• Journal of the Korean Geosynthetics Society
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• v.18 no.3
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• pp.23-32
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• 2019

This study investigated the scour characteristics of artificial reef according to unreinforced and reinforced artificial reefs through laboratory test and numerical analysis. In this study, geogrid was used as a reinforcement of seabed. Three different reinforced areas were selected; one time, three times and five times bottom area of artificial reef. Two-dimensional water channel test was carried out to investigate scour patten of sand and silt grounds. Numerical analysis was also performed to see the velocity vector and scouring patten around artificial reef which was same condition with experiment. The numerical results were in good agreements with the experimental test results. It was found that the geogrid-installed soft ground under artificial reef tends to reduce scour, compared to unreinforced soft ground.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.37 no.3
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• pp.249-254
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• 2004

The hydro-acoustic method is widely used for estimating biomass and distribution of fisheries resources along the coast and in the ocean. High costs and time are necessary to construct systems for this method and to initially educate specialists. It has been used in fisheries of advanced nations like Japan and Norway, because it is more efficient than other methods. In order to research the behavior of fish around an artificial reef using an echo sounder, volume backscattering strength (SV) and fish per cubic meter (FPCM) of darkbanded rockfish around the model artificial reef in a water tank were measured. Moreover, behavior of fish was observed in an adjacent artificial reef, which was constructed at Tongyeong marine ranching area. Following that, an acoustics survey was conducted at Mirukdo around the Tongyeong marine ranching area, in order to understand the spatial distribution and strength of fisheries resources. Very high patches of fish were found in a wide area around the artificial reef. It is thought that an approaching fish school around the artificial reef can be measured accurately by using an echo sounder of high resolution. Moreover, use of other monitoring methods like of diving or ROV simultaneous with an echo sounder is required in order to grasp the species and ecology of fish inhabiting the area around the artificial reef.

• The Journal of Fisheries Business Administration
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• v.44 no.3
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• pp.103-109
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• 2013

This paper analyzed that the economic effectiveness of the artificial fish reef project in the Tae-an Marine Ranching. Benefit-cost(B/C) model used to indicate the effects of economic valuation. B/C model is based on the sub-models which are Benefit Cost Ratio(BCR), Net Present Value(NPV) and Internal Ration of Return(IRR). First, the Sum of Incremental Benefit and Cost for total vessel by year in Artificial Fish Reef Area(AFRA) estimated 2,381 million won. And then, using 5.5% discounting rates and the survey data, the sub-models showed economically feasible in the all of analysis and analyzed the results as follows. BCR is 2.66, NPV is 28,014million won, and IRR is 22.78%. In conclusion, these results indicated that the artificial fish reef project in Tae-an Marine Ranching would be increase the income of fishermen as well as fish biomass.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2001.05a
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• pp.234-239
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• 2001

The subsidence characteristics of artificial reef in the unsteady flow such as tidal flow were investigated. The scour and subsidence characteristics were confirmed in the steady flow field, wave field and steady flow-wave field. In a main study, the interaction of Flow-Sediment Movement-Structure Behavior and scour.subsidence mechanism were discussed in the unsteady flow field and the unsteady flow-wave field. Most of all, the continuous artificial reef subsidence from the scour was occurred by periodic behavior of artificial reef. This behavior is result from the asymmetric ground, and is influenced by maximum velocity, duration time and direction of flow.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.41 no.3
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• pp.208-214
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• 2008

This study monitored a variety of marine communities during monthly or bimonthly censuses from February 1999 to August 2000. The communities investigated included artificial reefs composed of various substrates, which were placed on an area of sandy bottom at 8, 10, and 13m depths in Muronohana, Ikata, Shikoku, Japan. Economically important shell fishes, such as the turban shell and abalone, appeared on the artificial reefs after 1 month of construction. Shell fishes were recorded at levels of five to 20 individuals per reef. A total of 37 species (4 orders, 19 families) were identified during the experimental period. Apagon semilineatus, Trachurus japonicus, Pteragogus sp., and Pterogobius elapoides accumulated over an average of 100 individuals during the study period. Apagon semilineatus, Pteragogus sp., and P. elapoides accumulated over 1,000 individuals on all artificial reefs in May 1999. Trachurus japonicus reached well over 500 individuals in the artificial iron reef during June and July 2000. Higher monthly variation in fish abundance occurred during periods of high temperature, as compared to periods of low temperature between December 1999 and March 2000. More fish were observed in the artificial iron reef than in the artificial concrete reef, because the former offered a broader inner space and the shadows of the roofs served as a shelter for fish.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.6 no.3
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• pp.141-147
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• 2013

An artificila fish-reef is a artificail structure installed at marine ranching under the littoral sea. The artificial fish-reefs provide the function of fish spawning ground, habitation, nursery ground, and enhance the productivity of fising industry devastated by environmental pollution. After the installation of artificila fish-reef, continuous monitoring is demanded to check the validity of artificila fish-reef plan. However, the support of follow-up management is impossible because of the lack of a huge budget and professional manpower. Therefore, the artificial fish-reef combined with IT devices can be controled IT devices through the IT artificial fish-reef management system, and collect the marine environment information for the fair management. This paper shows the example of systematization for the management of artificial fish-reef based on the marine rancing management system.

• Journal of Ocean Engineering and Technology
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• v.33 no.3
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• pp.280-288
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• 2019

A submerged breakwater is one of the coastal structures used to reduce wave energy and coastal erosion. However, a submerged breakwater has a negative aspect in that a strong rip current occurring around an open inlet due to a difference in mean water levels at the front and rear sides of the structure leads to scouring. Such scouring has a bad effect on its stability. In order to eliminate this kind of demerit, this study investigated an artificial reef of the overflow type with openings. We also developed a program where the flows around the artificial reef of the overflow type could be analyzed numerically. An unstructured grid system was used to cover the various geometries, and the level set method was applied to treat the movement of the free surface. To verify these numerical schemes, hydraulic physical tests were performed on the submerged breakwater and double breaking type artificial reef. Then, the wave height and velocity distribution around the reef were examined using the experimental results. Comparisons between the results of hydraulic and numerical tests showed reasonable agreement.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.46 no.3
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• pp.266-272
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• 2013

The objective of this study was to monitor and evaluate the schooling characteristics, including the distribution density (volume backscattering strength) and acoustic size (target strength), of commercially valuable species swimming in response to artificial reefs installed at Suyeong Man, Busan, Korea. Fish aggregations at two artificial reef areas and at a nearby natural rocky reef habitat were recorded and analyzed using a 70 kHz split-beam echo sounder and 330 kHz side-scan sonar from August to September, 2006. An underwater CCTV camera system was also used to observe marine organisms in physical contact with and swimming very close to artificial reefs. During the acoustic observations at three reef sites, useful information about schooling characteristics of fish aggregations responding to artificial reefs were obtained, but more trials are needed to confirm significant differences in schooling behavior and geographical distributions in areas containing natural reef structures and artificial reefs.

• Ocean and Polar Research
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• v.23 no.3
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• pp.311-313
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• 2001

Eighteen species of fish were identified by SCUBA diving observations around experimental artificial reefs at Tongyeong marine ranching area between November 1998 and November 1999. The highest species number of 14 was observed in September while the lowest number of 2 was observed in November. Fishes showed three typical behavioral patterns against the experimental artificial reef.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2005.11a
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• pp.140-141
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• 2005

This study describes the postinstallation maintenance technology of artificial reefs and their improvement. The maintenance technology of artificial reefs consists of four steps; the investigation of volumes of installed reefs, the removal of fishing gears entangled in reefs, the estimation of reef functions, and the establishment of surveyed results in the data base. The proper understandings of their steps is the key to improve the maintenance technology of artificial reefs.