• Journal of the Korea Institute of Military Science and Technology
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• v.10 no.3
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• pp.16-24
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• 2007

The high-frequency analysis method of back-scattering cross section spectrum of rotating targets is established. The time history of the back-scattering cross section is calculated using a quasi-stationary approach, based on a physical optics and a physical theory of diffraction, combining an adaptive triangular beam method to consider the shadow effect. And the spectra of back-scattering cross section by the Doppler effect are analyzed applying a simple fast Fourier transform method to its time history. The numerical calculation for rotating targets, such as rotating metal plates and underwater propeller, are carried out. The time history appears to be periodic with respect to the number of wings. The backscattering cross section spectrum level and its frequency shift are dependent on the rotating speed, direction, and the shape of the targets.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.3
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• pp.478-484
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• 2003

The electromagnetic wave scattering problems from inhomogeneous material bodies are considered. The formulation is made in terms of mixed potentials for the moment methods (MoM). The surfaces of a three-dimensional inhomogeneous scatterer of arbitrary shape are divide into triangular patches for descretization. Application of the boundary conditions leads to the coupled surface integral equations to be satisfied for the unknown surface equivalent electric and magnetic currents. The radar cross-section (RCS) for some structures is computed and the results are compared with the reported data.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.20 no.1
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• pp.11-16
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• 1984

The backscattering cross sections of live fish and the probability density function of fish echoes were measured at side aspect. The measurements were made at 40 and 170 in KHz. The specimen fishes on the experiments were two catfish-total length of 16.8cm(L/λ is about 4.5, where the L is length, the λ is the sound wavelength) and 23cm(L/λ, ~6.1), a carp(Cyprinus carpio) of 17.5cm(L/λ, ~4.7), a Telapia(Tilapia mossambica)of 19.5cm(L/λ, ~5.2) and several fishes. Those lengths ranged from 10.7 to 24.0cm. The results of the measured maximum backscattering cross sections were 5.62$\times$10 super(-5) to 7.23$\times$10 super(-4) m super(2). Huang and clay reported that, when the fish was moving gently, the probaiblity density function of the fish echces was approximately the same with the Rayleigh probability density function. Thereafter Ehrenberg et al. also reported that the Rayleigh probability density function on fish was performed at the critical acoustic length ratio or more in theoretical base. Recently Dahl and Mathisen tested the Rayleigh probability density function on fish when the fish-length-to-wavelength ratios were greater than 100. In this paper the experimental result was also not accorded with the Rayleigh probability density function when the fish-length-to-wavelength rations were lower than the critical ratio.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.9
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• pp.979-986
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• 2010

This paper presents an algorithm for retrieving precise radar cross sections(RCS) of various trihedral corner reflectors (TCR) which are external calibrators of synthetic aperture radar(SAR) systems. The theoretical RCSs of the TCRs are computed based on the physical optics(PO), geometrical optics(GO), and physical theory of diffraction(PTD) techniques; that is, the RCS computation includes the single reflections(PO), double reflections(GO-PO), triple reflections(GO-GO-PO), and edge diffractions(PTD) from the TCR. At first, we acquire an SAR image of the area that five TCRs installed in, and then extract the RCS of the TCRs. The RCSs of the TCRs are extracted accurately from the SAR image by adding up the power spill, which is generated due to the radar IRF(Impulse Response Function), using a square window. We compare the extracted RCSs with the theoretical RCSs and analyze the difference between the theoretical and experimental RCSs of the TCR for various window sizes and various backscattering coefficient levels of the adjacent area. Finally, we propose the minimum size of the integration area and the maximum level of the backscattering coefficients for the adjacent area.