• Journal of Korean Society of Coastal and Ocean Engineers
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• v.17 no.3
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• pp.202-212
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• 2005

In the design of an of offshore structure located near an underwater shoal, the same amount of attention given to the wave height may have to be put to the wave induced current as well since some of the wave energy translates to the current. In the present study, two numerical models each based on the nonlinear Boussinesq equation and the linear mild slope equation are applied to calculate the wave deformation and secondly induced current around a shoal. The underwater shoal in Vincent and briggs' experiment (1989) is used here, and all non-breaking wave conditions of the experiment with various monochromatic and unidirectional or multidirectional spectral wave incidences are concerned. Both numerical models clearly showed wave induced currents symmetrically farmed along the centerline over the shoal. The calculated wave heights along a preset line also generally showed very nice agreements with the experimental values.

• Journal of Environmental Science International
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• v.2 no.3
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• pp.235-243
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• 1993

Extreme environments and freak wave characteristics in the coastal waters of Korean Peninsula are analyzed using the observed wave data. Freak wave has been intensely emphasized as an important environmental force parameter in several recent research works. However, the mechanism and occurrence probability of freak wave are not clarified. The aims of this study we: to summarize the distribution of extreme environment for wind waves, and to find occurrence probability of freak wave in the coastal waters of Korean Peninsula. These extreme sea conditions are discussed by applying extreme value analysis method, and the statistic characteristics are summarized which can be used to the design and analysis of coastal structures. The mechanism and the occurrence probability of freak wave are also discussed in detail using wave parameters in considered with wave deformation in the coastal waters. Key Words : extreme wave, freak wave, extreme analysis, design wave, probability density.

• Steel and Composite Structures
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• v.27 no.1
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• pp.109-122
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• 2018

In This work an analysis of the propagation of waves of functionally graduated plates is presented by using a high order hyperbolic (HSDT) shear deformation theory. This theory has only four variables, which is less than the theory of first order shear deformation (FSDT). Therefore, a shear correction coefficient is not required. Unlike other conventional shear deformation theories, the present work includes a new field of displacement which introduces indeterminate integral variables. The properties of materials are supposed classified in the direction of the thickness according to two simple distributions of a power law in terms of volume fractions of constituents. The governing equations of the wave propagation in the functionally graded plate are derived by employing the Hamilton's principle. The analytical dispersion relation of the functionally graded plate is obtained by solving an eigenvalue problem. The convergence and the validation of the proposed theoretical numerical model are performed to demonstrate the efficacy of the model.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.7 no.3
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• pp.219-226
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• 1995

The wave interaction with flexible membrane such as PVC and PU fabrics is studied to prove its applicability to portable breakwaters. To analyze the wave deformation due to the flexible membrane. eigen-function expansion method is employed. The fluid domain is seperated into two regions. The velocity potential in each regions and the deformation of membrane are coupled by the body boundary conditions. Herein the deformation of membrane is obtained by solving the membrane equation. As a numerical example, transmission and reflection coefficients according to the change of several design parameters such as tensile force. mooring line stiffness and membrane height are investigated. It is found that the efficiency of flexible membrane breakwater is significantly affected by these design parameters. The angle of incident wave is an important role to the performance of breakwater. Finally we conclude that flexible membrane can be used to engineering material for the future breakwaters.

• Journal of Mechanical Science and Technology
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• v.17 no.6
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• pp.787-795
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• 2003

Mechanical properties of the materials used for transportations and industrial machinery under high strain rate loading conditions such as seismic loading are required to provide appropriate safety assessment to these mechanical structures. The Split Hopkinson Pressure Bar (SHPB) technique with a special experimental apparatus can be used to obtain the material behavior under high strain rate loading conditions. In this paper, dynamic deformation behaviors of the aluminum alloys such as A12024-T4, A1606 IT-6 and A17075-T6 under both high strain rate compressive and tensile loading conditions are determined using the SHPB technique.

• Journal of Korean Association for Spatial Structures
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• v.1 no.2 s.2
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• pp.101-110
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• 2001

A large floating structure is attracting great attention in recent years from the view of ocean space utilization. Its huge scale in the horizontal directions compared with the wavelength and relatively shallow depth make this type of floating structure flexible and its wave-induced motion be characterized by the elastic deformation. In this paper, a boundary integral equation method is proposed to predict the wave-induced dynamic response mat-like floating offshore structure. The structure is modeled as an elastic plate and its elastic deformation is expressed as a superposition of free-vibration modes in air. This makes it straightforward to expand the well-established boundary integral technique for rigid floating bodies to include the hydroelastic effects. In order to validate the theoretical analysis, we compare with the experimental result of reduced model test. Satisfactory agreement is found between theory and experiment.

• Journal of the Korean Society of Industry Convergence
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• v.4 no.4
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• pp.433-439
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• 2001

A large floating structure is attracting great attention in recent years from the view of ocean space utilization. Its huge scale in the horizontal directions compared with the wavelength and relatively shallow depth make this type of floating structure flexible and its wave-induced motion be characterized by the elastic deformation. In this paper, a boundary integral equation method is proposed to predict the wave-induced dynamic response mat-like floating offshore structure. The structure is modeled as an clastic plate and its elastic deformation is expressed as a superposition of free-vibration modes in air. This makes it straightforward to expand the well-established boundary integral technique for rigid floating bodies to include the hydroelastic effects. In order to validate the theoretical analysis, we compare with the experimental result of previous model test. Satisfactory agreement is found between theory and experiment.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.943-947
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• 2008

Dynamic response characteristics of a beam undergoing impulsive force are investigated using the wavelet transform method in this study. When an impulse is applied to an arbitrary position of a beam, it will generate a structural deformation wave. The characteristics of the wave are changing in the domain of time and space. The maximum amplitude of each natural frequency mode and the time to reach the maximum amplitude are obtained in this study. The effects of the location of impulse on the variations of the dynamic characteristics is also investigated.

• Proceedings of the KSME Conference
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• 2000.11a
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• pp.268-273
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• 2000

Mechanical properties of the materials used for transportations and industrial machinery under high strain rate loading conditions are required to provide appropriate safety assessment to these mechanical structures. The Split Hopkinson Pressure Bar(SHPB) technique, a special experimental apparatus, can be used to obtain the material behavior under high strain rate loading condition. In this paper, dynamic deformation behaviors of the aluminum alloys, Al2024-T4, Al6061-T6 and Al7075-T6, under high strain rate compressive and tensile loading are determined using SHPB technique.

• Journal of the Korean Society of Visualization
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• v.18 no.3
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• pp.35-41
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• 2020

We conduct numerical simulations of the interaction of a deformable structure with two-phase compressible flow. The finite volume method (FVM) is used to simulate fluid phenomena including a shock wave, a gas bubble, and the deformation of free surface. The deformation of a floating structure is computed with the finite element method (FEM). The compressible two-phase volume of fluid (VOF) method is used for the generation and development of a cavitation bubble, and the immersed boundary method (IBM) is used to impose the effect of the structure on the fluid domain. The result of the simulation shows the generation of a shock wave, and the expansion of the bubble. Also, the deformation of the structure due to the hydrodynamic loading by the explosion is identified.