• Journal of the korean society of oceanography
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• v.32 no.1
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• pp.28-37
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• 1997

Two marine bivalve shells were collected from the eastern and western coastal regions of Korea, respectively. Stable oxygen and carbon isotope profiles are constructed using the incremental sampling along the axis of maximum growth to provide the continuous ${\delta}^{18}$O and ${\delta}^{13}$C records, which register the physical, biological and chemical properties of seawater where the organisms live. Cycles in the ${\delta}^{18}$O profiles are interpreted as annual along with the identification of annual growth bands; the maximum ${\delta}^{18}$O values correspond with the coldest temperature of seawater whereas the minimum ${\delta}^{18}$O values with the warmest temperature. The primary control on the amplitude of the ${\delta}^{18}$O profiles is seasonal variation of seawater temperature. The offset of the baseline between ${\delta}^{18}$O values of the two specimens is attributed to differences in both temperature and seawater ${\delta}^{18}$O values between two localities. The ${\delta}^{13}$C profiles show the similar seasonality of carbon cycling associated with phytoplankton productivity. The offset in the ${\delta}^{13}$C profiles between two specimens may be, as in the case of oxygen isotope profile, attributed to the different ${\delta}^{13}$C value of the seawater DIC (dissolved inorganic carbon) between the western coast and the eastern coast. Relationships between the shell isotopic composition and the coastal water properties of shell growth are readily interpreted from the ${\delta}^{18}$O-${\delta}^{13}$C pair diagram of the shell isotope data, similar to the use of salinity-${\delta}^{18}$O diagram for identifying water masses. The preliminary stable isotope results of this study suggest that mollusk shell isotope geochemistry may be useful to monitor the properties of water masses in the coastal and inner shelf setting around Korea and improve the interpretation of paleoceanography, provided the fossil mollusks are well preserved.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.1193-1194
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• 2015

The volume electrical resistivity of $3.777{\times}10^{13}{\Omega}{\cdot}cm$ of dried CSPE for 660~750 days after seawater & freshwater soaking is lower than $4.011{\times}10^{13}{\Omega}{\cdot}cm$ of that before seawater soaking. The peak binding energy of oxygen and sulphur of CSPE after seawater & freshwater soaking are shifted above 1.0ev. The grass transition temperature($T_g$) of $-19.76^{\circ}C$ of seawater & freshwater soaked CSPE are lower than $-19.59^{\circ}C$ of that of non-soaked CSPE. The melting temperatures($T_m$) of seawater & freshwater soaked and non-soaked CSPE are $45.58^{\circ}C$ and $45.59^{\circ}C$, respectively.

• Journal of Power System Engineering
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• v.20 no.5
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• pp.92-97
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• 2016

In this study, the seawater Heat Pump System using seawater with temperature of annual domestic conditions ($0^{\circ}C$ to $25^{\circ}C$) is designed in order to compare its performance against the Heat Pump using unused heat of seawater. As a potential replacement for current refrigerants that exacerbate global warming and ozone delpetion, a Low GWP refrigerant's performance is analyzed. The basic water to water Heat Pump system is chosen and three commercial refrigerants - R134a, R410a, R32 - are used to compare against new Low GWP refrigerant R1234ze. When seawater with temperature of $25^{\circ}C$ is used, the performance change showed maximal increase in COP, 38.3%. low GWP refrigerant R1234ze, showed great performance characteristics reach to 5.242 and Existing commercial refrigerant, R134a showed only less than 0.03 performance difference against R1234ze. The study confirms notable performance of R1234ze refrigerant through simulation as environmentally friendly refrigerant for domestic seawater Heat Pump.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.19 no.2
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• pp.164-168
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• 2014

To determine the optimal storage method and longest possible storage period of Zostera marina seeds, we examined post-storage germination rates using different storage methods and periods for Z. marina seeds harvested in southern coast of Korea. Storage methods included in seawater at room temperature with air supply, seawater at $4^{\circ}C$, seawater at $30^{\circ}C$, an aquarium with continuous seawater circulation, seawater at room temperature in an airtight tank, a refrigerator at $-20^{\circ}C$, and a desiccator at room temperature. Germination rates of Z. marina seeds stored in seawater at $4^{\circ}C$ showed highest germination (52.0%), whereas those of seeds stored in seawater at room temperature and an aquarium were 27.4% and 17.7%, respectively. But the seeds stored in seawater at $30^{\circ}C$, a refrigerator, and a desiccator did not germinate. Storage periods were 10, 20, 30, 60, 180 and 240 days of storage. Z. marina seeds maintained germination rates of 46.4~52.4% until 10~60 days of storage, but showed rapidly decreasing germination rates after then and no germination after 240 days.

• KIEAE Journal
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• v.16 no.3
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• pp.25-34
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• 2016

Purpose: The temperature in Seoul has risen 3 times more than the average global temperature increase for the past 100 years. Today, summer starts 15 days earlier than the early 20th century and is 32 days longer. This tendency causes rapid increase of cooling energy demand. Following this effect, seawater heat resources are to be used as an countermeasure for global warming. Incheon Port near the Western Sea has the lowest water temperature in the winter in South Korea in which it is suitable to use seawater cold heat resources. Method: The cold heat resource is gained from seawater when the water temperature is the lowest in the winter time and saved in a seasonal thermal storage. This can be used as cold heat resource in the summer time. A heat exchanger is essential to gain seawater cold energy. Due to this necessity, sea water heat resource heat exchangers are modeled by heat transfer equations and the fluid characteristics are analyzed. Also, a CFD (computational fluid dynamics) program is used to conduct simulation on the fluid characteristics of heat exchangers. The analyzed data of deducted from this process are comprehensively analyzed and discussed. Result: Regarding the performance of the heat exchanger, the heat exchanger was operated following the prediction within the range of heat transfer rate of minimum 3.3KW to maximum 33.6KW per device. In the temperature change analysis of the heat exchanger, fluid analysis by heat transfer equations almost corresponded to the temperature change by CFD simulation. Therefore, it is considered that the results of this study can be used as design data of heat exchangers.

• Journal of Environmental Science International
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• v.21 no.9
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• pp.1079-1085
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• 2012

Ground seawater quality was investigated, and the algal growth potential (AGP) tests were performed along the Tongyeong coast to examine the inflow of materials, which is needed for the red tide species Cochlodinium polykrikoides to grow. The study was conducted to determine the mechanism for C. polykrikoidesred tides. Water temperature, salinity, pH, and dissolved oxygen (DO) ranged from 16.05 to $20.74^{\circ}C$, 18.20 to 32.11 psu, 6.00 to 7.61, and 3.41 to 7.91 mg/L (41.4-96.1%), respectively. No seasonal variation was observed in water temperature. The salinity, pH, and DO saturations at most stations were lower than those of coastal seawater at Tongyeong. The ${NH_4}^+$-N, ${NO_{2+3}}^-$-N, ${PO_4}^{3-}$-P concentrations ranged from 0.43 to 16.00 ${\mu}M$, 1.50 to 132.38 ${\mu}M$, and 1.30 to 6.29 ${\mu}M$, respectively; the values at some stations were much higher than observed in Tongyeong coast seawater. Using seawater from station B, C. polykrikoides grew consistently, with a high growth rate, similar to the red tide in nature. This seawater appeared to contain materials needed by C. polykrikoides to grow. Therefore, C. polykrikoides red tides seem to occur wherever the ground sea water contains materials that are needed for its growth.

• Development and Reproduction
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• v.13 no.1
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• pp.35-41
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• 2009

In the present study, we investigated the effects of rearing condition during the winter period on artificial maturation and reproduction of cultured female eel, Anguilla japonica. The female eel was adapted by combination of environmental conditions (seawater/low temperature, $10^{\circ}C$; seawater/high temperature, $20^{\circ}C$; freshwater/low temperature, $10^{\circ}C$; freshwater/high temperature, $20^{\circ}C$) during 8 weeks of the winter period. Then, the female eel cultivated by different conditions during the winter were transferred to seawater at $20^{\circ}C$ for induction of artificial maturation by salmon pituitary extraction (SPE) injection. The results shown that gonadosomatic index (GSI) and plasma levels of estradiol-$17{\beta}$ (E2) were significantly higher in female eel were reared in seawater than in freshwater, and were the highest at eel adapted by seawater/low temperature. Also, reproduction coefficient were higher in seawater/low temperature than in the other groups. These results will provide valuable information for elevation of the artificial maturation and reproduction coefficient in the cultured female eel.

• Journal of Environmental Science International
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• v.19 no.11
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• pp.1397-1405
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• 2010

Mass mortalities of cultivated organisms have occurred frequently in Korean coastal waters causing enormous losses to cultivating industry. The preventive measures require continuous observation of farm environment and real-time provision of data. However, line hanging aquaculture farm are generally located far from monitoring buoys and has limitations on installation of heavy equipments. Substituting battery pack for solar panels and miniaturizing size of buoy, newly developed system can be attached to long line hanging aquaculture farm. This system could deliver measured data to users in real-time and contribute to damage mitigation and prevention from mass mortalities as well as finding their causes. The system was installed off Gijang and Yeongdeck in Korea, measuring and transmitting seawater temperature at the sea surface every 30 minutes. Short term variation of seawater temperature, less than one day, in Gijang from June to July 2009 corresponded tidal period of about 12 hours and long term variation seemed to be caused by cold water southeast coast of Korea, particularly northeast of Gijang. Seawater temperature differences between Gijang station and the other station that is about 500 m away from Gijang station were $1^{\circ}C$ on average. This fact indicates that it is need to be pay attention to use substitute data even if it is close to the station. Daily range of seawater temperature, one of crucial information to aquaculture, can be obtained from this system because temperature were measured every 30 minutes. Averages of daily range of temperature off Gijang and Yeongdeok during each observation periods were about $2.9^{\circ}C$ and $4.7^{\circ}C$ respectively. Dominant period of seawater temperature variation off Yeongdeok was one day with the lowest peak at 5 a.m. and the highest one at 5 p.m. generally, resulting from solar radiation.

• Ocean and Polar Research
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• v.30 no.3
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• pp.249-258
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• 2008

Oxygen isotopic composition(${\delta}^{18}O$) of walleye pollock, Theragra chalcogramma, otoliths were measured to investigate interannual and regional correlation with habitat temperature. Specimens were collected from fishermen in Korea and Japan between $1997{\sim}1999$, while seawater temperatures were obtained from Korean and Japanese Oceanographic Data Centers. Seawater temperature was generally lower off the eastern Korean Peninsula than off eastern Hokkaido(Japan). Sagittal otoliths were removed for measurement of ${\delta}^{18}O$ using a micro-drilling technique. In most cases, ${\delta}^{18}O$ and habitat temperature exhibited negative relationship in Korean and Japanese waters. Higher ${\delta}^{18}O$ was observed in Korean pollock compared to Japanese pollock. The marginal parts of otoliths exhibited higher ${\delta}^{18}O$ than cores from both regions. This is an indication that somatic growth of walleye pollock occurs in deeper and cooler waters. Interannual variation in ${\delta}^{18}O$ was also observed. Mean ${\delta}^{18}O$ values acquired from 1997 otoliths were lower(2.15%) than those of 1998(2.67%) and 1999 (2.65%) in Korean pollock. These measurements coincided with changes in observed temperature in Korean waters, in which mean seawater temperature was warmer in 1997 than in 1998 and 1999. In Japanese waters, mean seawater temperature was lowest in 1997, which coincided with highest ${\delta}^{18}O$ values in the same year.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2005.10a
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• pp.158-159
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• 2005

This study showed that the highest temperature point of the Dongrae thermal spring in Pusan was moved to the north direction of the Dongrae fault as times goes by. The Br concentration(1.5mg/L) in Dongrae thermal waters indicated the influence of 2% seawater mixing. If the simple mixing without hydrochemical reaction occurs between seawater and thermal water, the concentration of Mg will be about 20mg/L. But the low concentration(0.1 mg/L) of Mg, contrary to high concentration(10 mg/L) of surrounding groundwater not affected by thermal water, suggested the thermal water, seawater and rock interactions. The calculation of saturation index(SI) by using the geochemical code of EQ3NR showed that the Mg in thermal groundwater, which was introduced by seawater, was removed by the precipitation of Antigorite (SI: log Q/K =71.753, $Mg_{48}Si_{24}O_{85}(OH)_{62}$) and Tremolite (SI: 8.463, $Ca_2Mg_5Si_8O_{22}(OH)_2$), Talc (SI: 6.409, $Mg_3Si_4O_{10}(OH)_2$), Dolomite (SI: 2.014, $CaMg(CO_3)_2$), Chrysotile (SI: 3.698, $Mg_3Si_2O_5(OH)_4$) in the crack of fault zone. The highest temperature point in the study area will move to north direction and stop in the Jangjun area without the input of seawater.