• 제목/요약/키워드: Surface Seawater

검색결과 546건 처리시간 0.026초

해수담수화 공정에서 역삼투막의 거동에 영향을 주는 요인 (Factors related to Performance of Reverse Osmosis Membrane in Seawater Desalination Process)

  • 박준영;홍성호;김지훈;정우원;남종우;김영훈;이창하;김형수
    • 상하수도학회지
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    • 제25권2호
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    • pp.171-176
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    • 2011
  • Organic matters that comprise a tiny part of seawater generally occur over 50% of membrane fouling in Reverse Osmosis Process. This study evaluates Foundation efficiency of reverse osmosis membranes under brackish and seawater conditions and resistance of organic fouling. Moreover, analyzing the membrane surface through roughness, contact angle and zeta potential results in roughness and contact angle are proportional to flux decline rate (FDR), yet FDR has high value when zeta potential is low level. Furthermore, with various membrane fouling of different raw water conditions, the flux tends to improve when pH value is high and raw water which is complex with organic and cation pollutes membrane faster than organic separated raw water condition.

Numerical modeling of seawater flow through the flooding system of dry ocks

  • Najafi-Jilani, A.;Naghavi, A.
    • International Journal of Naval Architecture and Ocean Engineering
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    • 제1권2호
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    • pp.57-63
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    • 2009
  • Numerical simulations have been carried out on the flooding system of a dry located at the south coasts of Iran. The main goals of seawater flow haracteristics in the intake channels conditions of the flooding system are imposed in the modeling. The upstream boundary condition is the tidal fluctuations of sea water level. At the downstream, the gradually rising water surface elevation in the dry described in a transient boundary condition. The numerical results are compared with available laboratory a good agreement is obtained. The seawater discharge through the flooding system and the required time to filling up the dry dock is determined at the worst case. The water current velocity and pressure on the rigid boundaries are discussed.

양극산화 후 실링처리된 알루미늄 합금의 해수 내 내식성과 캐비테이션 침식 저항성 평가 (Evaluation of Corrosion and Cavitation Erosion Resistance of Sealed Aluminum Alloy after Anodizing Treatment in Seawater)

  • 박일초;이정형;한민수;김성종
    • 한국표면공학회지
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    • 제51권2호
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    • pp.87-94
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    • 2018
  • Various sealing techniques were applied to the anodized 5083 aluminum alloy for marine environment to reduce corrosion and cavitation erosion damage. Electrochemical experiments and cavitation erosion tests were conducted to evaluate the corrosion resistance and cavitation resistance of the anodic oxide film treated with sealing in natural seawater solution. Then, damaged surface morphology was analyzed by scanning electron microscope(SEM) and 3D microscope. As the results of the electrochemical experiments, it was observed that the surface damage of all the experimental conditions in the anodic polarization experiment was locally grown by the combination of crack and corrosion damage. In the Tafel analysis, the corrosion resistance of all sealing treatment conditions was improved compared to the anodizing. On the other hand, cavitation erosion tests showed that the anodizing and all the sealing treatment conditions generated local pit damage by cavitation erosion attack and grew to crater damage in the observation of damaged surface by SEM. Also, the weight loss and the surface damage depth measured with the experiment time presented that most of the sealing treatment conditions showed better cavitation erosion resistance than the anodizing, and they had an incubation period at the beginning of the experiment.

남해 연안해역의 부영양화 2. 남해 연안해역의 저질 및 수질의 부영양화 실태 (Eutrophication in the Namhae Coastal Sea 2. The Aspects of Eutrophication of Bottom Mud and Surface Seawater in the Namhae Coastal Seas)

  • 김성재
    • 한국습지학회지
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    • 제3권2호
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    • pp.107-118
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    • 2001
  • The aim of this paper is to grasp eutrophication aspects in Namhae coastal seas, statistically analyzing existing data for their surface seawater and bottom mud. A pollution level(ignition loess) of bottom mud, on the whole, trended to increase as moving the coastal sea around Mokpo-Wando toward the east(Gyeongnam Namhae coastal seas). Especially, the pollution level(ignition loss=10.5%) of bottom mud for the coastal sea around Tongyeong-Keoje-Gosung was similar to that(10.3%) for the coastal sea around Masan-Jinhae, whose coastal marine pollution was the severest in Namhae coastal seas. It indicates that large amounts of pollutant from aqualculture facilities have been, thus far, accumulated on the coastal sea around Tongyeong-Keoje-Gosung, considering there was no significant inflow of sewage and industrial wastewater into this coastal sea. A COD, T-N, and T-P level of surface seawater, on the whole trended to increase as moving the coastal sea around Mokpo-Wando toward the east(Gyeongnam Namhae coastal seas). A COD level appeared to be the second grade of coastal water quality over the entire year throughout all Namhae coastal seas A T-N level exceeded the third grade of coastal water quality throughout all Namhae coastal seas except the coastal sea around Mokpo-Wando. Especially, a T-N level exceeded as many as three and six times over the third grade of coastal water quality in the coastal sea around Tongyeong-Keoje-Gosung and Masan-Jinhae, respectively. A T-P level appeared to be the second grade of coastal water quality in the coastal sea around Mokpo-Wando and the third grade of coastal water quality in the coastal sea around Yosu-Narnhae and Tongyeong-Keoje-Gosung, while it exceeded as many as two times over the third grade of coastal water quality. A degree of eutrophication of the surface seawater was 1.5 in the coastal sea around Mokpo-Wando and 11.9 In the coastal sea around Tongyeong-Keoje-Gosung, gradually increasing as moving toward the east(Gyeongnam Narnhae coastal seas). It sharply increased to 146.1 in the coastal sea around Masan-Jinhae. Because the degree of eutrophication throughout all Namhae coastal seas exceeded 1, a red tide organism could pose a possibility of proliferation at any place of Namhae coastal seas if other requirements were satisfied. It indicates that a red tide may move to another place once a red tide breaks out at a place of Namhae coastal seas.

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해양 환경 하에서 16.7Cr-10Ni-2Mo 스테인리스강의 표면 손상에 미치는 캐비테이션의 영향 (Effect of cavitation on surface damage of 16.7Cr-10Ni-2Mo stainless steel in marine environment)

  • 정상옥;한민수;김성종
    • Corrosion Science and Technology
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    • 제14권5호
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    • pp.239-246
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    • 2015
  • Stainless steel is generally known to have characteristics of excellent corrosion resistance and durability, but in a marine environment it can suffer from localized corrosion due to the breakdown of passivity film due to chloride ion in seawater. Furthermore, the damage behaviors are sped up under a cavitation environment because of complex damage from electrochemical corrosion and cavitation-erosion. In this study the characteristics of electrochemical corrosion and cavitation erosion behavior were evaluated on 16.7Cr-10Ni-2Mo stainless steel under a cavitation environment in natural seawater. The electrochemical experiments have been conducted at both static conditions and dynamic conditions inducing cavitation with different current density parameters. The surface morphology and damage behaviors were compared after the experiment. After the cavitation test with time variables morphological examinations on damaged specimens were analyzed by using a scanning electron microscope and a 3D microscope. the galvanostatic experiment gave a cleaner surface morphology presented with less damage depth at high current density regions. It is due to the effect of water cavitation peening under the cavitation condition. In the cavitation experiment, with amplitude of $30{\mu}m$ and seawater temperature of $25^{\circ}C$, weight loss and cavitation-erosion damage depth were dramatically increased after 5 hours inducing cavitation.