• Proceedings of the KIPE Conference
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• 2006.06a
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• pp.56-58
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• 2006

본 논문은 PVD(Physical Vapor Deposition)의 마그네트론 스퍼터(Magnetron sputter) 박막코팅(Thin film coating) 공정에서 플라즈마(Plasma)를 발생시키고 제어하는 DC 전원공급 장치에 관한 것이다. 이 논문에서는 임피던스의 변화가 심하고 아크(Arc)가 빈번히 발생하는 플라즈마 부하의 특성에 대해, 과도상태(Transient state)의 출력제어 성능을 향상시키고 아크 발생 시 부하로 전가되는 아크에너지를 저감시키기 위한 직류 전원 공급 장치에 대해 소개한다. 전원장치는 수하특성을 가지며 플라즈마 부하에 적합한 출력 제어성을 확보하고 아크 에너지를 최소화하기 위해 고주파 L-C 직렬공진회로 기법을 적용한다. 개발된 DC 20kW급 전원 장치는 인버터와 고주파 절연변압기, 정류기로 구성된다. 인버터는 $100{\sim}200kHz$의 제어주파수로 PFM 및 PWM 제어를 하며, 단위용량 5kW급 컨버터 4개를 직, 병렬 연결하여 출력리플을 최소화 하였다. 개발된 장치의 우수한 제어성능은 실제 플라즈마 공정에서 시험 평가한 결과를 통해 검증할 수 있었다.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.3
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• pp.674-679
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• 2011

In this paper, we experimented and analyzed about electric fire risk assessment methods of LED lightings for outdoor. LED lighting is composed of AC power lines, AC/DC converter, DC power lines and LED lamps. There are some risk factors of electric fire in LED lighting such as short circuit between power lines or power line and ground, dielectric breakdown, leakage current, abnormal voltage inflow, poor contacts(connections), etc. As a result of this study, insulation coverings of wire was ignited due to dielectric breakdown between power lines and molten marks were formed in copper conductor. LED lighting was blown out while short circuit, beside that, electrical disorder did not occur. When abnormal voltage was inflowed, electronic components such as varistor, condenser were damaged. Partial heating was produced and insulation was melted and carbonized by arc and heating while poor contacts were happened. We expect that the results of this study would be helpful for electrical safety of LED lightings for outdoor.

• Proceedings of the KIEE Conference
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• 1993.07b
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• pp.605-608
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• 1993

Breakdown characteristics of a small rod-to-rod microairgap has been studied for obtain an optimum breakdown voltage and an airgap spacing to be used as an emission control means by the electrical arc-burning unburnt carbon particulates exhausted from a power station burner. It is found that the breakdown voltage at the rod-to-rod airgap spacing in the rang of $1{\sim}100{\mu}m$ decreased with decrease in the rod-to-rod airgap spacing. And there were no minimum breakdown voltage on a $V_b$-Pd characteristics which is known as the minimum voltage in Paschen's law in air atmosphere. Breakdown voltages of the airgap at the constant airgap spacing were $V_{b-dc}>V_{b-ac}>V_{b-pulse}$, and it was lowest for the pulse voltage applied. As a result, it is found that a pulse power was one of effective power compared with dc or ac to be used as such an unburnt carbon particulate emission control means and the airgap spacing became to several tens ${\mu}m$, then the breakdown voltages were down to several handreds voltages.

• Proceedings of the KIEE Conference
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• 2005.10c
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• pp.276-278
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• 2005

For over 25 years, the stray currents from DC electric railroads have caused serious interference problems with underground metallic infrastructures in Korea. The most serious interference is reported at the pipelines near the depot areas. Our field survey proves that this phenomena is mainly due to the missing of dedicated rectifiers for mainline, depot and/or workshop areas. Because it takes so much time and costs too much to replace the traction power system, we consider a stray current confinement method which collects the stray currents and drains them to the negative terminal of the rectifier. This can be realized by installing a stray current collecting wire along the depot boundary. Moreover, we found the stray current collecting reinforcement bar located beneath the rails of concrete slab tracks. Using this bar, we arc going to draing the stray currents from mainline rails. In this paper we show the result of field survey on railroad facilities and present the stray current confinement method under field test.

• Journal of the Korean institute of surface engineering
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• v.34 no.5
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• pp.391-394
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• 2001

A new type plasma reactor is proposed to decompose CF4 diluted with N2 gas in atmospheric pressure. The arc plasmas is surrounded with a waterwall which acts as a source of water vapor, the solvent of HF, resultant product after decomposition, and conveyer to take away fluorine compound from exhaust gas. Abatement more than 99% is achieved by small size plasmas such as 1 cm in diameter, 25cm in length and 3.4KW of DC discharge power in such gas as the mixture of 100 sccm of CF4 and 15 slm of N2. Reactors of this type are to be expanded to such a system as Nitrogen flow of 50 slm with 200 sccm of CF4 and 7-8 KW discharge power.

• The Korean Journal of Ceramics
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• v.2 no.4
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• pp.212-215
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• 1996

This paper focuses the strength and wear resistance of CVD diamond films. The strength of free-standing CVD diamond films synthesized by microwave plasm CVD, DC plasma CVD, RF plasma CVD and arc discharge plasma jet CVD has been measured by three-point bending test. The wear resistance of CVD diamod films has been evaluated by the pin-on-disk type testing. diamond films coated on the base of sintered tungsten carbide pin by hot filament CVD have been rubbed with a sintered diamond disk in muddy water. Volume removed wear of CVD diamond has been compared with stellite, WC alloy and bearing steel.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.4
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• pp.735-741
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• 2009

This paper presents an algorithm for the permanent magnet shape optimization of a large scale BLDC(Brushless DC) motor to minimize the cogging torque. A response surface method (RSM) using multiquadric radial basis function is employed to interpolate the objective function in design parameter space. In order to get a reasonable response surface with relatively small number of sampling data points, additional sampling points are added on the basis of design sensitivity analysis computed by using FEM. The algorithm has 2 stages: the first stage is to determine the PM arc angle, and the 2nd stage is to optimize the magnet pole shape. The developed algorithm is applied to a 5MW BLDC motor to get a minimum cogging torque. After 3 iterations with 4 design parameters, the cogging torque is reduced to 13.2% of the initial one.

• Proceedings of the KIPE Conference
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• 2007.11a
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• pp.43-46
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• 2007

In this paper, a novel new pulse power generator based on IGBT stacks is proposed for pulse power application. Proposed scheme consists of series connected 9 power stages to generate maximum 60kV output pulse and one series resonant power inverter to charge DC capacitor voltage. Each power stages are configured as 8 series connected power cells and each power cell generates up to 850VDC pulse. Finally pulse output voltage is applied using total 72 series connected IGBTs. The synchronization of gating signal is important for series operation of IGBTs. For gating signal synchronization, full bridge inverter and pulse transformer generates on-off signals of IGBT gating and specially designed gate power circuit was used. Proposed scheme has lots of advantages such as long lifecyle, compact size, flat topped pulse forming, small weight, protection for arc, high efficiency and flexibility to generate various kinds of pulse output.

• Proceedings of the KIPE Conference
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• 2011.07a
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• pp.263-264
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• 2011

최근 들어 디지털 제품의 급증으로 인해 직류를 사용하는 부하가 증가하고, 직류 배전망에 대한 관심이 높아 지고 있다. 하지만 직류는 교류와 다르게 직류 배전시 부하의 단락 사고가 발생하면 지속적으로 아크전압이 발생하는 문제가 있기 때문에 차단이 어렵다. 인체의 안전과 전력설비 및 기기의 안전성을 확보하기 위해서는 고장전류로부터 계통을 보호하기 위한 차단기술이 필요하다. 본 논문에서는 효과 적인 직류 차단에 대하여 실험적으로 연구하였다.

• Journal of Biomedical Engineering Research
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• v.8 no.2
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• pp.161-170
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• 1987

A new type of motor-driven total artificial heart system with a rolloing-cylinder mechanism has been developed. The prototype system consists of a brushless DC motor inside of a rolling-cylinder, two arc shaped pusher-plate s, and two ventricles of smooth, seamless polyurethane sacs. The motor-driven pump has the advantages of being portable and quiet compared to the present air-driven pump. It can also be controlled more accurately. This rolling-cylinder type electromechanical pump has several structural advantages including small size and weight, as compared to other research groups' motor-driven pumps. The results of mock circulation tests confirm sufficient pump output capacity(cardiac output . 9 L/min, at aortic pressure'120mmHg, with heart rate . 120 BPM) for animal implantation of our prototype system.