• Journal of the Korean Institute of Telematics and Electronics A
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• v.29A no.11
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• pp.19-24
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• 1992

In this paper, a high frequency method is developed which combines the uniform Geometrical Theory of Diffraction(GTD) and the Aperture Integration(AI) to analyze electromagnetic plane wave scattering by a perfectly-conducting, open-ended, semi-infinite parallel plate waveguide with a uniform layer of absorbing material on its inner wall, and with a slanted planar termination inside. In this method, first, the field of an arbitary point inside the paraller plate waveguide is computed by the GTD. Second, the field scattered into exterior region by the waveguide is found using the equivalent current, which can be obtaind from the aperture field of the waveguide and using the AI. Numerical results based on this GTD method are presented and compared with those based on the mode matching method.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.2
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• pp.31-37
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• 1995

A ray-based approach is developed to calculate the scattering from inhomogeneous dielectric objects. This approach is a natural extension of the "shooting and bouncing ray(SBR)" technique developed earlier for calculating the radar cross section of cavity structures and complex targets. In this formulation, a dense grid of rays representing the incident field is shot toward the scatterer. The curved trajectory, amplitude, phase and polarization of the ray fields inside the inhomogeneous object are computed numerically based on the laws of geometrical optics. The contributions of the exting rays to the exterior scattered field are then calculated by using the equivalence principle in conjunction with " a ray-tube integration" scheme. The ray-based approach is applied for the effect of an arcjet plasma plume on satellite reflector performance and backscattering from inhomogeneous objects.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.11
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• pp.1-7
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• 1995

The problem of amplitude-and frequency-modulated waveforms is analyzed when a linearly polarized electromagnetic wave is scattered by a slowly rotating rotor with metal plates. ECM in conjunction with a quasi-stationary method is used to analyze the modulated waveforms. The modulated waveforms depend on the orientation and dimension of the object. its rotation speed, and very strongly on the incident and scattering directions. The modulate waveforms of a rotating non-skewed metal plate and a rotor with two blades are functions of twice the rotating frequency of those. Similar results are discussed for a rotating skewed metal plate, but the modulated waveforms is a function of the rotating frequency. Numerical results based on our ECM are presented and compared with those of Sikta's and PO solution.

• Proceedings of the KIEE Conference
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• 2003.10a
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• pp.78-81
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• 2003

In this paper, we analyze the transient electromagnetic response from three-dimensional dielectric bodies using a time-domain PMCHW (Poggio, Miller, Chang, Harrington, Wu) formulation. The time-domain unknown coefficients of the equivalent currents are approximated by a set of orthonormal basis functions that are derived from the Laguerre polynomials. Numerical results computed by the proposed method are presented.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.4B
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• pp.391-399
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• 2001

In this paper, electromagnetic wave scattering from a bianisotropicaly coated cylinder is formulated by using wave functions for bianisotropic media and boundary-value method. The cross section of the cylinder is made of a conducting core, a lossless dielectric layer which is both electrically magnetically bianisotropic, and a bianisotropic impedance sheet and a different uniaxial bianisotrpic coating. The solutions to arbitrary polarization angles are presented in two-dimensional. This paper presents and exact solution to the problem of scattering by a long composite circular cylinder using the boundary method. The validity of this solution is verified by comparing numerical results with those in literature. The numerical results for various geometrical and electrical parameters on bistatic scattering cross-section are presented.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.52 no.9
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• pp.412-417
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• 2003

In this Paper, we propose a time-domain magnetic field integral equation (TD-MFIE) formulation for analyzing the transient electromagnetic response from three-dimensional (3-D) dielectric bodies. The solution method in this paper is based on the Galerkin's method that involves separate spatial and temporal testing procedures. Triangular patch basis functions are used for spatial expansion and testing functions for arbitrarily shaped 3-D dielectric structures. The time-domain unknown coefficients of the equivalent electric and magnetic currents are approximated tv a set of orthonormal basis function that is derived from the Laguerre polynomials. These basis functions are also used for the temporal testing. Numerical results computed by the proposed method are presented and compared.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.5
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• pp.85-93
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• 1996

The far-zone scattered field patterns of a hyperbolic reflector antenna are analyzed by using uniform geometrical theory of diffraction(UTD). The main objective of this paper is to obtain the higher order diffraction contributions which provide the continuity over the shadow boundaries of the first order solution. to obtain the scattered magnetic field characteristics, the scattered field components of the secodn-order diffraction, diffraction-reflection, diffraction-reflection-diffraction terms are added to the result of the previous research. The results of the present research are compared to those of the first order solution and the method of moments. One can observe the improvemtn of the current approach over the first order solution. also, the results of the present method agree very well with those of the moment methods especially in the transition regions near the first order diffraction shadow boundaries.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.3
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• pp.38-44
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• 1995

The scattered electric field from a multilayered circular dielectric cylinder is caculated. Approximate boundary condition used in on-surface radiation boundary condition(OSRC) method has been applied to all the boundary surface of N-layered dielectric cylinder. It was assumed that scattered electric field at inner boundary surface in one region transmitted to the adjacent region at outer boundary surface. In the whole region, the unknown coefficients of electric field are acquired by the given incident electric field with ease. Electric field distribution at each boundary surface and the scattered electric field in free space are taken with the calculated unknown coefficients. the results obtainted were compared with those results that were used by regular surface boundary condition.

• Proceedings of the IEEK Conference
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• 2002.06a
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• pp.191-194
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• 2002

We analyzed radiation characteristics of dipole antenna in a lossy 9round with conducting object located above ground. Electric field integral equation is used to solve the problem. In this integral equation, GPOF(Generalized Pencil of Function) method is applied to derive the closed form of the electric field due to a current source. Surface current on a conductor is expanded with a well-known vector triangle basis function. The singular integration of a triangle patch is transformed to the non-singular integration by Duffy's method. This transformed non-singular integration is easily calculated by using one-dimensional Gaussian quadrature rule, instead of usual closed form evaluation.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.6
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• pp.566-576
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• 2016

Inverse synthetic aperture radar(ISAR) image generated from bistatic radar(Bi-ISAR) represents two-dimensional scattering distribution of a target, and the Bi-ISAR can be used for bistatic target identification. However, Bi-ISAR has large variability in scattering mechanisms depending on bistatic configurations and do not represent exact range-Doppler information of a target due to inherent distortion. Thus, an efficient training DB construction is the most important factor in target identification using Bi-ISARs. Recently, a database construction method based on realistic flight scenarios of a target, which provides a reliable identification performance for the monostatic target identification, was applied to target identification using high resolution range profiles(HRRPs) generated from bistatic radar(Bi-HRRPs), to construct efficient training DB under bistatic configurations. Consequently, high identification performance was achieved using only small amount of training Bi-HRRPs, when the target is a considerable distance away from the bistatic radar. Thus, flight scenarios based training DB construction is applied to target identification using Bi-ISARs. Then, the capability and efficiency of the method is analyzed.