• Journal of Advanced Marine Engineering and Technology
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• v.34 no.1
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• pp.177-182
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• 2010

Sediment transport around artificial habitat which is induced by the change of flow due to installation of the structure plays a role not only as a defect function of subsidence and burial but also bottom-environment control function. Using Side Scan Sonar (SSS), Differential Global Positioning System (DGPS) and Scuba diving equipment, we investigated a facility condition of a dice reef installed on Pohang coast of the East Sea. Investigation result, at total 139 place, 10,526 dice reef was discovered. As the level which affects function of the above 0.5m, the case 4 place of burial (0.5~1.2m, 2.9%), scour appeared with 3 place (0.5m, 2.2%) and broken was appeared with 183 artificial reefs (1.74%). As a result, dice reef installed Pohang coast appeared to mostly stable.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.42 no.1
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• pp.38-43
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• 2006

The 3-D modeling of ocean finite element method(OFEM) using $k-{\varepsilon}$ turbulent model and tetrahedron grids has been used to investigate the internal wave generation during the expansion of the deep water from the open sea to the shelf with a simple shape, which can be widely used in the fields of submarine development, ocean environment and meteorology, etc. In this paper, the detailed configuration of internal wave with its length and height and also the distribution of salinity and turbulent kinematic energy, etc. were derived. It is hoped that this OFEM method can be successfully applied to the numerical calculation of internal wave for and the oceanographic problems (tidal flows around underwater hill, plateau, Georges Bank, etc.) and ocean engineering problems(flow past artificial sea reefs) in future.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.26 no.1
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• pp.31-40
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• 1993

This paper deals with static tension analysis method for Floating Tire Breakwater(FTB). FTB can be used for the limited wave height. It is especially focused on Goodyear type FTB easily applied to the breakwater for the fisheries cultivating region. The numerical examples for FTB design procedure was reviewed. It is also studied the static analysis method of offshore catenary spread mooring system. The general calculation procedure for the tension versus excursion curves for the multi-line system using the basic catenary relationship was studied. Calculation results showed good agreement with some existing mooring results. To extend this mooring force calculating method to the floating fisheries caitivating cages, the strength of synthetic fiber was considered. This analysis method can be used to the estimation of the mooring force for the floating structures such as floating breakwaters and floating artificial reefs.

• Journal of Fisheries and Marine Sciences Education
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• v.20 no.3
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• pp.487-499
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• 2008

This study was analyzed and assessed the environmental factors on small marine ranching sites around Gunsan Coast, West Sea of Korea. Standards of assessment are followed in the reports on the choice of marine ranching sites and regulation factors of proper site on marine artificial reefs of MOMAF. Max. current speed around Gunsan were ranged between 25.52 ~ 57.49cm/sec. These values were satisfied by comparing assessment factor such as current speed.. Factors of temperature, salinity, transparency and pH were evaluated as the proper extent. DO was not distributed as the proper extent due to different criterion. between the same assessment factor. COD, SS and nutrients were partly suited to the criteria. Especially, SS was almost higher than that of criterion. So, we are proposed to be reflected in environment characteristics of West Coast such as SS. Moreover, the extent of pollution load factors have to be specified clearly in the regulations of assessment criteria.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2001.05a
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• pp.557-558
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• 2001

인공어초 사업은 어족의 서식환경을 개선하기 위하여 1971년부터 현재까지 약 4000여 억 원을 투자해오고 있으며 앞으로 계속 시설할 예정이다(한국해양수산개발원, 2000). 현재 시설 중인 일반 어초에는 사각형, 원통형, 반구형 등이 있으며(국립수산진흥원,1992) 이중 해조류, 패류를 대상으로 하는 연안 어초 중 반구형어초를 대상으로 어초 설치 유형에 따른 모여든 어종 및 그 규모 차이를 알기 위하여 경남 통영시 산양면 저도 연안에 설치된 반구형 어초에서의 월별 어류상 변화를 조사하였다. (중략)

• Ocean and Polar Research
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• v.41 no.1
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• pp.11-18
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• 2019

This acoustic experiment noted that fish species in Chilam-Gijang marine ranching area were more densely distributed in the pelagic zone during nighttime than daytime. In each season, the gill nets caught 15 different fish species and the estimated average target strengths were -44.0 dB and -44.4 dB for autumn and winter surveys, respectively. The estimated autumn fish biomass were 7.7 tons and 26.0 tons during daytime and nighttime, respectively. Winter biomass was 2.27 tons and 30.97 tons during daytime and nighttime, respectively. Different fish species form schools that exhibit different movements and behaviors, and thereby occupy varying water layers. These results explained the estimated fish biomass, and variation with seasons and time of the surveys around artificial reefs in Chilam Bay, Korea.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.3
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• pp.533-544
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• 2015

Unlike the concrete structure built on land, that exposed to the marine environment is greatly degraded in durability due to the exposure to not only the physical action caused by sea wind, tide, and wave, but also the harsh conditions, including the chemical erosion and freeze-thaw which result from $SO_4{^{2-}}$, $Cl^-$ and $Mg^{2+}$ ions in seawater. In the process of the large scaled construction of submerged concrete structures, of course environmental hazardous substance, such as alkaline (pH) and heavy metals, may be leached. Thus, this issue needs to be adequately reviewed and studied. Therefore, this study attempted to develop a CSA (Calcium Sulfo Aluminate) activator using electric arc furnace reducing slags, as well as the eco-friendly concrete for artificial reefs using electric arc furnace oxidizing slag as aggregate for concrete. The strength properties of the eco-friendly concrete exposed to the marine environment were lower than those of the normal concrete by curing 28 days. This suggest that additional studies are needed to improve the early strength of the eco-friendly concrete. With respect to seawater resistance of the eco-friendly concrete, the average strength loss against 1 year of curing days reached 8-9%. the eco-friendly concrete using high volume of ground granulated blast furnace slags and high specific gravity of electronic arc furnace oxidizing slag demonstrated the sufficient usability as a freeze-thaw resistant material. With respect to heavy metal leaching properties of the eco-friendly concrete, heavy metal substances were immobilized by chemical bonding in the curing process through the hydration of concrete. Thus, heavy metal substances were neither identified at or below environmental hazard criteria nor detected, suggesting that the eco-friendly concrete is safe in terms of leaching of hazardous substances.

• Journal of Advanced Marine Engineering and Technology
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• v.34 no.1
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• pp.168-176
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• 2010

Stability and durability of the artificial reefs (ARs) for wildstock enhancement have been a key issue. We surveyed the side scan sonar (SSS), multi beam echo sounder (MBES) and scuba diving surveys confirmed that the ARs stability was age and type-dependent. A case of the stability of 8,438 ARs (60 group ARs) installed at 4 sites (Yangyang, Gangeung, Donghae and Samcheok) along the Gangwon coast of the East Sea (Sea of Japan). And a confirmation amount to 85.4% ARs remained safe, the rest 14.6% being influenced by a physical parameter of the waters. The representative influences by their circumstances were of breakage (6.3%). capsizing (8.3%). A group of a ARs to 61.7% ARs remained safe, the rest 38.3% being influenced by a physical parameter of the waters. The representative influences by their circumstances were of buried.

• Journal of Advanced Marine Engineering and Technology
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• v.35 no.1
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• pp.108-117
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• 2011

Old train carriages have been used to create artificial reefs (AR) as part of programs to enhance ocean fisheries and recreational resources. This study conducted hydraulic modeling experiments to estimate the structural stability of a train carriage AR. By applying fixed- and movable-bed conditions and Froude similitude, theoretical and hydraulic experiments revealed major design forces(e.g., water waves and currents). The results of this study showed that some dimensionless design parameters (e.g., surf similarity parameters, water particle velocity, scouring, and deposition) also affect the stability of an AR under various wave and current field conditions. In the fixed-bed condition, movement of the AR occurred when dimensionless water particle velocity based on the surf similarity parameter was larger than about 0.32. In the moveable-bed condition, the settlement depth (field values) of the AR ranged from 6 to 30 cm. The results indicated that characteristics of the sediment/bed condition and the direction of external forces acting on an AR should be considered when selecting AR sites.

• Journal of Ocean Engineering and Technology
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• v.35 no.1
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• pp.75-81
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• 2021

Artificial Coral Reefs (ACRs) have been introduced to help solve coastal erosion problems, but their feasibility has not been assessed with field data. This study conducted a feasibility analysis of ACRs on their erosion mitigation effects by performing a case study of Cheonjin-Bongpo beach, South Korea. A numerical-physical combined analysis was carried out using a SWAN model simulation and physical model test with a scale of 1/25 based on field observations of Cheonjin-Bongpo beach. Both Dean's parameter and the surf-scaling parameter were applied to comparative analysis between the absence and presence conditions of the ACR. The results for this combined method indicate that ACR attenuates the wave height significantly (59~71%). Furthermore, ACR helps decrease the mass flux (~50%), undertow (~80%), and maximum wave set up (~61%). The decreases in Dean's parameter (~66%) and the surf-scaling parameter suggest that the wave properties changed from the dissipative type to the reflective type even under high wave conditions. Consequently, an ACR can enhance shoreline stability.