• Journal of Fisheries and Marine Sciences Education
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• v.27 no.2
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• pp.526-536
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• 2015

Changes of oxygen consumption in juvenile giant grouper, Epinephelus lanceolatus were investigated in order to find out the physiological responses associated with freshwater and low salinities acclimation. Salinity changes in this experiment were set as follows; 35 psu (Exp. I) as control, decrease in the manners of $35{\rightarrow}20{\rightarrow}10{\rightarrow}0$ psu (Exp. II), $35{\rightarrow}10{\rightarrow}0$ psu (Exp. III) and $35{\rightarrow}0$ psu (Exp. IV). The average oxygen consumption at $27^{\circ}C$ in Exp. I (control) was $106.9{\pm}0.7mg$ $O_2/kg/h$. In Exp. II, according to the changes of $35{\rightarrow}20{\rightarrow}10{\rightarrow}0$ psu in freshwater acclimation, fish showed the gradual decrease in oxygen consumption as $108.1{\pm}2.1$, $99.6{\pm}2.9$, $74.6{\pm}0.9$ and $62.7{\pm}1.0mg$ $O_2/kg/h$, respectively. The fish in Exp. III also revealed the same tendency as $106.5{\pm}1.3$, $77.0{\pm}1.2$ and $64.7{\pm}1.2mg$ $O_2/kg/h$, respectively. In Exp. IV, fish showed the decreased oxygen consumption from $109.0{\pm}0.9mg$ $O_2/kg/h$ of 35 psu to $71.6{\pm}2.0mg$ $O_2/kg/h$ of 0 psu. Giant grouper is thought to be a diurnal fish species, because the level of oxygen consumption during light period was higher than that during dark period.

• The Journal of the Acoustical Society of Korea
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• v.34 no.1
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• pp.1-11
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• 2015

Salinity affects sound speed in the low salinity environment, in the seas where freshwater from large rivers and flows into the marginal sea area near the Yangtze River and the Niger River. In this paper, SSC (Surface Sound Channel) formed by low salinity water was investigated in the East China Sea and the Gulf of Guinea of rainy season. The data from KODC (Korea Oceanographic Data Center) in the East China Sea and from ARGO (Array for Real-time Geostrophic Oceanography) in the Gulf of Guinea of the tropical area were used for analysis. SSC haline channel was formed 14 times among 32 SSC occurrences when the 90 data from 9 points were analyzed during a decade (2000 ~ 2009) in the East China Sea. In the Gulf of Guinea, haline channel was formed 18 times among 20 SSC occurrences during 3 years (2006 ~ 2009). When the sound speed gradient was analyzed from temperature-salinity gradient diagram, the gradients of both salinity and temperature affect SSC formation in the East China Sea. In contrast, the salinity gradient mostly affects SSC formation due to the least change of temperature in the well-developed mixed layer in the Gulf of Guinea. Their acoustic characteristics show that channel depth is 6.5 m, critical angle is $1.5^{\circ}$ and difference of transmission loss between surface and thermocline is 11.5 dB in the East China Sea, while channel depth is 18 ~ 24 m, critical angle is $4.0{\sim}5.4^{\circ}$ and difference of transmission loss is 21.5 ~ 27.9 dB in the Gulf of Guinea. These results are expected to be used as a basic understanding of the acoustic transmission changes due to low salinity water at the estuaries and the ocean with heavy precipitation.

• Journal of Internet Computing and Services
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• v.1 no.1
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• pp.73-86
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• 2000

The Geographic Information System (GIS) is a system that collects, stores, analyzes and processes geographic object data existing in space. The GIS is widely used in application fields related to geography such as city planning, land-register management, forest resources management, etc. The importance and necessity of the GIS have been well demonstrated, and therefore many studies on this system have been carried out. However, most of those studies have just treated geographic information as spatial information, but have not considered or have overlooked changes of spatial data dependent on time. For example, transportation information management and atmospheric phenomena forecast, have not exactly reflected the actual world which changes with the flow of time. In this thesis, a temporal GIS is established to effectively and precisely process information on space objects changing with time and a database is built up in reference to changes in water temperature and salinity. And the isotherm and isohaline forecast system implemented to support graphical tool.

• Korean Journal of Ichthyology
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• v.12 no.2
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• pp.111-117
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• 2000

There were observed the histomorphological alterations such as chloride cell hyperplasia, branchial lamellar epithelial separation, the increased cellular turnover of chloride cells, glomerular shrinkage and blood congestion in rainbow trout (Oncorhynchus mykiss) during the seawater adaptation. The ultrastructure by scanning electron microscope (SEM) indicated that the gill secondary lamella of rainbow trout exposed to seawater, were characterized by rough convoluted surfaces during the adaptation. There were observed a large number of mitochondria with the elongate and well-developed cristae in chloride cells exposed to seawater by transmission electron microscope (TEM). The presence of two mitochondria- rich cell types is discussed with regard to their possible role in the hypoosmoregulatory changes which occur during seawater-adaptation. Glomerulus shrinkage and blood congestion were occurred higher in nephrons of seawater-adapted fish than those living in freshwater. Our findings demonstrated that rainbow trout tolerated moderately saline environment and the increased body weight living in seawater was relatively higher than that living in freshwater in spite of histopathological changes.

• Journal of The Korean Society of Agricultural Engineers
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• v.54 no.2
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• pp.103-113
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• 2012

본 연구에서는 하수재이용에 따른 논에서의 토양염분 변화를 추정하기 위하여 경기도 화성시 수원환경사업소 인근에 위치한 병점지구를 대상으로 수문순환과 작물성장과의 관계를 고려한 SWAP (Soil-Water-Atmosphere-Plant) 모형을 이용하여 평가하였다. 실험에 사용한 관개용수는 지하수 (TR#1), 하수처리장 방류수+여과+UV (TR#3)로 분류하여 모형에 사용하였다. 유입관개수의 EC (Electrical Conductivity)는 지하수 관개수인 TR#1이 다른 처리구에 비해 작았고, TR#3의 경우 0.442~0.698 dS $m^{-1}$의 범위를 보였다. 모형의 보정과 검정을 위해서 대상지구에 FDR (Frequency Domain Reflection)을 설치하여 토양수분함유량과 염분농도를 토심에 따라 일단위로 모니터링 하였다. 토심 (50, 100, 140 cm)에 따른 토양함수량의 RMSE는 검정기간 중 TR#1에서 0.003~0.064 $cm^3\;cm^{-3}$, TR#3에서 0.001 $cm^3\;cm^{-3}$ 범위를 보여 주었고, 토양염분의 보정기간 중 토심별 RMSE는 TR#1에서 0.018~0.037 dS $m^{-1}$, TR#3에서 0.004~0.014 dS $m^{-1}$ 범위를 보여 적용성이 있는 것으로 나타났다. 토양내의 염분수지 분석 결과, 토양에서의 염분저장량이 (-)로 나타나 토양내로 침출되는 것으로 나타났으며, WMRI (Water Management Response Indicators)을 이용한 분석 결과, 높은 침투능으로 인하여 토양에서의 염분 집적 영향은 낮은 것으로 평가되었다.

• The Korean Journal of Malacology
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• v.29 no.4
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• pp.303-311
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• 2013

This study investigated survival, falling and structural changes of foot in Haliotis discus hannai with various water temperature and salinity. Experimental conditions were composed of control with $20^{\circ}C/33.5$ psu, higher temperature group with 23, 26, 29 and $32^{\circ}C$, lower temperature group with 3, 6, 9 and $12^{\circ}C$, and different salinities group with 33.5, 26.8, 20.1, 13.4, 6.7 and 3.3 psu. Experimental period was 7 days. Survival and falling rate of the abalone exposed to 7 days at control and experimental condition of $12^{\circ}C$ and $23^{\circ}C/33.5$ psu were 100% and 0%, respectively. Mortality and falling rate of the abalone exposed to the different temperature and salinity were dose dependent by experimental condition. Histopathological changes in epithelial and muscular layer of foot showed more obvious with experimental condition of salinity decrease than different temperature condition.

• The Korean Journal of Malacology
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• v.19 no.1
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• pp.1-8
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• 2003

The present study was performed to describe the influence of water temperature and salinity on the filtration rates of the short-necked clam, Ruditapes philippinarum. The clams were collected at tidal flat near Yeosu city, Cheollanamdo, Korea, from July 2001 to August 2001. Diatoms, Phaeodactylum tricornutum (KMCC B-128), were indoor-cultured by f/2 medium, and were used to measure the filtration rate of the clams. Filtration rates of the clams were measured by indirect method. Cell concentrations of food organisms were determined by direct counting cells using the hemacytometer under the light microscope. The filtration rate of the clams increased with temperatures up to the optimum temperature, circa 25$^{\circ}C$. Above this optimum temperature, the filtration rate decreased drastically. Also the filtration rate of the clams increased with salinity up to 35 psu. The maximal filtration rates of the clams were recorded at 20-25$^{\circ}C$, similar to be known as the optimal temperature for their growth, and 25-35 psu, respectively. The minimal filtration rates of the clams were recorded at 5$^{\circ}C$ and 15 psu. At the similar temperature and salinity, the filtration rate of the younger clams was higher than that of the older ones. Thermal coefficient, Q$_{10}$ values at low temperature range were much higher than those at high temperature range. These results indicate the short-necked clam is more sensitive in cold water. As they grow up, they become more stronger against their ambient environmental changes, such as thermal-shock, salinity changes.

• Journal of the Korean Society for Marine Environment & Energy
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• v.9 no.4
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• pp.225-234
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• 2006

Using the data from the sea water monitoring system installed at the Ieodo Ocean Research Station, we have analyzed the water properties around the station as well as the characteristics of the fresh water from the Changjiang River and the influence of typhoons on the sea water. In general, the accuracy and stability of the temperature data are high, but those of the salinity data are worse than the specification of the instruments. The daily variation of temperature and salinity is mainly controlled by the vertical motion of a water column due to semi-diurnal tide and diurnal change in the solar insolation. Seasonal change is prominent in temperature data. The freshwater from the Changjiang River is the main cause of large salinity variation. In August 2003 and August 2004, about 10 days before fresh water was observed near the Jeju Island, low salinity water was observed at the Ieodo Station. On the other hand, in July 2005 fresh water was observed at the station but not at around the Jeju Island. In other words, the fresh water observed at the Ieodo Station does not always expand to the Jeju Island. Two strong typhoons passed by the station in September 2003 and August 2004. The effects of the typhoons were lasted for 3 to 4 days.

• Proceedings of the Korean Aquaculture Society Conference
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• 2004.05a
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• pp.211-212
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• 2004

• Journal of the Korean Society of Marine Environment & Safety
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• v.23 no.5
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• pp.513-523
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• 2017

We evaluated the viability of phytoplankton along the salinity gradient in the flood and ebb tides of spring tide of February and the ebb tide of neap tide of March 2017 in the Seomjin River Estuary. Additional laboratory experiments were also conducted to determine the reason of the pH changes along the salinity gradient using the field natural sample in February. In field, saltwater was well mixed at downstream vertically and the salinity gradient was horizontally appeared toward upstream of freshwater zone. There were strong negative correlations between salinity and nutrient (nitrate + nitrite R=0.99, p<0.001, and silicate R=0.98, p<0.001), implying that those two nutrients of freshwater origin were gradually diluted with mixing the saltwater. On the other hands, relatively high phosphate concentration was kept in the stations of saltwater over 15 psu, indicating that it was caused by resuspended sediments of Gwangyang Bay and downstream by tidal water mixing.Among phytoplankton community structure in winter, Eucampia zodiacus have occupied to be c.a. 70 % in the most stations. Based on the field survey results for survivability of phytoplankton by phytoPAM instrument, there was positive correlations between salinity and chlorophyll a (R=0.82, p<0.001) and, salinity and active chlorophyll a (R=0.80, p<0.001), implying that the dominant marine diatom species may have significantly damaged in low salinity conditions of upstream. Also, maximum mortality rate of phytoplankton caused by low salinity shock was appered to be 75% in the upstream station. In particular, the pH in spring tides of February had tended to increase with high phytoplankton accmulated stations, suggesting that it was related with absorption of $CO_2$ by the photosynthesis of dominant diatom. In laboratory experiments, phytoplankton mass-mortality caused by low salinity shock was also occurred, which is confirmed with reducing the photosynthetic electron transport activity. Following the phytoplankton mass-mortality, bacteria abundance was significantly increased in 24 hours. As a result, the mass-proliferating bacteria can produce the $CO_2$ in the process of biodegradation of diatoms, which can lead to pH decrease. Therefore, marine phytoplankton species was greatly damaged in freshwater mixing area, depending on along the salinity gradient that was considered to be an important role in elevating and reducing of pH in Seomjin River Estuary.