• Korean Journal of Environmental Biology
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• v.20 no.2
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• pp.118-129
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• 2002

Zooplankton was sampled vertically with a Norpac net from Gamag Bay in April, July, September and December, 2001. Copepods were predominant in April and December, and cladocerans in July and Noctituca scintillans in September, respectively. There are high spatio-temporal fluctuations in the abundance of zooplankton with a range of 22-17,197 indiv.$m^3$. In the copepod community, neritic species, Eurytemora pacifica, Acartia omorii, Centropages abdominalis and Calanus sinicus were predominant in April ; Labidocera rotunda and A. erythraea in July; A. erythraea and Paracalanus parvus s. 1. in September; A. omorii and E. pacifica in December. However, oceanic species Eucalanus sp. and Neocalanus sp. were abundant in September. It indicates that although Gamag Bay is semi-closed, the distribution pattern of zooplankton is seasonally strongly affected by oceanic waters in addition to neritic ones.

• 한국해양학회지
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• v.17 no.1
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• pp.12-18
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• 1982

Tidal exchanges of sea water are studied by using drogue experiments and tidal current measurement data in Gamag Bay which has two channels. At the spring tide, the volume of tidal transport in the bay was estimated to be 46∼52% of the total volume of sea water in Gamag Bay, 7.1 10$\^$8/㎥. The tidal transport through the wide channel occupies 87% of the total tide transport of the bay. Residual current was deduced to flow north-northeastward at the rate of 3.254 10$\^$5/㎥ per tidal cycle. the tidal exchange of the sea water during the flood flow was estimated to be approximately 26% of the tidal transport, while that during the ebb flow was 41%. The tidal exchange through the wide channel during the flood flow occupies 77% of total tidal exchange of the bay through both channels, whereas that during the ebb flow does 88%. The diffusion coefficient of 2.08∼ 2.30 10$\^$7/$\textrm{cm}^2$/sec at the narrow channel was greater than that at the wide channel which was 1.2∼2.8 10$\^$6/$\textrm{cm}^2$/sec.

• 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 for Marine Environment & Energy
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• v.8 no.4
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• pp.213-219
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• 2005

In this study, we try to Quantitatively assess the micropollutants in Gwangyang bay, Gamag bay and Yeoa bay, using simultaneous analytical method fir 310 chemicals. In the results, several dozen organic pollutants were detected in sampling sites, and the major chemicals detected were CH type chemicals, such as aliphatic and polycyclic compounds, and CHN(O) type chemicals, such as aromatic ammines and nitro compounds. The concentration of organic pollutants was higher in summer than in winter. However, there was no association of species of organic pollutants with season. The total concentration of pesticides at each sampling site was measured within the range of $ND{\sim}9.11{\mu}g/L$. Insecticides and fungicides of pesticide type were detected in Gwangyang bay and Gamag bay, while six kinds of endocrine disrupter were detected in southern coastal waters. From the results of this study, we should estimated that the insecticides, the fungicides, and a few of the endocrine disrupters are major pollutant factors in southern coastal waters.

• Journal of the Korean Society of Marine Environment & Safety
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• v.23 no.1
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• pp.83-90
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• 2017

To understand the spatial-temporal distribution of seawater in Korea's South Sea, seawater movement and the distribution of water temperature has been analyzed using a hydrodynamic model (the Princeton Ocean Model). The directions of tidal currents were generally westward during flood tides and eastward during ebb tides. Northeastward Tsushima Warm Currents in the open sea, which is deeper than 50m were stronger than in coastal areas. Analysis of data from the hydrodynamic model showed that the water temperature in the semi-closed bay was relatively higher ($26{\sim}28^{\circ}C$) than in the open sea ($18{\sim}22^{\circ}C$). The exchange volume of semi-closed seawater was $10,331m^3/sec$ in Gwangyang Bay, $16,935m^3/sec$ in Yeosu-Gamag Bay and $13,454m^3/sec$ in Geoje-Hansan Bay. Therefore, it was shown that the lower seawater exchange volume is, the higher seawater temperature will be.

• The Korean Journal of Malacology
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• v.28 no.1
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• pp.73-79
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• 2012

Seasonal changes in biochemical composition of muscle, gonad-viceral, mass and whole body of the cultured ark shell, Scapharca broughtonii in the Gamag bay of Yeosu city were studied from December 2008 to November 2009 in relation to environmental condition and reproductive cycles. Average monthly water temperature in the winter was in the range of $7-12^{\circ}C$ and $20-25^{\circ}C$ in the summer, while the salinity fluctuated in the range of 30.1%-33.8‰ on the average. Seasonal fluctuation of the concentration of nutrient salt was the highest in September ($13.04{\mu}g/L$) with average annual concentration of $4.6{\mu}g/L$. The main spawning season of the ark shell was during the months of July and August, and the gonads were in inactive stage during the winter. The gonad-visceral mass contained lower amounts of proteins than the other body parts. The most marked changes in body composition were lipids and carbohydrates within the gonad-visceral mass, and protein for each of the organs was relatively consistent throughout the year. All the parts in the visceral sac displayed the highest changes during the gametogenic cycle while the contents of moisture and lipid within the visceral act displayed somewhat inverse relations with each other. Moisture content was the lowest during the inactive stage during which the lipid content is the highest. The lipid content was the lowest immediately following spawning with increase in the moisture content as the lipid is being consumed. Protein mass within the visceral sac was low in comparison to the muscle mass. It is deemed that carbohydrates, lipids and proteins in the visceral sac play the major role as the source of energy during the development process of the gonads, and used for maintenance of base metabolism when available food is scarce.