• International Journal of Ocean Engineering and Technology Speciallssue:Selected Papers
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• v.6 no.1
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• pp.15-21
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• 2003

A common feature in the three-dimensional numerical model experiments of coastal discharge with simplified model and idealized external forcings is investigated. The velocity fields due to the buoyancy and flaw flux, are spreaded radiately and the surface velocites are much greater than the homegeneous discharges. The coastal dischargd due to the Coriolis force and flaw flux are shaped a anticyclical gyre (clockwise) and determined the scale of the gyre in the coastal zone, respectively. The bottom topography restricts a outward extention of the coastal fronts and it accelerates a southward flow.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.09b
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• pp.842-845
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• 2005

A method for the numerical simulation of two-dimensional free-surface flow resulting from the propagation of regular gravity waves over topography with arbitrary bottom shape is presented. The method is based on the numerical solution of the Euler equations subject to the fully nonlinear free-surface boundary conditions and the appropriate bottom, inflow and outflow conditions using a hybrid finite-differences and spectral-method scheme. The formulation includes a boundary-fitted transformation, and is suitable for extension to incorporate large-eddy simulation (LES) and large-wave simulation (LWS) terms for turbulence and breaking wave modeling, respectively. Results are presented for the simulation of the free-surface flow over two different bottom topographies, with constant slope values of 1:10 and 1:20, two different inflow wave lengths and two different inflow wave heights. An absorption outflow zone is utilized and the results indicate minimum wave reflection from the outflow boundary. Over the bottom slope, lengths of waves in the linear regime are modified according to linear theory dispersion, while wave heights remain more or less unchanged. For waves in the nonlinear regime, wave lengths are becoming shorter, while the free surface elevation deviates from its initial sinusoidal shape.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.29 no.3
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• pp.275-281
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• 2011

To acquire an underwater topographic information is necessary for the design and construction of structures in marine and inland water. It consists of water depth information by bathymetric survey and underwater bottom topography image information can be obtained by side scan sonar in different ways. For the purpose of providing high quality data by means of engineering site survey, it is necessary to apply simultaneous acquisition of two information and carry out the integrated interpretation to each other. The present research aims to obtain information of the underwater topography and water depth at the same time using interferometer technique, and to validate interferometer technique with accuracy estimation.

• Ocean and Polar Research
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• v.35 no.4
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• pp.291-298
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• 2013

In order to investigate the topography and exposure duration of the Siheung tidal flat, tidal ranges and DEM constructed by remote sensing techniques were analyzed. A cross-sectional diagram of the intertidal area reveals that it is relatively flat in the upper zone and then abruptly plunges into the bottom of the main channel where elevations increase in an upstream direction. The waterline during the Highest Low Water (HLW) is drawn back to the bottom of the channel at the middle part of the tidal flat and is formed along the slant of the channel during the Lowest High Water (LHW). The intertidal zone is located between -410 cm and 510 cm in terms of elevation and its total area is $0.65km^2$. An area between the Highest High Water (HHW) and Lowest High Water (LHW), occupying about 80% of the total area, occupies $0.52km^2$ of total area and accounts for 56% of the exposure duration. The boundary of wetland protection area in the Siheung tidal flat did not exactly coincide with the intertidal regime and differs by more than 15%. This study, which precisely analyzed the tidal flat area, tidal environment, and topography, would be useful in making a conservation plan and in learning how to use a wetland protection area in a sustainable manner.

• The Journal of the Korea Contents Association
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• v.13 no.2
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• pp.505-511
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• 2013

A new boundary treatment technique which can be applied to axi-symmetric topography with inclined bottom was developed. Although the finite element method is good for complex geometry, there is no proper boundary treatment when a boundary is not a vertical section because the water depth at the coastline becomes zero. In this study, we developed a new boundary treatment for inclined bottom using the analytical solution for long wave. To develope a model, the mild-slope equation was used and then, a computational domain is divided into an analytical region and a numerical region. By combining a numerical and an analytical solutions, a complete solution was obtained. The developed solution was validated by comparing with a previous analytical solution.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.6 no.3
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• pp.309-325
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• 1994

Ocean circulation in the Gulf of Alaska is remarkably constant throughout the year despite of being forced by one of the largest seasonal wind stresses in the world. To explain the small seasonal changes in the transport of Alaska Stream. a set of numerical models is employed. First a diagnostic approach is applied to reproduce circulation from the observed density structure. The results reveals the very small seasonal changes in the Alaska Stream transport. Next a series of the prognostic models is used: a barotropic model. a flat bottom baroclinic model, and baroclinic model with topography. These models reveal the influence of topography and baroclinicity on the ocean's response to the seasonal wind forcing. The intercomparisons of the various model results suggest that the seasonal response of the baroclinic ocean is primary barotropic and the resultant barotropic circulation is weakened by the scattering effect of the bottom topography.

• Journal of Ocean Engineering and Technology
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• v.17 no.2
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• pp.1-7
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• 2003

A common feature in the three-dimensional numerical model experiments of coastal discharge with simplifed model and idealized external forcings is investigated. The velocity fields due to the buoyancy and flow flux, are spreaded radiately and the surface velocites are much greater than homegeneous discharges. The coastal dischargd due to the Coriolis force and flow flux are shaped a anticyclical gyre (clockwise) and determined the scale of the gyre in the coastal zone, respectively. The bottom topography restricts a outward extention of the coastal fronts and it accelerates a southward flow.

• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
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• 1997.10a
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• pp.39-44
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• 1997

As wind waves generated in deep water approach nearshore zone, they experience various physical phenomena caused by bathymetric variations, nonlinear interactions among different wave components and interferences with man-made coastal structures. Among these, the bathymetric variations may play a significant role in the change of wave climate. The accurate calculation of reflection and transmission coefficients of incident waves over a bottom topography is indispensible for the proper and economical design of coastal structures. (omitted)

• Korean Journal of Fisheries and Aquatic Sciences
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• v.22 no.6
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• pp.375-384
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• 1990

A numerical experiment is made to study the combined effect of differential cooling and bottom topography on the formation of Ulleung Warm Eddy. The Ulleung Warm Eddy appears after the passage around the Ulleung Basin of coastal trapped baroclinic waves generated in the north initial density front to the north, the continental slopes both to the west and south, and the Yamato Rise to the east. It resides therefore always inside the Ulleung Basin, as confirmed by observations.

• 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.