• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.05a
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• pp.221-224
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• 2003

In the open die forging process, it is difficult to optimize process parameters such as die shape, initial ingot size, feeding pitch, rotation angle and other process parameters in the operational environments. Therefore in this study, 3D finite element analysis has been performed to obtain optimal process condition for open die forging process. FEM analyses at various feeding pitches and rotation angles provide process conditions to make round bar having precise dimensional accuracy.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.12B no.1
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• pp.7-12
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• 2002

This paper presents a method to estimate an effective length of a 1000-kVA superconducting generator using three-dimensional FE analysis. Flux linkage of stator coil and the induced voltage are calculated with FEM program and Faraday's law. An effective length of the stator coil is estimated using the calculated voltage and geometric configurationn of the machine. In order to verify the estimation method, 30-kVA superconducting generator is built and tested. The test result agrees reasonably well with the estimation.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.4
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• pp.596-602
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• 2008

This paper presents the dynamic characteristic analysis of Permanent Magnet Linear Synchronous Motor(PMLSM) according to variable load. In order to analyze dynamic characteristics, finite element method(FEM) was used for calculation of the parameter and the Matlab simulink was used for dynamic characteristic simulation. The measuring system of the dynamic characteristics was manufactured and the experiment results were compared with the simulation results.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.3
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• pp.34-39
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• 2008

The purpose of this paper is characteristic analysis of multi-disk axial-gap pm motor for turbo compressor. The axial-gap permanent magnet motor has shown a growing interest in high-speed application for its high-efficiency, compact size and low vibration characteristics due to core-less structure. To achieve high-power, the axial-gap PM motor has multi-disk structure of stator and rotor disk. Because of its complicated magnetic flux path, it is not easy to calculate a dynamic characteristics using finite element analysis. In this paper, the simplified 2-D unfolded model to predict EMF characteristic is presented. To verify thesuggested 2-D unfolded model analysis of back-EMF characteristic was calculated and compared 3-D finite element. Finally the proposed method is verified by experimental results and shows good agreement with test results.

• Proceedings of the KIEE Conference
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• 1998.11a
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• pp.103-105
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• 1998

This paper presents the compensated 2-D magnetic fields analysis of superconducting AC generator(SCG) by using efficient 2-D model. 3-D analysis is necessary for the accurate analysis because SCG has a large leakage flux owing to the air cored winding and end ring structure. However, in 3-D FEM, considering the movement of rotor is difficult, so efficient 2-D model which can compensate the leakage flux has been proposed and the movement of rotor is easily considered. The characteristics in transient state of SCG and the prime role of damper also have been evaluated.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.4
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• pp.39-45
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• 2012

In this paper, process conditions are investigated for elimination of the grain coarsening and improved material flow during forging process by both of experiments and FEM analysis. Particular interest has been given to understand role of preform shape on the grain coarsening behavior and magnitude of the hammer forging load. As the results of FEM simulation by using DEFORM-3D, the simulated forging loads were 2,200ton in the case of a machined bar which is machined from 65mm to 60mm diameter, and below 1,900ton in the case of machined preform, respectively. The use of preform has been beneficial for reduction of the forging load and elimination of the grain coarsening. However, in the case of as received bar and the round bar, which was machined to 2.5mm thickness in surface layer, some degree of local grain coarsening behavior has been observed. The optimized preform shape could be properly designed by applying the FEM simulation.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2001.10a
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• pp.233-235
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• 2001

Residual stress in the forged parts affects the resistance to mechanical failure, dimensional uniformity, and the service life of the parts. In order to elucidate the development of residual stress in open-die forging process, elasto-plastic finite element analysis was implemented to radial forging process. Super duplex stainless steel SAF 2507 was selected as workpiece material and a series of mechanical tests followed by numerical compensation to deformation heating was conducted to obtain necessary flow data. The residual stress distributions were calculated using commercial 3-D FEM code and the effects of process design were evaluated from selected results.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1197-1198
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• 2008

There have been few papers using finite element method(FEM) to analyze arc driving force for spiral type vacuum interrupter electrode up to date while there have been many papers dealing with AMF type electrode by means of FEM. AMF analysis is very important in AMF type electrode because it has proportional relation with effective area which means the area of magnetic flux density above critical magnetic flux density to diffuse arc. In the same manner, arc driving force is an important factor to drive arc by Lorentz force. In this paper two models were calculated and compared by using commercial FEM software Maxwell 3D.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.10a
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• pp.501-502
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• 2012

• Structural Engineering and Mechanics
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• v.50 no.1
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• pp.105-119
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• 2014

This study presents a steel container crane movement analysis and assessment based on structural health monitoring (SHM). The accelerometers are used to monitor the dynamic crane behavior and a 3-D finite element model (FEM) was designed to express the static displacement of the crane under the different load cases. The multi-input single-output nonlinear autoregressive neural network with external input (NNARX) model is used to identify the crane dynamic displacements. The FEM analysis and the identification model are used to investigate the safety and the vibration state of the crane in both time and frequency domains. Moreover, the SHM system is used based on the FEM analysis to assess the crane behavior. The analysis results indicate that: (1) the mean relative dynamic displacement can reveal the relative static movement of structures under environmental load; (2) the environmental load conditions clearly affect the crane deformations in different load cases; (3) the crane deformations are shown within the safe limits under different loads.