• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.574-578
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• 2006

Tidal amplification by construction of the sea-dike and sea-walls had been detected not only near Mokpo Harbor but also at Chungkye Bay which is connected with Mokpo Harbor by a narrow channel. This brings about increase of tidal flat area and in particular increase of surge-wave combined runup during storms. The purpose of this study is to examine an efficient operational model that can be used by civil defense agencies for real-time prediction and fast warnings on wind waves and storm surges. Instead of using commercialized wave models such as WAM, SWAN, the wind waves are simulated by using a new concept of wavelength modulation to enhance broader application of the hyperbolic wave model of the mild-slope equation type. Furthermore, The predicting system is composed of easy and economical tools for inputting depth data of complex bathymetry and enormous tidal flats such as Mokpo coastal zone. The method is applied to Chungkye Bay, and possible inundation features at Mokpo Harbor are analyzed.

• Journal of Ocean Engineering and Technology
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• v.19 no.4 s.65
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• pp.49-55
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• 2005

We constructed and demonstrated a numerical CADMAS-SURF(V4.0) model that reproduces the wave run-up characteristics on the slope of coastal structures and applied it to a permeable coastal structure. We also compared the numerical model with published experimental results on the hydrodynamic phenomena of structures and some numerical results for a modified Pbreak model. In conclusion, the CADMAS-SURF model efficiently simulated wave run-up on the slope of a permeable coastal structure. The inflow/outflow effects from the porous structure boundary were approximately $15\%$ more than with the modified Pbreak model. Nevertheless, the descriptions of the internal hydraulic characteristics still could not be full!! exacted from the result(Fig. 1 참조)s obtained in our model experiment.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.2B
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• pp.249-259
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• 2008

The present paper studies the effect of the slope gradient of a fully permeable submerged breakwater using a newly developed numerical model that is able to consider the flow through a porous midium with inertial, laminar and turbulent resistance terms, i.e. simulate directly WAve-Structure (submerged breakwater)-Sand seabed interaction and can determine the eddy viscosity with LES turbulence model in 2-Dimensional wave field (LES-WASS-2D). The developed model was validated through the comparison with an existing experimental data, and further used for various numerical experiments in oder to investigate the complicated hydrodynamics on the varying slope gradient of permeable submerged breakwater. We found an acceptable phenomenon, as we expect intuitively, that reflection and transmission coefficients decrease simultaneously as slope gradient decrease. In addition, the breaking point, the circulation flow and mean vorticity around a submerged breakwater are throughly discussed.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.10 no.4
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• pp.174-186
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• 1998

A Galerkin's finite element model incorporating infinite elements for modeling of radiation condition at infinity has been developed, which is based on an extended mild-slope equation. To illustrate the validity and applicability of the present model, the example analyses were carried out for a resonance problem in the rectangular harbor of Ippen and Goda (1963) and for wave transformations over circular shoals of Sharp (1968) and Chandrasekera and Cheung (1997). Comparisons with the results obtained by hydraulic experiments and hybrid element method showed that the present model gives very good results in spite of the rapidly varying topography. Numerical experiments were also performed for wave transformations over a circular concave well which may be an alternative to conventional wave barriers.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.3
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• pp.440-447
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• 2012

Numerical model experiments of wave transformation due to the reclamation and the construction of breakwater in case of 50 years design wave were performed using time dependent mild slope equation included shoaling, refraction, diffraction, reflection and wave breaking. As waves propagate to the shore, wave height gradually diminishes by the bottom friction and wave breaking etc.. After the reclamation and the construction of 75 m length breakwater, wave height distributions in the lee of breakwater have the range of 29~128 cm. To make better the harbor tranquility the length of breakwater needs to extend more than 100 m. After the construction of breakwater, wave height in the lee of the structure was deduced over 80%.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2004.08a
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• pp.217-225
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• 2004

Introduction of wave model, considered the effect of shoaling, refraction, diffraction, partial reflection, bottom friction, breaking at the coastal waters of complex bathymetry, is a very important factor for most coastal engineering design and disaster prevention problems. As waves move from deeper waters to shallow coastal waters, the fundamental wave parameters will change and the wave energy is redistributed along wave crests due to the depth variation, the presence of islands, coastal protection structures, irregularities of the enclosing shore boundaries, and other geological features. Moreover, waves undergo severe change inside the surf zone where wave breaking occurs and in the regions where reflected waves from coastline and structural boundaries interact with the incident waves. Therefore, the application of mild-slope equation model in this field would help for understanding of wave transformation mechanism where many other models could not deal with up to now. The purpose of this study is to form a extended mild-slope equation wave model and make comparison and analysis on variation of harbor responses in the vicinities of Ulsan Harbor and Ulsan New Port, etc. due to construction of New Port in Ulsan Bay. This type of trial might be a milestone for port development in macro scale, where the induced impact analysis in the existing port due to the development could be easily neglected.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.1 no.1
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• pp.22-30
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• 1989

Wave propagation is changed by the effect of shoaling, current-depth refraction and shelter-ing etc. To solve these problems. numerous models have been developed. In the present study, a coordinate system is proposed based on the wave ray equation with the wave number equation including diffraction effects . The governing equation for the study was derived from the mild slope wave equation in non-steady state, including current effects (Kirby, 1986a) and trans-formed into an orthogonal curvilinear coordinate system on the basis of the wave ray equation. To obtain a numerical solution, an explicit finite difference scheme was used, and solved by the relaxation method. This model was tested for various cases: Firstly a submersed circular shoal and a constant unit depth. Secondly a submerged elliptic shoal on a slope, and finally a breakwater harbour with obliquely incident waves on a slope. The model was found to simulate the experimental results and other theoretical results in wave height and wave angle fairy well, and the applicability of the model around an arbitrary shaped coastal structure was also verified. To demonstrate the general usefullness of the present approach , the model is to be applied to a field situation with a complex bed topography.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.20 no.4
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• pp.401-412
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• 2008

Simulations of three-dimensional numerical wave tank are performed to investigate wave force acting on a large cylindrical structure and consequent wave deformation, which are induced by bore after breaking waves. The numerical model is based on the three-dimensional Navier-Stokes equations with a finite-difference method combined with a volume of fluid(VOF) method, which is capable of tracking the complex free surface, including wave breaking. In order to promote wave breaking of the incident wave, the approach slope was built seaward of the structure with a constant slope and a large cylindrical structure was installed on a flat bed. The incident waves were broken on the approach slope or flat bed by its wave height. In the present study, all waves acting on the large cylindrical structure were limited to breaking bore after wave breaking. The effects of the position of the structure and the incident wave height on the wave force and wave transformations were mainly investigated with the concern of wave breaking. Further, the relations between the variation of wave energy by wave propagation after wave breaking and wave force acting on the structure were discussed to give the understanding of the full-linear wave-structure interactions in three-dimensional wave fields.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.21 no.2
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• pp.117-126
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• 2009

In order to test the accuracy between the modified mild slope equation (MMSE) without evanescent modes and the plane-wave approximation (PA) of eigenfunction expansion method, various numerical results from both models are presented. In this study, analytical solutions of two models are employed, one based on the MMSE derived by Porter (2003) and the other on the scatterer method of PA by Seo (2008a). Judging from direct comparisons against existing results of rapidly varying topography, the PA model gives better predictions of the wave propagation than the MMSE model.

• Journal of Korea Water Resources Association
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• v.31 no.6
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• pp.845-854
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• 1998

Following the approach of Ebersole (1985), water wave transformation is predicted using the eikonal equation and transport equation for wave energy which are reduced from the extended mild-slope equation of Massel (1993), and also the irrotationality of wave number vectors. The higher-order bottom effect terms, i.e., squared bottom slope and bottom curvature, are neglected in the study of Ebersole but are included in the present study. It was expected that, if these terms are included in this study, the approach would give more accurate solution in the case of rapidly varying topography. But, the expectation was frustrated. It is probably because, in the case of rapidly varying topography, the diffraction effect which is included in the eikonal equation does not work well and thus the solution is deteriorated.