• 한국해양학회지
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• v.30 no.5
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• pp.493-511
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• 1995

Analysis of the Late Quaternary benthic foraminifera in the cores from the western part of the East Sea, Korea, indicates several distinct changes in the paleoenvironments during the deposition. The palecology of biofacies of Cores PC-1 from the upper slop and PC-2 from the rise shows several distinct changes in bottom water temperatures during the late Quaternary. The Core PC-4 from the Ulleung Basin generally consists of agglutinated genus, Muiliammina, and anaerobic calcareous genus, Bolivina, in biofacies, suggesting that the anoxic bottom condition was prevailed during the deposition. Benthic foraminiferal rare or barren zones in the Cores indicate the limits of water circulation caused by lower sea-level in the regions during the glacial period through the Late Quaternary. The changes of benthic foraminiferal biofacies reflect temporal and spacial variations in overall bottom environments, such as bottom water temperature, dissolved oxygen, and water circulation pattern. The benthic foraminiferal data can be used to interpret paleoclimatic conditions and predict global sea-level changes, and the results of these studies should be useful to understand the evolutional history of the East Sea through the Late Quaternary.

• Journal of the Korean Society for Marine Environment & Energy
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• v.7 no.1
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• pp.42-46
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• 2004

Deep Ocean Water (DOW) is formed within restricted area including polar sea (high latitude) by cooling of surface seawater and globally circulating in the state of isolation from surface seawater. Although it is not as obvious as estuaries mixing, brine ground water is mixture of recirculated seawater and ground water. Seawater having high osmotic pressure infiltrates into an aquifer which is connected to the sea. In order to clarify the characteristics of deep ocean water and brine ground water, we investigated their origins, chemical compositions, water qualities and resources stabilities. While concentrations of stable isotopes (/sup 18/O and ²H) in seawater is 0‰, those in brine ground water is on meteoric water line or shifted toward oxygen line. It means that origin of brine ground water is different than that of deep ocean water. The ions dissolved in seawater (Na, Ca, Mg, K) are present in constant proportions to each other and to the total salt content of seawater. However deviations in ion proportions have been observed in some brine ground water. Some causes of these exception to the rule of constant proportions are due to many chemical reactions between periphery soil and ground water. While DOW has a large quantity of functional trace metals and biological affinity relative to brine ground water, DOW has relatively small amount of harmful bacteria and artificial pollutants.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.20 no.4
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• pp.199-205
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• 2015

Nitrogen and phosphorus are the limiting elements for growth of phytoplankton, which is a major primary producer of marine ecosystem. Incidentally the stoichiometry of N/P of ocean waters, measured by the (nitrate + nitrite)/phosphate ratio converges to a constant of 16. This characteristic ratio has been used widely for the understanding the ecosystem dynamics and biogeochemical cycles in the ocean. In the East Sea, several key papers were issued in recent years regarding the climate change and its impact on ecosystem dynamic and biogeochemical cycles using N/P ratio because the East Sea is a "miniature ocean" having her own meridional overturning circulation with the appropriate responding time and excellent accessibility. However, cited N/P values are different by authors that we tried to propose a single representative value by reanalyzing the historical nutrient data. We present N/P of the East Sea as $12.7{\pm}0.1$ for the year 2000. The ratio reveals a remarkable consistency for waters exceeding 300m depth (below the seasonal thermocline). We recommend to use this value in the future studies and hope to minimize confusion for understanding ecosystem response and biogeochemical cycles in relation to future climate change until new N/P value is established from future studies.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.22 no.2
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• pp.95-100
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• 2010

In this study we predicted some of the negative effects on the ocean ecosystem and water quality, caused by a coastal reclamation project in semi-closed bay that makes it extremely difficult to be purified by natural process. In order to predict change of water quality triggered by coastal reclamation, the 3D hydrodynamic model and material cycle model are used. And we suggested new ecological park, an artificial beach and eco-friendly revetments on the reclamation area to mitigate the environmental impacts affecting this area using the numerical simulation results and observation data.

• Korean Journal of Microbiology
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• v.53 no.1
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• pp.67-69
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• 2017

Complete genome sequences were retrieved from the strain RR3-28 that was isolated from a seawater recirculating aquaculture system and related to the genus Nitratireductor. The genome sequence consists of a single, circular chromosome of 3,357,577 bp with 58.6% G+C content. The genome was identified to contain twenty-one genes related to denitrification and one intact prophage.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.11 no.1
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• pp.11-20
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• 2006

The Nakdong Estuary is complex water system, where sea water and fresh water meet each other. It has undergone the significant change of its environmental conditions since the construction of the Nakdong River Barrier in 1987. Prior to its construction, mixing and circulation processes in the Nakdong Estuary was dominated by tidal current. However, after the dam construction, those processes were greatly altered by the artificial control of the fresh river water discharge. In this paper, the influence of opening and closing the floodgate of Nakdong River on the outflow behavior of estuarine water from the Nakdong Estuary is analyzed in detail.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.8 no.3
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• pp.295-306
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• 2003

Recently efforts are underway to analyze the impacts of anthropogenic $CO_2$ on the global environments and the amount of oceanic uptake increase. The East Sea is now viewed as a miniature ocean because its circulation pattern is similar to the ocean conveyer belt. The biological pump of the East Sea is a vital component to understand the carbon cycle quantitatively. In this paper, the biological pump is estimated utilizing the stoichiometric ratio between carbon and phosphorus. A simple phosphate budget model is constructed based on the seawater and dissolved oxygen box model that can simulate the recent structural change in deep water circulation of the East Sea. A model run from you 1952 to 2040 shows the steadily intensifying biological pump. Currently it exports about 0.016 Pg C yr$^{-1}$ , which corresponds to 35％ of the carbon introduced into the seawater by the air-sea exchange. An increased oxygen supply to the central water mass as a result of from the transition in the ventilation system might enhance the remineralization of sinking biogenic particles. This should strengthen the upward nutrient flux into the surface layer. Consequently, the biological sequestration of anthropogenic carbon is expected to increase with time. The estimated biological uptake of the anthropogenic carbon in the East Sea since the Industrial Revolution is estimated as 0.025 Pg C.

• Journal of the Korean Society for Marine Environment & Energy
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• v.8 no.3
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• pp.140-147
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• 2005

We investigated the interactions between coastal waters of the Yeongil Bay, Korea, and oceanic waters of the Eastern Sea, as wet 1 as the development mechanism of vertical circulation currents in the bay. The oceanic waters of the bay have an average water temperature of $12.2{\sim}18.4^{\circ}C$ and salinity of $33.32{\sim}34.43$ PSU. Results of spectral analysis have shown that the period of revolution between oceanic and coastal waters is about 0.84-0.91 years in the surface waters and 1.84 years in the bottom layer. The wind direction in the bay shifts between SW and NE, with the main wind direction being SW during the winter period, and water mass movement is influenced by such seasonal variations in wind direction. Vertical circulation currents in the bay are structured by two phenomena: the surface riverine outflow layer from the Hyeong-san River into the open sea and the bottom oceanic inflow layer with high-temperature and salinity into the bay. These phenomena start the spring when the water mass is stable and become stronger in the summer when the surface cold water develops over a 10-day period. Consequently, tidal currents have little influence in the bay; rather, these vertical and horizontal circulation currents play an important role in the transport of the pollutant load from the inner bay to the open sea.

• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.217-217
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• 2019

해안과 하천이 위치해 있는 낙동강하구의 담 염수 경계면 추적 연구에서 담 염수 경계면의 담수기원특성을 분석하기 위해서는 담 염수 경계면을 이루는 담수의 기원이 하천 혹은 지하수 인지를 규명하는 것이 매우 중요하다. 담 염수 경계면에 있는 담수는 일반적으로 하천과 지하수에 의한 것으로, 낙동강하구 일원을 대상으로 지하수공 내 해수침투 여부 파악을 위해 화학적(유기물) 분석을 실시하였다. 이와 아울러 낙동강하구 일원에서 담 염수 경계면에서 채취한 수질시료의 담수기원을 분석하기 위하여 K-water연구원 수질안전센터에 지하수공 7개지점(BH-1~7호공)의 심도별 물시료 2~4개지점(총 23개 지점), 하천(1개 지점), 해수 및 해안유출수(각 1개 지점)를 포함한 26개 시료를 LC-OCD(Liquid Chromatography-Organic Carbon Detector)로 분석하였다. LC-OCD 분석결과 특성은 기본적으로 유기물질이 물에서 유래한 aquagenic 혹은 토양층에서 유래한 pedogenic 유기물질 인지에 달려있다. 댐 또는 하천에서 pedogenic 유기물의 농도는 일반적으로 유역분지의 수문 또는 수리지질학적 경로에 의존한다. pedogenic 유기물들은 주로 상대적으로 작은 분자량을 갖는 친수성, 높은 사슬밀도 및 내화성 분자특성을 갖는 펄빅산으로 구성된다. aquagenic 유기물질은 수생 식물성 생물이나 플랑크톤의 분해 산물로서 세포벽에서 유래된 peptidoglycans와 고분자량의 polysaccharides 등을 포함한다(Chio & Jung, 2008; Buffle, 1988). 담 염수 경계면 추적을 위한 7개 관측공의 심도별 수질시료는 하천, 해수, 그리고 해안유출수의 용존유기탄소를 분석하기 위하여 LC-OCD로 정밀분석하였다. 그 결과, humic, 휴믹물질의 산화물질인 building blocks, 생물고분자 물질(bio-polymers), neutrals, acids로 분석되었으며, 일반적인 자연유기물질의 기원은 pedogenic과 aquagenic 유기물질로 분류된다. IHSS 표준물질 분석 등을 통한 SUVA 값으로부터 자연유기물질의 기원정보를 제공하는 HS-Diagram으로 도시한 결과, 2018년 11월 2일 조사한 26개의 원수시료 전체는 pedogenic fulvic acid〉aquagenic fulvic acid으로 하천의 기원이 우세한 것으로 분석되었다. BH-1호공과 BH-6호공의 특정 1개구간 GL.-6m를 제외한 모든 구간에서 aquagenic FA의 지하수 기원으로 분석되었으며, 나머지 지하수공(BH-2, 3, 4, 5, 7)과 하천 및 해안유출수는 유역분지 수문학적 경로인 pedogenic FA의 하천 기원의 담수인 것으로 분석된다.

• Journal of the Korea Convergence Society
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• v.8 no.10
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• pp.45-52
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• 2017

Drifter is an equipment for observing the characteristics of seawater in the ocean, and it can be used to predict effluent oil diffusion and to observe ocean currents. In this paper, we design models or the prediction of drifter trajectory using machine learning. We propose methods for estimating the trajectory of drifter using support vector regression, radial basis function network, Gaussian process, multilayer perceptron, and recurrent neural network. When the propose mothods were compared with the existing MOHID numerical model, performance was improve on three of the four cases. In particular, LSTM, the best performed method, showed the imporvement by 47.59% Future work will improve the accuracy by weighting using bagging and boosting.