• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.3
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• pp.292-298
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• 2013

A signal processing technique is introduced in this paper in order to estimate the lengths of missile targets. To measure the length of a target, it is necessary to know the information on the target's location and aspect angle. Chirp waveforms and stretch processing are used to estimate the location and angle of a missile as well as HRRP(High Resolution Range Profile). RELAX(relaxation) algorithm, which is one of the spectral estimation techniques, were used to find scattering centers of a missile from HRRP. From the information on the distribution of one-dimensional(1-D) scattering centers on a target, we can discriminate the length of a missile.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.2
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• pp.266-269
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• 2012

This paper introduces a signal processing technique for discrimination of ballistic missile's warhead. An interceptor missile to destroy the enemy's ballistic missile requires an information on the location of missile's warhead. In order to detect and locate the missile's warhead, a seeker radar in the interceptor missile makes use of chirp waveform to generate high resolution range profiles(HRRPs). We applied one of the well known spectral estimation technique called ESPRIT (Estimation of Signal Parameters by Rotational Invariance Technique) to these HRRPs to estimate scattering centers on the target. Using the information on the one-dimensional(1-D) scattering centers, we can find the location of the warhead by estimating the length of the missile, Simulation results show that the proposed signal processing technique is efficient in discriminating the warhead of an ballistic missile.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.4
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• pp.153-158
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• 2016

In this paper, TE(transverse electric) scattering problems by a conductive strip grating between grounded double dielectric layer are analyzed by applying the PMM(point matching method) known as a numerical method of electromagnetic fileld. The boundary conditions are applied to obtain the unknown field coefficients, the scattered electromagnetic fields are expanded in a series of Floquet mode functions, and the conductive boundary condition is applied to analysis of the conductive strip. The numerical results for normalized reflected power are analyzed by according as the width and spacing of conductive strip, the relative permittivity and thickness of the double dielectric layers, and incident angles. The most normalized reflected powers of the sharp variations in minimum values are scattered in direction of the other angles except incident angle. The numerical results for the presented structure of this paper having a grounded double dielectric layer are shown in good agreement compared to those of the existing papers.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.9
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• pp.938-943
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• 2014

The scattered field by a gap/crack on the PEC surface of a large object having low-observable RCS cannot be negligible, but may not be analyzed by the known high-frequency technique. If the electrical width of the crack is very small, the crack can be modeled by an impedance strip, whose scattering formulation can be analytically obtained based on a low-frequency approximation. The scattering solution is formulated for the 2D strip and TE(Transverse Electric) or TM(Transverse Magnetic) wave incidence, from which a 3D ILDC(Incremental Length Diffraction Coefficients) can be extracted. Using the ILDC formulation, the scattering by any arbitrary shaped crack can be estimated. In this paper, an improved ILDC equations are proposed, which combine the known TE and TM solutions. The improved accuracy of the proposed solution is numerically verified.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.2
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• pp.65-70
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• 2015

In this paper, the solutions of TE (transverse electric) scattering problems by a conductive strip grating over grounded two dielectric layers are analyzed by applying the PMM (point matching method) known as a numerical method of electromagnetic fileld. The boundary conditions are applied to obtain the unknown field coefficients, the scattered electromagnetic fields are expanded in a series of Floquet mode functions, and the conductive boundary condition apply to analysis of conducting strip. The most normalized reflected powers of the sharp variations in minimum values are scattered in direction of the other angles except incident angle. The numerical results for normalized reflected power are analyzed by according as the width and spacing of conductive strip, the relative permittivity and thickness of the two dielectric layers, and incident angles. The numerical results of present numericl analysis are shown in good agreement compared to those of the existing papers using FGMM (fourier galerkin moment method).

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.2
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• pp.73-79
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• 2018

In this paper, TM(transverse magnetic) scattering problems by a conductive strip grating between a double dielectric layer are analyzed by applying the PMM(point matching method) known as a numerical method of electromagnetic fileld. The boundary conditions are applied to obtain the unknown field coefficients, the scattered electromagnetic fields are expanded in a series of Floquet mode functions, and the conductive boundary condition is applied to analysis of the conductive strip. The most normalized reflected powers of the sharp variations in minimum values are scattered in direction of the other angles except incident angle. Generally, in the case of numerical analysis except for reflection and transmission power in free space, as the dielectric constants of the double dielectric layer increases, the reflected power increases and the transmitted power decreases relatively, respectively. The numerical results for the presented structure of this paper having a grounded double dielectric layer are shown in good agreement compared to those of the existing papers.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.9 no.6
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• pp.735-745
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• 1998

The method of moments has been widely used in the analysis of TM scattering problems. Recently, significant advances in the development of fast and efficient techniques for solving large problems have been reported. In such methods, iterative matrix solvers are preferred by virtue of their speed and low memory requirements. But for near resonant and strong multiple scattering problems, e.g., involving an aircraft engine inlet, a large number of iterations is required for convergence. In this paper, an efficient approximate inverse based preconditioner is used to reduce this number of iterations. By using the matrix partitioning method, the computational is used to reduce this number of iterations. By using the matrix partitioning method, the computational cost for obtaining the approximate inverse is reduced to O(N). We apply this preconditioner to an O(NlogN) algorithm, the multilevel fast multipole algorithm, for the aircraft engine inlet problem. The numerical results show the efficiency of this preconditioner.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.2
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• pp.87-92
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• 2016

In this paper, the solutions of TE(transverse electric) scattering problems by a conductive strip grating over two dielectric layers are analyzed by applying the PMM(point matching method) known as a numerical method of electromagnetic field. The boundary conditions are applied to obtain the unknown field coefficients, the scattered electromagnetic fields are expanded in a series of Floquet mode functions, and the conductive boundary condition apply to analysis of conducting strip. The most normalized reflected and transmitted powers having a sharp variations are scattered in direction of the other angles except incident angle. The numerical results for the normalized reflected and transmitted powers are analyzed by according as the width and spacing of conductive strip, incident angles, and the relative permittivity and thickness of the two dielectric layers. To confirm the validity of this paper, the numerical results of presented structure are shown in good agreement compared to those of the existing papers.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.2
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• pp.83-88
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• 2017

In this paper, TE(transverse electric) scattering problems by a conductive strip grating between a double dielectric layer are analyzed by applying the PMM(point matching method) known as a numerical method of electromagnetic fileld. The boundary conditions are applied to obtain the unknown field coefficients, the scattered electromagnetic fields are expanded in a series of Floquet mode functions, and the conductive boundary condition is applied to analysis of the conductive strip. The numerical results for the normalized reflected and transmitted power are analyzed by according as the width and spacing of conductive strip, the relative permittivity and thickness of the double dielectric layers, and incident angles. The most normalized reflected powers of the sharp variations in minimum values are scattered in direction of the other angles except incident angle. The numerical results for the presented structure of this paper are shown in good agreement compared to those of the existing papers.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.10
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• pp.1087-1094
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• 2014

An numerical technique of impedance boundary condition to improve an efficiency in the process of moment method with CFIE(Combined Field Integral Equation), which is widely used to analyze the scattering property of dielectric scatterers, and results of its cross-validations are presented in this study. Application of the impedance boundary allows to represent the equivalent surface currents of dielectric scatterer depicted by both kinds of electric/magnetic surface currents(Js, Ms) to the single surface current by Js or Ms only. Accuracy of this technique is validated by the existing CFIE and theoretical values such as Mie-series solution and small perturbation scattering model. The computational difference of less than 1 dB was verified within an imaginary part of dielectric constant more than 12, as well.