• Proceedings of the KSR Conference
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• 2011.10a
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• pp.2814-2820
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• 2011

Railway bridge, contact of vehicle needs to design considering the running safety about the running train load of the railway bridge, ride comfort and dynamic safety. Also, upper structure of the railway bridge has to satisfy design standard about moving load(train). So, the railway bridge has to satisfy the requirement for vertical acceleration of the bridge deck, vertical displacement of the bridge and face distortion, which is suggested railway design standard in Korea(2011.5.). In this study, it was investigated and evaluated to the running safety about the running train load of the railway bridge, ride comfort and dynamic safety with railway design standard for steel composite(Steel Box Girder) railway bridge considering KTX, freight train and standard train load.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.1
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• pp.71-81
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• 1994

A method is presented for the analysis of curved segmentally erected prestressed concrete box girder bridges including time-dependent effects due to load history, temperature history, creep, shrinkage, aging of concrete and relaxation of prestressing steel. The segments can be either precast or cast-in-place. Thin-walled beam theory and finite element method are combined to develop a curved nonprismatic thin-walled box beam element. The element consists of three nodes and each node has eight displacement degrees of freedom, including transverse distortion and longitudinal warping of the cross section.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.3
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• pp.365-370
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• 2004

Simultaneous measurement with PLIF(Planar Laser-Induced Fluorescence) and Stereo-PIV(Stereo Particle Image Velocimetry) was performed to investigate the structural characteristics of flow field in Rushton Turbine Mixer. Instantaneous 3D velocity fields are measured by two 2K${\times}$2K CCD cameras focused on an object plane with the angular displacement methods while the concentration fields are obtained through the measurement of the fluorescence intensity of Rhodamine B tracer excited by the second pulse of Nd:Yag laser light. Image distortion due to the camera view-angle is compensated by a mapping function. Finally, the spatial structures of turbulent flow around Rushton turbine were identified by the calculation of synchronized data of the velocity field and concentration field.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.12
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• pp.1926-1932
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• 2001

In this second part of the paper, the automatic mesh generation and remeshing algorithm using bubble packing method is applied to the nonlinear problem. The remeshing/refinement procedure is necessary in the large deformation process especially because the mesh distortion deteriorates the convergence and accuracy. To perform the nonliear analysis, the transfer of state variables such as displacement and strain is added to the algorithm of Part 1. The equilibrium equation based on total Lagrangian formulation and elasto-viscoplastic model is used. For the numerical experiment, the upsetting process including the contact constraint condition is analyzed by two refinement criteria. And from the result, it is addressed that the present algorithm can generate the refined meshes easily at the largely deformed area with high error.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2006.04a
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• pp.255-258
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• 2006

With the increasing availability of high-resolution satellite imagery, the demand for ortho-rectified products will also be growing. High-resolution of the imagery (up to 1m) the desired accuracy of the ortho-rectification is more sensitive to a number of factors. including satellite position, velocity, internal sensor error (specifically, misalignment. lens distortion, etc.). sensor modeling, relief displacement and matching error, etc. The main objective of this study is to analysis the accuracy of high resolution satellite data using simulation data.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.05a
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• pp.285-290
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• 2002

Screw in injection molding machine is affected by heat flux, pressure on inside barrel, geometry of screw including flight number, pitch and flight angle. Volumetric efficiency increases as the flight number increases, but it didn't show steady tendency according to helix angle of flight. Heat flux from heating pad and injection pressure play a very important role on the thermal behavior characteristics. The increased number of multi-flight is merits and demerits for a screw efficiency. So, we have to optimize flight number of the screw considering temperature, displacement, distortion and stress of the screw.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.50 no.11
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• pp.506-513
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• 2001

The islanding detection for distributed resources (DR) becomes an important and emerging issue in power system protection since the distributed generator installations are rapidly increasing and most of the installed systems are interconnected with distribution network. In order to avoid the negative impacts from islanding operations of DR on protection, operation and management of distribution system, it is necessary to effectively detect the islanding operations of DR and rapidly disconnect it from distribution network. Generally, it is difficult to detect islanding operation by monitoring only one system parameter This paper presents a new logic based islanding detection method for distributed resources(DR) which are interconnected with distribution network. The proposed method detects the islanding operation by monitoring four system parameter: voltage variation, phase displacement, frequency variation, and the variation of total harmonic distortion(THD) of current; therefore, it effectively detects island operation of DR unit operating in parallel with the distribution network. We also verified the efficiency of the proposed algorithm using the radial distribution network of IEEE 34 bus model.

• Journal of Power System Engineering
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• v.16 no.6
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• pp.86-91
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• 2012

A multi purpose environmental monitoring system has been developed as a commercially available standard using the techniques which are FBG(Fiber Bragg Grating), Hetero-core spliced fiber optic sensor and etc, for the purposes of monitoring large scaled structures and preserving natural environments. The monitoring system has been tested and evaluated in a possible outdoor condition in view of the full scaled operation at actual sites to be monitored. Additionally, the developed systems in the previous works conveniently provided us with various options of sensor modules intended for monitoring such physical quantities as displacement, distortion, pressure, binary states, and liquid adhesion. In this paper, we extend the previous results to a water leakage detection problem and develop a sensing system as a result. By the experimental study, it is verified that multi-point leakage detection is possible using single line optical fiber.

• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.1287-1289
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• 2001

This paper presents the logic based islanding protection algorithm for distributed resources(DR) which are interconnected with distribution network. Due to the negative impacts from islanding operations of DR on protection, operation and management of distribution system, it is necessary to effectively detect the islanding operations of DR and disconnect it from distribution network rapidly. Generally, it is difficult to detect islanding operation by monitoring only one system parameter. The proposed islanding protection algorithm utilizes multi-criteria, voltage variation, phase displacement frequency variation, the variation of total harmonic distortion(THD) of current; therefore it effectively detects island operation of DR unit. We also verified the efficiency of the proposed algorithm using the radial distribution network of IEEE 34 bus model.

• Journal of Welding and Joining
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• v.10 no.1
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• pp.20-34
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• 1992

Characteristics of two correcting methods, a new Autogeneous GTAW heating (TIG) method and the conventional GMAW bead-on plate welding(MIG) method, for distorted aluminum fabrication structures were studied. As a result of microscopic study of Autogeneous GTAW heating and GMAW bead-on plate welding areas, porosities in weld metal and surface cracks in local heating zone were found. Through the mechanical tests, it was verified that porosities decrease tensile strength and surface of distortion, angular displacement and transeverse shrinkage were measures and compared. In order to investigate changes of material properties in heating area and cause of defects such thermal stresses were calculated by ADINA. Through the computations of transient thermal stresses and microscopic observation of fracture surface, thermal stress was found to be the cause of crack during Autogeneous GTAW heating.