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Kafe 바로가기주관연구기관 | 전남대학교 산학협력단 Chonnam National University |
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보고서유형 | 최종보고서 |
발행국가 | 대한민국 |
언어 | 한국어 |
발행년월 | 2012-02 |
과제시작연도 | 2010 |
주관부처 | 농림축산식품부 Ministry of Agriculture, Food and Rural Affairs(MAFRA) |
등록번호 | TRKO201400026375 |
과제고유번호 | 1545002022 |
사업명 | 수산기술개발 |
DB 구축일자 | 2014-11-14 |
DOI | https://doi.org/10.23000/TRKO201400026375 |
○ 연구결과
-기존 부침식 가두리 시설의 메커니즘 분석
-압축공기를 이용한 부침식 가두리 시설의 부침 기능 해석
-자동 부침 가두리 시설 개념 및 모형 설계
-자동 부침 기능 제어 기법 최적 설계 및 알고리즘 개발
-개발 가두리 시설의 수리 모형실험 및 역학적 특성 해석
-파랑 및 흐름 중 가두리시설의 계류삭 안정성 해석
-실용화 보급을 위한 자동 부침 가두리 산업화 시작품 모델 개발
-자동 부침 가두리 시설의 경제성 분석
In Korea, offshore is typically defined of at least in 35 m depth. It is well known that the conventional floating cage(e.g. raft) will not survive offshore conditions, especially those related to typhoon events. The fish cage system analyzed as part of this project has a more robust design and can
In Korea, offshore is typically defined of at least in 35 m depth. It is well known that the conventional floating cage(e.g. raft) will not survive offshore conditions, especially those related to typhoon events. The fish cage system analyzed as part of this project has a more robust design and can be submerged to better survive the rigors of the offshore environment. As in Korea, the development of submersible fish cage systems in other parts of the world is becoming more important.
Similar to the traditional Korean surface cages, that allow harvesting, stock inventory and inspection without the need of divers, a new system was developed to save operational costs. The cage design includes a buoyancy system that controls the vertical motion of the cage with variable ballast tanks. It is operated by an air control program that detects surface environmental conditions such as wave height, wind speed and other parameters. The air control system adjusts the weight of the cage and the buoyancy forces to freely move the cage vertically within the water column. While the development of offshore submersible fish cages is ongoing, few design details are available in the literature, especially with respect to air control systems.
Building upon this body of work, the primary objective of this study is to develop an automatic submersible fish cage system using compressed air control. The goal is to develop the algorithm required to control the cage system and to verify the ability of the automatic submersion mechanism to function in a still water tank and a large wave tank.
The submersible fish cage system designed as part of this study can move vertically within the water column by adjusting the weight and buoyancy of the cage with an automatic control system. The automatic control system monitors environmental parameters such as wave height and wind speed so the cage can be submerged in extreme sea states and then surfaced after the weather has passed.
Being able to remotely remove fish cages from the sea surface during extreme storm events will help to prevent damage.
The fish cage was designed to consist of 12-angled rigid frame components, with both a containment and cover net, 12 variable ballast tanks, mooring ropes, anchors, a upper station(15 3-way motor valves, PCB board, cushion air chamber, etc.), a lower station(a seawater pump, a 3-way, motor valve, water leak sensor, etc.), 12 chambers(a main control chamber, two air compressor chambers, four battery chambers, a reserve air tank chamber), four high pressure tanks, a surface float(an emergency lamp, an antenna, main and remote control system, a wind gauge), various fittings including nipples, air hoses and ball valves, waterproof connectors(for 10A and 30A) to electric wires and water pressure gauge. The buoyancy of the variable ballast tanks is remotely and automatically adjustable with main and the remote control system.
A surface control system operates a switch that enables compressed air or seawater to enter the tanks to either submerge or surface the fish cage. The main control system can regulate both the inflow and outflow of air or seawater to and from the variable ballast tanks by responding to the surface environment conditions.
The main control system incorporates wind speed sensors, with a water pressure gauge and controller(six PCB boards, data acquisition components). If the sea state is considered to be safe, the fish cage is then surfaced. To do this, the compressed air is used to displace the seawater in the variable ballast tanks.
In this study, a set of model experiments were conducted to investigate the automatic submerging and surfacing characteristics of a submersible fish cage system by air control in a still water tank and wave tank. It was shown that the fish cage could submerge under the water surface automatically when it sensed wave conditions at the surface to be higher than a critical value. It would then resurface automatically when the values of environmental conditions returned to normal. The algorithm and program required to control the submersible fish cage system were developed, and model experiments were performed to validate the techniques. In addition, the performance results obtained from testing of the model cage in a still water tank, compared well with the results from the numerical model. The surfacing and submerging characteristics of the model cage calculated with the numerical technique were relatively similar to the measurements obtained from the model tests by air control. The result of the model experiments under waves, whose heights were larger than the critical value and incident to the model cage, showed that the cage was automatically submerged to the target water level and surfaced to the original location after a certain time duration at the submerged target level. The usefulness of algorithm and controller developed in this study was confirmed for the auto submerging and surfacing of the fish cage system according to wave height.
A submersible fish cage operated remotely with a tethered surface control system was designed to protect contained fish from high waves and strong currents, etc.
The design included variable ballast tanks attached to the fish cage that are used with a compressed air source to change buoyancy characteristics allowing it to be placed either at the surface or submerged. In either position, the cage can be moved vertically within the water column by adjusting the weight and buoyancy by filling or emptying the variable ballast tanks with the control system. While the functional parts of the control system are also located on the cage structure, it is remotely controlled from the surface through a tethered connection. The dimensions of the cage were 5.18 and 2.86 m in diameter and depth, respectively. Each variable ballast tank was designed with a piston-valve, so that when it was flooded with water, the cage descended.
In the development process, in-situ tests were conducted to assess the performance of the submersion mechanism and the reliability of the control system.
The first set of tests was performed to assess just the variable ballast tank components with focus on the piston valve operation with and without biofouling.
These second experiment was conducted with the fish cage, variable ballast and control system assembly. In both tests, the vertical position in the water column was measured and the data presented. The successful performance of the piston valves while covered with biofouling and the effective vertical movements of the fish cage during the tests, shows promise that such a system could be used to avoid extreme winds and waves and other types of surface contamination where a worker can remotely operate the fish cage from a surface vessel Finally, small-scale automatic submersible fish cage system was manufactured and then in-situ tests were conducted to assess the performance of the submersion mechanism and the reliability of the cage system. The successful performance of the cage system and the effective vertical movements of the fish cage during the tests, shows promise that such a system could be used to avoid extreme winds and waves and other types of surface contamination by automatic operation or remotely control system.
The next step would be to design a commercial size system and perform an engineering to investigate if a system like this could be incorporated effectively in the marine aquaculture industry.
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