• Journal of Advanced Navigation Technology
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• v.18 no.1
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• pp.78-83
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• 2014

In this paper, the solutions of TM (transverse magnetic) scattering problems by perfectly conducting strip grating on two dielectric layers are analyzed by applying the FGMM (Fourier Galerkin moment method) as a numerical method. For the TM scattering problem, the induced surface current density is expected to the very high value at both edges of the strip, then the induced surface current density on the strip is expanded in a series of the multiplication of the functions of appropriate edge boundary condition and the Chebyshev polynomials of the first kind. The numerical results are obtained for the magnitude of induced current density, the normalized reflected power and transmitted power. The numerical results using proposed functions were improved the convergence faster than existing exponential functions, and the numerical results shown the good agreement compared to those of the existing papers.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.6 no.1
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• pp.10-16
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• 1995

The E-polarized scattering problems by a perfect conductor strip grating are analyzed by the method of moments. For an E-polarization the induced surface current density is expected to blow up at the strip both edges. Then the induced surface current density on the strip is expanded in a series of multiplication of Ultraspherical ploynomials with zeroth order and functions with appropriate edge boundary condition. The numerical results for current density and reflection cofficient are compared with other functions, it is shown that numerical results better improves the convergence of the moment method soulutions with general incident angles than the existing several other functions. The sharp variation points in the magnitude of geometric-optical reflection coefficient can be moved by varying the incident angle, strip width, and strip spacing.

• Journal of Advanced Navigation Technology
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• v.15 no.3
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• pp.349-354
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• 2011

In this paper, H-polarized scattering problems by a resistive strip grating with zero resistivity at strip-edges over a grounded dielectric plane according to the strip width and grating period, the relative permittivity and thickness of a dielectric layer, and incident angles of a transverse electric (TE) plane wave are analyzed by applying the Fourier-Galerkin Moment Method (FGMM). The tapered resistivity of resistive strips has zero resistivity at strip edges, then the induced surface current density on the resistive strip is expanded in a series of Chebyshev polynomials of the second kind as a orthogonal ploynomials. The sharp variations of the reflected power are due to resonance effects were previously called wood's anomallies, the numerical results for the reflected power are compared with those of uniform resistivity in the existing papers.

• Journal of Advanced Navigation Technology
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• v.15 no.4
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• pp.543-548
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• 2011

In this paper, H-polarized electromagnetic scattering problems by a resistive strip grating over a grounded dielectric plane according to the strip width and grating period, the relative permittivity and thickness of a dielectric layer, and incident angles of a TE (transverse electric) plane wave are analyzed by applying the FGMM (Fourier-Galerkin Moment Method). The tapered resistivity of resistive strips in this paper varies from finite resistivity at one edge to zero resistivity at the other edge, then the induced surface current density on the resistive strip is expanded in a series of Jacobi polynomials of the order ${\alpha}=1$, ${\beta}=0$ as a kind of orthogonal polynomials. The numerical results of the normalized reflected power show in good agreement with those of existing papers.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.16 no.2
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• pp.211-221
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• 2018

Nodal transport methods are proposed for solving the simplified even-parity neutron transport (SEP) equation. These new methods are attributed to the success of existing nodal diffusion methods such as the Polynomial Expansion Nodal and the Analytic Function Expansion Nodal Methods, which are known to be very effective for solving the neutron diffusion equation. Numerical results show that the simplified even-parity transport equation is a valid approximation to the transport equation and that the two nodal methods developed in this study also work for the SEP transport equation, without conflict. Since accuracy of methods is easily increased by adding node unknowns, the proposed methods will be effective for coarse mesh calculation and this will also lead to computation efficiency.

• Journal of the Korean Institute of Telematics and Electronics
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• v.17 no.3
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• pp.45-51
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• 1980

In this paper, a method for constructing Galois switching functions is presented. Single variable Galois switching function is constructed at fi tost by developing Lagrange's Interpolating formula into polynomial forms and then the constructing theory for two variables is driveloped. With these developed theory, multitle-variable Galois switching functions are constructed. Some examples for illustrating the theory are adopted from the existing papers and the results quite agree with the ones in the other papers.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.1
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• pp.39-46
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• 1993

In this paper, an offset paraboloidal reflector antenna satisfied efficiency of over 60% and sidelobe envelope line of 29-25$log\theta$ was designed and manufactured for Ku-band VSAT(Very Small Aperture Terminal) antenna. The radiation patterns of experimental antenna were computed by applying the series expansion method using the Zernike polynomials. The measured patterns are in good agreement with the computed results. The Gain, efficiency, and sidelobe envelop line fairly well satisfy the design specifications except first sidelobe level.

• Proceedings of the Korean Nuclear Society Conference
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• 1997.10a
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• pp.44-49
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• 1997

액체금속로용 2차원적 연소 해석 코드 REBUS-2[1]에 횡방향 적분법 및 다항식 전개법에 기초한 3차원적 육방형 노달 방법을 결합하여, 3차원적 연소 해석 코드 REBUS-K를 개발하였다. REBUS-K는 3차원적 중성자속 분포 계산 및 미시적 연소 계산을 통해 노내 연소 해석을 수행하며, 또한 핵연료 방출/재배치 및 재장전, 재처리, 성형가공 등의 노외 주기 계산을 수행한다. 비평형주기 및 평형주기 해석을 수행하며, 평형주기 해석 시에는 지정된 제한 연소도 및 증배계수를 만족시키는 주기 길이와 장전 농축도를 탐색한다. 개발된 코드의 검증 계산을 450 MWt 액체금속로의 비평형주기 및 평형주기 문제에 대하여 수행하였으며, 계산 결과를 Argonne 연구소의 3차원적 연소 해석 코드 REBUS-3[2]의 결과와 비교하였다. 그 결과 원자로 증배계수, 출력 분포, 증식율, 연소도, 장전 핵연료의 농축도, 주기 길이 등의 연소 특성이 수렴 조건 이내에서 일치하였다.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.20 no.4
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• pp.493-499
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• 2007

The Taylor expansion expresses a differentiable function and its coefficients provide good approximations for the given function and its derivatives. In this study, m-th order Taylor Polynomial is constructed and the coefficients are computed by the Moving Least Squares method. The coefficients are applied to the governing partial differential equation for solid problems including crack problems. The discrete system of difference equations are set up based on the concept of point collocation. The developed method effectively overcomes the shortcomings of the finite difference method which is dependent of the grid structure and has no approximation function, and the Galerkin-based meshfree method which involves time-consuming integration of weak form and differentiation of the shape function and cumbersome treatment of essential boundary.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.8 no.2
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• pp.161-172
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• 1997

In this paper, electromagnetic scattering by a perfectly conducting strip grating on dielectric multilayers is analyzed for the normalized reflected and transmitted power by applying the Fourier-Galeakin moment method. The induced current density is expanded in a series of multiplication of chebyshev polynomials of the first kind and functions with appropriate edge boundary condition, the continuous condition of electromagnetic field is applied in the boundary planes. The confirm the validity of the proposed method, the nor- malized reflected and transmitted power obtained by varying the relative permittivity and thickness of each dielectric layers are evaluated and compared with those of the existing numerical method and a paper, and then the numerical results in this paper are in good agreement with those of the existing numerical method and the paper. The sharp variation position in the geometrically normalized reflected and transmitted power can be moved by the incident angle, grating period, and the relative permittivity and thickness of the dielectric multilayers, these sharp variation points which are called the Wood's anomaly of the Geome- trically normalized reflected power are observed as a main factor when the reflected powers of the higher order mode are transitted between propagating and evanescent modes, and the local minimum positions are slightly moved to the left hand direction in which grating period is getting small according to the increase of the relative permittivity of dielectric layers.