• The Journal of the Acoustical Society of Korea
• /
• v.27 no.8
• /
• pp.411-417
• /
• 2008

An alternative formulation of the Helmholtz integral equation derived to express the pressure field explicitly in terms of the velocity vector of a radiating surface is used to solve acoustic radiation and fluid/structure interaction problems. This formulation, derived for arbitrary sources, is similar in form to the Rayleigh's formula for planar sources. Because the surface pressure field is expressed explicitly as a surface integral of the surface velocity, which can be implemented numerically using standard Gaussian quadratures, there is no need to use BEM 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.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.2 no.2
• /
• pp.38-41
• /
• 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.

• Journal of the Korea Convergence Society
• /
• v.6 no.5
• /
• pp.9-14
• /
• 2015

In this paper, we analysis the electromagnetic scattering of an arbitrary shape dielectric cube subjected to plane wave incidence in three dimensions. MoM(Method of Moments)in which a surface of a body is divided with small triangular patches and equivalence principle are used to fuse the PMCHW(Poggio, Miller, Chang, Harrington, and Wu) Integral Equations with respect to equivalent currents on a dielectric body. Triangular patch and loop-patch basis functions that is robust in wide frequency ranges are used for MoM formulations. Proposed method is very useful to analysis the induced current of arbitrary dielectric bodies and numerical results for a dielectric cube are presented.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.17 no.2
• /
• pp.277-284
• /
• 1993

Interfacial surface crack perpendicular to the surface, which is imbedded into bonded quarter planes under single anti-plane shear load is analyzed. The problem is formulated using Mellin transform, form which single Wiener-Hopf equation is derived. By solving the equation stress intensity factor is obtained in closed form. This solution can be used as a Green's function to generate the solutions of other problems with the same geometry but of different loading conditions.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.12 no.6
• /
• pp.571-579
• /
• 1987

The integral equations used in electromagnetic fields theory can be used for scattering problems. We can obtain various characteristics of scatterer. Ie, power pattern, scattered field, by finding current distribution on the scatterer. In this paper, current distribution on polygonal cylinder is obtained using integral equations in 2 dimension. For numerical aualysis, the moment method is used with pulse function as a basis function and integral equation is used with extrapolation method, which saves cpu time.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.27 no.2
• /
• pp.120-124
• /
• 1991

An interaction of turbulent boundary layer and local roughness effects was evaluated to investigate the shear frictional coefficient in diffuser. Clauser roughness function was applied to Karman's integral equation for governing equation. The roughness of overall and local diffuser surfaces were calculated using Cole's wall and wake law and Clauser's roughness function for turbulent boundary layer characteristics. The calculating results were compared with the experimental results of other paper. It shows some significant improyements for shear frictional coefficient. Computer code was then used to confirm the behavior of local frictional coefficient along with diffuser roughness surface for some reduction of shear flow stress.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.15 no.1
• /
• pp.1-8
• /
• 1990

In this paper, the transient electromagneti wave scattering at dielectric cylinder is studied by new numerical analysis method. Basic formulation of boundary integral equation (BIE) for numerical method is started weighted residual technique. BIE is made to two simultaneous equation at surface inner and outside point of dielectric cylinder in extended boundary condition (EBC) and surface boundary condition (SBC). Numerical method is used Boundary element method (BEM) that is two form, one is direct method and the other is indirect method, so that this method that transformes operator inversion martics is used numerical analysis. A good agreement of this numerical solution and the other results is obtained.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.27 no.4B
• /
• pp.379-387
• /
• 2002

In this paper, we present a procedure to obtain the transient scattering response from three-dimensional arbitrarily shaped and closed conducting bodies using time-domain magnetic field integral equation (TD-MFIE) with triangular patch functions. This approach results in accurate and comparably stable transient responses from conducting scatterers. Detailed mathematical steps are included, and several numerical results are presented and compared with results from a time-domain electric field integral equation (TD-EFIE) and the inverse courier transform solution of the frequency domain results.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.16 no.1
• /
• pp.33-42
• /
• 2003

This paper deals with the FEM analysis of nonlinear sloshing of incompressible, invicid and irrotational flow in two dimensional rectangular tank. We use laplace equation based on potential theory as governing equation. For large amplitude sloshing motion, kinematic and dynamic free surface conditions derived from Bernoulli equation are applied. This problem is solved by FEM using 9-node elements. For the time integration and accurate velocity calculation, we introduce predictor-corrector time marching scheme and least square method. Also, numerical stability in tracking of free surface is obtained by direct calculation of free surface location to time variation. Numerical results of sloshing induced by harmonic excitations, while comparing with those of linear theory and references, prove the accuracy and stability. After verification of our program, we analyze sloshing response characteristics to the fluid height and the excitation amplitude.

• Journal of the Society of Naval Architects of Korea
• /
• v.28 no.1
• /
• pp.27-37
• /
• 1991

In this paper the nonlinear free surface flows for an axisymmetric submerged body oscillating beneath the free surface are solved and the forces acting on the body are calculated. A boundary integral method is applied to solve the axisymmetric boundary value problem and the Runge-Kutta 4-th order method is used for the time stepping of the free surface location. The nonlinear forces acting on the axisymmetric body are computed and compared with published results.