• 한국정밀공학회지
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• 제14권2호
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• pp.152-159
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• 1997

The asymptotic convergence of a coupled dynamic system, which is motivated from infinite dimensional adaptive systems, is investigated. The convergence analysis is formulated in abstract Banch spaces and is shown to applicable to a broad class of infinite dimensional systems including adaptive identification and adaptive control. Particularly it is shown that if a uniquely existing solution is p-th power integrable, then the solution converges to zero asymptotically. The persistence of excitation(PE) of a signal which arises in an infinite dimensional adaptive system is investigated. The PE property is not completely known yet for infinite dimensional adaptive systems, however it should be investigated in relation to spatial variable, boundary conditions as well as time variable.

• Kyungpook Mathematical Journal
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• 제13권1호
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• pp.63-68
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• 1973

• 천문학회보
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• 제32권1호
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• pp.36.1-36.1
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• 2007

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 1992년도 춘계공동학술대회 발표논문 및 초록집; 울산대학교, 울산; 01월 02일 May 1992
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• pp.13-13
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• 1992

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2013년도 춘계학술대회 논문집
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• pp.53-55
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• 2013

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1994년도 봄 학술발표회 논문집
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• pp.137-144
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• 1994

In this study, a new procedure for solving 2-D dynamic problems of semi-infinite medium in time domain by boundary element method (BEM) is presented. Efficient modelling of the far field region, infinite boundary elements are introduced. The shape function of the infinite boundary element is a combination of decay functions and Laguerre functions. Though the present shape functions have been developed for the time domain analysis, they may be also applicable to the frequency domain analysis. Through the response analysis in a 2-D half space under a uniformly distributed dynamic load, it has been found that an excellent accuracy can be achieved compared with the analytical solution

• Interaction and multiscale mechanics
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• 제1권1호
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• pp.157-175
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• 2008

A brief review of the research works on ground vibrations caused by trains moving in underground tunnels is first given. Then, the finite/infinite element approach for simulating the soil-tunnel interaction system with semi-infinite domain is summarized. The tunnel is assumed to be embedded in a homogeneous half-space or stratified soil medium. The train moving underground is modeled as an infinite harmonic line load. Factors considered in the parametric studies include the soil stratum depth, damping ratio and shear modulus of the soil with or without tunnel, and the thickness of the tunnel lining. As far as ground vibration is concerned, the existence of a concrete tunnel may somewhat compensate for the loss due to excavation of the tunnel. For a soil stratum resting on a bedrock, the resonance peak and frequency of the ground vibrations caused by the underground load can be rather accurately predicted by ignoring the existence of the tunnel. Other important findings drawn from the parametric studies are given in the conclusion.

• Journal of Mechanical Science and Technology
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• 제16권8호
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• pp.1117-1126
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• 2002

A conducting crack in an electrostrictive ceramic under combined electric and mechanical loading is investigated. Analysis based on linear dielectric model predicts that the surfaces of the crack are not open completely but they are contact near the crack tip. The complete solution for the crack with a contact zone in a linear electrostrictive ceramic under combined electric and mechanical loading is obtained by using the complex variable formula. The asymptotic problems for a semi-infinite crack with a partial opening zone as well as for a fully open semi-infinite crack in a nonlinear electrostrictive ceramic are analyzed in order to investigate the effect of the electrical nonlinearity on the stress intensity factor under small scale nonlinear conditions. Particular attention is devoted to a finite crack in the nonlinear electrostrictive ceramic subjected to combined electric and mechanical loading. The stress intensity factor for the finite crack under small scale nonlinear conditions is obtained from the asymptotic analysis.

• 한국소음진동공학회논문집
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• 제23권6호
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• pp.574-580
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• 2013

At high frequencies, the statistical approach such as statistical energy analysis(SEA) and energy flow analysis(EFA) has been applied for estimation of vibroacoustic responses of various built-up structures. The energy coupling relationship between finite coupled structures is required to estimate vibrational energetics of built-up structures. Mindlin plate theory includes the rotatory inertia and shear deformation effects which are dominant as frequency increases. In this paper, the wave transmission analysis is successfully performed for EFA of co-planar coupled Mindlin plates.

• The Journal of the Acoustical Society of Korea
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• 제17권3E호
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• pp.35-42
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• 1998

Transient acoustic and elastic wave propagation in inhomogeneous media are studied by using the Fourier method. It is known that the fourier method has advantages in memory requirements and computing speed over conventional methods such as FDM and FEM, because the Fourier method needs less grid points for achieving the same accuracy. To verify the proposed numerical scheme, several examples having analytic solutions are considered, where two different semi-infinite media are in contact along a plane boundary. The comparisons of numerical results by the Fourier method and analytic solutions show good agreements. In addition, the fourier method is applied to a layered half-plane, in which an elastic semi-infinite medium is covered by an elastic layer of finite thickness. It is showed how to derive the analytic solutions by using the Cagniard-de Hoop method. The numerical solutions are in excellent agreements with analytic results.