• Proceedings of the KSR Conference
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• 2011.10a
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• pp.1511-1516
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• 2011

The maintenance of the turnout is composed of signal field and track field on business, the electrical and mechanical field on system. adjustment and maintenance carry forward through coordination with these fields. In the case of turnout equipment used in a first phase of Seoul-Busan high-speed train, it is treated by classifying as mechanical adjustments and electrical adjustments. Mechanical adjustment is conducted with focus on fine adjustment to meet maintenance standards limits(1mm or less) about interval of basic rail and tongue rail about each part of track transition equipment. This refers to mechanical adjustments performed mainly with physical changes and movement characteristics between basic rail and tongue rail by considering the overall environment surrounding track side of section installed track transition equipment. However, these series of maintenance are conducted in state that high-speed train is not in the process from 1 am to 4 am at night, but common workers for maintenance are not familiar with the operation and checking about various situation, and the workers are even insufficient. Maintenance training using mixed reality is conducted in the place of business, we tried to overcome several problems of safety and time reduction through this training.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.4
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• pp.22-28
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• 2000

By using the finite element method, the Oyane's ductile fracture integral I was calculated from the histories of stress and strain according to every element and then the forming limit of hydroforming process could be evaluated. The fracture initiation site and the forming limit for two typical hydroforming processes, tee extrusion and bumper rail under different forming conditions are predicted in this study. For tee extrusion hydroforming process, the pressure level has significant influence on the forming limit. When the expansion area is backed by a supporter and bulged, the process would be more stable and the possibility of bursting failure is reduced. For bumper rail, the ductile fracture integral i is not only affected by the process parameters, but also by the shape of preforming blank. Due to no axial feeding on the end side of the blank, the possibility of cracking in hydroforming of the bumper rail is influenced by the friction condition more strongly than that of the tee extrusion. All the simulation results show reasonable plastic deformation, and the applications of the method could be extended to a wide range of hydroforming processes.

• Proceedings of the KSME Conference
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• 2000.04a
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• pp.230-235
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• 2000

By using the finite element method, the Oyane's ductile fracture integral I was calculated from the histories of stress and strain according to every element and then the forming limit of hydroforming process could be evaluated. The fracture initiation site and the forming limit fer two typical hydroforming processes, tee extrusion and bumper rail under different forming conditions are predicted in this study. For tee extrusion hydroforming process, the pressure level has significant influence on the forming limit. When the expansion area is backed by a supporter and bulged, the process would be more stable and the possibility of bursting failure is reduced. For bumper rail, the ductile fracture integral I is not only affected by the process parameters, but also by the shape of preforming blank. Due to no axial feeding on the end side of the blank, the possibility of cracking in hydroforming of the bumper rail is influenced by the friction condition more strongly than that of the tee extrusion. All the simulation results show reasonable plastic deformation, and the applications of the method could be extended to a wide range of hydroforming processes.

• Computational Structural Engineering
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• v.9 no.2
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• pp.143-151
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• 1996

The optimal design for Electro-magnetic Launcher (EML : Rail Gun) considering structural and electrical constraints are presented. For the structure of EML under high pulsed currency, the cross section is minimized subject to maximum stress of each element(rail, side wall, ceramic, and steel) within allowable stress and preload limits. The electrical constraint is the effective ceramic thickness which prevents the eddy current effect reducing the performance of EML. The stress analysis and optimization procedure of 90mm EML is conducted with ANSYS Code. The optimal design under preload is reduced to 53% of area compared with optimal design without preload. In case of rail with arc angle .theta.=45.deg., the performance of EML is the best among the other rail arc angles. The optimal design for rail with arc angle .theta.=45.deg., results in the reduction of 9% of area and 10.4% of deformation compared with Fahrenthold's design. The optimal preload 59.8MPa is much lower than Fahrenthold's design(186MPa). The results show that the optimal design of EML meets the design requirements.

• Geomechanics and Engineering
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• v.34 no.2
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• pp.209-220
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• 2023

In this study, a series of three-dimensional numerical analyses were carried out to investigate the penetration performance of a dynamically installed Hall anchor. The advanced coupled Eulerian-Lagrangian (CEL) technique was adopted to accurately simulate the large soil deformation during the vertical penetration of a Hall anchor. In total, 52 numerical analyses were conducted to investigate the relationship between anchor penetration depth and the initial kinematic energy. Moreover, a sensitivity analysis was performed to investigate the effects of soil shear strength and soil type on the penetration mechanism of a drop anchor under self-weight. There is a monotonic increase in the penetration depth with an increasing anchor weight when the topsoil of the riverbed is not subjected to erosion. On the other hand, all the computed depths significantly increase when soil erosion is taken into consideration. This is mainly due to an enhanced initial kinematic energy from an increased dropping depth. Both depths increase exponentially with the initial kinematic energy. An enhanced shear strength can potentially increase the side resistance and end-bearing pressure around a drop anchor, thus significantly reducing the downward penetration of a hall anchor. Design charts are developed to directly estimate penetration depth and associated plastic zone due to dynamically installed anchor at arbitrary soil shear strength and anchor kinematic energy.

• Journal of Welding and Joining
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• v.34 no.5
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• pp.6-12
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• 2016

This study was performed bead welding of pure titanium by using fiber laser. Since titanium is very sensitive to oxidation and nitriding during welding, it is important to compose the shielding equipment compared with different material. Thus side and coaxial shield nozzle, rail and chamber type shielding equipment are widely used to protect effectively the weld during welding. Experiments were performed by changing nozzle angle and distance using side and coaxial shield nozzle. The bead colors of gold, brown, blue, purple and yellowish white were obtained by changing variables of shield nozzle, and then its weldability was investigated. As experiment result, sound and not brominated beads were formed when side nozzle angle and distance were respectively $45^{\circ}$ and 10 mm.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.05a
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• pp.357-360
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• 2008

In roll forming process, a sheet metal is continuously progressively formed into a product with required cross-section and longitudinal shape, such as a circular tube with required diameter, wall-thickness and straightness, by passing through a series of forming rolls in arranged in tandem. In this process, each pair of forming rolls installed in a forming machine play a particular role in making up the required cross-section and longitudinal shape of the product. In recent years, that process is often applied to the bumper rail in the automotive industries. In this study, a optimal SILL SIDE manufacturing technology, model deign and proper roll-pass sequences can be suggested by forming number of roll-pass and bending angle. And also effects of the process parameters on the final shape formed by roll forming defects were evaluated.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.4
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• pp.307-317
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• 2012

The LRT(light rail transit) system, which has medium transport capacity between subway and bus is an advanced transportation system. It has many benefits like chap construction and operational cost down through driverless and flexible route planning. The rubber tired AGT(K-AGT) is a kind of LRT, which has rubber wheels and side guides. The side guides has many advantages, but brings vibration and noise problems from the friction between the guide rail and the wheels. This is the major source for the of passengers' discomfort. The purpose of this paper is to analyze dynamic characteries and running stability of the rubber tired AGT localization bogie if the AGT's speed is increased from 70 km/h to 80 km/h. The current design parameters of bogie suspension, as it is designed, was examined to satisfy the comfort index of the railway vehicle in performance test.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.1
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• pp.65-70
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• 2002

An analysis method for calculating motion accuarcy of double sides hydrostatic table is proposed in this paper. In this method, profiles of each rails are assumed as periodic function, therefore it is represented as the sum of spacial frequencies. Bearing clearance at any position rail is depended on the variation of linear, angular motion error of table and the form errors of both sides of a rail. Finite element method is applied to calculate pressure distributions in bearing clearance. In order to simplify the analyzing process, double sides table model is converted into equivalent single side table model. Results calculated by the proposed modeling method agree well with the results directly caculated by double sides modeling method, and also agree well with experimental results. From the theoretical and experimental analysis, it is verified that the proposed analysis method is very effective to analyze the motion accuracy of double sides hydrostatic table.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.2
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• pp.143-147
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• 2006

The rail clamp is the device to prevent that a crane slips along rails due to the wind blast as well as locate the crane in the set position for loading and unloading containers. The wedge type rail clamp should be designed to consider the structural stability and the durability because it compresses both rail side with large clamping force by the wedge working as the wind speed increases. In this research, the kriging interpolation method using sequential sampling is utilized to find the optimum shape of the jaw in the rail clamp. The suggested method predicts more accurate response value than the response surface method. The optimum results obtained by the proposal method are compared with those by the commercial software.