• Title, Summary, Keyword: Floating collar

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Dynamic behavior of a submersible fish cage rigged with a circular floating and a sinking collar (상하가 원형 파이프로 구성된 부침식 가두리의 동적 거동 해석)

  • Lee, Chun-Woo;Lee, Ji-Hoon;Choe, Moo-Youl;Lee, Gun-Ho
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.46 no.1
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    • pp.20-31
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    • 2010
  • In this research, the submersible fish cage was designed to avoid structural and biological damage during harsh sea conditions. The submersible cage system consists of netting, mooring ropes, a floating collar, floats, sinkers and anchors. Whole elements of the cage were modeled on the mass-spring model. The computer simulations were carried out to investigate the dynamic behavior of the cage and to calculate mooring line tension subjected to tidal currents and waves. As expected, the tension values in the mooring line of the submerged position are 36% less compared to that of the surface cage under the same loading conditions. As the wave was used in combination with the current velocity of 1m/s, the average tensile load for the submerged cage showed 85% of the value for the floating cage. The simulation results provide an improved understanding of the behaviors of the structure and valuable information on the optimized design of the cage system exposed to open ocean environmental factors.

A Study of Structural Stability of HDPE Pipe during Installation (고밀도 폴리에틸렌 파이프의 설치중 구조안정성에 대한 연구)

  • Song, Hyun-Bae;Kim, Do-Kyun;Choi, Han-Suk;Park, Kyu-Sik
    • Journal of the Korean Society for Advanced Composite Structures
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    • v.6 no.1
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    • pp.59-66
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    • 2015
  • In this study, structural stability of large diameter high density polyethylene (HDPE) pipe during installation was numerically investigated in order to investigate the effect of concrete collar dimension, water depth and tension (pulling force). From the numerical simulation results, the total stress of HDPE pipe with designed concrete collar was within 2.5%, so the total weight of concrete collar for sinking of HDPE is important rather than concrete collar dimension. Furthermore, the tension area for possible installation is decreased as the air filling rate is increased. Therefore, it is important to calculate the reasonable tension range before actual installation for safe installation of HDPE pipe.

Design and Simulation Tools for Moored Underwater Flexible Structures (계류된 수중 유연구조물의 설계 및 시뮬레이션 도구 개발)

  • Lee, Chun-Woo;Lee, Ji-Hoon;Choe, Moo-Youl;Lee, Gun-Ho
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.43 no.2
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    • pp.159-168
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    • 2010
  • This paper presents a mathematical model and simulation method for investigating the performance of set net systems and fish cage systems influenced by currents and waves. Both systems consist of netting, mooring ropes, a floating collar and sinkers. The netting and ropes were considered flexible structures and the floating collar was considered an elastic structure. Both were modeled on a mass-spring model. The structures were divided into finite elements and mass points were placed at the mid-point of each element, and the mass points were connected by mass-less springs. Each mass point was subjected to external and internal forces and the total force was calculated at every integration step. An implicit integration scheme was used to solve the nonlinear dynamic system. The computation method was applied to dynamic simulation of actual systems simultaneously influenced by currents and waves in order to evaluate their practicality. The simulation results improved our understanding of the behavior of the structure and provided valuable information concerning the optimized design of set net and fish cage systems exposed to an open ocean environment.

A Study on Floating Collar of Dragged Gears (인망그물의 부양깃판에 관하여)

  • 장지원
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.22 no.1
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    • pp.1-5
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    • 1986
  • In order to improve the net-mouth height of dragged gears, the authors devised models of floatingcollars of nylon cloth instead of floats and experimented with 4 types-A type (length 65em, breadth 3em), B type (length 65em, breadth 4em), C type (length 65em, breadth 5em) and D type (length 65 em, breadth 6em) attached respectively to the front edge of square of a model net after preliminary experimentation. These various types of floating collars were experimented in a circulating water channel to evaluate the characteristics of net-mouth height and hydrodynamic resistance and the effect of the length of bridles were also examined. The results obtained were as follows: 1. In case of attaching floats, the model net-mouth height reduced from 80 em to 20 em when current velocity was increased from 0.25m/see to 1m/sec. 2. In case of attaching floating collars, the model net-mouth heights were maintained 70 em, 71 em, 80 em, 78 em in maximum and 55 em, 63 em, 69 em, 73 em in minimum respectively even the current volocity was increased from 0.25 m/see to 1 m/see. 3. The model net-mouth height was reduced to 10 em maximum according to the current velocity and types of floating collars when the bridles were shortened 3~4 mm in length. 4. Hydrodynamic resistance of D type only was increased to 700 g in maximum and those of A, B, C type were reduced to 460 g in maximum at current velocity beyond 0.5 m/ see when bridles were shortened 3-4 mm in length. 5. But the model net-mouth heights became higher in accordance with breadth of floating coliars, B type was the best for this model net in case that hydrodynamic resistance was taken into account.

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