• Proceedings of the KIEE Conference
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• 2007.10c
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• pp.209-210
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• 2007

This paper describes the various wavelengths of electrical arc on overhead contact line for improvement of the current collection performance. The tests are performed with the arc measuring device and a welding machine to generate electrical are artificially. The experimental result shows the electrical are on overhead contact line and pantograph could be analyzed by artificial discharge.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.7
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• pp.555-562
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• 2013

The new recycling technology for aged aluminum wires in overhead conductor has been carried out. The authors are attempting to develop remanufacturing method for them for more effective way of recycling in stead of its conventional remelting process. The new recycling technology for aged aluminum wire in overhead conductor was composed of four steps in different develop process, destranding process for conductor, surface cleaning process, welding process and drawing process for aluminum wire. This paper investigates the properties during recycle process of aged aluminum wire. The results of microscopic analysis and mechanical properties were discussed to underscore recycling aluminum wire. Various graphs are presented accompanied by discussion about their relevance on the process. In conclusion, we confirmed the possibility of remanufacturing technique by using new process.

• Structural Engineering and Mechanics
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• v.61 no.4
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• pp.475-481
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• 2017

An overhead travelling crane structure of two doubly symmetric welded box beams is designed for minimum cost. The rails are placed over the inner webs of box beams. The following design constraints are considered: local buckling of web and flange plates, fatigue of the butt K weld under rail and fatigue of fillet welds joining the transverse diaphragms to the box beams, fatigue of CFRP (carbon fibre reinforced plastic) laminate, deflection constraint. For the formulation of constraints the relatively new standard for cranes EN 13001-3-1 (2010) is used. To fulfill the deflection constraint CFRP strengthening should be used. The application of CFRP materials in strengthening of steel and concrete structures are widely used in civil engineering applications due to their unique advantages. In our study, we wanted to show how the mechanical properties of traditional materials can be improved by the application of composite materials and how advanced materials and new production technologies can be applied. In the optimization the following cost parts are considered: material, assembly and welding of the steel structure, material and fabrication cost of CFRP strengthening. The optimization is performed by systematic search using a MathCAD program.

• Journal of the Korean Society for Nondestructive Testing
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• v.15 no.2
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• pp.395-406
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• 1995

Classification of flaws in weldments from their ultrasonic scattering signals is very important in quantitative nondestructive evaluation. This problem is ideally suited to a modern ultrasonic pattern recognition technique. Here brief discussion on systematic approach to this methodology is presented including ultrasonic feature extraction, feature selection and classification. A stronger emphasis is placed on probabilistic neural networks as efficient classifiers for many practical classification problems. In an example probabilistic neural networks are applied to classify flaws in weldments into 3 classes such as cracks, porosity and slag inclusions. Probabilistic nets are shown to be able to exhibit high performance of other classifiers without any training time overhead. In addition, forward selection scheme for sensitive features is addressed to enhance network performance.

• Journal of Korean Society of Steel Construction
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• v.16 no.4 s.71
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• pp.479-492
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• 2004

When U-ribs of steel deck plates are connected at the field, overhead welding should be done with backing strips. Misalignments may occur and lead to eccentric moments as well as high stress concentrations at welded joints. In this study, stress analyses and fatigue tests were carried out. Stress analyses for U-ribs' welded joints with backing strips were performed with different misalignments, root shapes, root gaps, and backing strip sizes. From the stress analyses, the stress concentration factors increased with increasing misalignments and root gaps. With the fixed misalignments and root gaps, the stress concentration factors obtained in the case of the semi-circle root shape were lower than those in the case of the right-angle root shape. It was verified that backing strip sizes have little influence on stress concentration factors. The fatigue tests for U-ribs' welded joints with backing strips indicated that increased misalignments shorten fatigue life drastically and cracks usually initiate at the root of the base metal and are propagated to the weld bead surface. Based on the results of the stress analyses, root-shape control methods were developed to mitigate stress concentration by changing welding condition control, radius curvature, and flank angle.