• Title/Summary/Keyword: 경계치문제

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The Stress Distribution in a Long Circular Cylinder under a Discontinuous Boundary Conditions on the Curved Surface (곡면상에 불연속경계조건을 간는 원주의 응력분포)

  • Lee, Doo-Sung
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.2 no.2
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    • pp.38-41
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    • 1978
  • 이 논문에서는 표면의 일부에 기지의 압력을 밥는 긴 원주내의 응력분포를 구하는 문제를 고찰하였다. 문제를 혼합경계치조건에서 발생되는 쌍적분방정식의 해를 구하는 문제로 간단히 한후에 제 2종 Fredholm 적분방정식을 해결하는 문제로 하였다. 이 적분방정식의 수직해를 전자계산기에 의하여 구한 다음 도시하였다.

A Numerical Analysis on the solution of Poisson Equation by Direct Method (직접법을 이용한 Poisson 방정식 수치해법에 관하여)

  • Y.S. Shin;K.P. Rhee
    • Journal of the Society of Naval Architects of Korea
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    • v.32 no.3
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    • pp.62-71
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    • 1995
  • In the numerical analysis of incompressible unsteady Navier-stokes equation, large time is required for solving the pressure Poisson equation of the elliptic type at each time step. In this paper, a numerical analysis by the direct method is carried out to solve the pressure Poisson equation and the computing time is analyzed as mesh size increases. The pressure Poisson equation can be transformed to the boundary value problem by the Green theorem. The computing time for the convolution type of the domain integral can be reduced by using F.F.T. and the computing time in the direct method depends entirely on obtaining the solution of the boundary value problem. The numerical analysis on the known solutions is carried out and compared for the verification of the direct method. And the numerical analysis on the body boundary and domain decomposition problem are carried out with the computing time less than O($n^{3}$) in the (n.n) mesh.

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Modeling of Elastodynamic Problems in Finite Solid Media (유한 고체내 탄성동역학 문제의 모델링)

  • Cho, Youn-Ho
    • Journal of the Korean Society for Nondestructive Testing
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    • v.20 no.2
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    • pp.138-149
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    • 2000
  • Various modeling techniques for ultrasonic wave propagation and scattering problems in finite solid media are presented. Elastodynamic boundary value problems in inhomogeneous multi-layered plate-like structures are set up for modal analysis of guided wave propagation and numerically solved to obtain dispersion curves which show propagation characteristics of guided waves. As a powerful modeling tool to overcome such numerical difficulties in wave scattering problems as the geometrical complexity and mode conversion, the Boundary Element Method(BEM) is introduced and is combined with the normal mode expansion technique to develop the hybrid BEM, an efficient technique for modeling multi mode conversion of guided wave scattering problems. Time dependent wave forms are obtained through the inverse Fourier transformation of the numerical solutions in the frequency domain. 3D BEM program development is underway to model more practical ultrasonic wave signals. Some encouraging numerical results have recently been obtained in comparison with the analytical solutions for wave propagation in a bar subjected to time harmonic longitudinal excitation. It is expected that the presented modeling techniques for elastic wave propagation and scattering can be applied to establish quantitative nondestructive evaluation techniques in various ways.

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원형 실린더에 의한 3차원 비선형 산란 문제의 수치해석

  • 성홍근;최항순
    • Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
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    • 1998.09a
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    • pp.88-93
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    • 1998
  • 수치 파수조기법은 해양구조물에 작용하는 비선형 파랑하중을 해석할 수 있는 가장 유망한 도구로 인식되고 있다. 이러한 수치 파수조기법은 새롭고 다양한 형태의 해양구조물에 대한 정확하고 엄밀한 설계는 물론이고, 실험 조파수조의 여러 가지 문제점을 극복하기 위해서도 매우 필요한 기법이라고 할 수 있다(Kim, 1995). 수치 과수조기법을 위한 경계치 문제 해석법으로는 고차경계요소법을 이용한 해석법이 가장 효율적인 것으로 알려져 있다. (중략)

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Computational Method of Fuel Optimal Control in Regulator System

  • Lee, Bong-Jin
    • Nuclear Engineering and Technology
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    • v.1 no.2
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    • pp.79-85
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    • 1969
  • Determination of a two-point boundary value problem is the key of finding the control function u(f) with the application of the fundamental idea of Minimum principle. The late development shows the discovery of the initial testate vector for the solution of a two-point value problem. As a new technique of determining the optimal control function, Newton's sequential method is examined in this paper.

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Computer Simulation of the Computational Method in Fuel Optimal Control

  • Lee, B.J.
    • Nuclear Engineering and Technology
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    • v.4 no.1
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    • pp.11-22
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    • 1972
  • Determination of a two-point boundary value problem is the key of finding the control function u(t) with the application of the fundamental idea of Minimum principle. The late development shows the discovery of the initial costate vector for the solution of a two-point value problem. As a new technique of determining the optimal control function, Newton's Sequential method is examined about a number of engineering problems and found available.

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A study on the transmission efficiency of electromagnetic wave propagation in cross type tunnels in time domain (시간영역에서 십자형 터널 내의 전파 전파의 전송 효율에 관한연구)

  • ;Kazunori UCHIDA;Kiyotoshi YASUMOTO
    • Journal of the Korean Institute of Telematics and Electronics D
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    • v.34D no.4
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    • pp.1-7
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    • 1997
  • This paper presents an analysis of the wave propagation in cross-type tunnels using the finite volume time domain (FVTD) method. Because the FVTD method is based on the volume intergrations of themaxwell's equations with respected to arbitrary shaped small polyhedron cells and the fields at every center point of the cells ar eassigned in a average fashion, the method can handle arbitrary boundary problems with inhomogeneous media. In this paper, the wave propagation in cross-type tunnels has been analyzed using the fVTD method with the PML (perfectly matched layer) absorbing bundary conditons, and the numerical results are verified with a set of experimental data.

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The Resistance Characteristics of the Microwave Dipole Antenna (마이크로파 다이폴 안테나의 저항특성)

  • 양인용;이상설
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.3 no.4
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    • pp.5-15
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    • 1966
  • The real part of the impedance of dipole antenna is computed rigorously instead of solving a boundary value problem of a partial differential equation. In this paper the resistance of the dipole antennas, whose shape was determined from an ordinary differential equation of first order and the length 2h is in the limits of , were computed and measured. The frequency used was 1500MC and the image screen, 93$\times$93$\textrm{cm}^2$ rectangular aluminium plate, was used for the measurements. The measured resistance was consistent with the theoretical result.

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Prediction of Hydodynamic Impact Loads on Three-Dimensional Bodies (3차원 물체에 작용하는 유체동력학적 충격하중추정)

  • Troesch, Arimin W.;Kang, Chang-Gu
    • Bulletin of the Society of Naval Architects of Korea
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    • v.27 no.3
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    • pp.73-88
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    • 1990
  • The three dimensional aspects of hydrodynamic impact are discussed. Theoretical and experimental results for a sphere and a cusped body are presented. The cusped body is axisymmetric and resembles the bow profile of a ship with flare. The sphere was subjected to both vertical and oblique impact angles while the cusped body experienced only vertical motion. Three dimensional calculations using normal dipole distributions and an equi-potentioal free surface are compared with experimental results. The theoretical boundary value problem was solved using a known interior flow. This procedure reduced computation times significantly. Comparisons between theory and experiment show that, depending upon the body shape theoretical estimates of the maximum impact force may be larger or smaller than the experimental values. But the theoretical estimate can be used for practical purposes.

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On the Study of Nonlinear Wave Diffraction by the Breakwaters (방파제 주위에서의 비선형 회절 현상에 대한 고색)

  • 조일형;김장환
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.5 no.4
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    • pp.350-356
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    • 1993
  • We carry out a numerical calculation to understand the nonlinear wave deformation around breakwaters using the Boussinesq equation, which is weakly nonlinear and weakly dispersive shallow water equation. A numerical method based on a finite element scheme and fourth order Runge-Kutta algorithm is employed to investigate the diffraction of incident waves by the breakwater. As a computational model, two-dimensional wave flume is treated. The breakwaters is perpendicular to the side wall of a channel. From the numerical results, the wave deformations according to the change of the length and the thickness of breakwaters are investigated. We also investigate the effect of the nonlinearity by comparing the results with the linear solutions.

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