• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
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• 2006.09a
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• pp.21-24
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• 2006

• Journal of the Korean Society for Marine Environment & Energy
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• v.14 no.2
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• pp.121-129
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• 2011

The EFDC model has been simplified to enhance the computing performance in hydrodynamic modeling. Water quality module and unnecessary conditional statements were deleted in subroutine list and memory allocation. The performance of the enhanced model (EFDC-E) was checked by applying EFDC and EFDC-E models to simulating the tidal flow in Mokpo coastal zone. Both two-dimensional models and threedimensional models have been applied and compared. Three-dimensional models showed better simulation results agreeing with observed currents than two-dimensional models. The simulation results of EFDC-E model gave good results agreeing with the simulation results of EFDC model and the observed data. The computing speed of EFDC-E model is improved 3 times faster than that of EFDC model in modeling hydrodynamic flow for real time of 3 days in both 2-dimensional modeling and 3-dimensional modeling. The EFDC-E model can be used widely for hydrodynamic modeling because of improved simulation speed.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.21 no.3
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• pp.230-240
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• 2009

The ESCORT model is applied at Mokpo coastal zone to analyze the effect of fresh water discharge released from the gates of the Youngsan River sea-dyke. Applicability and validity of both 2-D and 3-D hydrodynamic modules could be guaranteed by simulating hydrodynamic feature with ebb dominance characteristics. Then, effects of the released discharge on the hydrodynamics are investigated. And analysis of the effects on diffusion phenomena show that 3-D model is essential for such diffusion modelling. Moreover, vertical salinity distributions near the gates are examined, and the influence range of fresh water is also estimated, which shows that dilution of fresh water is going on slowly because of poor flushing.

• Journal of the Korean Society of Marine Environment & Safety
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• v.15 no.3
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• pp.187-203
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• 2009

This study monitored marine environments in system coastal waters of the South Sea of Korea during the period of 2005-2007 and analyzed the data from environmental parameters and nutrients, which contributed to fluctuate marine environmental characteristics in aquaculture. On the basis of the fluctuation of temperature depending on seasons and sampling sites, too seasons of winter and summer showed a remarkable temperature gap of $5^{\circ}C$ compared with spring and autumn. Salinity in spring and summer approached 9 psu in Morkpo. Most of sampling sites showed COD below 2mg/L, indicating somewhat optimal environmental conditions. T-N and T-P also had desirable horizontal distributions all year round the concentration of SS was higher, but Chi. a was well-distributed horizontally except for Morkpo. Marone environmental parameters of surface water were similar to those of bottome water except for Morkpo. Most of sampling sites showed the ratio of N/P below 16, impling that nitrogen played an important role in growth of phytoplankton as a limiting factor. The relationship between Chi. a and nutrients was positive linear, whereas the relationship between Chi. a and COD were very strong positive. winder, Spring and Summer showed the strong relationship between Chi. a and COD. In the analysis of dendogram based on environmental parameters using SPSS ver. 10.0, the station 7 did not belong to other stations, and kept an independent place. The relationships of waters between Jindo, Wando and Heanam ware close, compared with other waters. Consequently, these regions except for Morkpo into which fresh water is introduced by the dike showed somewhat optimal environmental parameters and nutrients in year, and were assumed to maintain the desirable marine conditions for aquaculture.

• Journal of the Korean Society for Marine Environment & Energy
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• v.11 no.1
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• pp.13-23
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• 2008

In coastal region, eutrophication, Do deficit and red tide are frequently occurred by influx of fresh water. When the fresh water containing pollutants is discharged into the sea, the surrounding water is contaminated by dispersion of freshwater flowing into coastal waters. The prediction and analysis about the dispersion process of the discharged fresh water should be conducted. A modeling system using GUI was developed to simulate hydrodynamic flow and fresh water dispersion in coastal waters and to analyze the results efficiently. The modeling module of the system includes a tide model using a finite element method and a fresh water dispersion model using a particle-tracking method. This system was applied to predict the tidal currents and fresh water dispersion in Mokpo coastal zone. To verify accuracy of the hydrodynamic model, the simulation results were compared with observed sea level and time variations of tidal currents showing a good agreement. The fresh water dispersion was verified with observed salinity distribution. The dispersion model also was verified with analytic solutions with advection-diffusion problems in 1-dimensional and 2-dimensional simple domain. The system is operated on GUI environment, to ease the model handling such as inputting data and displaying results. Therefore, anyone can use the system conveniently and observe easily and accurately the simulation results by using graphic functions included in the system. This system can be used widely to decrease the environmental disaster induced by inflow of fresh water into coastal waters.

• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
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• 2008.09a
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• pp.232-235
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• 2008

• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
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• 2009.10a
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• pp.148-151
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• 2009

• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
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• 2008.09b
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• pp.232-235
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• 2008

• Journal of Environmental Science International
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• v.14 no.2
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• pp.177-184
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• 2005

This study was to determine the fluctuation in phytoplankton assemblages with regarding to environmental conditions and nutrients, which were surveyed around Mokpo waters in the southwestern waters, Korea. Sampling was carried out on the Mokpo, Sinan, and Wando coasts from March to November 2003. The maximum sea surface temperature was recorded in August, and it ranged around $25^{\circ}C$ regardless of sampling sites. However, salinity in Mokpo waters showed a great variation, which ranged from 5-30 psu and recoded the minimum of 5 psu in July and the maximum of 30 psu in November. Moreover, in Mokpo waters, the chlorophyll a and SS concentration of the surface layer were also the highest values of $20\;{\mu}g\;l^{-1}\;and\;40\;{\mu}g\;l^{-1}$, respectively than those of Sinan and Wando waters. The concentrations of $NH_4-N,\;NO_2-N,\;NO_3-N,\;and\;PO_4-P$ were also he highest values of $0.018\;{\mu}mol\;^l{-1},\;0.062\;{\mu}mol\;l^{-1},\;1.2\;{\mu}mol\;l^{-1}\;and\;0.078\;{\mu}mol\;l^{-1}$, respectively in Morpo waters than those of Sinan and Wando waters. During the period of this study, the majority of the taxa were diatoms; Thalassiosira rotula, Rhizosolenia setigera, Prorocentrum minimum, Chaetoceros curvisetus, Leptocylindrus danicus, Pseudonitzschia pungens, and Chaetoceros spp. were detected in the dominant species of phytoplankton. The dinoflagellates were relatively abundant during the summer season in Wando waters, which attained an abundance of $10-20\%$. In Mokpo waters, DIN/DIP was the highest value of 700 in March, whereas the lowest was shown in Wando waters. However, DIN/DIP value in summer at Wando waters was extremely reversed, which appeared to be associated with the development of dinoflagellates. On the bais of factor analysis using SYSAT 6.0, nutrient showed somewhat correlation with chlorophyll a. Consequently, the process of discharge of fresh water in Mokpo waters plays an important role in extremely fluctuation in nutrients and conditions. Although Wando waters maintains a lack of nutrients, it should be influenced by different water current and may be associated with a concentration of nutrients.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.18 no.4
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• pp.348-359
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• 2006

The city of Mokpo suffers lowland inundation damages by sea water flooding even without harsh weather like a typhoon, due to the low level urban infrastructure facilities, oceanic environmental changes by constructions of seadike/seawall and sea level rise caused by global warming. This study performs constructing the simulation system which employs the MIKE21 software. And the system is applied to several typhoon- induced surges which had resulted in inundation at Mokpo. Virtual situation of flooding is simulated in case 59 cm of surge height, which had been occurred actually by RUSA(0215), coincides with Approx. H.H.W. Then the water level of 545 cm corresponds to the extreme high water level(544 cm) for 10 year return period after the construction of Geumho seawall. The results show rapid and broad inundation at Inner-Port, requiring additional preparations for flood protections.