• 한국해양학회지
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• v.28 no.3
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• pp.177-185
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• 1993

The theory for long wave scattering (Proudman, 1914: Longuet-Higgins, 1970) is applied to a tidal-frequency Kelvin wave propagating around a small cylindrical island in a shelf sea of uniform depth. The theory includes the effects of bottom friction on wave propagation. The theoretical analysis of the Kelvin wave around the island. this amplitude change results in a uniform amplitude of the total wave along the circumference of the island in an inviscid fluid, and the dynamic cause of this is explained in terms of Coriolis effects. Bottom friction attenuates the amplitude of the total wave from the frontal side of the island to the leeward side, but the amplitude variation along the coast becomes symmetric to the line connecting both idea. The phase of the scattered wave contributes to more rapid travel of the total wave in the front and leeward side than farther offshore. The effects of bottom friction on the wave phase around the island are negligible.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 1998.04a
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• pp.106-112
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• 1998

A numerical experiment is conduced to study the wave screening effectiveness of wave barriers which are constructed to reduce the ground-transmitted vibration. The finite element method is used for the simulation of the wave propagation behavior. In order to reduce the computational burden the absorbing boundary's one employed. Validity of the numerical model is checked by comparing the results with the published data. The screening effectiveness of the in filled trenches is then studied for different trench dimensions and material properties.

• Bulletin of the Korean Mathematical Society
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• v.33 no.2
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• pp.177-186
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• 1996

Colton and Wendland [1] have considered acoustic wave propagations in a spherically symmetric medium. They used constructive method for in a spherically symmetric medium. They used constructive method for solving the exterior Neumann problem. Jones [2] has derived an integral equation for the exterior acoustic problem. Jones has also discussed analytical and numerical solution of the acoustic problem.

• Bulletin of the Korean Chemical Society
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• v.32 no.6
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• pp.1849-1850
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• 2011

• Proceedings of the Optical Society of Korea Conference
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• 1999.08a
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• pp.170-171
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• 1999

• Proceedings of the Optical Society of Korea Conference
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• 1999.08a
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• pp.210-211
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• 1999

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.2 s.93
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• pp.174-181
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• 2005

In this paper, a hybrid model is developed, which can estimate scattering properties of a target embedded inside a forest. The model uses a physic-based channel model for a forest to accurately calculate the penetrated field through a forest canopy. The channel model is based on a fractal tree geometry and single scattering theory. To calculate scattering from the target physical optics(PO) is used to compute an induced current on the target surface since the dimension of the target is generally very large and the shape is very complicated. Then using reciprocity theorem, scattering generated by the PO current is calculated without an extra computational complexity.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.5 no.4
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• pp.336-339
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• 2004

In this paper the two-dimensional scattering rates were calculated in pseudomorphic Al/sub x//Ga/sub 1-x//As/Ga/sub y/In/sub l -y//As/GaAs heterostructure systems. The electronic states of the square quantum well were determined by the numerical self-consistent solution of Poisson's and Schrodinger's equations. The numerically obtained wave functions and energy levels were used to obtain the major two-dimensional scattering rates in this structure. Polar optical- and acoustic-phonon scattering, piezoelectric, ionized impurity and alloy scattering were considered for the first two sub-bands. The results were compared to the three-dimensional scattering rates also calculated in the same region.

• Journal of the Korean Society for Nondestructive Testing
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• v.18 no.4
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• pp.304-312
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• 1998

In order to assure the reliability and integrity of structures such as bridges, Power and petrochemical plants, nondestructive evaluation techniques are recently playing more important roles. Among the various kinds of nondestructive evaluation techniques, ultrasonic technique is one of the most widely used methods for nondestructive inspection of internal defects in structures. For the reliable quantitative evaluation of internal defects from the experimental ultrasonic signals, a numerical analysis of ultrasonic scattering field due to a defect distribution is absolutely required. In this paper, the SH-wave scattering by multi-cavity defects using elastodynamic boundary element method is studied. The effects of shape of defects on transmitted and reflected fields are considered. The interaction of multi-cavity defects in 50-wave scattering is also investigated. Numerical calculation by the boundary element method has been carried out to predict near field solution of scattered fields of ultrasonic SH-wave. The presented results would be useful to improve the sensitivity of flaw defection for inverse analysis and pursue quantitative nondestructive evaluation for inverse problem.

• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.347-348
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• 2004

Nonlinear scattering of difference frequency acoustic wave in a water-saturated sandy sediment was investigated. Difference frequency acoustic wave was observed to be scattered due to the nonlinearity of water-saturated sandy sediment when the collinear acoustic waves with two different fundamental frequencies are incident on the sediment. The pressure level of the difference frequency acoustic wave was 6 dB higher than the background noise level. It seems very useful to evaluate the nonlinear parameter of water-saturated sandy sediment without disturbing the sediment. Such nonlinear acoustic response of water-saturated sandy sediment can be used as background acoustic data for estimating the gas void fraction in marine gassy sandy sedimen.