• Title, Summary, Keyword: Set net

Search Result 591, Processing Time 0.062 seconds

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
    • /
    • v.43 no.2
    • /
    • pp.159-168
    • /
    • 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 the Selectivity of the Mesh type Escape Device and the Applicability in a Set Net (망목형 탈출장치의 선택성과 정치망에 적용 가능성)

  • Kim, Seong-Hun;Kim, Tae-Kyung;Kim, Hyung-Seok;Lee, Ju-Hee
    • Journal of Fisheries and Marine Sciences Education
    • /
    • v.25 no.4
    • /
    • pp.928-936
    • /
    • 2013
  • This thesis is the fundamental study on the adaptation of escape device for reducing small fishes in set-net. The escape devices for experiments were made the mesh-type devices with three different mesh sizes (60.6, 75.8 and 120.0mm). The experiments of size selectivity on escape devices were conducted by using two kinds of species as black rockfish (Sebastes schlegeli) and sea perch (Lateolabrax maculatusi) in the experimental tank. The size selectivity curve was fitted by using a logistic function and the parameters of selectivity curve were estimated by a maximum likelihood method. In the results; 50% selection ranges for the mesh-type escape devices with three different mesh sizes were; a black rockfish was 18.99 in mesh size 60.6mm and 21.96 in mesh size 75.8mm (120mm could not estimate). A sea perch was 22.02 in mesh 60.6mm and 24.46 in mesh size 75.8mm (120mm could not estimate). The 50% selection range of a black rockfish was wilder than a sea perch about 1.1~.2 time. Therefore, the small fishes are able to reduce by using the mesh type escape device. However, the optimum mesh size should be decided to consider the size of target species and economics of catches.

Species Composition and Seasonal Variations of Fishes Collected by Set Net in Coastal Waters of Gijang, Korea (기장 연안 정치망에 어획된 어류의 종조성 및 계절변동)

  • Lee, Dong Jin;Kang, Sukyung;Choi, Kwang Ho;Jung, Kyung-Mi
    • Korean Journal of Fisheries and Aquatic Sciences
    • /
    • v.47 no.6
    • /
    • pp.983-996
    • /
    • 2014
  • Fish catches by a set net from January 2007 to November 2009 were analyzed to assess fish species composition and seasonal variations in the coast of Gijang, Korea. Over 389 kg fish representing 78 species, 45 families and 17 orders were collected during three years of the study. Dominant species were jack mackerel Trachurus japonicus, anchovy Engraulis japonicus and herring Clupea palasii, and these three species comprised 67.3% of the total number of individuals and 60.7% of the total biomass. Size distribution of the dominant species for jack mackerel, anchovy and herring ranged from 2.2 cm to 22.6 cm, from 2.5 cm to 14.8 cm, from 4.0 cm to 29.0 cm in fork length, respectively. Anchovy was the only species that occurred throughout all seasons in the Gijang coast. Generally, species richness was highest in spring (April to June) when sea temperature began to increase.

Species composition and variation of catches by a set net in the coastal waters of Gyudeok, Jeju island (제주도 귀덕 연안에서 정치망에 의해 채집된 어획물의 종조성 및 어획량 변동)

  • Kim, Maeng Jin;Lee, Jong Hee;Lee, Chang Heon;Kim, Byung-Yeob
    • Journal of the Korean Society of Fisheries and Ocean Technology
    • /
    • v.50 no.3
    • /
    • pp.407-415
    • /
    • 2014
  • Fish was caught by a set net in Gwideok, Jeju island that was studied to determine monthly variation of species composition and catch from May 2005 to October 2006. Total catch was 54 species, 44,118 individuals, and 2,152,423.7 g during survey period. Dominant species were Trachurus japonicus and Siganus fuscescens that held 91.3% of total individuals and 71.3% of total abundance. The highest individuals and abundance of catch were in July 2005, and the lowest individuals and abundance of catch were in October 2006 and in October 2005, respectively. As the result, temporal change in abundance have corresponded with changing water temperature.

Job Resource relation-Net Modeling for the Simulation of FMS (유연 생산 시스템의 시뮬레이션을 위한 JR-Net 모델링)

  • Choi, Byoung-Kyu;Han, Kwan-Hee
    • IE interfaces
    • /
    • v.8 no.3
    • /
    • pp.61-73
    • /
    • 1995
  • As the level of maunfacturing system automation increases, the issues of modeling and simulation of AMS(Automated Manufacturing System) are becoming more important. Proposed in this paper is the JR-Net(Job Resource relation-Net) modeling framework which naturally mimics the process of designing an AMS by FA(Factory Automation) engineers. Its main purpose is to provide a modeling tool which facilitate modeling work of AMS for FA engineers unfamiliar with simulation modeling. The proposed modeling scheme is based on the extensive observation that typical AMSs are built from the set of 'standard' components(or catalog items). As an application of the proposed model, two real examples of FMS('G7'FMS model plant, RPI FMS) are modeled by JR-Net, and in case of FMS model plant, a simulation program development procedure using JR-Net modeling results is explained. Finally, simulation result of FMS model plant is analyzed.

  • PDF

ON THE C-NETS

  • Lee, Seung On;Pi, Young Jin;Oh, Ji Hyun
    • Journal of the Chungcheong Mathematical Society
    • /
    • v.23 no.1
    • /
    • pp.109-117
    • /
    • 2010
  • In this paper, we define the concept of a c-net and study the convergence of c-nets. Also we show that a c-net in a topological space X has a convergent sub-c-net if and only if X is a $Lindel{\ddot{o}}f$ space, if every $G_{\delta}$ set is open in X.

Fault-tolerance Analysis of Link Line of Beta-network in the Multicomputer System (다중 컴퓨터 시스템에서의 Beta-network의 링크선에 관한 Fault-tolerance 분석)

  • 전우천;김성천
    • Journal of the Korean Institute of Telematics and Electronics
    • /
    • v.24 no.4
    • /
    • pp.610-617
    • /
    • 1987
  • This thesis is concerned with fault-tolerance of a B-net (Beta-network) which is a kind of interconnection network in the multicomputer system. In this paper, a method for obtaining Maximal Tolerable Fault Set(MTFS) of link line connecting switching elements in the arbitrary B-net is presented. Using this method, it is seen that testing of DFA capability is possible when s-a-faults of link line occur, and criterion for determining degree of fault- tolerance of a B-net in terms of link line is introduced.

  • PDF

Species composition and quantitative fluctuation of fishes collected by gape net in coastal waters of Yeosu, Korea (여수연안 낭장망에 어획된 어류의 종조성 및 양적변동)

  • Han, Kyeong-Ho;Oh, Yong-Seok
    • Journal of the Korean Society of Fisheries and Ocean Technology
    • /
    • v.43 no.4
    • /
    • pp.261-273
    • /
    • 2007
  • To analyze quantitative fluctuation in abundance and species composition in coastal waters of Dolsan, Yeosu, the fished were collected by gape net from March to November, 2000. The fish species caught by set net collected fishes were identified 63 species, 56 families, 42 orders, and the number of appearance and biomass was 2,230,297 individuals and 16,076.8kg. The most dominant orders were Perciformes, Clupeiformes and Tetraodontiformes which accounted for 71.4% of the total. The dominant species in number were Engraulis japonicus, Sardinops melanostictus, Trichiurus lepturus which accounted for 99.2% (2,211,642 individuals) of the total fishes collected. The dominant species in biomass were Engraulis japonicus which accounted for 79.7% (12,807g) of the total fishes collected. Temporal occurence of the dominant species such as the Engraulis japonicus, Sardinops melanostictus, Trichiurus japonicus, Ilisha elongata, Leiognathus nuchalis was closely correlated with water temperature, which is expressed as following regression equation, $y=0.0864x-0.2311(r^2=0.3516)$. The species collected during the sampling yearly period were Engraulis japonicus, and migratory fish were Ilisha elongata, Trichiurus japonicus, Scomberomorus nipphnius, Scomber japonicus, Konosirus punctatus, Sphyraena pinguis, Pseudosciaena polyactis.

Fundamental Study on the Migrating Course of Fish Around the Set Net - The Bottom Contour Contour and the Tidal Current around Set Net - (정치망어장의 어도형성에 관한 기초연구 ( 2 ) - 해저지형의 해수유동-)

  • Lee, Ju-Hui;Yeom, Mal-Gu;Park, Byeong-Su
    • Journal of the Korean Society of Fisheries and Ocean Technology
    • /
    • v.24 no.1
    • /
    • pp.12-16
    • /
    • 1988
  • The observation of the tidal current and the bottom contour around the set net fishing ground were carried out at four different regions of the southern part of Korea in order to obtain the basic information on the migrating course of fishes. The bottom contour was surveyed with portable echo sounder, and the tidal current was observed by two different methods at the same time. One was 25 hour observation at the fixed position with self-recording current meter (Inter Ocean Model 135 type) and the other was the drift observation of radar reflectors. Most of the set nets have been set near bottom valleys. It was regarded that the fish school became to dense easily near the valley according to the combined effect of the tidal current and the bottom contour.

  • PDF