• Water Engineering Research
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• 제1권4호
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• pp.293-298
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• 2000

Optimal values of $\alpha$ characterizing the linear dispersion property in the modified Boussinesq equations are determined by minimizing the combined relative errors of the phase and group velocities. The value of $\alpha$ is fixed in previous studies, whereas it is varying in the present study. The phase and group velocities are calculated by using variable $\alpha$ and compared to those of the linear Stokes wave theory and previous studies. It is found that the present study produces the best match to the linear Stokes theory.

• International Journal of Ocean Engineering and Technology Speciallssue:Selected Papers
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• 제6권1호
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• pp.7-14
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• 2003

The interaction of monochromatic incident waves with a submerged horizontal porous membrane is investigated in the context of two-dimensional linear hydro-elastic theory. It is assumed that the membrane is made of material with very fine pores so that the normal velocity of the fluid passing through the porous membrane is linearly proportional to the pressure difference between two sides of the membrane (e.g. Darcy's law). Using the Eigen-function expansion method, the wave-blocking performance of a submerged horizontal porous membrane is tested with various membrane tensions, porosities, lengths, and submerged depths. It is found that an optimal combination of design parameters exists for given water depth and wave characteristics.

• 물과 미래
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• 제20권1호
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• pp.49-54
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• 1987

일정수심에 해역에 주기적인 파장의 사련이 있는 겨우 파의 반사특성을 경계요소법의 선형요소에 의해 해석하였다. 파랑은 2차원 선형파 이론으로부터 해석하였으며, 입사파 방향은 사련상에 임의방향 (직각입사 또는 경사입사)으로 진행한다고 가정하였다. 본 계산의 신뢰도를 검증하기 위하여 기존의 실험적, 이론적 결과 및 수치결과와 각각비교하였다. 직각입사파에 대한 본 수치계산 결과, 사련의 파장이 수면파장의 1/2인 경우에 발생하는 Bragg공진반사가 잘 예측되었다.

• 한국해양공학회지
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• 제8권2호
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• pp.80-92
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• 1994

The dynamic response characteristics of a floating ocean city are examined for presenting the basic data for the design of huge offshore structures supported by a large number of floating bodies in waves. The numerical approach which is accurate in linear system is based on combination of a three dimensional source distribution method, wave interaction theory and the finite element method of using the space frame element. The hydrodynamic interactions among the floating bodies are taken into account in their exact form within the context of linear potential theory in the motion and structural analysis. The method is applicable to an arbitrary number of three dimensional bodies having any individual body geometries and geometrical arrangement with the restriction that the circumscribed, bottom-mounted. Imaginary vertical cylinder for each body does not contain any part of the other body. The validity of this procedure was verified by comparing with experimental results obtained in the literature.

• 소성∙가공
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• 제10권6호
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• pp.449-456
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• 2001

The concept of stress wave was introduced through the quantized kinetic energy which is related to the potentional energy change of atom, molecular bond energy. Differentiated molecular bond energy $\varphi$() by the lst order displacement u becomes force F(F = d$\varphi$($u_i$)/du), if resversely stated, causing physically atomic displacement $u_i$. Such physical phenomena lead stress(force/area of applied force) can be expressed by wave equation of linearly quantized physical property. Through the stress wave concept, formation of dislocation, which could not explained easily from a theory of continuum mechanics, can be explained. Moreover, this linearly quantized stress wave equation with a stress concept for grains in a crystalline solid was applied to three typical metallic microstructures and a simple shape. The result appears to be a product from well treated equations of a quantized stress wave. From this result, it can be expected to answer the reason why the defect free and very fine diameters of long crystalline shapes exhibit ideal tensile strength of materials.

• 대한조선학회논문집
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• 제37권3호
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• pp.45-56
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• 2000

규칙파중 상자형 부유식 방파제의 특성을 살펴보기 위하여 실험과 이론 연구를 수행하였다. 선형포텐셜이론으로 부유식방파제의 특성을 잘 해석할 수 있음을 확인하였다. 투과계수는 파장/부체폭과 부체폭/부체흘수의 비의 함수이며 최소 투과계수가 나타나는 점이 있음을 확인하였다. 부체폭/부체흘수 비가 클수록 최소 투과계수를 가지는 파장/부체폭의 값이 커지며, 과도한 계류력은 부유식방파제의성능을 저하시킬 수 있다.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2004년도 학술대회지
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• pp.85-89
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• 2004

The wave interactions with fully submerged and floating dual buoy/vertical porous membrane breakwaters has been investigated in experimentally to validate the developed theory and numerical method in the previous study, in which multi-domain hydro-elastic formulation was carried out in the context of linear wave-body interaction theory and Darcy's law. It is found that the experimental results agrees well with the numerical prediction. Transmission and reflection can be quite reduced simultaneously especially in the region of long waves. The properly tuned system to incoming waves can effectively dissipate wave energy and also offset each other between incident and scattered waves using its hydro-elasticity and geometry.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2000년도 춘계학술대회 논문집
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• pp.133-138
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• 2000

In this paper some shapes of the FBW cross sections were examined to improve the performance of FBW for the long wave. Trapezoidal section and prominence section were examined. Linear potential theory is used and the boundary element method is use for numerical computation. Proper choice of the pontoon geometry may improve the transmission coefficient in the long wave range for a given wave period.

• Coupled systems mechanics
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• 제7권4호
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• pp.373-393
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• 2018

This paper is concerned with the wave propagation behavior of rotating functionally graded temperature-dependent nanoscale beams subjected to thermal loading based on nonlocal strain gradient stress field. Uniform, linear and nonlinear temperature distributions across the thickness are investigated. Thermo-elastic properties of FG beam change gradually according to the Mori-Tanaka distribution model in the spatial coordinate. The nanobeam is modeled via a higher-order shear deformable refined beam theory which has a trigonometric shear stress function. The governing equations are derived by Hamilton's principle as a function of axial force due to centrifugal stiffening and displacement. By applying an analytical solution and solving an eigenvalue problem, the dispersion relations of rotating FG nanobeam are obtained. Numerical results illustrate that various parameters including temperature change, angular velocity, nonlocality parameter, wave number and gradient index have significant effect on the wave dispersion characteristics of the understudy nanobeam. The outcome of this study can provide beneficial information for the next generation researches and exact design of nano-machines including nanoscale molecular bearings and nanogears, etc.

• 한국해양공학회지
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• 제14권1호
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• pp.1-5
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• 2000

A numerical analysis for wave motion in the shallow water is presented. The method is based on potential theory. The fully nonlinear free surface boundary condition is assumed in an inner domain and this solution is matched along an assumed common boundary to a linear solution in outer domain. In two-dimensional problem Cauchy's integral theorem is applied to calculate the complex potential and its time derivative along boundary.