• Title/Summary/Keyword: Towing cage

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Estimation of vertical and horizontal spreading force of the towing cage for transporting the live fish by model test and simulation (모형실험과 시뮬레이션을 통한 활어 이송용 예인 가두리의 수직 및 수평 전개력 추정)

  • Park, Subong;Lee, Chun Woo
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.50 no.2
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    • pp.176-184
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    • 2014
  • Nowadays, consumption of fisheries products is increasing. There are several factors, one of which is a quantitative development through aquaculture. Another factor is an increase qualitative consumption of fish which require that fish be supplied alive. This requires a lot of technical effort to transport the live fish that have low survival rate (c.f. tuna and mackerel) in coastal waters and in the open sea. To develop a towing cage for transporting the live fish, model test in a circulate water channel and simulation by computer tool were carried out. In order to spread vertically, floats were attached at the upper part of the cage, and iron chains attached at the lower part of the cage. For horizontal spreading, kites were attached on the cage. The tension and spreading performance of the cage were measured. The result shows that the tension and reduction ratio of inside volume of the cage were tended to increase with increased towing speeds. The suitable operation condition in towing cage was 1.0 m/s towing speeds with vertical spreading force 8.7 kN, horizontal spreading force 5.6 kN; in this case the reduction ratio of inside volume of the cage was estimated as 25%.

Hydrodynamic Forces on Fish Cage Systems under the Action of Waves and Current (가두리 시설이 파랑과 흐름에 의해 받는 유체력 특성)

  • Kim, Tae-Ho;Kim, Chang-Gil;Kim, Ho-Sang;Baik, Chul-In;Ryu, Cheong-Ro
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.38 no.3
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    • pp.190-196
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    • 2002
  • In order to analyze the hydrodynamic forces on fish cage systems, made of frames and nettings, under waves and current, hydraulic model experiments for square type and circular type of fish cage system were carried out in a towing tank. Both cage systems consist of net cages supported by floating frames made of two concentric pipes and four weights hanging from the bottom corners of the nets. There was little difference in the hydrodynamic force on the square type of fish cage system by wave heading under regular waves and the peak frequency of the force on each cage system was in a good agreement with that of induced irregular wave. In addition, it was also observed that the circular type of cage system was more stable to the action of waves and current than the square type.

Dynamic Motions of Model Fish Cage Systems under the Conditions of Waves and Current (파랑 및 흐름중 모형 가두리 시설의 운동 특성)

  • KIM Tae-Ho;KIM Jae-O;RYU Cheong-Ro
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.34 no.1
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    • pp.43-50
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    • 2001
  • In order to analyze the dynamic motions of fish cage systems made of a frame and a netting under the conditions of waves and current, the hydraulic model experiment at towing tank and the numerical computation using boundary integral element method based on linear potential theory were carried out on a square and a circular type of fish cage, The computed and measured results for the dynamic motions of model fish cage systems showed that the heave and pitch motions were almost unaffected by the inclusion of nets, while the surge motions were very reduced by drag force acting on them. In addition, irregular wave-induced motions of fish cages included non-negligible 2nd order harmonic components at high frequency nearly twice the wave frequency. The reason why these motions were considered was due to resonance or structural components of frames being overflown and out of water during a wave cycle. It was found that circular type was more desirable structure in the open sea than square one only in the respect of dynamic motions due to waves and current. Further verifications were needed considering hydrodynamic forces, fatigue life, and structure analysis based on long term stochastic waves including frequency and time domain for the purpose of analyzing and designing fish cage systems.

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