• 한국가시화정보학회:학술대회논문집
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• 한국가시화정보학회 2004년도 추계학술대회 논문집
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• pp.30-33
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• 2004

In order to analyze the heat transfer phenomena in the plasma flames, a mathematical model describing heat and fluid How in an electric arc has been developed and used to predict heat transfer from the arc to the steel bath in a DC Electric Arc Furnace. The arc model takes the separate contributions to the heat transfer from each involved mechanism into account, i.e. radiation, convection and energy transported by electrons. The finite volume method and a SIMPLE algorithm are used for solving the governing MHD equations, i.e., conservation equations of mass, momentum, and energy together with the equations describing a standard $k-\varepsilon$ model for turbulence. The model predicts heat transfer for different currents and arc lengths. Finally these calculation results can be used as a useful insight into plasma phenomena of the industrial-scale electric arc furnace. from these results, it can be concluded that higher arc current and longer arc length give high heat transfer.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1987년도 정기총회 및 창립40주년기념 학술대회 학회본부
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• pp.278-282
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• 1987

Computational and theoritical investigations of an arc plasma have been made for the design of a circuit breaker. Modeling of an arc plasma used to be very involved and difficult because of the many variables and factors, In this paper, the dynamic behavior of an arc plasma is investigated by solving the MHD equations. Comparing an $SF_6$-blast arc with a non-blast arc, it has been found that the effect of gas-blast has a great influence on density rather than temperature.

• Journal of Advanced Marine Engineering and Technology
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• 제28권8호
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• pp.1251-1257
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• 2004

In order to analyze the heat transfer phenomena in the plasma flames, a mathematical model describing heat and fluid flow in an electric arc has been developed and used to predict heat transfer from the arc to the steel bath in a DC Electric Arc Furnace. The arc model takes the separate contributions to the heat transfer from each involved mechanism onto account, that is radiation, convection and energy transported by electrons. The finite volume method and a SIMPLE algorithm are used for solving the governing MHD equations, that are conservation equations of mass, momentum and energy together with the equations describing a standard k-${\varepsilon}$ model for turbulence. The model predicts heat transfer for different currents and arc lengths. Finally these calculation results can be used as a useful insight into plasma phenomena of the industrial-scale electric arc furnace. From these results, it can be concluded that higher arc current and longer arc length give high heat transfer

• 대한치과교정학회지
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• 제34권5호
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• pp.429-438
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• 2004

본 연구는 Plasma arc light를 이용하여 금속 브라켓의 부착시 광조사 방향, 중합시간 그리고 경화시간이 전단결합강도에 미치는 영향을 평가하기 위해서 시행되었다. 240개의 발거된 소구츠를 16군으로 나눈 후. 광중합기(Plasma arc light와 Halogen light), 중합시간(Plasma arc light 2. 4. 6초와 Halogen light 20초). 그리고 광조사 방향(Vertical 방향과 Oblique 방향)을 다르게 하여 브라켓을 부착하였다. 광증합 접착제는 Transbond XT를 이용하였으며 브라켓 부착 후 5분과 24시간 후에 만능물성시험기를 이용하여 전단결합강도를 측정하였다. 결과는 다음과 같다. 광중합기의 종류와 중합시간에 관계없이 Vertical군과 Oblique군간의 전단결합강도는 유의한 차이가 없었다.(p>0.05) Plasma arc light를 이용하여 2초 동안 광중합한 군들의 전단결합강도는 다른 중합시간의 군들보다 현저히 낮았다(P<0.05). 부착 5분 후의 전단결합강도는 24시간 후보다 현저히 낮았다(P<005), ARI 점수는 군들 간에 통계적으로 유의한 차이가 없었다. 이상의 결과는 plasma arc light를 사용한 금속 브라켓의 부착시 광조사 방향은 전단결합강도에 영향을 끼치지 않으며. Halogen light와 유사한 결합강도를 얻기 위해서는 4초 이상의 중합시간이 필요함을 시사한다.

• 한국연소학회지
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• 제11권3호
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• pp.1-7
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• 2006

A reaction mechanism of methane partial oxidation, which consists of thermal and plasma chemistry reaction pathways, has been investigated using with an arc-jet reactor. The reaction zone of the arc-jet reactor is spatially separated into thermal and non-thermal plasma zone. Methane conversion rates, selectivity of $H_2$ and $C_2$ chemicals in each zone are obtained, which reveals clearly different characteristics of reaction pathways depending on the temperature conditions. The conversion rates obtained in thermal plasma zone is higher than those in non-thermal plasma zone. The selectivity, however, obtained in non-thermal plasma zone is significantly higher than those in thermal plasma zone. Further parametric study on $O_2/C$ ratio, arc length and SED shows that the present process is mainly governed by thermal chemistry pathways.

• 전기의세계
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• 제22권2호
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• pp.57-69
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• 1973

The aim of this study was to investigate the behaviors of plasma jet under coaxial magnetic field in paralled with it for controlling optical characteristics and input power of plasma jet without impurity and instability of arc plasma column. Because the discharge characteristics of plasma jet were so distinctively different according to the existence or non-existence of magnetic field, the input power, luminous intensity of plasma jet and thermal efficiency were comparatively studied in respect of such variables as arc current, gap of electrode, quantity of argon flow, magnetic flux density, diameter and length of nozzle, with the use of several materials which were different in diameter and length of nozzel. The results were as follows; 1) The voltage tends to show a drooping characteristic at law current and then rises gradually. The luminous intensity of plasma jet increases exponentially with arc current. 2) Arc voltage increases and luminous intensity tends to decrease gradually as gap of electrode increases. 3) Arc voltage and luminous intensity tends to decrease gradually as gap of electrode increases. 3) Arc voltage and luminous intensity increase in accordance with the quantity of argon flow. 4) At first step, arc voltage increases to maximum value with the growth of flux density and then tends to show a gradual decrease. Luminous intensity decreases with the growth flux density. 5) Arc voltage decreases as the constriction length of nozzle increases, maximum decrease is shown at the constriction length of 20(mm) and it increases beyond that value. The luminous intensity decreases as the constriction length grows. 6) Arc voltage and luminous in tensity increase with the growth of diameters of nozzle. 7) Thermal efficiency has values between 50% and 75%, being influenced by arc current, the quantity of argon flow, flux density, the length of electrode gap and the constriction length of nozzle.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제52권9호
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• pp.395-399
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• 2003

In this paper, physical phenomena which are related to the high temperature and high pressure arc plasma generated during the fault current interruption by SF6 gas circuit breakers are reviewed. In particular, in order to analyze nozzle ablation induced by the heats transferred to the surface of the poly-tetrafluoroethylene(PTFE) nozzle through arc radiation, a governing equation for the calculation of PTFE concentration is added to the governing equations for SF6 arc Plasma analysis. The proposed method is applied to the steady state analysis of $SF_6$ arc plasma generated by direct current taking account of the nozzle ablation and the results are presented.

• 대한전기학회논문지
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• 제45권3호
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• pp.415-425
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• 1996

This study presents an analytical method of solving the behaviors of arc plasma in a nozzle constricting transferred-type torch and purposes to obtain the basic data for the design of a plasma torch, which can be obtained from the temperature, pressure, velocities and voltage distributions. We have to solve some conservation equations simultaneously and need to know the exact thermal gas properties in order to obtain the correct behaviors of arc plasma. It is also necessary to give the relevant physical or geometric boundary conditions. For the simplicity of analysis, we assumed that (a) the plasma flow is laminar, (b)the local thermodynamic equilibrium, i.e. LTE, prevails over the entire arc column region. The electrode sheath effects were neglected and the nozzle area was excluded from the analysis by assuming that the current flow into the nozzle is zero. We solved the momentum transfer equation including the self-magnetic pinch effect, and obtained the temperature distribution from the energy conservation equation. From this temperature, we could get arc voltage distribution. (author). refs., figs., tabs.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2009년도 추계학술대회 논문집
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• pp.358-361
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• 2009

The increasing interest in the surface modification technology by the plasma transferred arc overlaying process in the material processing is placing stringent demands on the manufacturing techniques and performance requirements, and the manufacture employs the high quality and efficiency plasma transferred arc overlaying technology. This paper covers recent technical trends of plasma transferred arc overlaying technology including the COMPENDEX DB analysis.

• 전기학회논문지P
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• 제61권3호
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• pp.116-121
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• 2012

Recently, in the field of renewable energy such as solar cells including the semiconductor and display industries, thin film deposition process is being diversified. Furthermore, to deal with trend of making high-quality and fast, the high-capacity and output plasma power supply which can control high density plasma is required. The biggest problem is arc discharge caused by using high voltage power supply. Thus, the key function of plasma power supply is to prevent arc discharge and there is a need to maintain the possible minimum arc energy. In DC sputtering power supply, on a periodic basis (-)voltage powering up is able to significantly reduce arcing, as well as arc discharge prevention, and maintaining uniform charge density. This conventional method for powering up (-)voltage requires heavy mutual inductance of the transformer to avoid distortion problem of the output voltage. This study is about energy recovery circuit for arc discharge prevention in sputtering plasma power supply. By using energy recovery circuit, it is possible to reduce the mutual inductance and size of the transformer dramatically, prevent distortion of the output voltage and has a stable output waveform. This work was proved through simulation and experimental study.