• 수산해양기술연구
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• 제49권2호
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• pp.106-115
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• 2013

A series of fishing experiments were carried out in the western coastal waters of Korea from May, 2006 to September, 2007, using gill nets of different mesh sizes (m=101, 121.8, 152.5, 176.8, and 191 mm) to determine the mesh selectivity of gill net for swimming crab, Potunus trituberculatus. The catch species was composed of swimming crab (87%), Thomas's rapa whelk Rapana venosa (5%), arthritic neptune Neptunea cumingi (2%), Japanese swimming crab Charybdis japonica (2%), marbled sole Pleuronectes yokohamae (1%), pen shell Atrina pectinata, ocellate spot skate Okamejei kenojei, and so on. The carapace length (CL) of each swimming crab caught in the experimental nets was measured. Sponge crab (egg-bearing female crab) was appeared from the end of June to August in the coastal waters. The master selection curve was estimated by applying the extended Kitahara's method. The selection curve showed that the gill nets of larger mesh size allowed more crabs of small carapace size to escape. The optimum value (CL/m) was 0.645 and the CL/m was estimated to be 0.301, 0.354, 0.391, 0.422, and 0.450 when the retention probabilities were 0.1, 0.2, 0.3, 0.4 and 0.5, respectively.

• Ocean and Polar Research
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• 제25권3호
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• pp.331-345
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• 2003

The fishing ground surrounding Wangdol-cho is not only overexploited by the littering of dilapidated fishing net and equipment, but also by fishermen's overfishing, surpassing optimum fisheries resources. In addition, increasing fishing efforts (number of fishing vessel and fishing net, etc) contribute to the deterioration of fishing ground, and it is urgently required that schemes to tackle the problems should be taken. To effectively address the problems as such, this paper aims to propose sustainable utilization and management scheme of fishing ground through classification of fishing ground surrounding Wangdol-cho as one area which is less than 50m deep, measuring $13.66km^2$ and the other, permission fishing area of Gill Net fishery, measuring $347.23km^2$. The analysis shows that, for the water area less than 50m deep, implementation from a short-term perspective includes autonomous management fishery by gill net and trap fishery. For the permission fishing area of Gill Net fishery, implementation includes limit on fishing period, real name system of fishing equipment and limit on fishing equipment. Implementation from a medium and long-term perspective includes limit on scuba diving, designation of underwater sightseeing zone, sea farming, facilities of surveillance, adoption of approval system for the permission fishing area of Gill Net fishery and introduction of report system for fishing.

• 수산해양기술연구
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• 제49권4호
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• pp.341-351
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• 2013

Physical characteristics of PA (Polyamide) gill net and biodegradable gill net made by PBS (Polybutylene succinate) (mesh size 63mm, mesh thickness number 2, 2.5, 3) were analyzed to investigate catching efficiency of the biodegradable gill net for Pacific herring. Total 11 numbers of catching efficiency tests were carried out using commercial fishing vessel at Imwon port in Kangwon province from May to June 2013. The amount of catches were 1,535.7kg (18 species) through the catching efficiency tests and it is expected that the practicalization of biodegradable gillnet is possible because there is no difference for catches between PA gillnet and PBS gillnet. Catches of herring according to the thickness of net twine was the highest at No.2 and the thicker net twine tends to decrease the catches.

• 한국수산과학회지
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• 제49권2호
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• pp.137-145
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• 2016

This study screened the biological activity of an acidified gill extract of the Manila clam Ruditapes philippinarum including antimicrobial, hemolytic, membrane permeabilization, and DNA-binding activity, and purified the antimicrobial material. The acidified gill extract showed potent antimicrobial activity against Bacillus subtilis and Escherichia coli without significant hemolytic activity, but showed no membrane permeabilization or DNA-binding ability. An antimicrobial material was purified from the acidified gill extract using C₁₈ reversed-phase and cation-exchange high-performance liquid chromatography (HPLC). Treatment of the purified material with trypsin completely abolished all of the antibacterial activity against Bacillus subtilis, suggesting that the purified material is a proteinaceous antibiotic. The molecular weight of the purified material was 2571.9 Da, but no primary structural information was obtained due to N-terminal blocking. A future study should confirm the primary structure. Our results suggest that the Manila clam gill contains proteinaceous antibiotics that have a role in first-line defense. This information could be used to better understand the Manila clam innate immune system.

• 대한전기학회논문지:전력기술부문A
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• 제53권5호
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• pp.257-265
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• 2004

The complex documentation involved in power system analysis software require a well-defined and friendly database system. We have developed an object-oriented database management system for power system analysis, and have described load flow analysis and transient stability analysis using object-oriented database(OODB). Database management systems are widely used and achieve high reliability of data management in the engineering fields. However relational database system have shortcomings in application to power system analysis. ill relational database, the data model is too simple for modeling complex data and database languages are very different from programming languages. Object-oriented techniques are sufficiently powerful to support data-modeling requirements of GUI applications. The GUI is implemented using C++ on a MS windows platform. The OODB supports data modeling requirements of GUI applications and the performance is well acceptable for Gill applications.

• 수산해양기술연구
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• 제43권2호
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• pp.116-125
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• 2007

An experiment to acoustically analyze the shape of gill-net in the current was conducted in Jaran Bay, Gosung, Korea on the 9th to 10th September(spring tide) and 28th to 29th September(neap tide) 2006. It was measured by a 3D underwater positioning system with a radio-acoustic linked positioning buoys. Six of 7 acoustic transmitters used in the experiment were attached on the float line of the gill-net and the other was fixed on the sea bed. During spring tide, the maximum movement of the gill-net was 27.0m(22:00) in the west(4.4cm/s, $311.9^{\circ}$) and 20.6m(04:00) in the east(3.9cm/s, $66.5^{\circ}$). The maximum extension of the gill-net(the distance between P1 and P6) was 119.8m(21:00, 11.6cm/s, $321.9^{\circ}$) and the minimum was 109.9m(23:00, 16.1cm/s, $88.5^{\circ}$). During neap tide, the maximum movement was 38.0m(20:00) in the east(9.6cm/s, $278.2^{\circ}$) and 11.0m(12:00) in the west(1.9cm/s, $232.1^{\circ}$). The maximum extension was 99.6m(14:00, 12.5cm/s, $94.7^{\circ}$) and the minimum was 85.0m(06:00, 9.0cm/s, $265.8^{\circ}$). During spring tide, the maximum height of the gill-net from the sea bed was 3.7m(02:00, 7.4cm/s, $151.6^{\circ}$) and the minimum was produced the three times as 1.5m. At that time, the current speed and direction was 17.9cm/s and $85.3^{\circ}$(23:30), 16.1cm/s and $249.4^{\circ}$(05:00), and 13.7cm/s and $291.4^{\circ}$(06:30), respectively. During neap tide, the maximum height was 3.6m(12:30, 2.1cm/s, $242.3^{\circ}$) and the minimum was 1.5m(14:00, 12.5cm/s, $94.7^{\circ}$).

• 수산해양기술연구
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• 제41권3호
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• pp.199-206
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• 2005

As the basic study about improvement of yellow croaker drift gill net fishing implement and development of the fishing system, this study drew problem after synthetically analyzing hauling system of yellow croaker drift gill net used in the coast of Chuja Island and tested several characters and analyzed in hauling process with 5 step net hauler model for improving the problem. The analysis results are as follows. When the angle between axises of drum centers was small, it showed the tendency that hauling time was fast. Hauling time was faster when drum was 5 step rather than 3 step. When drum was 5 step, slippery phenomenon was small and hauling was stable. Tension was larger when drum was 5 step rather than 3 step. When drum was 5 step, the range of change of the maximum and minimum value was small and hauling was stable. When drum was 3 step, there was following formula between hauling time ($Ht_3$) and angle between axises of drum centers ($A_g$) $Ht_3$ : ($7.15Hs^{-0.81}$) $A_g^{-0.81}$, when drum was 5 step there was following formula.$Ht_5$ : ($6.45Hs^{-0.75}$) $A_g0.10$, here, Hs is hauling speed. When drum was 3 step and hauling speed was 28cm/sec, tension was $T=0.08A_8^3-1.60A_g^3-0.49A_g+369.56(r=0.99)$, when drum was 5 step, tension was, $T=-0.01A_g^3+1.96A_g^2-34.05A_g+414.58$ (r-0.99), here, T was tension(g).

• 한국수산과학회지
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• 제34권1호
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• pp.51-56
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• 2001

염분변화에 따른 숭어와 틸라피아의 아가미 조직과 전어체의 일반성분을 조사한 결과를 요약하면 다음과 같다. 사육수의 염분조절은 담수로부터 1일만에 $33\%_{\circ}$의 해수가 되도록 사육수를 교환하였고, 이후 15일 후에 다시 담수로 사육수를 교환하여 15일간 담수로 유지하였다. 전 실험기간중 숭어의 아가미 조직상은 별다른 차이를 보이지 않았다. 그러나 틸라피아는 염분상승에 따른 조직의 손상이 관찰되었으며, 해수 2일째에는 아가미 2차 새변 (gill lamella)의 모세혈관들이 응혈 (bloodclot)되고 새변이 중첩되는 조직상을 보였다. 염분이 상승함에 따라 숭어의 아가미 염류세포는 개구부 (apical pit)가 뚜렷하였으며, 많은 수의 미토콘드리아를 가지고 있었다. 틸라피아에서는 실험개시시에는 염류세포 개구부가 거의 닫혀있는 형태를 나타냈으며, 미토콘드리아는 담수 보다 해수에서 증가되었다. 숭어 전어체의 수분 함량은 실험개시시 $74.0\pm0.6\%$, 해수사육 15일째 $73.6\pm0.5\%$, 담수사육 15일째 $74.5\pm0.3\%$로 서로간에 유의한 차이를 보이지 않았다. 그러나 틸라피아에서는 실험개시시 $72.2\pm0.1\%$였다가 해수사육 2일째에는 $70.2\pm0.2\%$로 유의하게 낮아졌다. 숭어의 전어체 단백질 함량은 실험개시시와 15일째 유의한 차이를 보이지 않았다. 틸라피아의 지질 함량은 차이를 보이지 않았으나, 회분 함량은 차이를 나타냈다.

• 수산해양기술연구
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• 제32권1호
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• pp.33-41
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• 1996

In order to obtain the most favourable classification system for fishing gears, the problems in the existing systems were investigated and a new system in which the fishing method was adopted as the criterion of classification and the kinds of fishing gears were obtained by exchanging the word method into gear in the fishing methods classified newly for eliminating the problems was established. The new system to which the actual gears are arranged is as follows ; (1)Harvesting gear \circled1Plucking gears : Clamp, Tong, Wrench, etc. \circled2Sweeping gears : Push net, Coral sweep net, etc. \circled3Dredging gears : Hand dredge net, Boat dredge net, etc. (2)Sticking gears \circled1Shot sticking gears : Spear, Sharp plummet, Harpoon, etc. \circled2Pulled sticking gears : Gaff, Comb, Rake, Hook harrow, Jerking hook, etc. \circled3Left sticking gears : Rip - hook set line. (3)Angling gears \circled1Jerky angling gears (a)Single - jerky angling gears : Hand line, Pole line, etc. (b)Multiple - jerky angling gears : squid hook. \circled2Idly angling gears (a)Set angling gears : Set long line. (b)Drifted angling gears : Drift long line, Drift vertical line, etc. \circled3Dragged angling gears : Troll line. (4)Shelter gears : Eel tube, Webfoot - octopus pot, Octopus pot, etc. (5)Attracting gears : Fishing basket. (6)Cutoff gears : Wall, Screen net, Window net, etc. (7)Guiding gears \circled1Horizontally guiding gears : Triangular set net, Elliptic set net, Rectangular set net, Fish weir, etc. \circled2Vertically guiding gears : Pound net. \circled3Deeply guiding gears : Funnel net. (8)Receiving gears \circled1Jumping - fish receiving gears : Fish - receiving scoop net, Fish - receiving raft, etc. \circled2Drifting - fish receiving gears (a)Set drifting - fish receiving gears : Bamboo screen, Pillar stow net, Long stow net, etc. (b)Movable drifting - fish receiving gears : Stow net. (9)Bagging gears \circled1Drag - bagging gears (a)Bottom - drag bagging gears : Bottom otter trawl, Bottom beam trawl, Bottom pair trawl, etc. (b)Midwater - drag gagging gears : Midwater otter trawl, Midwater pair trawl, etc. (c)Surface - drag gagging gears : Anchovy drag net. \circled2Seine - bagging gears (a)Beach - seine bagging gears : Skimming scoop net, Beach seine, etc. (b)Boat - seine bagging gears : Boat seine, Danish seine, etc. \circled3Drive - bagging gears : Drive - in dustpan net, Inner drive - in net, etc. (10)Surrounding gears \circled1Incomplete surrounding gears : Lampara net, Ring net, etc. \circled2Complete surrounding gears : Purse seine, Round haul net, etc. (11)Covering gears \circled1Drop - type covering gears : Wooden cover, Lantern net, etc. \circled2Spread - type covering gears : Cast net. (12)Lifting gears \circled1Wait - lifting gears : Scoop net, Scrape net, etc. \circled2Gatherable lifting gears : Saury lift net, Anchovy lift net, etc. (13)Adherent gears \circled1Gilling gears (a)Set gilling gears : Bottom gill net, Floating gill net. (b)Drifted gilling gears : Drift gill net. (c)Encircled gilling gears : Encircled gill net. (d)Seine - gilling gears : Seining gill net. (e)Dragged gilling gears : Dragged gill net. \circled2Tangling gears (a)Set tangling gears : Double trammel net, Triple trammel net, etc. (b)Encircled tangling gears : Encircled tangle net. (c)Dragged tangling gears : Dragged tangle net. \circled3Restrainting gears (a)Drifted restrainting gears : Pocket net(Gen - type net). (b)Dragged restrainting gears : Dragged pocket net. (14)Sucking gears : Fish pumps.

• Coupled systems mechanics
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• 제2권2호
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• pp.159-174
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• 2013

The present work aims at investigating the nonlinear dynamics, bifurcations, and stability of an axially accelerating beam with an intermediate spring-support. The problem of a parametrically excited system is addressed for the gyroscopic system. A geometric nonlinearity due to mid-plane stretching is considered and Hamilton's principle is employed to derive the nonlinear equation of motion. The equation is then reduced into a set of nonlinear ordinary differential equations with coupled terms via Galerkin's method. For the system in the sub-critical speed regime, the pseudo-arclength continuation technique is employed to plot the frequency-response curves. The results are presented for the system with and without a three-to-one internal resonance between the first two transverse modes. Also, the global dynamics of the system is investigated using direct time integration of the discretized equations. The mean axial speed and the amplitude of speed variations are varied as the bifurcation parameters and the bifurcation diagrams of Poincare maps are constructed.