• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.1
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• pp.120-125
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• 2008

A flip-chip bonding system using DPSS(Diode Pumped Solid State) Nd:YAG laser(wavelength : 1064nm) which shows a good quality in fine pitch bonding is developed. This laser bonder can transfer beam energy to the solder directly and melt it without any physical contact by scanning a bare chip. By using a laser source to heat up the solder balls directly, it can reduce heat loss and any defects such as bridge with adjacent solder, overheating problems, and chip breakage. Comparing to conventional flip-chip bonders, the bonding time can be shortened drastically. This laser precision micro bonder can be applied to flip-chip bonding with many advantage in comparison with conventional ones.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.12
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• pp.2359-2369
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• 2009

The study on the multi-level inverter has been increasingly progressing to reduce the switching loss and improve the THD of output current in photovoltaic inverter. Recently, the main topics of multi-level inverter are to reduce the number of devices maintaining the power quality. Therefore, the novel topology was proposed for these problem which is composed of the isolated H-bridge multi-level inverter using the three phase low frequency transformer. The proposed multi-level inverter may not be need for a independent DC power, diode and capacitor. Specially, It has a advantage in generating high voltage source. The proposed approach is verified through simulation and experiment.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.04a
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• pp.385-390
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• 2000

This paper deals with the design and simulation of the hybrid power filter to compensate reactive power and harmonic components of nonlinear load. Control target is a 3-phase diode full bridge rectifier with L-R-C nonlinear load, this load is assumed adjustable speed driver(ASD). The hybrid filter consists of a shunt active filter, shunt passive filters and series inductors. Control algorithm is based on instantaneous power compensation theory proposed by H.Akagi and etc. The result from simulation shows the hybrid filter is superior than other filters on the point of compensation performance and low cost. The PSCAD/EMTDC 3.0 is used as simulation tools.

• Proceedings of the KIPE Conference
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• 2002.07a
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• pp.746-749
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• 2002

This paper presents a new control method for the high frequency electronic ballast which is operated with raw rectified dc link using diode bridge. For the commercial electronic ballast, proper ac input power factor and crest factor of the lamp current are required. The most ballast, therefore, has a active or passive power factor collection (PFC) circuit. With the proposed method, it can be achieved simultaneously that grater than 0.9 of input power factor and less than 1.85 of lamp current crest factor without any PFC circuit. In this paper, the proposed ballast control scheme and the experimental results for the application to the fluorescent lamp are described.

• Proceedings of the KIPE Conference
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• 2002.07a
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• pp.326-329
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• 2002

In this paper, a single-phase inverter using a diode bridge-type resonant circuit to implement ZVT(Zero Voltage Transition) switching is presented. The current control algorithm is analyzed about how to design the circuit with auxiliary switch which can ZVT operation for the main power switch. The simulation and experimental results would be shown to verify the proposed current algorithm, because the main power switch is turn on with ZVT and the hi-directional inverter is operated.

• Proceedings of the KIPE Conference
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• 2010.07a
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• pp.196-197
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• 2010

This paper investigates a high performance converter topology for hydrogen gas generation electrolysis system. The proposed converter topology consists of full-bridge inverter, medium frequency transformer, and diode rectifier. Hydrogen gas generation electrolysis process considered in the paper is analyzed and characterized by its equivalent circuit. The electrolysis cell is modeled as effective resistance, capacitance, inductance, and internal emf voltage source. The proposed converter topology provides enhanced efficiency of hydrogen gas generation process under the operating condition of dc output voltage with high frequency ripple on it. The high performance operation of proposed converter is confirmed through the simulation with the electrolysis cell considered in the equivalent circuit model.

• Proceedings of the KIPE Conference
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• 2010.07a
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• pp.242-243
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• 2010

This paper investigates a power supply of medium voltage with enhanced ignition characteristics for plasma torch. Series resonant half-bridge topology is presented to be a suitable ignition circuitry. The ignition circuitry is integrated into the main power conversion system of a multi-phase staggered three-level dc-dc converter with a diode front-end rectifier. The plasma torch rated for 3MW, 2kA and having the physical size of 1m long is selected to be a high enthalpy source in waste disposal system. The steady-state and transient operations of plasma torch are simulated. The parameters of Cassie-Mary arc model are calculated based on 3D magneto-hydrodynamic simulations. Circuit simulation waveform shows that the ripple of arc current can be maintained within ${\pm}10%$ of its rated value under the existence of load disturbance. This power conversion configuration provides high enough ignition voltage around 5KA during ignition phase and high arc stability under the existence of arc disturbance noise resulting in a high-performance plasma torch system.

• Proceedings of the KIEE Conference
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• 1999.11b
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• pp.355-357
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• 1999

Single-Phase multi-level AC-DC converter that is composed of diode bridge and switch is proposed. The number of the supply current level is depending on the individual current level of the converter. A converter circuit, the number of the level is equal to $2^{M+1}-1$, where M is the number of Switching Converter. The proposed circuit has converter with 31 current levels. When the number of current level is increased, smoother sinusoidal waveform can be obtained directly and it is possible to control the supply current almost continuously from zero to maximum without generating high voltage step changes as pulse with modulation technology. The technique illustrates its validity and effectiveness through the PSIM.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.560-560
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• 2012

We report a one-step fabrication method of Poly(9,9-dioctylfluorene) (PFO) nanowire array with pronounced ${\beta}$-Phase. We use liquid-bridge-mediated nanotransfer molding (LB-nTM) which is a new direct nano-patterning method based on the direct transfer of various materials from a mold to a substrate via liquid layer. The formation of the ${\beta}$-phase morphology in the resulting PFO nanowire array was evidenced by the presence of an absorption peak at 435nm. With the collection polarizer oriented parallel to the wire long axis, the PL emission was most intense and an emission dichroic ratio, DRE, of 3.7 was determined. The nanowire array have been investigated by scanning electron microscopy (SEM). Also, we simply fabricated structure of device of ITO/PFO nanowire arrays/Al and the electroluminescence spectra were recorded at various applied voltage.

• Proceedings of the KIEE Conference
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• 2001.04a
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• pp.467-469
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• 2001

An investigation into power conditioners that interface with photovoltaic array and utilities has been completed. The rating for this investigation is residential system(3-5kW) that interface with a 220V single phase utility connection. As the result of this investigation, a 3kW high frequency PWM IGBT inverter feeding a high frequency isolation transformer with a sinusoidal current wave was selected. The output of the transformer rectified with a diode bridge rectifier, four IGBT, used as 60Hz switched, reverse the polarity of the rectified current on every other half cycle of the utility voltage. Even though the high frequency link system used more power semiconductors, a net size, weight, and parts cost saving result compared to the other systems due to elimination of 60Hz transformer.