• Korean Journal of Hydrosciences
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• 제4권
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• pp.93-104
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• 1993

This paper is concerned with the actual comparison analysis for the freshening process in the two selected experimental reservoirs. At the deep freshening reservoir, salinity and depth of the freshwater layer were estimated by simulation technique using the quantitative equation for the two layered flow structures. First of all, it is shown that the effects of underdraiange conduit in the lower layer were reported more effective for the control of upper layer salinity comparing with the case of no underdraiange conduit. Further the results of computation were later compared with the real observed values and the relating parameters of the salt balance equation are conformed even though approximately. Finally it was represented that the salinity of upper layer is easily diluted not only by the tidal gate but also by the underdraiange conduit in the lower layer of the freshening reservoir.

• 한국양식학회지
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• 제12권2호
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• pp.145-153
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• 1999

This study was conducted to determine the protein requirement of ayu (Plecoglossus altivelis). Two replicate groups of fish initially averaging 6.6 g were fed the five isocaloric diets containing different protein level from 29% to 57% in a flow-through freshwater system for 25 days. White fish meal was used as a sole protein source. Weight gain and feed efficiency of fish increased significantly with dietary protein level up to 43% (P＜0.05) with no additional response above this level. Protein and lipid retention, moisture, protein and lipid contents of body were not affected by dietary protein levels (P>0.05). Daily protein intake increased significantly with dietary protein level, whereas protein efficiency ratio of fish fed the 57% dietary protein decreased (P<0.05). The data obtained in this study indicate that a 43% dietary protein level could be recommended for the optimum growth of ayu.

• 한국해안해양공학회:학술대회논문집
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• 한국해안해양공학회 2002년도 한국해안해양공학발표논문집 Proceedings of Coastal and Ocean Engineering in Korea
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• pp.191-197
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• 2002

The prediction of the dynamic behaviors of buoyant water discharges into a large volume of water bodies, the flows of water accompanying the density differences due to temperature differences and sometimes also to salinity differences, have attracted great concern over several decades. Heated water surface discharges from power plants and freshwater discharges in estuaries are typical examples of the buoyant flows. (omitted)

• Animal cells and systems
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• 제2권3호
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• pp.333-339
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• 1998

Litter decomposition is a key process in energy flow and nutrient cycling in the freshwater littoral zone, and is regulated by physicochemical properties of litters. Using a litterbag method, we compared the decomposition rates of 16 different litter types from 10 plant species of the emergent macrophytes for one year in the littoral zone of the Paltangho Reservoir, Korea. The regression analysis fitted to the various decomposition models showed that mass loss of the litters with time best fitted an asymptotic function. The litters of the emergent macrophytes were composed of two compartments, labile and refractory. The macrophytic litters showed a great variety in decomposition dynamics depending on sources of litters. The labile compartment of the initial litter mass was in a wide range between 18% and 99%, and their decomposition rates varied from 0.0037 to 0.0131 day-1. The decomposition processes of the emergent macrophytes were determined by the relative amounts of the labile and refractory compartments and by the decomposition rate of the habile one in the littoral zone.

• 한국발생생물학회지:발생과생식
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• 제25권1호
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• pp.25-32
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• 2021

The main purpose of the current study was to obtain nuclear DNA content data among the representatives of the families and subfamilies of 31 endemic fishes that inhabit river of Korea. DNA contents of 31 endemic species were observed to rang from 1.5 to 4.8 pg DNA/nucleus. In Cyprinidae, DNA content of Abbottina springeri (1.5±0.03 pg DNA/nucleus) was the lowest value and DNA content of Carassius cuvieri (4.5±0.32 pg DNA/nucleus) was the highest value in all experimental groups. In Cobitidae, DNA content of Iksookimia longicorpa (3.9±0.17 pg DNA/nucleus) was the highest value and DNA content of Orthrias toni (1.5±0.18 pg DNA/nucleus) was the lowest value in all experimental groups. This study provides new information for a better understanding of the process of genomic evolution in 31 endemic species in river of Korea.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2023년도 학술발표회
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• pp.526-526
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• 2023

Water circulation plays a crucial role in regulating the salinity of estuaries, which is essential for the survival of estuarine organisms. Changes in freshwater inflows or sea level can have significant impacts on the distribution and abundance of species within these ecosystems. To better understand these dynamics, this paper presents a study of water circulation and salinity distribution in Seomjin River estuary using the Finite Volume Coastal Ocean Model (FVCOM) numerical model. An extreme scenario was simulated to assess the potential impact of tidal currents and river flow discharge on circulation and salinity distribution. The results of this study have important implications for managing estuarine ecosystems and conserving their associated biodiversity.

• 현장농수산연구지
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• 제16권1호
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• pp.123-133
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• 2014

We assessed the physical habitats of Microphysogobio longidorsalis in the Han river basin. Field monitoring was conducted for ecological and habitat conditions for 11 sites from October 2008 to November 2011. Twenty species (50.0%) including M. longidorsalis and Zacco koreanus were found endemic out of the 40 species in 10 families sampled during this study period. The most frequently found species was Z. platypus (26.2%) followed by Z. koreanus (17.7%), Coreoleuciscus splendidus (14.0%) and M. longidorsalis (13.4%). For M. longidorsalis, total fist length showing the highest number of samples were 8~10 cm (50.9%). the favored habitat conditions were estimated to be 0.4~0.5 m (56.1%) for water depth, 0.2~0.9 m/s (90.4%) for flow velocity, sand (0.1~1.0 mm)~cobbles (100.0~300.0 mm)(94.5%) for substrate size and run (60.2%) for habitat type, respectively.

• 대한환경공학회지
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• 제36권3호
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• pp.221-230
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• 2014

수생태적 건전성이 훼손된 하천을 자연형 생태하천으로 복원하고자 할 경우, 대상 수생태계에 서식하고 있는 담수어류는 핵심적 지표생물로서의 활용 가능성이 매우 크다. 어류의 서식환경에 대한 정보는 수환경의 생물학적 및 물리 화학적 특성을 반영할 수 있는 핵심적 요소임에도 불구하고 관련 연구가 미비하고 기존 데이터 또한 산재해 있는 등 데이터베이스(DB)화가 미흡하여 생태하천 복원사업의 추진 과정에서 이를 충분히 연계하지 못하고 있는 실정이다. 이러한 문제에 대응하기 위하여 국내에 서식하고 있는 주요 담수어종의 서식환경에 대한 전국 규모의 상세조사 결과를 바탕으로, 깃대종으로서의 활용도가 높을 것으로 판단되는 70종을 선정하여 각 어종별로 개체군 특성, 물리적 및 이화학적 서식특성을 DB화하고, 이를 생태하천 조성사업에 활용하는 방안을 제시하였다. 특히, 물리적, 이화학적 서식환경에 대해서는 서식범위와 최적범위를 산출하는 통계분석을 추가 수행하여 DB의 활용성을 제고하였다. 본 연구에서 구축한 DB는 생태하천 복원시 선정된 깃대종(어류)에 적합한 생태유량과 목표수질의 산정, 평가 및 서식환경 복원을 위한 기초자료로 활용될 수 있을 것으로 기대된다.

• Fisheries and Aquatic Sciences
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• 제5권3호
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• pp.229-234
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• 2002

Possibility of raising sunshine bass during the winter season in Korea was investigated. Also, the effect of feed on growth and body composition of sunshine bass was compared at the various salinity. Twenty sunshine bass $(Mean\;weight\;\pm S.D.\: :\;53.9 \pm 0.24 g)$ were stocked into the eighteen circular flow-through tanks. A 2 (feed) $\times$ 3 (salinity) factorial design with triplicate was used for this study. Feed was prepared into the 2 groups: the raw fish-based me>ist pellet (MP) containing $59.5\%$ crude protein and $9.4\%$ crude lipid, and commercial sinking red sea bream feed (CF) containing $49.9\%$ crude protein and $9.4\%$ crude lipid, respectively. And salinity was prepared into the 3 groups: freshwater $(0\%)$, brackishwater $(15\%)$, and seawater $(32\%)$. Fish were fed to satiation twice daily for 6 days a week. Fish were all survived at the end of the 8-week feeding trial. Weight gain (WG) and specific growth rate (SGR) of sunshine bass were significantly (P<0.05) affected by both feed and salinity. WG and SGR of sunshine bass fed the MP were significantly (P<0.05) higher than those of fish fed the CF in the same salinity. Amount of dry feed fed was significantly (P<0.05) affected by both feed and salinity. Feed consumption by sunshine bass fed on the MP was significantly (P<0,05) higher than by fish fed on the CF in the same salinity. Feed efficiency ratio (FER) was significantly (P<0,05) affected by salinity, but not by feed. Protein efficiency ratio (PER) was significantly (P<0.05) affected by both feed and salinity. Moisture and protein content of the whole-body of fish was not significantly (P>0.05) affected by either feed or salinity. However, lipid and ash content of the whole-body of fish was significantly (P<0.05) affected by salinity, but not by feed. In conclusion, the MP was superior to CF for growth of sunshine bass during the winter season in Korea and no mortality occurred. And sunshine bass seemed to grow better in freshwater $(0\%)$ and brac-kishwater $(15\%)$ than seawater $(32\%)$ under these experimental conditions, in terms of improvement in FER and PER in freshwater or brackishwater.

• 생태와환경
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• 제42권3호
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• pp.317-330
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• 2009

패류를 이용한 오염하천의 수질개선 가능성을 확인하고자 CROM기술을 응용한 S-CROM기법을 개발하고 현장에 직접 적용하였다. 실험은 하천에 형성된 소형 보에서 실시하고 자연유속을 그대로 이용하였으며, 패류의 섭식활동을 위해 현장의 퇴적물을 첨가하였다. 실험은 처리조를 현장수(대조군), 현장수+퇴적물(대조군), 현장수+퇴적물+패류 30개체 (D1), 현장수+퇴적물+패류 60개체 (D2) 등 4가지로 구성하고, 유속은 450mL $min^{-1}$, 시료채취는 12시간(주, 야)간격으로 실시하였다. 환경요인으로는 현장에서 직접 수온, pH, DO, 전기전도도, 탁도 등을 측정하였고 시료를 채취하여 Chl-$\alpha$, SS, TN, TP, $NO_2$-N, $NO_3$-N, $NO_4$-N, $PO_4$-P, BOD, 식물플랑크톤 등을 분석하였다. 실험결과 유기물 제어능은 패류밀도와 처리시간에 따라 차이를 보였는데, 최대효과는 운영 2일째, 낮 동안 그리고 고밀도 처리군에서 나타났으며, 부유물질 (57%)과 조류(72%)의 감소를 보였다. 고농도의 암모니아와 인산을 배출하였던 CROM(김 등, 2009)보다 뚜렷하게 낮은 수준을 보였으며, 패류의 밀도효과는 유의하지 않았다. 비록 S-CROM이 CROM에 비하여 낮은 제어율을 보였으나 이는 상대적으로 낮은 패류밀도 및 빠른 유속 등이 원인으로 판단되었다. 따라서 S-CROM를 이용한 하천의 유기물 제어는 하천환경과 패류밀도를 적절하게 조합한다면 높은 수질개선 효과를 기대할 수 있을 것으로 사료되었다.