• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.13 no.4
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• pp.308-319
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• 2008

Temporal variations in plankton assemblages and environmental factors in Asan Bay and their relationships were examined with the data collected from February till early June, 2005. Seawater temperatures showed typical pattern of temporal change observed in temperate waters. Salinity variation was minor. Phytoplankton biomass showed two peaks, one in February only in the inner part of the bay and the other in May in the whole bay. Phytoplankton succession was clearly shown with the increase of seawater temperatures. Diatom (Bacillariophyceae) dominated in February, diatom and cryptomonads (Cryptophyceae) prevailed in May, and dinoflagellates (Dinophyceae) was most abundant in June. Spring bloom in Asan Bay occurred about one month earlier than those observed in temperate seas. Among the inorganic nutrients (N, P and Si), only silicate concentration showed a significant negative correlation with phytoplankton biomass, indicating the sink of this nutrient in the bay to be the uptake by phytoplankton. Nitrate concentration seemed to be a limiting factor in this bay during the study period. Mesozooplankton abundances showed a significant positive correlation with seawater temperatures and a significant negative correlation with phytoplankton biomass. Increase of mesozooplankton abundance followed phytoplankton increase with the time lag of about two months. This increase of zooplankton seemed to be the result of increased seawater temperatures and food.

• Journal of The Korean Society of Agricultural Engineers
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• v.47 no.5
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• pp.3-13
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• 2005

The present study examined the 3 dimensional space distribution characteristics of sea water intrusion using data available from previous observations. For this study, we used 3D FEMWATER, which is a 3 dimensional finite element model. The target area was around Daechang-ri, Gimje-si, Jeollabuk-do. The area is relatively easy to formulate a conceptual model and has observation wells in operation for surveying sea water intrusion. Considering the uncertainty of numerical simulation, we analyzed sensitivity to hydraulic conductivity, which has a relatively higher effect. According to the result of the analysis, the variation of TDS concentration had an error range of $-1,336{\~}+107 mg/{\iota}$. Taking note that the survey data from observation wells were collected when the boundary between fresh water and sea water in the aquifer was in equilibrium, we set the range of time for numerical simulation and estimated the spatial distribution of TDS concentration as the range of sea water intrusion. According to the result of estimation, the spatial distribution of TDS concentration calculated when 1,440 days were simulated was taken as the range of sea water intrusion. Using the result of calculation, we can draw not only vertical views for a certain section but also horizontal views of different depth. These views will be greatly helpful in understanding the spatial distribution of the range of sea water intrusion. In addition, the result of this study can be used rationally in proposing an optimal quantity of water pumping through investigating the moving route of sea water intrusion over time in order to prevent excessive water pumping and to maintain an optimal number of water pumping wells per interval.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.32 no.2
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• pp.238-241
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• 1999

Experiments were performed to find out the physico-chemical properties of milt and the sperm motilities in various conditions using the grey mullet, Mugil cephalus. The average concentration of sperm in the milt was $1,11 \pm0.36\times10^{10}/ml$. Spermatocrit was 96.7$\pm$2.6. pH and osmolality of seminal fluid were 7.8$\pm$0.1, 370$\pm$6 mOsm/kg, respectively, Total protein concentration of sperm was higher than that of seminal fluid, but total lipid concentration of seminal fluid was higher than that of sperm. The sperm motility was high in the diluent of milt : artificial seawater (1:10, by volume) and in 822 mOsm/kg and 983 mOsm/kg similar to seawater osmolality, but it decreased after 20 minutes. But activity of sperm was highly maintained in 482 mOsm/kg which was a little higher than osmolality of seminal fluid, and was high in pH 7$\~$9.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.573-576
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• 2008

When the concrete structures are in contact with seawater, concentration of chloride for estimating chloride diffusion coefficient can be defined as the chloride concentration of sea water. However, in case the concrete structures, constructed in the seashore, aren't directly in contact with seawater, it is difficult to establish the interface concentration of chloride. In addition, marine concrete structures are greatly affected by salt attack such as rebar corrosion, among the cause of salt attack, airborne chlorides is primary factor. Therefore, in this study, salt attack environment by airborne chlorides was investigated in terms of a seasonal distribution at 72 spots, 27 areas in the East, West, South coast for 3 years from July '03 to June '06. Results indicated that in the East and South coast, the amount of the airborne chlorides is comparatively higher in summer, in the West coast, higher in winter according to the seasonal wind.

• Journal of the Korean Society of Marine Environment & Safety
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• v.21 no.1
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• pp.9-17
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• 2015

In order to elucidate the current state of marine pollution of heavy metals around major shipyards in Korea, seawater samples were collected at eleven sampling stations and four control stations around 4 major shipyards located in the southeastern coast of Korea in summer 2010, and 6 kinds of metals such as copper(Cu), zinc(Zn), iron(Fe), cadmium(Cd), lead(Pb) and mercury(Hg) in seawater samples were analyzed. The analyses of heavy metals in seawater showed that the mean Cu concentrations in seawater around 4 major shipyards were in the range of $0.817{\sim}1.638{\mu}g/L$ which were lower than Korean environmental standards of $20{\mu}g/L$ for the protection of human health(PHH) and of $3{\mu}g/L$ for short-term protection of marine ecosystem(SPME) but higher than Cu concentration at control station by a factor of up to 2.75. The mean Zn concentrations were in the range of $0.228{\sim}0.567{\mu}g/L$ which were lower than Korean environmental standards of $100{\mu}g/L$ for PHH and $34{\mu}g/L$ for SPME but higher than Zn concentration at control station by a factor of up to 5.91. The mean Fe concentrations were in the range of $3.332{\sim}7.410{\mu}g/L$ which were higher than Fe concentration at control station by a factor of up to 6.75. The mean Cd concentrations were in the range of $0.013{\sim}0.028{\mu}g/L$ which were lower than Korean environmental standards of $10{\mu}g/L$ for PHH and $19{\mu}g/L$ for SPME but higher than Cd concentration at control station by a factor of up to 2.33. The mean Pb concentrations were in the range of $0.007{\sim}0.126{\mu}g/L$ which were lower than Korean environmental standards of $50{\mu}g/L$ for PHH and $7.6{\mu}g/L$ for SPME. The mean Hg concentrations were in the range of $0.002{\sim}0.004{\mu}g/L$ which were lower than Korean environmental standards of $0.5{\mu}g/L$ for PHH and $1.8{\mu}g/L$ for SPME. Although the concentrations of metals such as Cu, Zn and Fe which were used in shipbuilding works were lower than Korean environmental standards for PHH and SPME, the fact that the concentrations of Cu, Zn and Fe at sampling stations around major shipyards were higher than those at control stations implies that the works in shipyards had some effects on marine water quality around shipyards. Therefore, marine environment management such as the prevention and control of the discharge of various pollutants from shipyards is required on national level.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.14 no.3
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• pp.223-234
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• 2016

This study aimed to the adsorption-removal of high- radioactive iodide (I) contained in the initially generated high-radioactive seawater waste (HSW), with the use of AgX (Ag-impregnated X zeolite). Adsorption of I by AgX (hereafter denoted as AgX-I adsorption) was increased by increasing the Ag-impregnated concentration in AgX, and its concentration was suitable at about 30 wt%. Because of AgCl precipitation by chloride ions contained in seawater waste, the leaching yields of Ag from AgX (Ag-impregnated concentration : about 30~35 wt%) was less than those in distilled water (< 1 mg/L). AgX-I adsorption was above 99% in the initial iodide concentration ($C_i$) of 0.01~10 mg/L at m/V (ratio of weight of adsorbent to solution volume)=2.5 g/L. This shows that efficient removal of I is possible. AgX-I adsorption was found to be more effective in distilled water than in seawater waste, and the influence of solution temperature was insignificant. Ag-I adsorption was better described by a Freundlich isotherm rather than a Langmuir isotherm. AgX-I adsorption kinetics can be expressed by a pseudo-second order rate equation. The adsorption rate constants ($k_2$) decreased by increasing $C_i$, and conversely increased by increasing the ratio of m/V and the solution temperature. This time, the activation energy of AgX-I adsorption was about 6.3 kJ/mol. This suggests that AgX-I adsorption is dominated by physical adsorption with weaker bonds. The evaluation of thermodynamic parameters (a negative Gibbs free energy and a positive Enthalpy) indicates that AgX-I adsorption is a spontaneous reaction (forward reaction), and an endothermic reaction indicating that higher temperatures are favored.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.09a
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• pp.446-449
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• 2004

High resolution geophysical imaging to delineate costal aquifer and seawater- freshwater interface has been applied in Baesu-eup, Yeonggwang-gun, Jeolla province Electrical resistivity information from vertical electrical sounding and 2-D electrical resistivity survey is key parameter to map equivalent Nacl concentration map over the survey area. Seismic velocity from refraction tomographic survey, on the other hand, gives more reliable information on the subsurface stratagraphy than electrical resistivity methods which frequently suffer from low resolution due to masking effect. We imaged high-resolution 3-D structure of costal aquifer by correlating the electrical resistivity with seismic velocity, and mapped equivalent NaCl concentration map using resistivity and hydro-geological information from well logging.

• Korean Journal of Environmental Biology
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• v.19 no.1
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• pp.7-17
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• 2001

Growth optima and tolerance ranges of marine algae species nay vary greatly during the developmental stage. The establishment stage is clearly of great importance for each generation, affecting the performance of the adult population. The present study was aimed to determine the effect of various concentrations of inorganic nutrients and heavy metals on germination and germlings of Ulva pertusa Kjellman (Chlorophyta). Percent germination increased rapidly as irradiance level increased, reaching the maximum at 100 ${\mu}$mol m$\^$-2/s$\^$-1/ in both east and west seawater. Percent germination in the east seawater was higher than that in the west seawater at irradiances lower than 30 ${\mu}$mol m$\^$-2/s$\^$-1/, and there was no difference in percent germination between the two different seawaters at irradiances higher than 60 ${\mu}$mol m$\^$-2/s$\^$-1/. Germling growth increased in the both cases with increasing irradiances but no growth was found in the dark. Overall germling area was larger in the east seawater than in the west seawater. Number of cell increased with increasing irradiance and became light-saturated at 100 ${\mu}$mol m$\^$-2/s$\^$-1/ in the both cases. Germlings grown in the east seawater had more cells than those cultivated in the west seawater at irradiances lower than 60 ${\mu}$mol m$\^$-2/s$\^$-1/. In various combinations of nitrate and phosphate, percent germination increased with increasing nitrate concentrations irrespective of phosphate concentrations. At 3 days after inoculation, nitrate concentration of 2.5 ppm with all phosphate concentrations promoted germination. Area and number of cell of germlings increased with increasing nitrate concentrations in all phosphate concentrations. In various combinations of copper and lead, germination was delayed as copper concentrations increased in all lead concentrations. Percent germination was severely reduced at 1 ppm Cu$\^$2+/. Area and number of cell of germlings decreased with increasing copper concentrations in all lead concentrations. The highest copper concentration (1 ppm) clearly suppressed the germling growth in U. pertusa.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.6
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• pp.735-749
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• 2018

In this study, one studied the principal factors and water-quality components that determine the concentration of chemical oxygen demand (COD) in seawater in estuaries, such as the Han, Geum, Youngsan, Seomjin, and Nakdong rivers in Korea. The principal factors determining the concentration of COD in seawater indicated by the principal component analysis were salinity, exogenous origin and autochthonous resources based on chlorophyll-a. Moreover, organic matter in the submarine sediment layer also had a secondary effect. Regression slope assessed the contribution of water-quality components to determine the concentration of COD in the estuary. One found that the effect of salinity on the overall survey was significant. Moreover, the effect of chlorophyll-a was also appeared in April and August. In each estuary, the most significant contribution factor was chlorophyll-a in the Nakdong River and salinity in the Han and Yongsan rivers. The contribution of salinity and chlorophyll-a were found to be the largest in the Geum River. The salinity and chlorophyll-a in the Seomjin River showed a low contribution.

• Journal of fish pathology
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• v.12 no.1
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• pp.32-41
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• 1999

Ozonization for rearing seawater in land-based culture system has recently been utilized for disinfection of pathogenic microorganisms and improvement of water quality. This study was conducted to examine the effects of total residual oxidants (TRO) in ozone-treated seawater on survival, blood parameters, osmolality and oxygen consumption, and gill tissue of the flounder. Paralichthys olivaceus. Experiments were carried out with the starved flounder of 12~19 cm in total length at $20^{\circ}C$. The 48-hr and 96-hr $LC_{50}$ for the flounder amounts to 26.4 ppb and 22.3 ppb, respectively. With increase of TRO concentration from 24 to 39 ppb, the values of hematocrit, hemoglobin concentration, red blood cell count and osmolality of the flounder with respect to exposure time were significantly elevated, however, the oxygen consumption rates decreased. In the case of the fish exposed to 13 ppb for 96 hrs, blood glucose increased with an elapse of exposure time, while survival rate was 100%. Death apparently resulted by massive destruction of gill lamellar epithelium, severe osmotic imbalance and the lack of oxygen uptake. The results of this experiment indicated that to protect aquaculture organisms, the ozone-treated seawater should not contain any residual oxidants, and that relatively long-term exposure to TRO of low concentration can impact on survival and physiological conditions of the flounder.