• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.731-736
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• 2001

Nowadays various simulation tools are widely used for the design and the analysis of power electronic converters. From the engineering point of view it is rather difficult to parameterize power semiconductor device models without the knowledge of basic physical parameters. In recent years some data sheet driven behavioral models or so called 'wizard' tools have been introduced to solve this problem. In this contribution some experiences with some user-friendly power semiconductor models will be discussed. Using special simulation test circuits it is possible to get information on the static and dynamic behavior of the parameterized models before they are applied in more complex schemes. These results can be compared with data sheets or with measurements. The application of these models for power loss analysis of inverter type arc welding power sources will be described.

• Proceedings of the KIPE Conference
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• 2000.07a
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• pp.529-534
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• 2000

Diode rectifier has been widely used as he preregulator of inverter arc welding machine(IAW). As it is linked to power utility a disorder of other instruments can be burst out. The adoption of voltage source PWM converters can be considered and which must catch the compromise of between performance and cost. So in this paper voltage source PWM converters which have single (i.e. PWM converter) control switch respectively are analyzed and evaluated through digital simulation and experiment. In addition the improved input characteristics of IAW are shown and compare to those of conventional one.

• Journal of Welding and Joining
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• v.13 no.1
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• pp.127-137
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• 1995

The possibility of new GMAW process using economic shielding gases including CO$_{2}$ gas was investigated on the effect of shielding gas on weldabilty. In the optimum welding condition using 600A power source, FCAW process showed low depositions rate, 114 g/min at 300A, but new GMAW using other mixed shielding gases exhibited high deposition rate, 208-224 g/min at 450A. TIME gas, Ar+CO$_{2}$ gas and Ar+CO$_{2}$+O$_{2}$ gas as a shielding gas were able to be used to the very high welding current(450A), moreover TIME gas and Ar+CO$_{2}$ gas showed the highest arc stability among shielding gases studied in this experiments. The weld penetration was performed by axial spray transfer mode of weld droplet. On the basis of workability, weldability and economic point of view, Ar mixture (80%Ar+20%CO$_{2}$) gas was recommended as a shielding gas for the development and application of new GMAW process. This shielding gas showed the low spatter, good weld quality, stable arc and low cost at the region of high welding current.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.117-120
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• 2001

Resistance spot welding is widely employed in a manufacturing process. In recent years, the requirement for more sophisticated quality control procedures has been in the mass production industries. The requirements for high productivity and good welding qualities have lead to the development of more widely available microprocessor or computer based control. In this study, the inverter-type power source and welding servo gun are developed.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.9
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• pp.1166-1174
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• 2000

This work presents a two-dimensional quasi-steady state model to study the fluid flow and heat transfer in high-power density welding process of thin AISI-304 stainless steel plates. The enthalpy method and the finite volume method were used for a numerical analysis of the mushy region phase change as well as the heat flow at the weld pool and the heat-affected zone. The results show that the mushy region distributed around the weld pool becomes wider downstream and the surface heat losses by convection and radiation can be significant factors in welding process especially when a welding speed is relatively low.

• Journal of Welding and Joining
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• v.31 no.2
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• pp.4-15
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• 2013

The laser/arc hybrid welding process is a new process combining the laser beam and the arc as welding heat source. The laser beam and arc influence and assist one another. By application of hybrid welding, synergistic effects are achievable, and disadvantage of the respective processes can be compensated. The laser-arc hybrid welding process has good potential to extend the field of applications of laser technology, and provide significant improvements in weld quality and process efficiency in manufacturing applications. This review analyses the recent advances in the fundamental understanding of hybrid welding processes using the works of the data base of Web of Science (SCI-Expanded) since the 2000 year. The research activity on the hybrid welding has been become more actively since 2006, especially in China, presenting the most research papers in the world. Since the hybrid welding process was adopted in manufacturing of the automobile in Europe in the early of 2000's, its adopting is widely expanded in the field of manufacturing of automobile, ship building, steel construction and the other various industry. The hybrid welding process is expected to advance toward higher productivity, higher precision, higher reliability through the mixing of high power and flexible fiber laser or disk laser and digitalized pulsed arc source.

• Proceedings of the KWS Conference
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• 2002.05a
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• pp.65-67
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• 2002

The gas metal arc welding(GMAW) is regarded as one of the best candidate for welding automation in industrial joining application. It is important to monitor the weld quality for the high performance of weld automation. The measured analog signal is frequency analyzed by digital signal process method. In order to observe the welding phenomena and control welding condition, arc light, voltage, and current are measured at the same time. They are analyzed and compared with arc sound. for these experiments, a power source of constant voltage characteristics was used in the pure metal transfer mode.

• Proceedings of the KIPE Conference
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• 2002.11a
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• pp.89-93
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• 2002

Hydrogen - Oxygen gas has obtained from water electrolysis reaction. It is mixed gas havingconstant volume ratio 2:1 Hydrogen and Oxygen, and it is used as a source of thermal energy by combustion reaction. This gas has betterristics in the field of economy, efficiency of energy, and environmental intimacy than used both of acetylene gas and LPG for gas welding machin. So nowdays many studies of Water-Electrolyzed gas are progressed, and commercially used as a source of thermal energy for gas welding In the industry. For Water-Electrolyzed Source, it was used diode rectifier or SCR rectifier for get DC source. This method which is not looking to improve a source for impossible current control or voltage and limited control intervals. In this paper, it was relized and designed in source of pulse type for complementing existing-DC source type, also by experiment it was acquired producting characteristics of Hydrogen -Oxygen Gas through feature of source

• Journal of Welding and Joining
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• v.15 no.2
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• pp.89-99
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• 1997

Spot welding is one of the important welding processes for the construction of thin metal sheet. Because of low investment cost, alternating welding current is widely applied for power source. Direct current type could be, however, recommened for high quality weldment. In this study, the effect of welding current type on the weldability and the electrode life in spot welding of aluminium alloy were investigated. Various welding tests were done by using three phase direct and alternating welding current, respectively. In spite of high variation of welding force, weld quality and electrode life with alternating welding current were shown better results than those with direct current for 2mm thick alumininum alloy sheets. This was due to excessive erosion of the positive electrode in direct welding current compared with the negative one. On the contrary to 2mm sheets, the welding parameters of alternating current for 1mm sheets must be carefully selected.

• Proceedings of the KIPE Conference
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• 2002.07a
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• pp.257-262
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• 2002

Water-Electrolyzed gas is a mixed gas has the constant volume ratio 2 1 Hydrogen and Oxygen gained from electrolyzed water, and it has better characteristics in the field of economy, efficiency of energy, and environmental intimacy than acetylene gas and LPG used for existing gas welding equipment. So nowdays many studies of Water-Electrolyzed gas are progressed, and commercially used as a source of thermal energy for gas welding in the industry. For Water-Electrolyzed Source, it was used diode rectifier or SCR rectifier for get DC source. This method which is not looking to improve a source for impossible current control or voltage and limited control intervals. In this paper, it was relized and designed In source of pulse type for complementing existing - DC source type, also by experiment it was acquired producting characteristics of Hydrogen -Oxygen Gas through feature of source