• Journal of Welding and Joining
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• v.17 no.1
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• pp.55-61
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• 1999

The effect of S content in welding wires on the arc stability was investigated, in the region of short circuit transfer and spray transfer. In the region of short circuit transfer, with increasing S content, average arcing time and average short circuit time were decreased. Therefore, droplet transfer frequency was increased, due to the reduction of arcing time and peak current at the moment of arc-reiginition was decreased, due to the decrease of short circuit time. In the region of spray transfer, the fluctuation degree of arc current and arc voltage became more stable, with increasing S content.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.7
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• pp.132-140
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• 2000

Plasma arc cutting is one of the most widely used processes in metal cutting fields and is a process that produces parted metal plates by cutting them with an arc plasma established between the electrode tip and the plate(workpiece). When the tip-to-workpiece distance varies during cutting, the cut quality, for example the kerf width, is deteriorated by the change of plasma arc. The variations of tip-to-workpiece distance are due to the different factors such as inaccuracies in setting the torch or workpiece, thermal distortions during cutting, and uneven surface of workpiece. The control to keep the tip-to-workpiece distance constant is thus indispensable to improve the flexibility of automatic plasma arc cutting system applications. In this study, an arc sensor which utilizes the electrical signal obtained from the plasma arc itself was developed. The arc sensor has an advantage that no particular sensing device is necessary and real-time sensing of the tip-to-workpiece distance is possible directly under the plasma arc. The relationship between plasma arc voltage and tip-to-workpiece distance was determined through the repeated experimental results. The model was used for developing an automatic tip-to-workpiece distance control system of plasma arc cutting. It could be shown that the proposed system has a successful capability of tip-to-workpiece distance control.

• The Transactions of the Korean Institute of Power Electronics
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• v.5 no.5
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• pp.419-426
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• 2000

Generally diode rectifier has been used as Preregulator of arc- welding machine. Its defect is the generation of high current harmonics which result In utility pollution. In this parer, using the three-phase PWM converter, the input performance of arc-welding machine is improved by increasing the input power factor. When the diode rectifier in the arc-welding machine is replaced with three-phase PWM converter, PWM converter should control DC voltage of the output side. If PI controller is used for the output DC voltage regulator, the output DC voltage has high ripple voltage due to the instantaneous load variation in the arc-welding machine. In this paper, the feedforward compensator has been introduced to reduce the DC voltage ripple. It lessens the influence of load current which is the disturbance of the output DC voltage regulator. Theoretical prediction of this analysis has been verified by comparing with experimental data

• Journal of Welding and Joining
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• v.28 no.6
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• pp.28-34
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• 2010

This paper was described on investigation to prevent porosity in high speed MIG Welding of Al 6082-T6. Porosity measurement was carried out by using image analysis of micrographs with the help of an analysis software. The main parameter was arc length and torch progressive angle. The porosity ratio was increased as arc length was increased. The arc length was increased depending upon the output voltage. By proper selection of pulse waveform parameter, the stable arc of one pulse one drop was generated. The porosity ratio of optimum condition in one pulse one drop was lower than high voltage condition. When torch progressive angle was an angle of advance $10^{\circ}$, porosity ratio was minium.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.53 no.3
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• pp.166-172
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• 2004

Arc Fault Current is an electric discharge which is occurred in two opposite electrode. In this Paper, arc current control algorithm is designed for the interruption of arc fault current which is occurred in the low voltage network. This arc Is one of the main causes of electric fire. Arc fault in electrical network has the characteristics of low current, high impedance and high frequency. Conventional control algorithm does not have the arc current interrupt function. Hence, Control algorithm of arc current is designed for the interruption of arc fault current which has the modified arc characteristics.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2009.10a
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• pp.159-160
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• 2009

AIP(arc ion plating)방법으로 CrN 코팅막을 합성하였다. 고분해능 SEM과 AFM 분석들로부터 negative bias voltage에 따른 미세구조의 영향을 나타내었다. negative bias voltage의 증가에 따라 columnar microstructure가 amorphous microstructure로 변화하였다. bias voltage effect에 의해 CrN 코팅막내 입자의 크기가 미세해지고 나노 복합체를 잘 형성하였다.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.6
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• pp.50-58
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• 2013

The Neutral Beam Injection(NBI) generates ultra-high temperature energy in the tokamak of nuclear fusion. The NBI consists of filament power supply acceleration and deceleration power supply and arc power supply(APS). The APS has characteristics of low voltage and high current. APS generate arc through constant output of voltage and current. So this paper proposed suitable buck converter for low voltage and high current. The case of proposed buck converter used parallel switch because it can increase capacity and decrease conduction loss. When an arc is generated, the NBI chamber occur high voltage. And it will break output capacitor of buck converter. Therefore the output capacitor was removed in the proposed converter. Thus buck converter with constant output is the most important design of the output inductor. In this paper, designed APS verified operation of system and stability through simulation and prototype.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.11
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• pp.1925-1929
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• 2007

This paper is studied on a novel Electric Safety Protection Device (ESPD) of high speed for incapable operation of Earth Leakage Circuit Breaker (ELB) and Molded_case Circuit Breaker (MCCB) using the low voltage distribution line. The major causes of electrical fire are classified to short circuit fault, overload fault, electric leakage and electric contact failure. The occurrence factor of the fire is electric arc or spark accompanied with electrical faults. Residual Current Protective Device (RCD), that is ELB and MCCB, of high sensitivity type used at low voltage wiring cuts off earth leakage and overload, but the RCD can't cut off electric arc or spark to be a major factor of electrical fire. As the RCDs which are applied low voltage distribution panel are prescribed to rated breaking time about 30[ms] (KS C 4613), the RCDs can't perceive to the periodic electric arc or spark of more short wavelength level. To be improved on such problem, this research development is proposed to a novel ESPD of high speed to trip of distribution line on electric arc or spark due to electrical fire. Some experimental results of the proposed ESPD are confirmed to the validity of the analytical results.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.21 no.9
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• pp.109-113
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• 2007

In this paper, an arc current controller was designed for the interruption of arc fault currents occurred in a low voltage network. Arc in an electrical network represents the characteristics of low current, high impedance, and high frequency. Conventional controllers do not have arc current interrupt functions. Thus, an arc current controller was designed for the interruption of arc fault currents.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.8
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• pp.48-53
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• 2006

An electric arc furnace being used in the steel industry is a time-varying non-linear load causing voltage fluctuations to the power system. Flicker can be defined as the effect produced on the human visual perception by a changing emission of light lamps subjected to magnitude fluctuations of their supply voltage. The level of flicker depends on the amplitude, frequency and duration of the voltage fluctuations. In this paper, the voltage fluctuation problem in an 154[kV] system due to the electric arc furnace loads is investigated and the analysis results of the static var compensator application for the voltage flicker mitigation are presented and evaluated by the IEC 61000-3-7.