• Journal of the Society of Disaster Information
• /
• v.8 no.2
• /
• pp.188-196
• /
• 2012

Dynamic parameters such as natural frequencies can provide global stiffness information of a structure, and thus be utilized in monitoring structural integrity of large structures such as a containment. To identify the dynamic parameters without interrupting normal operation, a modal analysis method based on ambient vibration measurements should be applied. In this study, dynamic parameters of the containment of Wolsong Unit 2 are identified using ambient vibration measurement data. The feasibility of the study is verified using a numerical model for the containment. From the modal analysis, dynamic parameters of the containment with acceptable correlation to analytical modes can be estimated.

• Korean Journal of Remote Sensing
• /
• v.17 no.1
• /
• pp.99-109
• /
• 2001

In order to establish effective fishing ground environment equipment and artificial reef in coastal area, the methodology to select the most suitable area for artificial reef should be applied after analyzing the correlation between fishing ground environment and ocean environment. In this paper, thematic maps were prepared by using satellite remote sensing and GIS for the sea surface temperature, chlorophyll, transparency, the depth of sea water and the condition of submarine geologic which are considered as the most elements when selecting suitable area for artificial reef in Tong-Yong bay. Then, the most suitable area for artificial reef was selected by giving weight score depending on the suitable condition of this area and analyzing spatial data. The results showed it makes possible for this methodology, which selects the suitable area for artificial reef using satellite remote sensing and GIS, to manage the institution of artificial reef more entirely and efficiently through analyzing and visualizing.

• Journal of Ship and Ocean Technology
• /
• v.5 no.1
• /
• pp.1-13
• /
• 2001

As Indonesia determines to increase its marine fishery production, the development of tradi-tional boatyards has to be included in the agenda as it will give the local fishing communities a better chance to compete with large capital intensive fishing companies. It will also spread job opportunities evenly throughout the country instead of concentration fishing vessel con- struction in a few large shipyards located primarily on the highly populated island of Java. However development every single boatyard in indonesia would not only be prohibitively ex-pensive, but it would also create social tensions as the introduced technology would not be immediately accepted by the rural societies whose own traditions are still culturally signif-icant. Both these problems can be reduced by developing a collaborative scheme between traditional boatyards and a larger shipyard. The shipyard, with modern facilities, can develop work packages containing knock down components which are then assembled in the tradi-tional boatyards. The work packages are planned and designed so that every component can be assembled with relatively simple tools. Radical changes can be avoided as new techniques can be introduced gradually, responding to the boatyard\\`s own requirements and aspirations. While this manufacturing procedure is conceptually straightforward its efficient implemen-tation is in practice complicated by the fact that each traditional boatyard has unique char-acteristics in terms of labour resources, technological capability, and transportation links. By developing a computer model to simulate the interaction between the main shipyard and small traditional a computer model to simulate the interaction between the main shipyard and small traditional boatyards work packages can be designed that ensure that activities at all manufacturing locations are efficient.

• Journal of IKEEE
• /
• v.25 no.3
• /
• pp.556-564
• /
• 2021

This paper presents trends of safety improvement technologies for an electric propulsion system of eco-friendly ships. As an effort to reduce a green house effect, demands for eco-friendly ships have been increased. An energy storage system (ESS) is one of key systems in an eco-friendly ship and a lithium-ion battery generally used in an ESS system due to its high power density and efficiency. However, a lithium-ion battery is considered as one of reasons for ESS fire hazard. Since a fire extinguishing facility is especially limited in the ocean, safety issue in an eco-friendly ship is important. In this paper, recent safety improvement technologies for traction motors, ESS batteries and structures for eco-friendly ships are presented.

• Journal of fish pathology
• /
• v.34 no.2
• /
• pp.255-259
• /
• 2021

This is the first report describing acute mass mortality occurred in juvenile olive flounder (Paralichthys olivaceus) caused by gas bubble disease (GBD). A total of 610 fish (average weight = 35 g), which were more than half of the fish acclimated at 17℃ in an aquarium, were killed within two days of acclimation. The dead and moribund fish showed excessively opened opercula and mouths, and occasionally, severe exophthalmia. Through microscopic observation, numerous gas emboli were found in the gills of the dead and live fish, while the fish were not infected with any microbial pathogens. The dissolved oxygen (DO) saturation level of the rearing water and seawater nearby the facility reached 145% and 286%, respectively, whereas other water quality parameters (such as salinity, pH, and chemical oxygen demand) were normal. The extreme saturation rate of seawater in the shore nearby seemed to be due to an enormous algal bloom that occurred there. Through molecular identification based on 18S rDNA sequences, the most dominant algal species was most closely related to Ulva californica (99.87% sequence identity) followed by U. prolifera, U. linza, and U. curvata (99.81%). Therefore, it can be concluded that supersaturated seawater due to mass algal bloom caused gas bubble disease in the olive flounder, leading to mass mortality. After technical adjustment, such as increased aeration, lowered water circulation rate, and inlet water filtration using micro-pore carbon filters, the DO level became normal, no further mortality occurred and the status of the fish was stabilized.

• International Journal of Naval Architecture and Ocean Engineering
• /
• v.13 no.1
• /
• pp.194-207
• /
• 2021

Vortex-Induced Vibration (VIV) is a major contributor to the fatigue damage of marine risers which are often arranged in an array configuration. In addition to helical strakes and fairings, studies have been strived in searching for possible VIV suppression techniques. Inspired by giant Saguaro Cacti, flexible cylinders of different cactus-shaped cross sections were tested in a water tunnel facility, and test results showed that cactus-like body shapes reduced VIV responses of a cylinder at no cost of significant increase of drag. A series of experiments were conducted on a pair of two tandem-arranged flexible cylinders and an array of four cylinders in a square configuration to investigate the effects of wake on the dynamic responses of cylinders and the VIV mitigation effectiveness of the cactus-like body shape. Results showed that the cylinders in a square configuration, either at the upstream or downstream positions, might have larger dynamic responses than those of a single cylinder. The cactus-like body shape could mitigate VIV responses of cylinders at upstream positions in an array configuration; however, similar to helical strakes, the mitigation efficiency was reduced on downstream cylinders. Note that the cactus-like cross-sectional shape investigated was not optimized for VIV suppression. The present study indicates that the modification of the cross-sectional shape of a cylinder to a well-designed cactus-like shape may be used as an alternative technique to mitigate the VIV of marine risers.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.27 no.4
• /
• pp.163-170
• /
• 2023

In the fluid-structure interaction analysis, the finite element formulation is performed for the wave equation for dynamic fluid pressure, and the dynamic pressure is defined as a degree of freedom at the fluid nodes. Therefore, to connect the fluid to the structure, it is necessary to connect the degree of freedom of fluid dynamic pressure and the degree of freedom of structure displacement through an interface element derived from the relationship between dynamic pressure and displacement. The previously proposed fluid-structure interface elements use conformal finite element meshes in which the fluid and structure match. However, it is challenging to construct conformal meshes when complex models, such as water purification plants and wastewater treatment facilities, are models. Therefore, to increase modeling convenience, a method is required to model the fluid and structure domains by independent finite element meshes and then connect them. In this study, two fluid-structure interface elements, one based on constraints and the other based on the integration of nonsmooth functions, are proposed in nonconformal finite element meshes for structures and fluids, and their accuracy is verified.

• Journal of Environmental Impact Assessment
• /
• v.29 no.1
• /
• pp.8-25
• /
• 2020

Industrialization has increased the production of road-deposited sediments (RDS) and the level of heavy metals in those RDS, which can have a significant impact on the surrounding aquatic environments through non-point pollution. Although the relationship between contamination characteristics and particle size of RDS is important for pollution control, there is very little information on this. In this study, we investigated the characteristics of grain size distribution and heavy metal concentrations in the road-deposited sediments (RDS) collected from 25 stations in Shihwa Industrial Complex. The environmental impact of RDS with particle size is also studied. I_geo, the contamination assessment index of each metal concentration, represents the RDS from Shihwa Industrial Complex are very highly polluted with Cu, Zn, Pb and Sb, and the levels of those metals were 633~3605, 130~1483, 120~1997, 5.5~50 mg/kg, respectively. The concentrations of heavy metals in RDS increased with the decrease in particle size. The particle size fraction below 250 ㎛ was very dominant with mass and contamination loads, 78.6 and 70.4%, respectively. Particles less than 125 ㎛ of RDS were highly contaminated and toxic to benthic organisms in rivers. RDS particles larger than 250 ㎛ and smaller than 250 ㎛ were contaminated by the surrounding industrial facility and vehicle activities, respectively. As a result of this study, the clean-up of fine particles of RDS, smaller than 125-250 ㎛, is very important for the control and reduction of non-point pollution to nearby water in Shihwa Industrial Complex.

• Journal of the Korean Society for Marine Environment & Energy
• /
• v.9 no.4
• /
• pp.193-202
• /
• 2006

The Consultative Meeting of the Convention on the Prevention of Marine Pollution by Dumping of Wastes and other matter, 1972 (London Convention 1972) has requested to International Maritime Organization (IMO) Marine Environmental Protection Committee to collaborate and help clarify a boundary issue between International Convention for the Prevention of Pollution from Shops, 1973 as modified by the Protocol of 1978 (MARPOL) and the London Convention concerning 'dumping' versus 'discharges' during normal operations of ships in 2004, and subsequently established a Joint London Convention/MEPC Correspondence Group. The Contracting Parties to London Convention expressed their environmental concerns on the broad interpretation of the "cargo-associated wastes" by the States, which could be discharged by ships under MARPOL. Regulatory regimes for the cargo residues appear to vary among states. Some countries require fur ships to discharge their cargo wastes into the port reception facility and IMO also recommends doing so. This paper examines the related current national and international legal texts for the regulation of disposal of wastes from ships in order to analyze the current global concern on the marine pollution associated with waste discharge during operations of ships. In particular, we attempt to evaluate the likely marine environmental consequences arising from the disposal of cargo residue using an hypothetical case for the coal cargo residue among bulk cargos in this paper, since location, magnitude and frequency of the discharge of coal cargo residues into the sea adjacent to Korean Peninsula are not readily available. The cargo residues may be discharged to the sea according to MARPOL 73/78; however, its marine environmental consequences can be significant depending upon the characteristics and amounts of wastes to be discharged. Also the public tolerance of the environmental consequences would be widely different among nations. Multilateral environmental agreements, in general, more strictly apply their rules if there are other options to disposal at sea, i.e. port reception facility in this case. Therefore, port reception facilities for the wastes generated by ships are recommended to be further constructed in major national ports in order to reduce the risk of environmental damages during the operations of ships.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.16 no.11
• /
• pp.7227-7236
• /
• 2015

The survey revealed that, due to the discharge characteristics of seafood wastewater, irregular inflow loads were caused, making it difficult to treat the wastewater safely. It is crucial for the operation of pressure and floating tanks for the treatment of high-concentration organic wastewater such as seafood wastewater. The survey of operation factors for the pressure and floating tanks revealed this: A/S ratio 0.05 (design criteria 0.01), the pressurized air pressure 8bar(design criteria 6bar), the pressure tank pressure 6bar (design criteria 4.5bar), and HRT 60sec(design criteria: 10sec). Also, the recirculation rate was changed to over 40%(design criteria: 30%), and the surface load rate was changed to under $13.7m^3/m^2{\cdot}hr$(design criteria: under $17.7m^3/m^2{\cdot}hr$); thus, compared to the initial design criteria, the operation factors were changed according to inflow characteristics, thus enhancing the pressure and floating tank performance. The survey of inflow load revealed BOD 140.7%, $COD_{Mn}$ 120.32%, and SS 106.3%, compared to the inflow design criteria, as well as T-N 135.5% and T-P173.3%, higher than the design criteria. The survey of the treatment facility annual operation cost revealed high portions in sludge treatment cost(27.7%) and chemicals costs(26.0%), and the sludge treatment cost will likely further increase due to the ban on ocean dumping. The unit cost for the treatment of seafood wastewater was found to be KRW 3,858 per ton, more than 27 times higher than the sewage treatment cost(KRW 142.6/ton), presumably because the seafood wastewater contains high-concentration organic substances and nutritive salts.