• Journal of the Korean Society for Marine Environment & Energy
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• v.1 no.1
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• pp.56-65
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• 1998

An oil spill model, Green Sea Ranger(GSR) based on trajectory and fate modeling of spilt oil behavior is introduced. The various physical models on weathering processes are reviewed and those adopted by GSR are described. A database for currents, which is necessary for the real-time simulation of oil spill, is generated on the south sea of Korea. The real-time prediction of tidal currents in the South Sea of Korea is carried out. Four major constituents (M₂, S₂, K₁, O₁ tide) are employed in the prediction, and those angular speeds and phases are determined from the astronomical arguments. The harmonic constants of the constituents are computed by solving shallow-water tide equations. The GSR has user-freiendly GUI and flexible framework which makes it easy to expand the database for sea environments in Korean coastal waters. The GSR is validated by the simulation of O-Sung oil spill caused by a grounded oil tanker in coastal sea near Maemol-do. The simulated trajectory is compared with observed one and it is shown that the GSR gives reasonable estimation on spilt oil bahavior.

• Magazine of the Korean Society of Agricultural Engineers
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• v.34 no.2
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• pp.73-84
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• 1992

The TIDE, finite element model for the simulation of tidal flow in shallow sea was tested for its applicability at the Saemangeum area. Several pre and post processors were developed to facilitate handling of the complicated and large amount of input and output data for the model developed. Also an operation scheme to run the model and the processors were established. As a result of calibration test using the observed data collected at 9 points within the region, linearlized friction coefficients were adjusted to be ranged 0.0027~0.0072, and water depths below the mean sea level at every nodes were changed to be increased generally by 1 meter. Comparisons of tidal velocities between the observed and the simulated for the 5 stations were made and obtained the result that the average relative error between simulated and observed tidal velocities was 11% for the maximum velocities and 22% for the minimum, and the absolute errors were less than 0.2m/sec. Also it was found that the average R.M.S. error between the velocities of observed and simulated was 0.119 m/sec and the average correlation coefficient was 0.70 showing close agreement. Another comparison test was done to show the result that R.M.S. error between the simulated and the observed tidal elevations at the 4 stations was 0.476m in average and the correlation coefficients were ranged 0.96~0.99. Though the simulated tidal circulation pattern in the region was well agreed with the observed, the simulated tidal velocities and elevations for specific points showed some errors with the observed. It was thought that the errors mainly due to the characteristics of TIDE Model which was developed to solve only with the linearized scheme. Finally it was concluded that, to improve the simulation results by the model, a new attempt to develop a fully nonlinear model as well as further calibration and the more reasonable generation of finite element grid would be needed.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.28 no.5
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• pp.265-276
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• 2016

The 2011 Tohoku, Japan Tsunami, which occurred on March 11, 2011, reached the Korean Peninsula and was recorded at numerous tide stations. In the records of the north-eastern tide stations, tsunami forerunners were found in only about a few minutes after the earthquake, which was much earlier than the expected arrival time based on a numerical simulation. Murotani et al. (2015) found out that the bathymetry effect is related to the tsunami forerunners observed in Japan and Russia. In this study, the tsunami forerunners observed in Korea were well reproduced by a numerical simulation considering the bathymetry effect. This indicates that it is important to consider the bathymetry effect for a tsunami caused by an earthquake on shallowly dipping fault plane(e.g. 2011 Tohoku, Japan Earthquake). However, since the bathymetry effect requires additional computation time, it is necessary to examine the problems that results from applying the bathymetry effect to the tsunami warning system.

• Journal of the Korean Society of Marine Environment & Safety
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• v.21 no.5
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• pp.583-590
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• 2015

Submarine cable installation is essentials for grid connection between existing power grid and newly produced electricity which will be from offshore wind farm in Southwest sea area of Korea. Especially, submarine cable route and protection method is designed in order to ensure the economical efficiency, workability and stability of submarine cable installation. On this paper, we will give the basic information about the submarine cable route and protection method of offshore wind farm which will be built in Southwest sea area of Korea. For this, we have a numerical simulation at high and low tide based on the third-generation wave model SWAN(Simulating WAves Nearshore) using the long term wave data from Korea Institute of Ocean Science and Technology(KIOST). The results of the study, year mean Hs is 1.03m, Tz is 4.47s and dominant wave direction is NW and SSW When the incident wave direction is NW(Hs: 7.0 m, Tp: 11.76s), the distribution of shallow water design wave height Hs was calculated about 4.0~5.0m at high tide and 2.0~3.0m at low tide. When the incident wave direction is SSW(Hs: 5.84 m, Tp: 11.15s), the distribution of shallow water design wave height Hs was calculated about 3.5~4.5m at high tide and 1.5~2.5m at low tide. The wave direction on a dominant influence in the section of longitude UTM 249749~251349(about 1.6 km) and UTM 251549~267749(about 16.2 km) in the submarine cable route are each NW and SSW. Prominently, wave focusing phenomenon appears between Wi-do and Hawangdeung-do, in this sea area is showing a relatively high wave hight than the surrounding sea areas.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.14 no.2
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• pp.136-150
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• 2002

To improve the water quality of the recently constructed Siwhaho, sluice gates were operated to allow free exchange of water with the sea. This estuarine lake connected to the outer sea through narrow gates is affected mainly by flushing by gate operation and river flows and wind forcing sometimes. As a predicting tool far the water qualities, a three-dimensional finite volume model CE-QUAL-ICM is incorporated into a finite element hydrodynamic model, TIDE3D. In coupling these two different modules, a new error minimization technique is applied by considering conservation of mass. Model tests for one year after calibration and validation using field observation show that eutrophication and other biological changes reach quasi-steady state after initial 60 days of simulation, thus it would be necessary to consider moderate ramp up option to remove initial uncertainties due to cold start option. Sediment-water interaction might not be a concern in the long-term simulation, since its effect is negligible. Simulated results show the newly applied scheme can be applied with satisfaction not only fur lessening of eutrophic processes in an estuarine lake but also looking for some active circulation to improve water quality.

• Journal of the Korean Society for Marine Environment & Energy
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• v.12 no.4
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• pp.264-272
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• 2009

Due to an oil spill accident occurred in Taean coastal zone wide range of coastal waters were polluted. Inaccurate prediction of spilled oil trajectory is known as a cause that has increased the pollution damage in the beginning stage. In this study, a numerical modeling of spilled oil dispersion has been conducted to know which physical factors caused the severe and wide pollution. Especially the simulation is focused on how to model hydrodynamic circulation accurately. The simulation results showed that the hydrodynamic flow is very important in predicting oil fate, specially, in the short-term dispersion of spilled oil.

• Journal of the Korean Society of Safety
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• v.33 no.2
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• pp.132-137
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• 2018

Compared with general rivers, fluctuations of the water level and the river bed are severe in the tidal river. In hydro-dynamic aspect, such fluctuation gives different river-bed data to us according to observing period. The time-dependent river-bed data and pre-estimation of the Manning's roughness coefficient which is the key factor of numerical modelling induces uncertainty of evaluating the design flood level. Thus it is necessary to pay more attention to calculate the flood level at tidal rivers than at general rivers. In this study, downstream of the Imjin River where is affected by tide of the West Sea selected as a study site. From the numerical modelling, it was shown that the unsteady simulation gave considerable mitigation of the water level from the starting point to 15 km upstream compared to the steady simulation. Either making a detention pond or optional dredging was not effective to mitigate the flood level at Gugok - Majung region where is located in the downstream of the Imjin River. Therefore, a more sophisticated approach is required to evaluate the design flood level estimation before constructive measures adopted in general rivers when establishing the flood control plan in a tidal river.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.5 no.2
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• pp.99-106
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• 1993

A two-dimensional numerical analysis is performed for the simulation of intertidal-flat and analysis of hydraulic characteristics during seadike construction in Sae-Man-Keum tidal basin. The shallow water equations are selected as a mathematical model and the Leendertse's ADI scheme is used as the corresponding numerical model. The simulated results of tide and current by the present model agree welt with the experimenta1 results by the hydraulic Lab. or ADC (1989). In the application of the model, the possibility of rapidly varied flow analysis and the introduction of turbulence model required for more accurate hydraulic calculation at closing gap are described. The successive simulation of flooding/drying effects by a modification of the method by Stelling et al. (1986) can easily be used for the intertidal-flat analysis during tidal reclamation.

• Journal of the Korean Society for Marine Environment & Energy
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• v.7 no.1
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• pp.1-12
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• 2004

The summer distribution of $Cha-{alpha}$ and physical processes for simulating outbreak region of red tide were estimated by the Eco-Hydrodynamic model in Chinhae Bay. As a result of simulation of surface residual currents, the southward flow come in contact with the northward flow at the inlet and western part of bay in case of windlessness and below wind velocity 2 m/sec. As wind velocity increases, the velocity and direction of currents were fairly shifted. The predicted concentration of $Cha-{alpha}$ exceeded 20 mg/㎥ in Masan and Haengam Bays, and most regions were over 10 mg/㎥, which meant the possibility of red tide outbreak. From the results of the contributed physical processes to $Cha-{alpha}$, accumulation sites were distributed at the northern part of Kadok channel, around the Chilcheon island, the western part of Kajo island and some area of Chindong Bay. On the other hand, inner parts of the study area such as Masan Bay were estimated as the sites of strong algal activities. Masan and Haengam Bay are considered as the initial outbreak region of red tide by the modeling and observed data, and then red tide expanded to other areas such as physical accumulation region and western inner bay, as depending on environmental variation. The increase of wind velocity led to decrease of $Cha-{alpha}$ and enlargement of accumulation region. The variation of intensity of radiation and sunshine duration caused to rapidly fluctuation of $Cha-{alpha}$: however, it was not largely affected by the variation of pollutant loads from the land only.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.23 no.3
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• pp.205-214
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• 2011

Finite element grid refinements with different intensities having 14 K, 52 K and 211 K on the Yellow Sea (YS) have been constructed to make precise tidal simulations. In the meanwhile 57 K grid was made to the extended North Western Pacific (NWP) sea. Numerical simulation were done based on 32 parallel processors by using pADCIRC v 49.21 model. In the YS tidal simulation on YS-G52K and YS-G211K grid structure, KorBathy30s and ETOPO1 bathymetry data are used and 4 major tidal constituents are prescribed from FES2004. Computed results are in good agreement within 0.138 meter in RMS error for amplification and 14.80 degree of phase compared to observed tidal records. Similar error bounds are acquired in the extended NWP tidal simulation on NWP-G57K grid with 8 tidal constituent prescription on the open boundary.