• Title/Summary/Keyword: 고유함수

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Vibration and Stability Characteristics of Cylindrical Panels by the Galerkin Method (Galerkin 해석법에 의한 원통 Panel의 진동 및 좌굴특성)

  • Park, Moon Ho;Park, Sung Jin
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.11 no.4
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    • pp.27-35
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    • 1991
  • This paper presents a numerical analysis procedure and a characteristics for vibration and buckling of the cylinderical panels. The panels with simply-simply or simply-clamped edge supports are subjectes to circumferential compressive or flexural stresses. The differential equations governing vibration and buckling for these panels are derived by using the fundamental differential equation of the Love-Timoshenko and are solved numerically via the Galerkin method. The panel with simply-clamped edge supports is used a trigonometric function or a eigen function of a beam as a trial function and the effects of trial functions on numerical solutions are displayed. Numerical results are presented to demonstrate the effects of the flexural parameters in natural frequencies and coefficients of critical buckling and some typical mode shapes of vibration and buckling are also presented.

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Parametric Instability of Cylinderical Panels (주기적(週基的)인 압축하중을 받는 원통(円筒) Panel의 동적(動的) 불안정(不安定) 특성(特性)에 관한 연구)

  • Park, Sung Jin;Mikami, Takashi
    • Journal of Korean Society of Steel Construction
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    • v.12 no.6
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    • pp.737-748
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    • 2000
  • This paper presents a numerical analysis procedure and a characteristics for dynamic of cylindrical panels. The panels with simply-simply or simply-clamped edge supports are subjectes to circumferential compressive or flexural stresses. The differential equations governing vibration and dynamic for these panels are derived by using the fundamental differential equation of the Love-Timoshenko and are solved numerically by the Galerkin method. The panel with simply-clamped edge supports is used a trigonometric function or an eigen function of a beam as a trial function and the effects of trial functions on numerical solutions are displayed. Numerical results are presented to demonstrate the effects of the flexural parameters in natural frequencies and coefficients of critical buckling, and some typical mode shapes of vibration and buckling are also presented.

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Hydraulic Experiments on Reflection of Regular Waves due to Rectangular Submerged Breakwaters (사각형형상 수중방파제의 반사에 관한 수리실험)

  • Cho, Yong-Sik;Lee, Jong-In;Kim, Young-Taek
    • Journal of Korea Water Resources Association
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    • v.35 no.5
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    • pp.563-573
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    • 2002
  • In this study, reflection of water waves over a train of rectangular submerged breakwaters is experimentally investigated. Measured reflection coefficients of regular waves are compared with predicted coefficients obtained from the eigenfunction expansion method. Although measured coefficients are slightly smaller than predicted ones, the overall agreement is very good.

Vibration Analysis of Rectangular Thick Plates Using Mindlin Plate Characteristic Functions (Mindlin판 특성함수를 이용한 직사각형 후판의 진동해석)

  • Lee, J.M.;Kim, K.C.
    • Journal of the Society of Naval Architects of Korea
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    • v.33 no.2
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    • pp.85-95
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    • 1996
  • An iterative Kantorovich method is presented for the vibration analysis of rectangular isotopic and orthotropic thick plates. Mindlin plate characteristic functions are derived in general forms by the Kantorovich method initially starting with Timoshenko beam functions consistent with the boundary conditions of the plate. Through numerical calculations of natural pairs, i.e. natural frequencies and corresponding modes, and dynamic responses of appropriate models, it has been confirmed that the presented method is superior to the Rayleigh-Ritz analysis or the FEM analysis in accuracy and computational efficiency.

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Wave Control Performance of Moored Pontoon-Type Floating Breakwater (계류된 사각형 부유식 방파제의 파랑제어성능)

  • Cho I. H.
    • Journal of the Korean Society for Marine Environment & Energy
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    • v.5 no.3
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    • pp.35-44
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    • 2002
  • In this paper, the analytic studies on the wave control performance of moored pontoon-type floating breakwater are presented. A two-dimensional eigenfunction expansion method is adopted to study the motion responses and the transmission coefficients of pontoon-type floating breakwater in beam waves. The stiffness coefficients of mooring line are idealized as linear elastic spring. Comparison of the analytical results with a numerical results (FEM) shows good agreement over a wide range of frequencies. The performance of mooed pontoon-type floating breakwater is tested with various design parameters such as sectional geometry, mooring line characteristics and wave frequencies. It is found that the properly designed floating breakwater can be an effective wave control structure.

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Computation of Wave Propagation by Scatter Method Associated with Variational Approximation (변분근사식과 연계된 산란체법에 의한 파랑변형 계산)

  • Seo, Seung-Nam
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.20 no.6
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    • pp.553-563
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    • 2008
  • If an arbitrary topography is approximated to a number of vertical steps, both variational approximation and eigenfunction expansion method can be used to compute linear wave transformation over the bottom. In this study a scatterer method associated with variational approximation is proposed to calculate reflection and transmission coefficients. Present method may be shown to be more simple and direct than the successive-application-matrix method by O'Hare and Davies. And Several numerical examples are given which are in good agreement with existing results.

Adaptive Beamforming Technique of Eigen-space Smart Antenna System (고유공간 스마트 안테나 시스템의 적응 빔형성 기술)

  • 김민수;이원철;최승원
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.13 no.10
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    • pp.989-997
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    • 2002
  • This paper presents a new technique that enhances the performance of the smart antenna system especially in signal environments of wide angular spread by adopting a weight vector obtained from two eigenvectors of theautocovariance matrix of the received data. While the conventional beamformingtechnique employs only one eigenvector corresponding to the largest eigenvalue, the proposed algorithm uses two eigenvectors corresponding to the largest and second largest eigenvalue in such a way that it can be robust enough to the signal environments of wide angular spread. An efficient adaptive procedure is shown to verify that the optimal weight vector consisting of the two eigenvectors is obtained with a reasonable complexity(3.5$N_2$+ 12N) and accuracy. it is also shown in this paper that the numerical results obtained from the proposed adaptive procedure well agree with those obtained from a commercial tool computing the eigen-function of MATLABTM.

On the near optimal composite regulator problem for the large scale linear time invariant system using matrix sign function (행렬 부호 함수를 이용한 대규모 선형 시불변 계통의 준최적 합성 제어기의 설계에 관한 연구)

  • 천희영;박귀택;이동기
    • 제어로봇시스템학회:학술대회논문집
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    • 1986.10a
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    • pp.566-570
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    • 1986
  • 본 논문의 목적은 대규모 선형 시불변 계통에 대한 합성 제어기의 설계에 관한 새로운 방법을 제시하기 위한 것이다. 주어진 계통을 행렬 부호 함수를 이용하여 그 고유치의 크기에 따라 블럭 대각 분해하고 각부 계통에 대한 최적 제어기 및 전체계통에 대한 준최적 합성 제어기를 설계한다. 이 방법은 주어진 계통의 고유치를 미리 알 필요가 없으며 계통의 블력 분해 과정에서 Riccati 방정식및 Lyapunov 방정식의 해를 구할 필요가 없고 특이섭등 기법이나 Two time scale seperation 방법에서의 제약조건에 관계없이 광범위하게 적용되는 장점이 있다.

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New Formulation of MNDIF Method for Eigenvalue Analysis of Acoustic Cavities (음향 공동의 고정밀도 고유치 해석을 위한 새로운 MNDIF 법 정식 개발)

  • Kang, S.W.
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2013.10a
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    • pp.658-663
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    • 2013
  • A new formulation of the MNDIF method is introduced to extract highly accurate eigenvalues of concave acoustic cavities with arbitrary shapes. It is said that the MNDIF method cannot yield accurate eigenvalues for concave cavities. To overcome this weak point, a new approach of dividing a concave cavity into two convex domains is proposed. The validity of the proposed method is shown through a case study.

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