• Water for future
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• v.24 no.4
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• pp.41-48
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• 1991

This paper describes the characteristics of tidal currents in the Gamag Bay by using the two-dimensional nonlinear hydrodynamic euation. The basic equations are derived by Navier-Stokes momentum equation and continuity equation and its characteristics critically are reviewed, and they are analysed by the implicit finite difference method. The numerical model is constructed two-dimensional(depth-averaged) simple layer model. This paper investigates the stability of solution and convergence of solution in application of the method to Gamag Bay, and the reproducibility of the simulation is also discussed in comparison with the results of field survey. The following items are clarifide through the numerical investigation; i)the reproduc-ibility of tidal range and currents are quite acceptable, comparing with the results of model tests and field data, and ii) tidal cycle for convergent solution is four tidal cycle, also, iii) bottom friction is successfully represented as c=(1/n))$h^{1/6}$.

• Journal of the Korean Society of Marine Environment & Safety
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• v.5 no.1
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• pp.9-18
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• 1999

To predict the oil spill dispersion phenomena in the ocean, the oil spill response model, which can be used for strategic purpose on the oil spill site, based on Lagrangian particle-tracking method was formulated and applied to the neighboring area with Pusan port where the oil spill incident occurred when the tanker ship No.1 Youil struck on a small rock near the Namhyungjeto on September 21, 1995. The real-time tidal currents to be required as input data of the oil spill model were obtained by the two-dimensional hydrodynamic model and the tide prediction model. Evaluation of tidal currents using observation data was successful. For wind data, other input data of oil spill model, observed data on the spot were used. To verify the oil spill model, the oil spill modelling results were compared with the field data obtained from the spill site. Compared the modelling results with the observation data, there exist some discrepancies but the general pattern of modelling results was similar to that of field observation. The modelling results on 7 days after spill occurred showed that the 40% of spilled oil is in floating, 36% in evaporated, 23% at shore, and 1% in out of boundary, respectively. According to the evaluation of weighting curves of effective components to the dispersion of oil, the winds make a 37% of contribution to the dispersion of oil, turbulent diffusion 39.5%, and tidal currents 23.5%, respectively. Provided the more accurate wind data are supported, more favorable results might be obtained.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2001.05a
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• pp.154-159
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• 2001

Nakdong estuary is located at south-eastern coast of the Korea. A lot of sediment from upper river was deposited at this area. It has caused many problems such as changes in topography and tidal current. In this paper, field observation data on tidal currents and sediments were investigated as well as historical topographic changes by dredging and reclamation of the foreshore. Then, the numerical model considered the settling velocity of the suspended solids according to the particle size was applied to examine the characteristic of deposition. The results are as follows : 1. Changes of characteristics of deposition were caused by topographic changes of Nakdong estuary 2. Characteristics of deposition were influenced by river plume and tidal currents. 3. Numerical model which considers settling velocity reappeared distribution of deposition by particle-size. 4. Used model is only resonable for discussion in the quality, so, it is strongly suggested that the new model development is needed including the quatitative deposition processes.

• Journal of Ocean Engineering and Technology
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• v.19 no.1 s.62
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• pp.1-7
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• 2005

Tidal circulation in a closed bay using a variation of bottom roughness was investigated through the numerical experiments based on a finite difference multi-level model. Various distributions of bottom roughness in the bay were implemented to determine their effects. It hadbeen determined that residual currents can be generated from the differences of the bottom roughness between streaming and reverse flow directions. The magnitude of residual currents and volume flow rate increase when the relative ratio of bottom roughness between streaming and reverse flow directions increase. Circulation in the closed bay is also improved by the employment of the change of bottom roughness.

• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
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• 2002.08a
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• pp.208-211
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• 2002

The Kyunggi Bay (125-l28E, 36-38N) is a macro-tidal bay in the western central port of Korean Peninsula(Fig. 1). The Bay characterizes its feature as wide tidal flats, deep tidal channels and tidal sand ridges running in parallel to tidal flows. The macro-tidal range (up to approximately 8.6m) and consequent strong tidal currents erode the bottom sediment and selectively transport to the low-energy area forming tidal ridges or tidal flats. (omitted)

• Ocean and Polar Research
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• v.39 no.3
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• pp.169-179
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• 2017

The "GeoDrifter" is a newly-developed surface drifter with high temporal resolution. It is the first time that high-frequency drifters have been deployed in the East/Japan Sea. The purpose of this study is to introduce the phenomena experienced by these drifters flowing along with the Tsushima Current across the East/Japan Sea, focusing on high-frequency variability, and to discuss them in comparison with previous observations. The observed basin-scale circulation of the Tsushima Current generally coincides well with the known schematic circulation. The GeoDrifter trajectories also show inertial oscillations almost everywhere in the oceanic regions of the East/Japan Sea, strong semi-diurnal tidal currents in the western part of Korea Strait, diurnal currents much stronger than semi-diurnal currents in the upstream region of the Nearshore Branch off the Japanese coast, and many warm eddies in the Yamato Basin, all comparable to the observational results reported in the previous studies. An interesting point is that the semi-diurnal tidal currents undergo a great spatial variation in the western part of the Korea Strait. The observed features that cannot be explained are, among others, strong counter-clockwise motions with oscillating period about 51 hours appearing in the upstream region of the Nearshore Branch off the Japanese coast and the different tidal behaviors between upstream and downstream regions of the latter.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.16 no.1
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• pp.47-55
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• 2004

A SS prediction system using GUI in coastal region has been developed to predict the dispersion of the suspended sediments occurred by dredging. The prediction system uses a finite element hydrodynamic model to calculate water level and velocities and a random-walk particle tracking model to simulate SS dispersion. The system was applied to hindcast the tidal currents and SS concentrations in the Kunsan coastal waters. The simulated tidal currents showed good agreements with the observed currents. The transport model was verified for analytic solutions and field observation showing good agreements.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.6 no.4
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• pp.335-339
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• 1994

The Tartar Strait currents of different scales are analysed using results of observations and modeling. The paper focuses on tidal phenomena and general circulation features. It is shown that the areas of maximal tidal currents are located in the regions of stable boundary streams. The stability of the streams under different meteorological conditions and energy concentration in the small areas may be explained by non-linear effects of tide over rough bottom topography.

• Journal of Energy Engineering
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• v.28 no.1
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• pp.65-72
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• 2019

The Korean government is aiming to produce 20% of the electricity using renewable energy sources by 2030. Ocean renewable energy sources which are abundant in South Korea can do an important role to achieve the goal. This paper introduces a tidal current energy converter utilizing flow induced vibrations which can efficiently work even in the currents slower than 1.0m/s and suggests optimal designs of the tidal energy converter based on speeds of the tidal currents in seven different coastal regions in South Korea. Moreover, the theoretical annual energy production by the tidal converter is estimated at theses costal areas. The total amount of the annual energy production by the tidal energy converter is predicted as 221.77 TWh which is equivalent to 42.3% of the electric consumption of South Korea in 2013. The result shows that the tidal current energy converter can be an important role to achieve the goal of the Korean government.

• Ocean and Polar Research
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• v.33 no.3
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• pp.309-319
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• 2011

This is a preliminary study of the feasibility of obtaining reliable tidal current harmonic constants, using one month of current observations, to verify the accuracy of a tidal model. An inference method is commonly used to separate out the tidal harmonic constituents when the available data spans less than a synodic period. In contrast to tidal constituents, studies of the separation of tidal-current harmonics are rare, basically due to a dearth of the long-term observation data needed for such experiments. We conducted concurrent and monthly harmonic analyses for tidal current velocities and heights, using 2 years (2006 and 2007) of current and sea-level records obtained from the Tidal Current Signal Station located in the narrow waterway in front of Incheon Lock, Korea. Firstly, the l-year harmonic analyses showed that, with the exception of $M_2$ and $S_2$ semidiurnal constituents, the major constituents were different for the tidal currents and heights. $K_1$, for instance, was found to be the 4th major tidal constituent but not an important tidal current constituent. Secondly, we examined monthly variation in the amplitudes and phase-lags of the $S_2$ and $K_1$ current-velocity and tide constituents over a 23-month period. The resultant patterns of variation in the amplitudes and phase-lags of the $S_2$ tidal currents and tides were similar, exhibiting a sine curve form with a 6-month period. Similarly, variation in the $K_1$ tidal constant and tidal current-velocity phase lags showed a sine curve pattern with a 6-month period. However, that of the $K_1$ tidal current-velocity amplitude showed a somewhat irregular sine curve pattern. Lastly, we investigated and tested the inference methods available for separating the $K_2$ and $S_2$ current-velocity constituents via monthly harmonic analysis. We compared the effects of reduction in monthly variability in tidal harmonic constants of the $S_2$ current-velocity constituent using three different inference methods and that of Schureman (1976). Specifically, to separate out the two constituents ($S_2$ and $K_2$), we used three different inference parameter (i.e. amplitude ratio and phase-lag diggerence) values derived from the 1-year harmonic analyses of current-velocities and tidal heights at (near) the short-term observation station and from tidal potential (TP), together with Schureman's (1976) inference (SI). Results from these four different methods reveal that TP and SI are satisfactorily applicable where results of long-term harmonic analysis are not available. We also discussed how to further reduce the monthly variability in $S_2$ tidal current-velocity constants.