• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.1736-1741
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• 2003

The characteristics plasma flow of an atmospheric plasma torch used for thermal plasma processing is studied. In general, it is produced by the arc-gas interactions between a cathode tip and an anode nozzle. The performance of non-transferred plasma torch is significantly dependent on jet flow characteristics out of the nozzle. In this work, the distribution of gas flow that goes out to the atmosphere through a plenum chamber and nozzle is analyzed to evaluate the performance of atmospheric plasma torch. Numerical analysis is carried out with various angles of an inlet flow which can create different swirl flow fields. Moreover, the size of plasma plume is experimentally depicted.

• 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.

• 한국산학기술학회논문지
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• 제10권11호
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• pp.3074-3079
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• 2009

지속적인 경제 발전과 인구증가로 인하여 에너지 소비가 급증하게 되면서 에너지의 효율적인 사용이 필요하다. 특히 에너지 손실이 많은 건물의 창호에 단열성능이 좋은 고효율 진공유리 사용이 절실한데 아직 가격 및 성능등의 문제로 보급화가 이루어지지 않고 있다. 따라서, 본 연구에서는 저가의 진공유리 개발을 위한 유리 용접용 토치를 설계 및 제작하였다. 연료는 고밀도 열원인 수소-산소 혼합가스를 사용하였고 주로 토치 형상, 노즐 직경, 노즐 배치 등의 최적화를 수행하였다. 끝으로 개발된 토치를 이용하여 두 장의 유리용접을 성공적으로 수행함으로써 저가의 진공유리 개발 가능성을 확인하였다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.3062-3067
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• 2007

HVOF thermal spray guns are now being widely used to produce protective coatings, on the surfaces of engineering components. HVOF technology employs a combustion process to heat the gas flow and melt the coating materials which are particles of metals, alloys or cermets. Particle flow which is accelerated to high velocities and combustion gas stream are deposited on a substrate. In order to obtain good quality coatings, the analysis of torch design must be performed. The reason is that the design parameters of torch influence gas dynamic behaviors. In this study, numerical analysis is performed to predict the gas dynamic behaviors in a HVOF thermal spray gun with various torch shapes. The CFD model is used to deduce the effect of changes in nozzle geometry on gas dynamics. Using a commercial code, FLUENT which uses Finite Volume Method and SIMPLE algorithm, governing equations have been solved for the pressure, velocity and temperature distributions in the HVOF thermal spray torch.

• 한국가스학회지
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• 제8권1호
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• pp.25-29
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• 2004

본 연구는 연료특성상 기존의 절단공정에 사용되던 에틸렌, 아세틸렌, LPG에 비해 불리한 천연가스를 절단분야에 적용하기 위해 천연가스용으로 개발된 절단노즐을 수치해석을 통해 해석하고, 수치해석 결과를 바탕으로 현장적용 실험을 수행하여 절단성능 및 적용 여부를 판단코자 하였다.

• 한국표면공학회지
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• 제36권1호
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• pp.69-73
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• 2003

The atmospheric pressure plasma is regarded as an effective method for surface treatments because it can reduce the period of process and doesn't need expensive vacuum apparatus. The performance of non-transferred plasma torches is significantly depended on jet flow characteristics out of the nozzle. In order to produce the high performance of a torch, the maximum discharge velocity near an annular gap in the torch should be maintained. Also, the compulsory swirl is being produced to gain the shape that can concentrate the plasma at the center of gas flow. In this work, the distribution of gas flow that goes out to atmosphere through a plenum chamber and nozzle is analyzed to evaluate the performance of atmospheric pressure plasma torch which can present the optimum design of the torch. Numerical analysis is carried out with various angles of an inlet flow velocity. Especially, three-dimensional model of the torch is investigated to estimate swirl effect. We also investigate the stabilization of plasma distribution. For analyzing the swirl in the plenum chamber and the flow distribution, FVM (finite volume method) and SIMPLE algorithm are used for solving the governing equations. The standard k-model is used for simulating the turbulence.

• 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.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 C
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• pp.1606-1608
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• 1994

A performance of the torch greatly depends on the plasma gas and the cooling gas. The plasma gas constricted by the nozzle concentrates electric power and momentum, so it can eject molten metal from a cut. As an electric arc constricted in a nozzle is more constricted through thermal pinch by the cooling gas, it is possible to transfer larger thermal concentration to the workpiece. The optimized parameter value in this study was given below. Plasma gas pressure is $4[kgf/cm^2]$ and gas mass flow is $30[{\ell}/min]$. Cooling gas pressure is $6[kgf/cm^2]$ and gas mass flow is $120[{\ell}/min]$.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2009년도 춘계학술대회 논문집
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• pp.169-170
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• 2009

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2010년도 추계학술대회 논문집
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• pp.791-792
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• 2010