• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.37 no.3
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• pp.214-222
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• 2001

A precise echosounding system to investigate the topographical characteristics of the coastal fishing ground was composed of a public-DGPS receiver, a single beam echosounder and a survey software. To confirm the usefulness of the system, a set-net fishing ground and the distribution of artificial reefs were surveyed. The results obtained are as follows : 1. The 2-D positioning error of the public-DGPS receiver with a DGPS mode and a GPS mode was 5.47 m, 7.03 m, respectively. 2. The experimented set-net fishing ground was located on the level ground at the depth of 9-10 m, a small size valley 1-2 m deep and approximately 10 m wide was found at a distance of 120 m from the set-net to the south. 3. In the artificial reefs' water area near the Jaran Bay, it was confirmed that twenty rectangular artificial reefs were established by the piece at the depth of 15-25 m and a natural reef 5-8 m high on the sea bed was located near the group of artificial reefs. 4. It was confirmed that the precise echosounding system was a useful tool in the pre-study to choice an appropriate water area to provide the artificial reef.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2011.06a
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• pp.233-233
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• 2011

This study describes the characteristics of accretion and scour around artificial reefs in Korea. The survey for accretion and scour was made at a dice reef set consisting of 137 dice reefs. The volume of a dice reef unit is 8 $m^3$. The reef set was placed on the muddy sand at 21.6 m in November of 1999. Equipment used in the survey includes Side Scan Sonar, Multi Beam Echo Sounder, Sub-Bottom Profiler and water current meter. According to the results, the artificial reefs are heaped up at two to three times (4 m) the height of the dice reef. The maximum current around the artificial reefs was 81.5 cm/sec at the ebb tide and 72.7 cm/sec at the flood tide. Scour around artificial reefs occurs upstream to the flow while accretion is formed at wake zone in the downstream. The height of accretion ranges from 2.4 to 3.0 m. The crest of the accretion is formed at the distance of about 10 m from the edge of the reef. The slope of accretion is formed steeply at the vicinity of the reef which is at right angles to the direction of main current, and grows gently lower with the increased distance from the reef. Scour is continuously caused by upwelling from the reef set and by side currents that flow parallel to side of the accretion. Also, scour takes place on the deposited sediment rather than on the remaining bottom sediments. This means that, once fully formed, the depth of scour gully on both sides to the direction of main current hardly changes.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.27 no.5
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• pp.535-548
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• 1994

Community structures and fish densit were investigated on three different types of artificial reefs, dice, turtle artificial reef and tubes, constructed in the Korean waters. Variations of fish fauna according to type of artificial reef and the proper artificial reef in each area for optimizing harvest were discussed. Fish were captured by trammel gill net during May, June, September and November, 1988 and both identified and counted. Fourty-five fish species were found in the artificial reefs. Of these, Sebastes spp., Hexagrammos otakii, Pleuronectidae, Navodon modestus and Stephanolepis cirrhifer showed high occurrence-frequency. The dominant species groups were coastal settlement, demersal or rock fishes such as Pleuronectidae, Rajiformes, Stephanolepis cirrhifer, Navodon modestus, Hexagrammos otakii and Sebastes spp. in all of the Artificial reefs except the oceanic area of southern waters. Scomber japonicus was predominant in the oceanic area of southern waters. Composition of demersal, rock and pelagic fishes were different depending on the types of artificial reef. Dice artificial reefs were occupied by rock fish, on the other hand turtle artificial reefs were dominated by dermersal fish. Fish density was high at the dice artificial reef in all survey areas except the middle area of Eastern waters, with high fish density evident in the Tube artificial reef. Fish community structures were remarkably different between Dice and Turtle artificial reefs. The Tube artificial reef showed intermediate characteristics between the above two types of artificial reefs. The coastal areas of Southern waters and the middle and southern areas of Western waters revealed similar fish fauna. Results from the oceanic areas of Southern waters were well associated with the middle and southern areas of Eastern waters.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.47 no.2
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• pp.139-145
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• 2011

Hydro-acoustic survey was carried out to estimate a fish distribution at marine ranching area and aggregated fish schools at artificial reef area in Oeyeondo, Korea. The survey system was set up with DGPS system, scientific echo sounder (EK60, Simrad Co.), and ECDIS (Mecys. Co. LTD). A track survey and a random survey was respectively applied to the marine ranching area (474.4ha) and to the artificial reef area (within a radius of 300m). As the result, fish distribution and MVBS values in marine ranching area showed that created fisheries resources didn't come to be abundant yet as to appear fish distribution in all of the area. In the artificial reef area, it was, however, able to detect many fish school signals on the top of and around artificial reefs and to confirm the luring effect of artificial reefs.

• Journal of Ocean Engineering and Technology
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• v.21 no.3 s.76
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• pp.58-64
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• 2007

New artificial fishing reefs are developed using modified sulfur concrete. Modified sulfur concrete, which is made of by-product aggregates and modified sulfur binder, has good properties, including high density, less water absorption, high strength, high salt resistance, and good affinity for living organisms. This paper shows the mechanical properties of modified sulfur concrete and its field tests under the sea. We have found that the pH-neutral materials attach microalgae and seaweed more readily, compared to the pH-high materials.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.37 no.5
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• pp.433-439
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• 2004

The movement range and diurnal behavior of red seabream (Chrysophrys major) tagged by the ultrasonic pinger externally were measured by acoustic telemetry techniques in the marine ranch of Tongyeong on 20 March to 30 October, 2003. The movement of fishes was monitored with the radio-acoustic linked positioning (RAP) buoy system and VR2 receivers. The test fishes showed behavior. pattern going to deep waters and returning to shallow waters. They moved gradually to deep waters as time goes by. They had a tendency to move wider range in night-time than day-time. It was found that the test fishes rarely showed a significant response to the artificial reefs.

• Journal of Fisheries and Marine Sciences Education
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• v.28 no.3
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• pp.630-644
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• 2016

We conducted a comprehensive review on artificial reefs (ARs) including seaweed reefs for marine afforestation in relation to their development and research from 1972 to 2016, and then systematically analyzed their current a state-of-the-art and practice. From the review, the followings conclusions are made. First, the objectives of AR projects in the Southeast Asia can be classified into three, i.e. protection and increase of fishery resources, local community's profits, and ecological tourism. Second, fish gathering effects by ARs can be determined in terms of wake region or wake length that tends to increase with the K-C (Keulegan-Carpenter) number. Third, ARs are desirable to deploy across a direction of the main flow but it is essential to keep the deployment interval two to four times the length of a single reef. Fourth, stability of ARs depends on how to evaluate drag coefficient, and Morison formula turns out to be practical. Fifth, local scours of ARs are likely to occur due to a downward flow around the center of the front surface. Finally, it is natural for ARs to positively contribute to the marine ecosystem but it is imperative to develop an evaluation method for the effects of ARs on the marine ecosystem.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.28 no.6
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• pp.408-415
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• 2016

Small fishing ports and coastal structures installed in a relatively low sea water depth disturb the wave induced current and cause the collapse of equilibrium state of sediment transport. These structures creates diffracted waves and matter the concentration of waves to cause the beach erosion. In order to mitigate these eroding problems on the beach, many counter measurements were proposed such as detached breakwater, groin or headland; however, these methods interrupt the aesthetic view of sandy beach due to the exposed structures above the sea level and have difficulty of applying to those beaches with the good scenery. Furthermore, some of these methods create secondary environmental problems after the installations. To eliminate these problems, one of the countermeasures, artificial reefs have been selected and used worldwide to minimize the disturbance of the scenery and secondary effects on the environment. Meanwhile, it is important to set the design elements for installing the artificial reefs such as that of length, opening width, clearing distances from the shoreline and more. Nevertheless, there are no construction manuals or standards for designing the artificial reefs with these important design elements yet. In this study, different conditions of artificial reefs were used with various cases throughout hydraulic model test to precisely analyze the changes of waves and currents to propose the standards of design elements to install the artificial reefs.

• Resources Recycling
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• v.16 no.5
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• pp.19-24
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• 2007

Reefs are the marine structure that can give resting, inhabiting, feeding and nursing spaces for a variety of fishes. Usually artificial reefs are made of cement and steels respectively in Japan as well as in Korea. However since resources deficiency has been getting serious, other materials are taken into consideration for the basic bodies of artificial reefs. About 300 thousand tons of waste agricultural plastic films are generated every yew in Korea, but no effective recycling techniques have been developed. In this sense, artificial reefs made of waste agricultural plastic films are the most representative symbol of the recycled products in the Resource Recycling Era. In particular, since these reefs could be made of the semi-cleaned waste agricultural plastic films that still contain high portion of soil, it is very environmentally friendly not only in manufacturing process but also in using under water. Furthermore they have some evident advantages as follows; 1) high fish swarming effect 2) good initial attachment of the marine growths 3) extremely low corrosion to brine 4) easy adjustment of the gravity 5) economical manufacture, transportation and jettison 6) excellent safety to ecosystem caused by lower elution of toxic substances 7) good recyclable property after application and so on.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.19 no.1
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• pp.8-34
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• 2014

We reviewed foreign evaluation systems based on the macrobenthic and macroalgal communities and developed a system, composed of a set of ecological indices able to evaluate the functionality (FI, Functional Index; estimation of stability and productivity) and maturity (MI, Maturity Index; comparisons with biological parameters of natural reefs) of artificial reefs by comparing the status in the adjacent natural reefs in Korean coastal waters. The evaluation system was applied to natural and artificial reefs/reef-planned areas (natural reefs), established in the 5 marine ranching areas (Bangnyeong-Daechung, Yeonpyung, Taean, Seocheon and Buan) in the west coast of Korea. The FI ranged between 31.6 (Bangnyeong-Daechung) and 72.5% (Buan) and MI did between 53.1 (Seocheon) and 76.9% (Taean) in average. The evaluation of artificial reefs by the two indices, showed the most appropriate status in Taean. The FI between the adjacent artificial and natural reefs were in significant linear relationship ($r^2=0.83$, p=0.01). This indicated the local status of biological community may be critical in determining the functionality of the artificial reefs. We have suggested an integrative but preliminary evaluation system of artificial reefs in this study. The output from the evaluation system may be utilized as a tool for environment/resource managers or policy makers, responsible for effective use of funds and decision making. Given the importance, we need to use the options to enhance and improve the accuracy as follows: (1) continuous validation of the evaluation system and rescaling the criteria of indicators, (2) vigorous utilization of observation and experience through the application and data accumulation and (3) development and testing of brand-new indicators.