• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2003.10a
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• pp.23-26
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• 2003

정치망은 어군의 자연적인 이동 경로를 길그물로써 차단하여 어군을 운동장으로 유도한 후, 비탈그물을 통해 원통으로 들어가게 하여 어획하는 소극적 어구이다. 정치망이 수중에 형성하고 있는 공간의 규모와 형태는 해면에 떠있는 뜸의 형상 및 각 부분의 부설 깊이와 침강 수심을 조사하여 추정하고 있으나, 정치망이 설치된 해역의 조류 방향과 유속에 따라 수중 형상의 크기나 형태가 변형되어 어획량에 영향을 주는 요인이 될 뿐만 아니라 강한조류나 악천후에 의한 파손 등으로 조업 손실을 초래하기도 한다. (중략)

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.38 no.2
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• pp.156-163
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• 2002

In order to development the construction and dimension of fishing gear for gizzard shad coastal purse seine, first of all investigated to the sinking speed and underwater geometry of net, behaviour of fish school to the net during the fishing operation In the field. The results obtained are summarized as follows; 1. Average sinking speed of net was 13cm/sec in bunt, 9.0cm/sec and 9.5cm/sec in 170m and 280m of center, 4.9cm/sec in end wing side, therefore was fastest in start of shooting and decreased gradually during the shooting process. 2. The most of leadline was reached in bottom from the shooting immediately to hauling time and the mean depth of timber bar used equipment for the escaping prevention of fish school was within the 2.7m. 3. The fish school of gizzard shad was appearanced higher density and remained to the most time in bottom than the surface and repeated to vortical movement, and its tendency to distinct in rapid time of tide current. 4. Behaviour of fish school in the net was showed to the vortical movement by sinking and rising immediately with the shooting of net and then divide with the two shape to follow round the wall of net and no patterns straightly movement in the net, and tendency easily catched in fish school of the wall of net. 5. Escaping of fish school in the gap of wing side was to busy after that seting the timber bar, therefore its function for escaping prevention of fish school was very lowed. 6. Escaping behaviour of fish school was differenced with the depth of fishing ground, the above 20m escaped to busy through the below in ledline because the sinking speed of fish school is fast than the net.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.31 no.4
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• pp.372-378
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• 1995

This study describes an analysis on the sinking characteristics in purse seine. The experiment was carried out using three simplified model seines in a flume tank under still water condition. The densities($\rho$) of netting materials were 0.91g/$cm^3$ for PP seine, 1.14g/$cm^3$ for PA seine and 1.38g/$cm^3$ for PES seine. Differential equations were derived from the conservation of momenta of the model seines and used to determine the sinking speeds of the depths of leadline and the other portions of seines. An analysis carried out by simultaneous differential equations for numerical method by subroutine Runge-Kutta-Gill. The results obtained were as follows: 1) Sinking speed of net margin was fastest for PP seine, followed by PA and PES seines. 2) The coefficient of resistance for netting of seine was estimated to be $K_D=0.061({\frac{\rho}{{\rho}_w}})^4$. 3) The coefficient of resistance for netting bundle of seine was estimated to be $C_R=0.91({\frac{\rho}{{\rho}_w}}$. 4) In all seines, the calculated depths of leadline closely agreed with the measured ones(meas.=0.99cal.).

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.39 no.2
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• pp.99-111
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• 2003

The fundamental studies on the productivity improvement of the purse seine fishery are presented in this paper. The experiment on net shooting and hauling was carried out in the near sea of Jeju Island (33$^{\circ}$37.8' N, 126$^{\circ}$31.1' E) by using the Cheju national university training ship (A-Ra, 990tons) which was constructed for the one boat system operation of purse seine. The corkline and leadline of the purse seine used for the experiment were 829.1m and 995.7m in length, respectively. Micro data recorder system, net sonde, and tensiometer were used to measure the depth of leadline and the tension of purse seine. Based on the measurement data, the motion and tension of purse seine at the time of shooting, hauling, and pursing were characterized. The experimental results are summarized as follows ; 1. The shooting and hauling of net were found to be possible in the one boat system experimental operation. 2. At the time of purse seine shooting, the relationship between the depth (Dp) of leadline and elapsed time (Et) was found to be Dp=7.58Et-6.48. 3. At the time of pursing, the relationship between the depth (Dp) of leadline and elapsed time (Et) was found to be Dp=-0.8Et$^2$＋7.42Et＋92.04. 4. At the time of pursing, the tension (metric tons) of purse seine attained its maximum value (14.7tons) when the elapsed time is 8 minutes. The relationship with the elapsed time was found to be T=-0.13Et$^2$＋3.23Et-5.72.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.28 no.2
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• pp.194-201
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• 1995

In order to make clear the resistance of bag nets, the resistance R of bag nets with wall area S designed in pyramid shape was measured in a circulating water tank with control of flow velocity v and the coefficient k in $R=kSv^2$ was investigated. The coefficient k showed no change In the nets designed in regular pyramid shape when their mouths were attached alternately to the circular and square frames, because their shape in water became a circular cone in the circular frame and equal to the cone with the exception of the vicinity of frame in the square one. On the other hand, a net designed in right pyramid shape and then attached to a rectangular frame showed an elliptic cone with the exception of the vicinity of frame in water, but produced no significant difference in value of k in comparison with that making a circular cone in water. In the nets making a circular cone in water, k was higher in nets with larger d/l, ratio of diameter d to length I of bars, and decreased as the ratio S/S_m$ of S to the area $S_m$ of net mouth was increased or as the attack angle 9 of net to the water flow was decreased. But the value of ks15m was almost constant in the region of S/S_m=1-4$ or $\theta=15-90^{\circ}$ and in creased linearly in S/S_m>4 or in $\theta<15^{\circ}$ However, these variation of k could be summarized by the equation obtained in the previous paper. That is, the coefficient $k(kg\;\cdot\;sec^2/m^4)$ of bag nets was expressed as $$k=160R_e\;^{-01}(\frac{S_n}{S_m})^{1.2}\;(\frac{S_m}{S})^{1.6}$$ for the condition of $R_e<100$ and $$k=100(\frac{S_n}{S_m})^{1.2}\;(\frac{S_m}{S})^{1.6}$$ for $R_e\geq100$, where $S_n$ is their total area projected to the plane perpendicular to the water flow and $R_e$ the Reynolds' number on which the representative size was taken by the value of $\lambda$ defined as $$\lambda={\frac{\pi d^2}{21\;sin\;2\varphi}$$ where If is the angle between two adjacent bars, d the diameter of bars, and 21 the mesh size. Conclusively, it is clarified that the coefficient k obtained in the previous paper agrees with the experimental results for bag nets.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.27 no.1
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• pp.31-40
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• 1991

This paper described on the availability fo the underwater telemetering by the ulterasonic multi-beam system made as a trial to expand detectable range of the fish school. The ultrasonic multi-beam system consisted of four transducers which reconstructed with the existing net recorder. The experiment for the telemetering carried out in the set net fishing ground. The results obtained are summerized as follows: 1. The detectable distance of a target by the linear arrangement of four transducers increased according to the sea depth and the interval between transducers. 2. When the fish school in the entrance of set net was measured by linear arrangement of transducers it was entered in depth of 2.5~3.5m at near position of leader, and in depth of 3.5~4.5m at near position of door net. 3. The deviations of error between the actual position and the position by transducer in case of the target depth 1m, 1.5m, 2m were 5.9~27.1cm, 3.2~28.9cm, 3.5~25.8cm respectively, and 68.3% probability radius of them were 14.6cm, 17.7cm, 17.0cm respectively. 4. When the fish school in the fish court of set net was measured by plane arrangement of transducer it was entered toward the opposite direction of tide current. 5. The available distance of telemetering by the multi-beam transducer was 1.8km and the telemetering was possible to control everywhere in case of sea depth more than three meters.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.33 no.2
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• pp.109-117
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• 1997

In order to hold the behavior of fish school to the set-net, a series of tag-recapture experiments were carried out in two fishing grounds of the middle sized set-nets which were located in 20m depth on the coast of Keojedo and Namhaedo in the Southern part of Korea from September to October in 1996. In the experiments, the leading ability of the leader and the fish court and the recapturing ability of the bag nets were checked out for the six species of fish in method of discharging the tagged fishes at side points of leader, and the middle points of the fish court and the bag nets in a hauling step, and recapturing them at the bag nets in the next hauling. The results obtained are as follows; 1. The ratio recaptured at the both side bag-nets in the next hauling after discharged from the fish court in the previous step was 20.3% in small size of mackerel Scomber japonicus, 16.2% in small size of horse mackerel Trachurus japonicus, 10.3% in black sea-bream Acanthopagrus schlegelii, 19.1% in red barracuda Syhyraena pinguis, 16.3% in halfbeak Hemiramphus sajori, 20.0% in gizzard shad Konosirus punctatus individually, and totally in six species of fish, that was 17.2%. 2. The ratio recaptured at the same bag net after discharged in the both side bag-nets was 21.7% in small size of mackerel, 21.5% in small size of horse mackerel, 6.7% in black sea-bream, 17.8% in red barracuda, 16.8 in half-beak, 19.1% in gizzard shad individually, and totally in six species of fish, that was 18.8%. 3. The leading ratio from side points of the leader departed from door in 25m to fish court was 58.9% in small size of mackerel, 74.6% in small size of horse mackerel, 38.0% in black sea-bream, 54.7% in red barracuda, 58.6% in half-beak, 54.5% in gizzard shad individually, and totally in six species of fish, that was 57.8%. So it was assumed that the leader of set-net was very effective in leading to the swimming direction of small size of mackerel, small size of horse mackerel, red barracuda, half-beak and gizzard shad. 4. Red barracuda, half-beak and gizzard shad entered into bag net of upstream in large numbers than bag net of downstream, and small size of horse mackerel and black sea-bream entered into bag net of downstream in large numbers than bag net of upstream. 5. Small size of mackerel and small size of horse mackerel had high remaining rate in the bag net of downstream, and black sea-bream, red barracuda and half-beak had high remaining rate in the bag net of upstream.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.36 no.4
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• pp.287-298
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• 2000

The charge of distance and the change of tack between paired boats were measured by ship's distance measuring system fixed MCS in the main boat and MS in the following boat. The operating depth of the anchovy boat seine was recorded and analysed by self memory temperature/depth sensor in order to compare the relationship between the distance between towing boats and geometry of the anchovy boat seine net. The results are as follow, (1) When distance between paired boat was 5m, the fishing net was spreaded down deeply and unstably in accordance with bag net and flapper may be help to pass out anchovy school. (2) When distance between paired boat was 100m, vertical opening of the net was gradually increased with higher slope of towing depth in the square, bosom and flapper. Therefore, fishing efficiency could be decreased by preventing the entering of anchovy due to unstable shape of the bag net. (3) When distance between paired boat was 200m, the geometry of the anchovy seine was stable condition with the end of bag net was up while flapper was down and it may cause bad effect in fishing efficiency. (4) When distance between paired boat was 300m, the shape from wing net to bag net was gradually slow down and stable enough as well as good shape in bag net and flapper. (5) The ship's distance measuring system could be used for measurement and accurate control of distance between paired boat in accordance of anchovy recordings by fish finder in order to get higher fishing efficiency in anchory boat seine operation.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.40 no.1
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• pp.29-36
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• 2004

This study deals with an analysis on the sinking resistance for the model purse seine, in the case of different netting material and sinkers. The experiment was carried out using rune simplified model seines of knotless nettings. Dimension of model seines 420cm for corkline and 85cm for seine depth, three groups of models rigged 25, 45 and 60g with the same weighted sinkers in water were used. These were named PP-25, PA-25, PES-25, PP-45, PA-45, PES-45, PP-60, PA-60 and PES-60 seine. The densitie($\rho$) of netting materials were 0.91g/cm$cm^3$, 1.14g/cm$cm^3$ and 1.38g/cm$m^3$. Experiments carried out in the observation channel in a flume tank under still water conditions. Sinking motion was recorded by the one set of TV-camera for VTR, and reading coordinate carried out by the video digitization system. Differential equations were derived from the conservation of momenta of the model purse seines and used to determine the sinking speeds of the depths of leadline and the other portions of the seines. An analysis carried out by simultaneous differential equations for numerical method by sub-routine Runge-Kutta-Gill The results obtained were as follows : 1. Average sinking speed of leadline for the model seines rigged 60g with the same weighted sinkers in water was fastest for 12.2cm/sec of PES seine, followed by 11.4cm/sec of PA and 10.7cm/sec of PP seines. 2. The coefficient of resistance for netting of seine was estimated to be $K_D=0.09(\frac{\rho}{\rho_w})^4$ 3. The coefficient of resistance for netting bundle of seine was estimated to be $C_R=0.91(\frac{\rho}{\rho_w})$ 4. In all seines, the calculated depths of leadline closely agreed with the measured ones, each 25g, 45g, 60g of weighted sinkers were put into formulas meas.=1.04cal., meas.=0.99cal. and meas.=0.98 cal.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.37 no.2
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• pp.78-84
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• 2001

Escape behaviour of the anchovy (Engralius japonica, total length 4-7cm) at the inside wing net and bag net in the anchovy boat seine was observed by underwater video camera in order to clarify the relationship between visual stimulus of the gear or relative water flow inside gear and reacting behaviour. The vertical attenuation coefficient of underwater illuminance in the offshore of Keoje island and Tongyoung was ranged from 0.24 to 1.03 and it could be affect visual range and visual contrast of the fishing gear. The relative water flow at the joint part between inside wing and bagnet while towing was 1.5 times higher than at the middle part of inside wing or fore part of bag net, but it was estimated under than maximum swimming speed of 4-7 cm anchovy. The mean escaping number of anchovy from end part of inside wing of 30 cm mesh to out side for a minute within visual range of video camera was 455 and anchovy swimming forward from bag net through flapper was 308. These results revealed anchovy could escape as voluntary response in spite of higher visual stimulus or higher water flow.