• Korean Journal of Fisheries and Aquatic Sciences
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• v.35 no.2
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• pp.146-154
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• 2002

To assess the adsorption and removal mechanism of dissolved inorganic nutrients in seawater by scattering yellow loess, a laboratory experiment was conducted for the change of nutrient concentration in seawater during the course of time depending on particle size and scattered concentration of the yellow loess. Twenty four hours after the addition of yellow loess in the size range of 0 $\mu$m to 500 $\mu$m in seawater, the removal rate of dissolved inorganic phosphorus (DIP) was increased with increasing amount of yellow loess. There was little difference among the removal rates depending on the size of yellow loess. On average, $26\%$ of dissolved inorganic silicate was reduced for the same period. No greate difference among the removal rate depending on both size and amount of yellow loess was found. Our results suggested that the removal mechanism of DU seemed to be associated with mostly the chemical bond with iron. More than $99\%$ of initial DU concentration was likely to be removed by this mechanism. In the case of inorganic dissolved silicate, the removal mechanism was likely to be attributed to a cation exchange between the yellow loess and seawater.

• 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 the Korean Society for Marine Environment & Energy
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• v.20 no.1
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• pp.1-11
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• 2017

Nakdong River Estuary is affected by the dam, barrage construction and dredge and reclaim worked artificially. So, we have studied the area input both freshwater and sea water to understand marine environment of Nakdong River estuary related to the effect of artificial work from 2013 to 2015. As a result, The discharge flow to the estuary remarkably decreased before barrage construction and the average of salinity at the estuary increased. So, the brackish water zone reduced under the influence of decreased discharge flow. The major sources of nitrate and silicate were freshwater, phosphate supplied from bottom and the open sea water. The concentration of phosphate and dissolved oxygen (DO) decreased remarkably in spring and summer. we investigated that phosphate in freshwater was removed under the influence of the estuary dam and phosphate in sea water was removed under the influence of phytoplankton. The low concentration of DO was due to decomposition of the organic compound by microorganism after phytoplankton blooms. Generally, the concentrations of chlorophyll-a in summer was higher than spring and fall. Therefore, the change of ecosystem in Nakdong river estuary was due to decrease of freshwater influx, the other change is facing because of the barrage.

• Membrane Journal
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• v.12 no.3
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• pp.182-191
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• 2002

Polyamide reverse osmosis (RO) membrane with thin film composite structure was commercialized for seawater desalination process. Recently, it has been reported that some RO processes for high pressure and recovery leads to reducing in energy cost and pretreatment scale compared with earlier process. The development of energy recovery, pumping device and RO elements with high pressure and rejection made high pressure and recovery process possible. In this study, permeation properties of commercialized seawater RO membrane were investigated under the condition of high pressure and recovery. In the RO sheet membrane test 3.5% NaCl of synthetic seawater was used. The synthetic seawater contained only sodium chloride. In the RO module test, natural seawater was used at Happo Bay, Masan city. As the results, RO membrane with high durability of pressure was better than that with high rejection of seawater for high pressure and recovery process. Seawater rejection of high concentrate tends to be improved by high pressure operation.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.3
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• pp.374-380
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• 2022

This paper shows the results of a study that predicts changes in seawater conditions in sea farms using machine learning-based long short term memory (LSTM) algorithms. Hardware was implemented using dissolved oxygen, salinity, nitrogen ion concentration, and water temperature measurement sensors to collect seawater condition information from sea farms, and transferred to a cloud-based Firebase database using LoRa communication. Using the developed hardware, seawater condition information around fish farms in Tongyeong and Geoje was collected, and LSTM algorithms were applied to learning results using these actual datasets to obtain predictive results showing 87% accuracy. Flask and REST APIs were used to provide users with predictive results for each of the four parameters, including dissolved oxygen. These predictive results are expected to help fishermen reduce significant damage caused by fish group death by providing changes in sea conditions in advance.

• The Journal of Engineering Geology
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• v.19 no.1
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• pp.9-14
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• 2009

In this work applicability of a sharp-interface model to well-scale problems is examined. In coastal areas one of the main concerns in groundwater development is saltwater intrusion. To determine the saltwater intrusion at a well one needs to evaluate the saltwater content from a pumping well. We conducted laboratory sand-tank experiments to determine if a sharp-interface model can simulate the saltwater content of a pumping well. Lateral saltwater intrusion experiments and freshwater lens experiments are conducted. A partially penetrating well and a fully penetrating well are used. Comparison between numerical results and observation results indicates that the sharp-interface model can determine saltwater contents reasonably well. We conclude that a sharp-interface model can be applied to well-scale groundwater flow problems in coastal areas.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2018.05a
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• pp.17-18
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• 2018

19세기 이전부터 유럽에서는 해양치유자원을 이용한 치유요법인 탈라소테라피(Thalassotherapy)가 국민들의 건강을 지켜오고 있다. 탈라소테라피(Thalassotherapy)란 바다를 뜻하는 그리스어 'Thalassa'와 치료를 뜻하는 'Therapy'가 합쳐진 말로 해양치유자원을 이용해 신체적 정신적 건강을 증진시키는 활동을 뜻한다. 최근 우리나라에도 건강한 삶을 추구하는 인식의 변화 속에 다양한 해양치유자원을 이용하는 해양치유의 수요가 증가하고 있다. 본 논문에서는 해양치유산업의 활성화를 위한 해양치유자원의 현황 및 활용방안에 대해 연구하였다. 우리나라 해양치유자원의 분포를 확인하기 위해 동해, 서해, 남해, 제주도 등 4개의 권역으로 구분하여 전국을 대상으로 총괄도를 제작하였으며 국내외 해양치유자원을 이용해 작성된 문헌을 통해 해양치유자원의 이용현황에 대해 조사하였다. 또한 해양치유산업 선진국인 독일, 프랑스, 일본을 모델로 우리나라에 맞는 해양치유자원 적합기준을 연구하였다. 그 결과, 각 지역별 해양치유자원은 경기도:(머드, 염생식물, 염지하수, 해조류), 충청남도:(머드, 해조류, 천일염, 해조류), 전라북도:(머드, 염생식물, 해조류 해풍), 전라남도:(해조류, 해수, 천일염, 머드 해풍), 제주도:(용암해수, 염지하수, 태양광, 해수욕장), 강원도:(심층수, 태양광, 해조류, 해송림), 경상남도:(해조류, 해수욕장, 태양광, 해풍), 경상북도:(해조류, 태양광, 심층수, 염지하수, 해송림), 울산:(해조류, 태양광), 부산 :(해조류, 해수욕장, 태양광)이 있었으며 해양치유 자원을 이용해 작성된 국내외 논문은 265편(해수:101편, 머드:27편, 소금:12편, 해양환경:39편, 해양생물:18편, 해조류:68편)이 있었다. 해양치유자원 적합기준은 각 나라별 해양치유자원의 이용기준을 활용하여 자원별로 제시하였다.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.911-914
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• 2008

It has been recognized for a long time that sulfate ions in seawater and soils can cause severe damage to concrete structures. There have been numerous field and lab. studies on the distress caused to concrete structures generated by sulfate attack. All these investigations emphasize that in order to understand the deterioration of concrete due to sulfate attack. Until now, however, it has been difficult to define the precise nature of the mechanism of sulfate attack because of its complex behavior. Thus, this work dealt with the deterioration mechanism caused by sulfate attack and the evaluation criteria.

• Ocean and Polar Research
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• v.26 no.4
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• pp.581-594
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• 2004

CREAHS II carried out an intensive hydrographic survey covering almost entire East Sea in 1999. Hydrographic data from total 203 stations were released to public on the internee. This paper summarized the results of water mass analysis by OHP (Optimum Multiparameter) method that utilizes temperature, salinity, dissolved oxygen, pH, alkalinity, silicate, nitrate, phosphate and location data as an input data-matrix. A total of eight source water types are identified in the East Sea: four in surface waters(North Korea Surface Water, Tatar Surface Cold Water, East Korean Coastal Water, Modified Tsushima Surface Water), two intermediate water types (Tsushima Middle Water, Liman Cold Water), two deep water types (East Sea Intermediate Water, East Sea Proper Water). Of these NKSW, MTSW and TSCW are the newly reported as the source water type. Distribution of each water types reveals several few interesting hydrographic features. A few noteworthy are summarized as follows: The Tsushima Warm Current enter the East Sea as three branches; East Korea Coastal Water propagates north along the coast around $38^{\circ}N$ then turns to northeastward to $42^{\circ}N$ and moves eastward. Cold waters of northern origin move southward along the coast at the subsurface, which existence the existence of a circulation cell at the intermediate depth of the East Sea. The estimated volume of each water types inferred from the OMP results show that the deep waters (ESIW + ESPW) fill up ca. 90% of the East Sea basins. Consequently the formation and circulation of deep waters are the key factors controlling environmental condition of the East Sea.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.19 no.4
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• pp.385-398
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• 2007

It was analysed that spatial and temporal change patterns of general water quality constituents were measured monthly from 2002 to 2005 in Jumunjin Harbour. The measured constituents are temperature, salinity, pH, SS and DO. Concentration difference of upper lower layer for general water quality constituents was small. Temperature and DO concentration show the clear difference at temporal concentration change pattern, but SS, pH and salinity have irregular change pattern. Also, water quality improvement effect of seawater exchange facilities and sewage treatment plants is analysed quantitatively using averaged spatial and temporal data set. From this result, it is found that effect of sewage treatment plants is small and seawater exchange facilities at zone 1 and 2 is clear concentration reduction effect to be about 26% and 16%, respectively. After sewage treatment plants operation, DO concentration reduced about 10% at inner zone of Jumunjin Harbour, the other side, after seawater exchange facilities concentration DO concentration increased about 10%. DO concentration at 2005 estimated little than that of 2002, it is concluded that a yearly change of DO concentration has about 10%.