• 설비공학논문집
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• 제14권3호
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• pp.261-267
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• 2002

The integral boundary layer equation for the air side and the diffusion equation for the frost layer are numerically analyzed in order to predict the behavior of frost layer growth. The thickness and density of the frost layer obtained from the present study agree well with those of previous numerical results and experimental data with a maximum error of 13%. The characteristics of heat and mass transfer within the frost layer and the frost layer growth along the flow direction are investigated by performing numerical analysis. The effects of operating conditions on the frost layer growth are also examined.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 추계학술대회논문집 II
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• pp.1078-1082
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• 2001

An alternative formulation of the Helmholtz integral equation is derived to express the pressure field explicitly in terms of the velocity vector of a radiating surface. This formulation, derived for arbitrary sources, is similar in form to the Rayleigh's formula for planar sources. Because the pressure field is expressed explicitly as a surface integral of the particle velocity, which can be implemented numerically using standard Gaussian quadratures, there is no need to use Boundary element method to solve a set of simultaneous equations for the surface pressure at the discretized nodes. Furthermore the non-uniqueness problem inherent in methods based on Helmholtz integral equation is avoided. Validation of this formulation is demonstrated for some simple geometries.

• Journal of applied mathematics & informatics
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• 제31권5_6호
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• pp.877-894
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• 2013

In this paper, we study the existence and uniqueness of solutions for a singular system of nonlinear fractional differential equations with integral boundary conditions. We obtain existence and uniqueness results of solutions by using the properties of the Green's function, a nonlinear alternative of Leray-Schauder type, Guo-Krasnoselskii's fixed point theorem in a cone. Some examples are included to show the applicability of our results.

• 한국음향학회지
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• 제27권8호
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• pp.411-417
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• 2008

본 논문에서는 헬름홀쯔 적분 방정식에서 유도된 식을 이용하여 구조물의 표면 압력을 구조진동 성분에 대한 단순한 적분형태로 표현하여 음향방사 및 구조/음향 연성 문제를 수치적으로 푸는 방법에 대하여 다룬다. 이 식은 임의의 형상에 대하여 유도된 식으로 Rayleigh 식과 유사한 형태를 갖는다. 이 식을 이용하면 표면 압력을 구조물의 속도에 대한 단순 적분 형태로 나타낼 수 있기 때문에 경계요소법과 같이 연립방정식에 대한 행렬식을 풀 필요가 없다. 또한 헬름홀쯔 적분 방정식에 기반을 둔 다른 방법 들이 가지는 해의 유일성 문제도 갖지 않는 장점이 있다. 본 논문에서는 구형 셀에 대하여 수치해와 정해를 비교하여 제안한 방법의 타당성을 검증하였다.

• Structural Engineering and Mechanics
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• 제10권4호
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• pp.393-404
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• 2000

Linear stress analysis without body force can be easily solved by means of the boundary element method. Some cases of linear stress analysis with body force can also be solved without a domain integral. However, domain integrals are generally necessary to solve the linear stress problem with arbitrary body forces. This paper shows that the linear stress problem with arbitrary body forces can be solved approximately without a domain integral by the triple-reciprocity boundary element method. In this method, the distribution of arbitrary body forces can be interpolated by the integral equation. A new computer program is developed and applied to several problems.

• 한국전자파학회논문지
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• 제25권10호
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• pp.1087-1094
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• 2014

본 연구에서는 유전체의 산란 특성 분석을 위해 이용되는 CFIE(Combined Field Integral Equation) 모멘트법의 계산효율을 높이기 위해 임피던스 경계면 조건을 적용시킨 수치해석 기법과 그 적용 범위에 대한 분석결과를 제시한다. 임피던스 경계면의 적용은 유전체의 등가 표면 전류(Js)와 등가 표면 자류(Ms)를 하나의 전류 또는 자류 성분으로 표현할 수 있으며, 임피던스 경계면 조건을 적용해 계산효율을 높인 수치해석 기법의 정확도는 기존의 CFIE 모멘트법과 이론값(Mie-series 해법, Small Perturbation 산란모델)을 이용하여 비교/분석하였다. 임피던스 경계면 조건을 적용한 수치해석 기법의 적용 범위 상대유전율 허수부 12 이상에서 1 dB 이내의 계산 편차를 확인하였다.

• 대한조선학회논문집
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• 제56권1호
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• pp.11-22
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• 2019

In this paper, a Rankine source method is applied and validated to analyze the hydrodynamic response of a three-dimensional floating structure in the frequency domain. The boundary value problems for radiation and diffraction problem are solved by using a desingularized indirect boundary integral equation method (DIBIEM). The DIBIEM is simpler and faster than conventional methods based on the numerical surface integration of Green's function because the singularities of Green's function are located outside of fluid regions. In case of floating structure with complex geometry, it is difficult to desingularize the singularities of Green's function consistently. Therefore a mixed approach is carried out in this study. The mixed approach is partially desingularized except singularities of the body. Wave drift loads are calculated by the middle-field formulation method that is mathematically simple and has fast convergence. In order to validate the accuracy of the developed program, various numerical simulations are carried out and these results are analyzed and compared with previously published calculations and experiments.

• 대한기계학회논문집A
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• 제32권2호
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• pp.148-161
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• 2008

A volume integral equation method (VIEM) is used to calculate the plane elastostatic field in an isotropic elastic half-plane containing multiple isotropic or anisotropic inclusions subject to remote loading. A detailed analysis of stress field at the interface between the matrix and the central inclusion in the first column of square packing is carried out for different values of the distance between the center of the central inclusion in the first column of square packing of inclusions and the traction-free surface boundary in an isotropic elastic half-plane containing multiple isotropic or anisotropic inclusions. The method is shown to be very accurate and effective for investigating the local stresses in an isotropic elastic half-plane containing multiple isotropic or anisotropic inclusions.

• 전자공학회논문지D
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• 제35D권12호
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• pp.21-29
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• 1998

E-분극된 평면파가 입사되는, 임의의 쐐기각을 갖는 완전도체쐐기에 대해 파수영역에서의 쌍적분 방정식을 유도하였다. 급수전개된 완전도체쐐기의 정확한 경계면 전자파를 파수영역에서의 쌍적분 방정식에 대입하여 해석적으로 적분함으로써 점근해를 유도하였다. 가상공간에서 적분 결과가 0이 되는 것을 보임으로써 적분과정의 타당성을 보였다.

• 충청수학회지
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• 제30권4호
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• pp.397-409
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• 2017

In this paper, we investigated the extinction, positivity, and decay estimates of the solutions to the initial-boundary value problem of the semilinear parabolic equation with nonlinear gradient source and interior absorption terms by using the integral norm estimate method. We found that the decay estimates depend on the choices of initial data, coefficients and domain, and the first eigenvalue of the Laplacean operator with homogeneous Dirichlet boundary condition plays an important role in the proofs of main results.