• Journal of Magnetics
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• v.16 no.3
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• pp.288-293
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• 2011

Generally, the discontinuous armature permanent magnet linear synchronous motor (PM-LSM) is composed by the stator block (accelerator, re-accelerator, and decelerator) and the free running section. However, the stationary discontinuous armature design involves the velocity variation of the mover during drive when the armature's non-installation part changes over to installation part as a result of the outlet edge of the armature. Therefore, we considered deforming the shape of the outlet edge at the armature and apply skew on the permanent magnet by displacing the two magnet segments of each pole. This paper presents the results of a three-dimensional (3-D) numerical analysis with a finite element method (FEM) of the force exerted by the outlet edge.

• The Journal of the Acoustical Society of Korea
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• v.43 no.1
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• pp.95-102
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• 2024

Due to technological advances, the cruising speed of high-speed trains is increasing, and aerodynamic noise generated from the flow outside the train has been an important consideration in the design stage. To accurately predict the flow-induced noise, high-resolution generation of sound sources in the near field and low-dissipation of sound propagation in the far field are required. This should be accompanied by a numerical grid and time resolution that can properly consider both temporal and spatial scales for each component of the real high-speed train. To overcome these challenges, this research simultaneously calculates the external flow and acoustic fields of five high-speed train cars of real-scale and at operational running speeds using a threedimensional unsteady Large Eddy Simulation technique. To verify the numerical analysis, the measurements of the wall pressure fluctuation and numerical results are compared. The Ffowcs Williams and Hawking equation is used to predict the acoustic power radiated from the high-speed train. This research is expected to contribute to noise reduction based on the analysis of the aerodynamic noise generation mechanism of high-speed trains.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.2B
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• pp.113-121
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• 2012

When a heavy rain brings flooding, a high turbid water is flowing into a reservoir. In this study, the effectiveness of the intake structures for the selective withdrawal from the various levels of a stratified reservoir was evaluated by the field experiments and the numerical modeling of the three-dimensional approaching flows. The temperature, the turbidity, and the velocity fields for the selective withdrawal were measured using both YSI6600EDS and YSI6600ADV, respectively. A threedimensional model, FLOW-3D, was used to predict the performance of the intake tower in Imha reservoir. The comparisons of the vertical velocity field showed a good agreement with the field measurements. The efficiency of the turbid-water elimination of the selective withdrawal method from low levels was higher up to 46% than that of the surface withdrawal. From the analysis of the numerical simulation, the efficiency of turbidity elimination increased by 10% for the selective withdrawal from middle levels, and by 30% from low levels. These results showed that the selective withdrawals from middle and low levels are more effective than the surface-water intake. The similar results were obtained by the one-dimensional model, SELECT, which is much more computationally time-efficient.