• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.5 no.2
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• pp.131-140
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• 2000

Heavy metals (Fe, Mn, Cr, Co, Cu, Ni, Zn, Pb) were determined in ninety-one surface sediments collected from Kwangyang Bay, south coast of Korea. The data show that the Fe, Cr, Ni, and Zn distribution in the bay can be described by metal vs. grain size relationship. However, the distribution pattern of Mn, Co, Cu and Pb were found to be changed because they are anthropogenically enriched to sediment. Correlation matrix and R-mode factor analyses revealed that two important factors controlling the distribution of metals in the bay are grain size and anthropogenic input.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.27 no.3
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• pp.168-174
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• 2015

Characteristics of high waves occurred in winter season on the west coast of Korea were investigated by analyzing the wave data observed at five observation locations. Records of four different high waves were subjected to the analysis together with the corresponding meteorological data during those time periods. The significant wave height reached its maximum of 6.42 m on December 4th, 2005. It was clarified that the high waves occurred due to strong wind fields that were formed over the west sea of Korea when the extra-tropical cyclone was excessively developed. Characteristics of the high waves generated in the west sea seemed to be predominantly wind sea as the temporal variation of the wave height at the coast were closely related to those of the wind speed measured at neighboring weather stations.

• Journal of the Korean Society for Marine Environment & Energy
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• v.4 no.1
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• pp.14-23
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• 2001

The characteristics of tidal circulation with Hyungsan River discharges in Youngil Bay by the numerical experiments is elucidated. For the simulation of tidal residual currents related to inflow by the river discharges in Youngil Bay located in the southeastern part of Korean Peninsula, the two-dimensional numerical experiment is peformed. The tidal elevation boundary conditions of the 4 main tidal harmonic constituents (M₂, S₂, K₁ and O₁) on the open boundary and river discharges at the river boundary are considered. The computed results obtained from numerical experiment showed good agreements with the field observation ones. The residual currents generally flow toward the inner bay through the western (Dalman-Gap) and central areas of the bay, and then the currents go toward the outer bay along the eastern shore (Changgi-Gap) of the bay with anti-clockwise circulation. Especially, in the numerical experiment without Hyungsan River discharges, these flow patterns are disappeared. Based on the results, it showed that the Hyungsan River discharges play the dominant role in the patterns of tidal residual currents. This flow pattern of tidal residual currents are important mechanism of water quality, material transport in Youngil Bay.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.6 no.2
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• pp.139-149
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• 1994

In this paper, a finite element technique is applied to the prediction of the wave resonance phenomena in harbors. The mild-slope equation is used with a partial reflection boundary condition introduced to model the energy dissipating effects on the solid boundary. For an efficient modeling of the radiation condition at infinity, a new infinite element is developed. The shape function of the infinite element is derived from the asymptotic behavior of the first kind of the Hankel's function in the analytical boundary series solutions. For the computational efficiency, the system matrices of the element are constructed by performing the relevant integrations in the infinite direction analytically. Comparisons with the results from experiments and other solution methods show that the present model gives fairly good results. Numerical experiments are also carried out to determine the proper distance to the infinite elements from the mouth of the halter, which directly affect the accuracy and efficiency of the solution.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.14 no.2
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• pp.116-127
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• 2002

Most of finite difference numerical models for the simulation of tsunami propagation developed so for are based on the shallow-water equations which are frequently solved by the leap-frog scheme. If the grid size is properly selected, this numerical scheme gives a correct dispersion effect fur constant water depth. However, if the water depth changes, the dispersion effect of tsunamis can not be accurately considered at every grid point in the whole computational domain. In this study we improved the existing two-dimensional dispersion-correction finite difference numerical scheme. The present scheme satisfies the local dispersion relationships of tsunamis propagating over a slowly varying topography while using uniform grid size and time step. To verify the applicability of the improved numerical model, a tsunami due to 1983 East Sea central earthquake is simulated for Korean harbors with the tide gage records such as Sokcho, Mukho, Pohang and Ulsan in the East Sea. Numerical results of the 1983 tsunami are compared with the measured data and the accuracy of the present numerical model is evaluated.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.4 no.4
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• pp.201-207
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• 1992

The averaged non-linear term in the turbulence equations, suggested by Yeo (1987), is analyzed theoretically and experimentally. It was formulated by applying the filtering concepts to the convolution integral average definition with the Gaussian response function. This filtering approach seems to be superior to the conventional averaging methods in which all four terms at the doubly average vol must be defined separately, and it also gives a very useful tool in understanding the turbulence structures. By theoretically analyzing the newly derived description for the averaged non-linear terms, it is found that the vortex stretching can be explicitly accounted for. Furthermore, comparisons of the correlation coefficients based on the experimental data show that the vortex stretching acts most significantly on the turbulence residual stress. Thus, it strongly supports the claim that the vortex stretching is essential in the transfer of turbulence. In addition. a general form of turbulent energy models in LES is derived, by which it is recognized that the Smagorinsky, the vorticity and the SGS energy models are not distinctive.

• Journal of the Korean Society of Marine Environment & Safety
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• v.20 no.2
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• pp.234-240
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• 2014

In this paper, the interface matrix of honeycomb composite panel has been derived by the governing equation of a honeycomb sandwich panel. The interface matrix of honeycomb panel is added to the previously developed transfer matrix method, thus analysis of the multi-layered insulation composite panel with honeycomb is accomplished. Furthermore, predictions of sound transmission loss(STL) for the ship's insulation panel with honeycomb and mineral wool are presented. The insulation performance of the honeycomb used for skin of the ship's insulation panel is better than that of 0.35 mm steel panel by 2dB, approximately. Although honeycomb panel has inefficient insulation performance beside steel panel, honeycomb panel achieve improvements in the performance of weight reduction. The surface density of the panel with honeycomb is rather than with steel by $5.2kg/m^2$. It is decrease in weight by 31.7 %.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.7 no.1
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• pp.91-107
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• 1995

In this paper, previously proposed mechanisms of generation and maintenance of rip currents are grouped into three broad categories; (1) prismatic topography models, (2) non-prismatic topography models and (3) structural controls by natural and/or constructed features, such as headlands, piers. groins, jetties. etc. The prismatic models can explain the occurrence of a rip current on a planar beach, while non-prismatic model needs undulatory topography inside the surf zone to generate and maintain a rip current. Yet more detailed and thorough studies need to be conducted to include all relevant variables and to clarify the mechanism(s) governing rip current. Next a simple model is presented to predict mean longshore currents behind a longshore bar (or submerged breakwaters) by considering mass transport over the bar and the bar morphology. This hydrodynamic model could be extended to include the sedimentary feedback mechanism.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.8 no.1
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• pp.28-36
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• 1996

The influence of vertical eddy viscosity to the nonlinear interaction of tidal current and wind-induced current is examined using a point model. A zero-equation turbulence model is derived by simplifying the q$^2$-q$^2$1 turbulence model under the assumption that the generation of turbulence kinetic energy is balanced with its dissipation and is further modified to include the depth of frictional influence properly The zero-equation turbulence model is derived and the possibility of resonance in the presence of Coriolis effect is suggested. The amplitudes of tidal currents remain the same regardless of the applied wind stress, but the over-tide component is generated due to the nonlinear interaction of tidal current and wind-induced current. Significant changes in the vertical profile of wind-induced currents can occur according to tide-induced background turbulence. The turbulence model can give rise to misleading results when applied to the wind-driven circulation in the tide-dominated sea such as Yellow Sea unless the tide-induced background turbulence is adequately included in the parameterization of vertical eddy viscosity.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.27 no.6
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• pp.391-405
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• 2015

A global tsunami prediction system was suggested for a distant tsunami using a finite fault model and a cyclic boundary condition. The possibility of the suggested system as a distant tsunami response system was checked by applying it into the case of 2014 Chile tsunami. A comparison between the numerical results(tsunami height and arrival time) with different conditions (boundary condition, governing equation, grid size and fault model) and measured data (DART buoy, tide station) showed the importance of the finite fault model and the cyclic boundary condition.