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Difference of holding power of concrete weight used in shellfish shell fishery by its shape characteristics

패류껍질어업에서 사용 중인 멍의 형태적 특성에 따른 고정력의 차이

  • LEE, Gun-Ho (Fisheries resource and environment Division, West Sea Fisheries Research Institute, National Institute of Fisheries Science) ;
  • CHO, Sam-Kwang (Fisheries resource and environment Division, West Sea Fisheries Research Institute, National Institute of Fisheries Science) ;
  • KIM, In-Ok (Fisheries Engineering Division, National Institute of Fisheries Science) ;
  • CHA, Bong-Jin (Fisheries Engineering Division, National Institute of Fisheries Science) ;
  • JUNG, Seong-Jae (Fisheries Engineering Division, National Institute of Fisheries Science)
  • 이건호 (국립수산과학원 서해수산연구소 자원환경과) ;
  • 조삼광 (국립수산과학원 서해수산연구소 자원환경과) ;
  • 김인옥 (국립수산과학원 수산공학과) ;
  • 차봉진 (국립수산과학원 수산공학과) ;
  • 정성재 (국립수산과학원 수산공학과)
  • Received : 2017.11.01
  • Accepted : 2018.01.19
  • Published : 2018.02.28

Abstract

In this study, the differences of holding power according to the shape and weight distribution of concrete weight used in shellfish shell fishery were investigated through the experiments. To investigate the differences in shape, five bar-shaped concrete weights with the same length and different cross-sectional shapes were produced. The sectional shape of each weight was square, triangle, circle, small cross, and large cross (SQ, TR, CI, CR-S, CR-L). Ten rectangular parallelepiped weights with different bottom area and cross-sectional area were produced. To investigate the differences by the weight distribution, the holding power on the square model (SQ) with six 50 g weights at different positions was investigated. All the holding power was obtained by measuring the tensile force generated when the concrete weight was pulled at a constant speed on the sand. As a result, there were no differences in holding power between the ten rectangular weights. However, the experiment on weights with different cross-sectional shapes showed differences in holding power. The holding power was higher in the order of CR-L > CR-S > CI > TR > SQ. In the weight distribution test, the holding power was higher as the front side of the weight was heavier. Generally, the frictional force is the same even if the shape is different, when two objects have the same value in the weight and the roughness. On the other hand, it seems to have a large impact when the shape of the bottom is deformed in the course of pulling the object. Particularly, the larger the degree of protrusion like cruciform weights, the more the holding power increased while deeply digging the bottom. It is also likely that the holding power increases as the front weight increases.

Keywords

Fishing gear loss;Concrete weight;Webfoot octopus pot;Holding power

Acknowledgement

Supported by : 국립수산과학원

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