• Journal of Ocean Engineering and Technology
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• v.17 no.6
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• pp.32-37
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• 2003

In this paper, finite element method is applied for the numerical analysis of wave height distribution. The mild-slope equation is used as the basic equation. The key of this model is to impose the effect of nonlinear waves. Numerical results are presented and agreed well with the results from experimental measurements and other numerical analysis. The present method to determine wave height distribution can be broadly utilized for the analysis of new harbor and port designs in the future.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2005.11a
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• pp.422-425
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• 2005

In an transversely isotropic composite laminates, the velocities, the particle directions and the amplitudes of reflected and transmitted waves were obtained using the equation of motion, the constitutive equation, and the displacement equation expressed by wave number and frequency Eigenvalue problem involving a velocity was solved by Snell's law. Finally, the results were confirmed by T300 Carbon fiber/5208 Epoxy materials. This approach could be applied to the detection of flaws in a transversely isotropic composite laminates by the water immersion C-scan procedure.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.04a
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• pp.697-702
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• 1999

Among several non-destructive testing methods, ultrasonic pulse velocity method has been widely used for the evaluation of concrete strength. However, this method might not provide accurate estimated results since factors influencing the relationship between strength and wave velocity is not considered. In this study, the evaluation methods of concrete strength using compression wave velocities measured by either ultrasonic pulse velocity method or impact-resonance method are proposed. A basic equation is obtained by the linear regression with velocity vs. strength data at a specific age and then, ageing factor is employed in the equation to consider the difference of the increasing rate between wave velocity and strength. Strengths predicted by the proposed equation agree well with test results.

• Journal of Ocean Engineering and Technology
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• v.5 no.1
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• pp.55-63
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• 1991

This study is to predict accurately the wave induced current accuring by the radiation stress which acts as the driving force around Nearshore structure. For the wave induced current, the depth integrated and time averaged governing equation of an unsteady nonlinear form is derived from the continuity and momentum equation of an incompressible fluid. Numerical solutions are obtained by a finite difference method for the governing equation. In the vicinity of a structure, computed flow patterns show good agreement with the hydraulic experimental data. The numerical results obtained by neglecting the convective term show a large change of alongshore and offshore current.

• Journal of the Korean Society of Propulsion Engineers
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• v.10 no.2
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• pp.62-69
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• 2006

In transversely isotropic composite laminates, the velocities, the particle directions and the amplitudes of reflected and transmitted waves were obtained using the equation of motion, the constitutive equation, and the displacement equation expressed by wave number and frequency. Eigenvalue problem involving a velocity was solved by Snell's law. Finally, the results were confirmed by 7300 Carbon fiber/5208 Epoxy materials. This approach could be applied to the detection of flaws in transversely isotropic composite laminates by the water immersion C-scan procedure.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.7 no.1
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• pp.1-11
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• 1995

A numerical shallow water wave deformation model to solve unsteady mild slope equation was develope(1. The energy equation of Izumiya and Horikawa(1984) for wave breaking and bottom friction was incorporated to estimate more realistically energy damping resulted from wave breaking and reflection. A numerical scheme for variable grid spacings was also introduced to complement the defect of unsteady mild slope equation limiting the grid spacings. This model was tested and compared with the existing analytic solutions and physical modelings, and applied to a practical situation.

• Journal of Ocean Engineering and Technology
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• v.1 no.1
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• pp.33-38
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• 1987

The first order mation responses of a floating structure and the hydrodynamic forces in regular waves are obtained by means of the linear potential theory. The first order potential is obtained directly from the numerical solution of the improved Green integral equation which is characterized by the combined surface distribution of sources and normal doublets. The mean second order wave drift force is also calculated by means of the near field method. It seems that the present method gives more accurate numerical results than other methods and the agreement between numerical and experimental results appears to be satisfactory.

• Journal of Ocean Engineering and Technology
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• v.10 no.3
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• pp.50-61
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• 1996

The breaking phenomenon of regular periodic waves generated by a numerical wave maker is simulated by finite-difference method which can cope with strong interface motions. The air and water flows are simultaneously solved in the time-marching solution procedure for the Navier-Stokes equation. A density-function technique is devised for the implemenation of the interface conditions. The accuracy is examined and applied to the simulation of two-dimensional breaking phenomena of periodic gravity waves.

• Transactions of Materials Processing
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• v.10 no.6
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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.

• Journal of Ocean Engineering and Technology
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• v.20 no.6 s.73
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• pp.35-40
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• 2006

In recent years, there's been strong demand for seawalls that havea gentle slope and permeability that serveswater affinity and disaster prevention from wave attack. The aim of this study is to examine wave transformation, including wave run-up that propagates on the coastal structures. A numerical model based on the weak nonlinear dispersive Boussinesq equation, together with the unsteady nonlinear Darcy law for fluid motion in permeable layer, is developed. The applicability of this numerical model is examined through Deguchi and Moriwaki's hydraulic model test on the permeable slopes. From this study, it is found that the proposed numerical model can predict wave transformation and run-up on the gentle slope with a permeable layer, but can't show accurate results for slopes steeper than about 1:10.