• Title/Summary/Keyword: Offshore units

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Development of Real-time Oceanographic Information System using Platforms of Aquaculture Farms (양식장 플랫폼을 활용한 실시간 해양환경 정보제공시스템 개발연구)

  • Yang, Joon-Yong;Suh, Young-Sang;Choi, Yong-Kyu;Jung, Kyu-Kui;Jeong, Hee-Dong;Park, Jong-Soo
    • Journal of the Korean Association of Geographic Information Studies
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    • v.10 no.2
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    • pp.47-57
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    • 2007
  • Real-time oceanographic information system was developed using platforms of aquaculture farms to examine causes of mass mortality of hatchery fishes, and to reduce the damage of mass mortality which has been occurred frequently off coast by abnormal change of ocean conditions. The system had the advantages of direct data distribution to fishermen at the farm and instant maintenance of equipments due to easy access to the farms and residents at the farms in comparison with offshore mooring buoy system. To avoid discontinued measurement of the system, repairs caused by malfunction of equipments, bimonthly preventive maintenances and daily monitoring of measured data were systematized. Confidence intervals calculated by a statistical method using accumulated data were applied to data management. Such activities could minimize discontinuance of measurement and keep information more trustful. In addition, the system has various ways of data distribution. Through homepage and e-mail in the internet, information was provided to public. Display units which were connected to equipments at the farm gave the measured data directly to fishermen, which guided them to run their farm scientifically. Finally large display unit was installed at a fish market and showed the measured data at the nearest station with tide and weather information. Proper region for aquaculture and wintering region were studied using temperature data obtained by the system in 2006. The system will contribute to reduce economic damage of coastal fishery and to understand coastal marine environment.

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Variation Characteristics of Wave Field around Three-Dimensional Low-Crested Structure (3차원저천단구조물(LCS) 주변에서 파동장의 변동특성)

  • Lee, Jun Hyeong;Bae, Ju Hyun;An, Sung Wook;Lee, Kwang Ho;Kim, Do Sam
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.31 no.3
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    • pp.180-198
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    • 2019
  • In recent years, countries like Europe and Japan have been involved in many researches on the Low-Crested Structure (LCS) which is the method to protect beach erosion and it is regarded as an alternative to the submerged breakwaters, and compiled its results and released the design manual. In the past, studies on LCS have focused on two-dimensional wave transmission and calculating required weight of armor units, and these were mainly examined and discussed based on experiments. In this study, three-dimensional numerical analysis is performed on permeable LCS. The open-source CFD code olaFlow based on the Navier-Stokes momentum equations is applied to the numerical analysis, which is a strongly nonlinear analysis method that enables breaking and turbulence analysis. As a result, the distribution characteristics of the LCS such as water level, water flow, and turbulent kinetic energy were examined and discussed, then they were carefully compared and examined in the case of submerged breakwaters. The study results indicate that there is a difference between the flow patterns of longshore current near the shoreline, the spatial distribution of longshore and on-offshore directions of mean turbulent kinetic energy in case of submerged breakwaters and LCS. It is predicted that the difference in these results leads to the difference in sand movement.

Correlation of Surface Chloride and Corrosion Amount for Steel Member Exposed in Marine Environment (해양환경에 노출된 강부재의 표면염분과 부식량 상관관계)

  • Min-Gyun Ha;Chang-Jae Heo;Hoon Yoo;Jin-Hee Ahn
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.27 no.4
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    • pp.45-53
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    • 2023
  • In this study, to analyze the correlation of surface chloride and corrosion amount level according to the installation location of steel members exposed to the marine environment, the surface chloride and mean corrosion depth were evaluated by member units for box girder members of the offshore steel bridge and box specimens. The surface chloride was measured monthly using the Bresle method for one year. The corrosion amount was evaluated by converting the weight loss due to corrosion products generated in the monitoring steel plate into mean corrosion depth. As a measurement result of the surface chloride and corrosion amount, relative differences in surface chloride and mean corrosion depth were appeared depending on the shape or installation location of the steel members. Moreover, even if members of the same shape were installed in the same bridge, it was confirmed that the corrosion amount was increased locally and rapidly. The tendency of corrosion amount depending on the surface chloride was evaluated to analyze the correlation between surface chloride and corrosion amount, and the relation equations that can asseses the corrosion amount depending on the surface chloride were analyzed. From the results of the correlation between surface chloride and corrosion amount, it was found that the corrosion amount of the steel member affected by the surface chloride was varied up to about 1.15 times depending on the structural detail.