• Journal of Korean Society of Coastal and Ocean Engineers
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• v.22 no.3
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• pp.163-170
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• 2010

Both scatterer method and transfer matrix method are compared to analyze their characteristics, which are wave propagation models due to topographic change based on plane wave approximation. Results from the scatterer method are closer to the results obtained by the more accurate existing models and it is appraised that the scatterer method gives the clearer explanation about physical process involved in the wave transformation. Since both methods have analytical solutions, in the computational point of view they are very fast and easy to be implemented. Both methods give a good prediction for wave scattering by relatively simple bedform.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.20 no.5
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• pp.439-451
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• 2008

Based on reflected and transmitted waves by a single step bottom, a new model of scatterer method is constructed which can be used to calculate wave transformation over a multi-step topography. The approximate results are tested by comparison with the more accurate results obtained from EFEM presented by Kirby and Dalrymple(1983). In the case of plane-wave approximation, solutions of the scatterer method and the EFEM are the same. Results obtained by the scatterer method with non-propagating modes are much better, in terms of phase for the calculated reflection and transmission coefficients, than those by plane-wave approximation. As the effect of non-propagating modes decreases, solutions of the scatterer method become closer to those of the EFEM.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1998.04a
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• pp.622-628
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• 1998

The SONAR(SOund NAvigation and Ranging) is the system that detects objects and finds their locations in water by using the echo ranging technique. In this paper, the scattering phenomena for a rigid spherical scatterer will be analyzed using closed form solution, Boundary Element Method and Finite Element Method. Scattering analysis for an elastic spherical scatterer will be analyzed, later. In oder to analyzing the sound wave scattering phenomena for an elastic scatterer in water coupled problem between acoustic and vibration must be considered.

• Journal of the Korea Society for Simulation
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• v.30 no.4
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• pp.21-29
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• 2021

Inverse synthetic aperture radar (ISAR) image is a powerful tool to show the major scattering regions (scatterer points) on the target. It is normally used to identify and classify targets. Finding information for the scatter points of ISAR image plays an important role in modeling the features of targets. In this paper, we propose a modeling method to extract some information about the scatterer points by minimizing approximating error. Here, the extracted information include not only the location of scatterer points but also some statistical data about the error of the their location. These extracted data can be used to implement the randomness of the location of the scatterer points. Furthermore, we reconstruct an image from the extracted data for scatterer points obtained by our proposed method. And we show that the reconstructed ISAR image is well approximated to the original ISAR image in order to justify our proposed modeling method.

• Proceedings of the KIEE Conference
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• 1987.07a
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• pp.13-17
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• 1987

Electromagnetic wave scattering from the two-dimensional scatterer was calculated by the Boundary Element Method (BEM). For the circular cylindrical scatterer, the BEM solutions agreed very well with the analytic solutions. The rectangular dielectric cylinder was also treated in the case of the lossy scatterer and the lossy medium.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.11 no.5
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• pp.323-331
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• 1986

By solving the current distribution, natual frequencies, and the amplitude of natural modes about the perfect conducting scatterer of revolution are presented. Singularity expansion method is applied to slove the time-domain response based on the simplified E-field integral equation by the application of the extended boundary conditin for the perfect conductin scatterer of revolution.

• Journal of Integrative Natural Science
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• v.1 no.1
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• pp.32-35
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• 2008

We fabricated surface pattern on a light guide panel (LGP) using $CO_2$ laser to improve the luminescence performance of inner-scatterer LGP, which is made of PMMA sample with exploiting Q-switched $2^{nd}$ harmonic Nd:YAG laser engraving system, and the effect of surface pattern in the brightness distribution of LGP was analysed. To prove the feasibility of proposed method in the enhancement of LGP performance, we designed three different surface patterns on the inner-scatterer LGP. The experimental results has proved the potential in the application of surface pattern to increasing the brightness of inner-scatterer LGP.

• Journal of Ship and Ocean Technology
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• v.4 no.2
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• pp.1-12
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• 2000

The present study concentrates on the weak-scatterer hypothesis for the nonlinear wave-body interaction problems. In this method, the free surface boundary conditions are linearized on the incoming wave profile and the exact body motion is applied. The considered problems are the diffraction problem near a circular cylinder and the ship response in oblique waves. The numerical method of solution is a Rankine panel method. The Rankine panel method of this study adopts the higher-order B spline basis function for the approximation of physical variables. A modified Euler scheme is applied for the time stepping, which has neutral stability. The computational result shows some nonlinear behaviors of disturbance waves and wave forces. Moreover, the ship response shows very close results to experimental data.

• The Journal of the Acoustical Society of Korea
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• v.23 no.1E
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• pp.31-39
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• 2004

Backscattered underwater signals from multiple scatterers contain information regarding resolvable spatial distribution of scatterers. This experimental study describes the spectral characteristics of backscattered signal from multiple scatterers, which are regularly or randomly spaced, in terms of their amplitude and phase and a proper signal analysis that will eventually provide scatterer spacing estimation. Air-filled tubes suspended in water, steel balls and plastic tubes buried in the sediment are the multiple scatterers. The cepstrum and the spectral autocorrelation (SAC) methods were used to estimate the scatterer spacing from the backscattered signals. It was found that the SAC method could be improved by employing singular value decomposition (SVD) to extract the effective rank for the spectral components. Unlike the conventional method of estimating the density of scatterers within the insonified volume of water, this type of estimation method would provide better understanding of the spatial distribution of scatterers in the ocean.

• Proceedings of the KIEE Conference
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• 1988.07a
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• pp.335-338
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• 1988

A numerical method is presented for the scattering by the perfectly conducting cylinder with arbitrary cross sections. The relevant integral equation considered by the E-field formulation is solved by method of moments, and thereby the surface current induced as well as the radar cross section of the scatterer are numerically computed to specify the scattering nature of the scatterer. Two separate methods, one with point matching and the other Galerkin's method, are considered to make cross checks to the results obtained. Taking two half pulses suggested to expand the surface current shows savings in computation time and accurate solutions for the corners on the scatterer.