권1호
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• pp.23-33
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• 1987

플라즈마 절단은 산업계에서 널리 사용되고 있으나 공정의 해석에 대한 연구는 매우 부족하다. 본 연구에서는 알미늄판재에 나타나는 온도분포를 해석함으로써 절달폭을 이론적으로 예측하고 자 하였다. 열유동을 해석하는데 있어서, 플라즈마 아아크의 강도가 폭방향으로는 정상분포 (Gaussian distribution)을 갖고 두께방향으로는 지수함수적으로 감소한다고 가정하였다. 측정된 아아크효율을 이용한 계산결과 이론적으로 예측된 절단부의 크기 및 형상이 실험치와 매우 잘 일치하였으며, 따라서 제안된 해석방법은 플라즈마 절달공정의 해석에 유용하게 적용될 수 있 었다.

• Journal of Welding and Joining
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• 제28권4호
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• pp.67-72
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• 2010

The purpose of this paper is to understand the behavior of GHTAW process under the space environment with the experimental and numerical analysis. Gas Hollow Tungsten Arc Welding (GHTAW) using a hollow tungsten electrode was adopted, since the ignition and discharge of a conventional GTAW process is not appropriate to the space environment due to low pressure in space. In order to clarify the phenomena of GHTAW under space environment, an investigation of thermal and physical properties of the GHTAW arc plasma was experimentally performed under low pressure conditions. Furthermore, the molten pool behavior and weldment of GHTAW were understood by CFD-based numerical analysis, based on the models of GHTA heat source, arc pressure and electromagnetic force induced by arc plasma, the characteristics of which were obtained by the captured images of a CCD camera.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회B
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• pp.2515-2518
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• 2008

The vacuum interrupter (VI) is widely used in medium-voltage switching circuits due to its abilities and advantages as an environmental friendly circuit breaker. An understanding of the vacuum arc flow phenomena is very important for improving the performance of vacuum interrupter. In order to closely examine the vacuum arc phenomena, it is necessary to predict the magnetohydrodynamic (MHD) characteristics by the multidisciplinary numerical modeling, which is coupled with the electromagnetic and the thermal flow fields, simultaneously. In this study, we have investigated arc plasma constriction phenomena and an effect of AMF on the arc plasma with the high-current vacuum arcs for the cup-type AMF electrode by using a commercial finite element analysis (FEA) package, ANSYS. The simulation results applied with various AMFs and constant Joule heat generation show that strong axial magnetic field (AMF) permits the arc to be maintained in a diffused mode to a high-current vacuum arc. However, further studies are required on the two-way coupling method and radiation model for arc plasma in order to accomplish the advanced analysis method.

• 반도체디스플레이기술학회지
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• 제8권4호
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• pp.89-94
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• 2009

The influence on a stability of thermal plasma has been investigated in an electrode structure of non-transferred plasma torch. The variations of dynamic characteristic of the arc voltage was analyzed and compared in terms of voltage character and nozzle types for both the step-shaped nozzles and magnetic-approved cylindrical nozzle. From the experimental results, an electrode gap, flow rate of arc gas, and currents are considered as major operational parameters. As conclusion, it was assured that a torch with step-shaped nozzles of magnetic-approved type produce the stable plasma jet.