• Proceedings of the KWS Conference
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• 2006.10a
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• pp.277-279
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• 2006

Due to the numerous environmental factors, cracks and corrosion are frequently occured especially in old steel bridge, which deteriorate the structural integrity; thus bring about the problems of structural safety of the steel bridge. Therefore, repair and reinforcement are required for the damaged structure. the replacement repair welding method is spotlighted for its brilliant features, i.e. it can be achieved without incurring traffic dislocation. the method cuts the damaged parts and replaces them with new steel plate by welding under live loads. However, the mechanical behavior of the welded joints under cyclic loads due to the traffic which passes along bridge is not clarified. In this paper, the fatigue strength of the replacement repair welded joints was investigated in order to improve reliability in the repair welded joints of old steel bridge.

• Journal of the Korean Institute of Gas
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• v.18 no.2
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• pp.62-68
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• 2014

Composite repair methods besides welding methods such as surfacing and sleeve welding have been used as repair of damaged gas pipelines in foreign countries. Importance of safety management of city gas pipelines have been emphasized recently and our own repair manuals and codes for repair of city gas pipelines are required. It is right time to conduct research on the composite repair methods since the composite repair was introduced rather recently compared to the welding repair methods which have been investigated for long time. In this study, as a starting point of safety assessment of gas pipeline repaird by composite materials, structural analysis of gas pipeline repaired by carbon fiber composite materials was conducted using finite element analysis(FEA) method and the results was discussed.

• Transactions of the Korean Society of Automotive Engineers
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• v.24 no.6
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• pp.709-715
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• 2016

This paper presents a comparison of an experimental study on spot and plug welding of an automotive body panel. Spot welding is a common joining technology used in automotive body panel assembly. In automotive body repair, however, plug welding is widely used due to its technical simplicity and cost benefit. Some researchers have focused on the use of spot welding in the manufacturing process, but there has been very little research done with respect to the engineering analysis of the plug welding process. In this study, two kinds of specimens are considered to compare the difference of failure strength between spot weld and plug weld: normal tension and shear tension. The experimental results show, in both normal tension and shear tension, that spot welding has higher failure strength than plug welding. In addition, plug welding is more vulnerable to shear tension than normal tension. This study can be applied to further studies on practical optimization for maintenance and repair of automotive body panels.

• Journal of Welding and Joining
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• v.17 no.1
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• pp.82-87
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• 1999

The basic remote sleeve repair-welding technology by the pulsed Nd:YAG laser for increasing the lifetime of the steam generator tube in a nuclear power plant has been developed. The relationship between the connection width and welding parameters have been investigated for the fundamental research to apply the sleeve-repair-welding technique to the nuclear industry. The Inconel 600 tube and Inconel 690 sleeve used for high temperature and high pressure service were welded as round lap welding by Nd:YAG laser. It was observed that the tensile shear strength, 340MPa of the welded specimen is equivalent to about 60% of that of the base metal (Inconel 600), 550MPa. The difference between the hardness of the base metal and that of the laser welds was about 10%. Ductile fracture was partly occurred in the weld but the cracking has not been observed. In spite of absence of the crack, the strength of welds was not sufficient in terms of the tensile shear strength.

• Journal of Advanced Marine Engineering and Technology
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• v.31 no.6
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• pp.729-735
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• 2007

AC cold arc welding process with AWS E Ni-CI and NiFe-CI is sometimes used to repair damaged cast iron parts in diesel engine room. But if some difference in hardness on welding zones, repaired parts would be cracked in a short. To overcome this default. this study is performed on varying preheating temperature of welding parts, selecting welding rod etc. Experimental results showed that difference in hardness on welding zones at $200^{\circ}C$ was less than $100^{\circ}C$ and less low current than high current. From this study we could conclude that repair welding at $200^{\circ}C$ preheating and low current as possible as welding in damaged cast iron parts was a little difference in hardness on welding zones.

• Journal of Welding and Joining
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• v.23 no.1
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• pp.22-25
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• 2005

• Journal of Welding and Joining
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• v.23 no.1
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• pp.26-29
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• 2005

• Journal of Welding and Joining
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• v.23 no.1
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• pp.30-34
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• 2005

• Journal of Welding and Joining
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• v.16 no.4
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• pp.19-25
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• 1998

• Journal of Welding and Joining
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• v.16 no.4
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• pp.26-35
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• 1998