• 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 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 the Convergence on Culture Technology
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• v.9 no.3
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• pp.619-624
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• 2023

In this paper, TE(transverse electric) scattering problems by a resistive strip grating between a double dielectric layer are analyzed by using the FGMM(fourier galerkin moment 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 resistive boundary condition is applied to analysis of the resistive strip. In order to deal with the problem of the double dielectric layer, numerical calculation was performed only when the thickness and relative permittivity of the dielectric layers had the same value. Overall, as the resistivity of the uniform resistivity increased, the current density induced in the resistive strip decreased, the reflected power decreased, and the transmitted power relatively increased. The numerical results of the structure proposed in this paper are shown in good agreement compared to the results of PMM, a numerical analysis method of the existing paper.

• The Journal of the Convergence on Culture Technology
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• v.9 no.3
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• pp.641-646
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• 2023

In this paper, TM(transverse magnetic) scattering problems by a resistive strip grating between a double dielectric layer are analyzed by using the FGMM(fourier galerkin moment 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 resistive boundary condition is applied to analysis of the resistive strip. Overall, as the uniform resistivity of the resistive strip increased, the size of the current density induced in the resistance band decreased, the reflected power decreased, and the transmitted power increased. In addition, As the thickness of the dielectric layer increased, the reflected power increased and the transmitted power relatively decreased. The numerical results of the structure proposed in this paper are shown in good agreement compared to the results of PMM, a numerical analysis method of the existing paper.

• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.7
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• pp.8-12
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• 1989

In this paper, dielectric waveguide gratings, which can be applied to the nonreciprocal devices such as isolators, are proposed. Those grating structures can be considered as cascade connections of step discontinuities between uniform dielectric waveguides and another uniform dielectric waveguides with a ferrite layer. Therefore, the nonreciprocal scattering characteristics of such gratings can be obtained form the scattering characteristics of step discontinuities and uniform dielectric wave guides. For the periodic grating structures, band-reject characteristics can be located inside or outside the frequency range of interest. Numerical analyses are performed at 35GHz and experimental results at X-band are also presented.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.39 no.10
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• pp.27-37
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• 2002

In this paper, we present various combined field integral equation (CFIE) formulations for the analysis of electromagnetic scattering from arbitrarily shaped three dimensional homogeneous dielectric body in the frequency domain. For the CFIE case, we propose eight separate formulations with different combinations of testing functions that result in sixteen different formulations of CFIE by neglecting one of testing terms. One of the objectives of this paper is to illustrate that not all CFIE are valid methodologies in removing defects, which occur at a frequency corresponding to an internal resonance of the structure. Numerical results involving far scattered fields and radar cross section (RCS) are presented for a dielectric sphere to illustrate which formulation works and which do not.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.40 no.8
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• pp.340-348
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• 2003

In this paper, we propose a novel formulation to solve a time-domain combined field integral equation (CFIE) for analyzing the transient electromagnetic scattering response from closed conducting bodies. Instead of the conventional marching-on in time (MOT) technique, tile solution method in this paper is based on the moment method that involves separate spatial and temporal testing procedures. Triangular patch vector functions are used for spatial expansion and testing functions for three-dimensional arbitrarily shaped closed structures. The time-domain unknown coefficient is approximated as a basis function set that is derived from tile Laguerre functions with exponentially decaying functions. These basis functions are also used as the temporal testing. Numerical results computed by the proposed method arc stable without late-time oscillations and agree well with the frequency-domain CFIE solutions.

• Radiation Oncology Journal
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• v.7 no.1
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• pp.85-92
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• 1989

Dosimerty based on electron spin resonance (ESR) analysis of radiation induced free radicals in amino acids is relevant to biological dosimetry applications. Alanine detectors are without walls and are tissue equivalent. Therefore, alanine ESR dosimetry looks promising for use in the therapy level. The dose range of the alanine/ESR dosimetry system can be extended down to 1 Gy. In water phantom the absorbed dose of electrons generated by a medical linear accelerator of different initial energies $(6\~21MeV)$ and therapeutic dose levels (1~60 Gy) was measured. Furthermore, depth dose measurements carried out with alanine dosimeters were compared with ionization chamber measurements. As the results, the measured absorbed doses for shallow depth of initial electron energies above 15 MeV were higher by$2\~5\%$ than those calculated by nominal energy $C_E$ factors. This seems to be caused by low energy scattered beams generated from the scattering foil and electron cones of beam projecting device in medical linear accelerator.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.11
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• pp.1183-1189
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• 2014

The accuracy of the resistive-sheet technique in calculating the RCS(Radar Cross Section) of a deciduous leaf is examined in this paper for various thicknesses and dielectric constants, and a range of thicknesses for the resistive sheet technique is proposed. At first, a leaf was assumed to be a lossy dielectric disk, and the dielectric disk was again assumed to be a resistive sheet with an appropriate resistivity for a given thickness, a dielectric constant, and a frequency. Then, the RCS of the leaf was computed using the physical optics(PO) method, and was compared with the calculation results of a numerical analysis: i.e., a commercial tool based on the FEM (Finite Element Method) technique. It was shown that the error increases as the thickness increases. The error was 0.1 dB, for example, when the thickness is 1.2 mm and 3.7 dB when the thickness is 3 mm with a dielectric constant of(21.4, 9.7) at 9.6 GHz. It was also found that the error decreases as the dielectric constant increases. This study will be very useful for calculating the scattering characteristics of numerous leaves in a vegetation canopy for estimating its radar backscatter using scattering model.