• Title/Summary/Keyword: green integral equation

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Analysis of Motion Response and Drift Force in Waves for the Floating-Type Ocean Monitoring Facilities (부유식 해상관측시설의 파랑중 운동 및 표류력 해석)

  • YOON Gil Su;KIM Yong Jig;KIM Dong Jun;KANG Shin Young
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.31 no.2
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    • pp.202-209
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    • 1998
  • A three-dimensional numerical method based on the Green's integral equation is developed to predict the motion response and drift force in waves for the ocean monitoring facilities. In this method, we use source and doublet distribution, and triangular and rectangular eliments. To eliminate the irregular frequency phenomenon, the method of improved integral equation is applied and the time-mean drift force is calculated by the method of direct pressure integration over the body surface. To conform the validity of the present numerical method, some calculations for the floating sphere are performed and it is shown that the present method provides sufficiently reliable results. As a calculation example for the real facilities, the motion response and the drift force of the vertical cylinder type ocean monitoring buoy with 2.6 m diameter and 3,77 m draft are calculated and discussed. The obtained results of motion response can be used to determine the shape and dimension of the buoy to reduce the motion response, and other data such as the effect of motion reduction due to a damper can be predictable through these motion calculations. Also, the calculation results of drift force can be used in the design procedure of mooring system to predict the maximum wave load acting on the mooring system. The present method has, in principle, no restriction in the application to the arbitrary shape facilities. So, this method can be a robust tool for the design, installation, and operation of various kinds of the floating-type ocean monitoring facilities.

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A Study on the Application of Analytic Nodal Method to a CANDU-600 Reactor Analysis

  • C.S. Yeom;Ryu, H.;Kim, H.J.;Kim, Y.H.;Kim, Y.B.
    • Proceedings of the Korea Society for Energy Engineering kosee Conference
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    • 2000.11a
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    • pp.115-120
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    • 2000
  • The analysis of flux distribution under stead-state in large power reactors with assymetry reactivity insertions requires the use of three-dimensional diffusion calculations. For the purpose, consistently formulated modern nodal methods based on higher order interface techniques have become popular tools for flux distributions in large commercial nuclear reactors. Among the earlier developments, the nodal Green's function method obtains its nodal interface equation from the transverse-integrated integral diffusion equation using a finite-medium Green's function. In this method, the outgoing current from a node surface is formulated as a response of the incoming currents and the spatially integrated neutron source within the same node. The well-known nodal expansion method is also based on an interface partial current formulation. Nodal methods high-level interface variables, i.e., interface net current and flux, may be more computationally efficient than the nodal Green's function method because they have one fewer unknown per interface. The Analytic Nodal Method(ANM), which can be classified as an interface net current technique and, was faster in solving some standard benchmark problems than the other two methods.(omitted)

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Unsteady Wave Generation by an Oscillating Cylinder Advancing under the Free Surface

  • D.C.,Hong
    • Bulletin of the Society of Naval Architects of Korea
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    • v.25 no.2
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    • pp.11-18
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    • 1988
  • The radiation problem for an oscillating cylinder advancing under the free surface with a constant horizontal velocity is studied using the Green integral equation in the frequency domain. The Green function expressed in terms of the complex exponential, is derived using the damped free surface condition. Special attention is given to the behavior of the numerical solution in the vicinity of the critical Brard number ${\gamma}_c=\omega{\cdot}u/g=0.25$ where $\omega$ is the circular frequency of encounter, u the advancing speed and g the gravitational acceleration. It is shown that the solution is finite in the vicinity of ${\gamma}_c$ although the Green function becomes singular at ${\gamma}_c$. It is also shown that the computed hydrodynamic coefficients agree well with those obtained from the solution of the same problem formulated in the time domain.

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EXISTENCE OF RESONANCES FOR DIFFERENTIAL OPERATORS

  • Kim, In-Suk
    • Communications of the Korean Mathematical Society
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    • v.9 no.2
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    • pp.337-353
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    • 1994
  • Let H be a Schrodinger operator in $L^2$(R) H =(equation omitted) + V(x), with supp V ⊂ [-R, R]. A number $z_{0}$ / in the lower half-plane is called a resonance for H if for all $\phi$ with compact support 〈$\phi$, $(H - z)^{-l}$ $\phi$〉 has an analytic continuation from the upper half-plane to a part of the lower half-plane with a pole at z = $z_{0}$ . Thus a resonance is a sort of generalization of an eigenvalue. For Im k > 0, ($H - k^2$)$^{-1}$ is an integral operator with kernel, given by Green's function(omitted)

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Real-time simulation on B-spline deformable volume-part III (B-spline volume 변형체의 실시간 시뮬레이션 II)

  • 전성기;조맹효
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2002.10a
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    • pp.70-77
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    • 2002
  • Since our physical world cannot be modeled as rigid body, deformable object models are important. For real-time simulation of elastic object, it must be guaranteed by its exact solution and low-latency computational cost. In this paper, we describe the boundary integral equation formulation of linear elastic body and related boundary element method(BEM). The deformation of elastic body can be effectively solved with 1ow run-time computational costs, using precomputed Green Function and fast low-rank updates based on Capacitance Matrix Algorithm.

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Good Choice of Positions and Impedances of Absorptive Materials for Effective Interior Noise Control (흡음재의 적절한 위치 및 임피던스 선정을 통한 효율적인 실내 소음 제어)

  • 조성호;김양한
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2003.05a
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    • pp.791-796
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    • 2003
  • Some basic guidelines for changing non-uniform boundary condition in an acoustically small cavity are presented. In this paper, modal summation technique is used to represent inside sound field. From this formulation, corner effect is defined and proposed. The corner in a cavity is good position for changing boundary condition effectively. Impedance circle with same absorption coefficient is defined to find appropriate impedance of absorptive material for better noise control performance.

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Computation of Circuit Parameters of Multiconductor Transmission Lines with Arbitrary Cross Section (임의 단말을 가진 전송선의 회로정수 산출)

  • 김종민;김종해;하상욱;라극환
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.26 no.12
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    • pp.1918-1925
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    • 1989
  • A method for computing the capacitance and inductance matrix for 2-D multiconductor transmission lines with arbitrary cross section in dielectric medium is presented. The integral equation is obtained by using a free space Green function in conjunction with free and bound charges existing on boundary surfaces. The numerical analysis is based on the moment method using point matching and Galerkin method. And kthe scheme to reduce memory and computation time is presented for symmetric structure.

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An Analysis of Transmission Line Structure by Combining Image Mode and Galerkin Methods (영상-모드 및 Galerkin법을 이용한 전송선 문제 해석)

  • 신규현;정현교;한송엽
    • The Transactions of the Korean Institute of Electrical Engineers
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    • v.40 no.12
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    • pp.1296-1301
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    • 1991
  • This paper presents a hybrid image mode Galerkin method for the analysis of the transmission line structures suspended between infinite parallel ground planes. A Green's function that consists of numerically accelerated image mode terms is developed, which is used in boundary integral equation. Transmission lines of arbitrary cross section are analyzed using Galerkin's method. Two kinds of configurations of transmission lines are studied in sample problems.

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Vibroacoustics of Axisymmetric Cylindrical Elastic Shells : Wall Impedance of the Plane Mode (축대칭 원통 탄성 셸의 진동음향 : 평면 모드의 벽 임피던스)

  • Park, Chan-Il
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.18 no.9
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    • pp.930-936
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    • 2008
  • Fluid loading of a vibrating cylindrical shell has influence on natural frequencies and vibration magnitudes of the shell and the acoustic pressure of fluid. The vibroacoustics of fluid-filled cylindrical shells need the coupled solution of Helmholtz equation and governing equation of a cylindrical shell with boundary conditions. This paper proposed the wall impedance of fluid-filled axisymmetric cylindrical shells, focusing on the inner fluid/shell interaction. To propose the impedance, shell displacements used the linear combination of in vacuo shell modes. Acoustic pressure prediction of fluid used Kirchhoff-Helmholtz integral equation with Green's function of the plane mode. For the demonstration of the proposed results, numerical applications on mufflers were conducted.

Vibroacoustics of Axisymmetric Cylindrical Elastic Shells (축대칭 원통 탄성 쉘의 진동음향)

  • Park, Chan-IL
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2008.04a
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    • pp.160-165
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    • 2008
  • Fluid loading of a vibrating cylindrical shell can change natural frequencies and vibration magnitudes of the shell and a vibrating cylindrical shell can also change acoustic pressure of fluid. The vibroacoustics of fluid-filled cylindrical shells need the coupled solution of Helmholtz equation and governing equation of a cylindrical shell with boundary conditions. This paper proposed the wall impedance of fluid-filled axisymmetric cylindrical shells, focusing on the inner fluid/shell interaction. To propose the impedance, shell displacements used the linear combination of in vacuo shell modes. Acoustic pressure prediction of fluid used Kirchchoff-Helmholtz Integral equation with Green function of the plane mode. For the demonstration of the proposed results, numerical applications on mufflers were conducted.

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