• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.11 no.1
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• pp.15-20
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• 1975

The catch per unit effort and the migration of Alaska pollack Theragra chalcogramma were deduced from the catch data of 1, 208 hauls of a stern trawler operated on and around the continental shelf east of the Kamchatka Peninsula and Kurile Islands from October 1974 to December 1975. Alaska pollack occupied more than ninety per cent of the total catch of approximately 17, 760 metric tons, while the cuttle and flat fishes occupied less than five percent. Beside those fishes, approximately 131 metric tons of Alaska pollack roe were produced during the voyage from February to April 1975. The mean catch per unit effort in each sub-area of fishing ground was approximately 15.5 metric tons and the peak of the CPUE occured in January and August. The CPUE in the continental shelf east of Kamchatka Peninsula ($50^{\circ}- 52^{\circ} N$ Lat) showed the maximum of 25-34 metric tons in August. The main fish school is thought to migrate southward speedily in August-September along the continental shelf from the Kamchatka Peninsula to the east of Kurile Islands. The CPUE on the continental shelf east of Kamchatka Peninsula was higher than that on the steeper continental slope. However, the CPUE on the steeper flank of the bank east of Paramushiru Island and Onekotan Island was remarkably higher than that on the relatively flat top of the bank. The small-sized fishes of less than thirty centimeter in fork length began to recruit in the fishing ground since August 1965.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.9 no.4
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• pp.287-292
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• 1976

The author studied the stability Tualities of stern trawlers in the North Pacific Ocean according to Kato's simple judging method. The author selected 1,000 gross tonnage of A and B types, and calculated each characteristics for various conditions under 5 different free-board and S different KG. Finally, authour obtained some data of stability factors for the two types, and pointed out the zone of safety and danger between stability factor, GM and GZ max. The results obtained here are summarized as follows: The A type of ship is judged that it has the condition of safety when displacement is 2,400 tonnage and the value of K￠ was 3.40m or 3.70m. The B type of ship is judged that it only has the condition of some safety when displacement was 2,400 tonnage and the value of KG is 3.40 m, but ships of the both types have the condition of danger when displacement is 1,300-2,200 tonnage and the value of KG is 3.40-4.60m. Any types of ships under various condition must have appropriate dimensions among GM, free-oard and GZ max for the stability of ships.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.36 no.4
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• pp.274-280
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• 2000

To analyze the resistance of the bottom trawl which is composed with 6 seams net, the field experiment was carried out on the sea near Kokunsan Is., western sea of Korea. The resistance was respectively measured in the otter board and the net according to the change of warp length and towing speed. The results obtained are summarized as follows : 1. Total resistance of the test trawl gear are slightly increased according to the length of warp. 2. The resistance of net is increasing a little according to the length of warp, but it is expressed. $$ R_n/=10 \frac{d}{\ell}$representatively. 3. The resistance of otter board can be expressed $Rb=1810_{\upsilon}^0.8.$ 4. Comparing with the value of measuring resistance and Koyama formula resistance by the length of warp respectively, the resistance of test trawl gear is high in the slow towing speed, and the resistance of Koyama formula is high in the fast towing speed, and that the cross-point of the both line between the resistance of the test net and Koyama formula is moved to high according to the increment of warp length.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.19 no.2
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• pp.106-110
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• 1983

As the first step to investigate the effect of ship's motion when detecting target with an echo sounder, variations in the incident sound level at the optional position within the sound beam due to roll motion of the transmitter have been measured and calculated. In this experiment, the transmitter (75 KHz) was mounted to the bottom of a FRP model of the 2,275 G. T. stern trawler and the receiver (75 KHz) was installed at each measuring point within the transmitter's beam. Then, the incident sound level was measured for the roll angles from the free roll test on the model ship. For a range of roll angle of $\pm$20$^{\circ}$from the vertical, the measuring values of the incident sound level at each measuring point were rapidly fluctuated from 12.9% to 78.1 depending on the roll angle, and agreed well with the caculated ones. Consquently, we concluded that the effect of ship's motion when detecting target with an echo sounder should be sufficiently considered.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.14 no.4
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• pp.260-264
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• 1981

The purpose of the present study is to measure the sound spectrum of the underwater noise generated by a stern trawler M/S Saebada (2,275 GT, 3600 ps) in the various operational conditions. Underwater noises were recorded by a hydrophone (B & K 8100) and analyses were made rising a digital frequency analyzer (B & K 2131) and level recorder (B & K 2370). The predominant frequency range was 100-500 Hz, and maximum sound pressure level was 121 dB(re. $1{\mu}Pa$). Underwater noise level increased with the increased speed of the vessel. Sound pressure level measured in the course of astern cruising was higher than that measured in the course of ahead cruising and also the noise spectrums were different in these two cases. At the time of cruising the underwater noise was higher than 10 dB compared to those values measured at the time at rest with only engine operation. The underwater noise of the vessel was mainly due to the main engine revolution of the propeller and the vibration of hull.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.31 no.1
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• pp.84-92
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• 1995

The methods by turning circle test and maneuvering indices have been used to study and evaluate the maneuverability of a ship. However recently many studies utilizing the GPS are made on the measurement of the turning circle and in the fishery and hydrographic survey. In this paper, the author carried out the turning circle test using the differential GPS and dumb card together, and compared the data measured by them and analyzed the accuracies of them to obtain the utility basic ones on the measurement of the turning circle by the DGPS. The main results area s follows : 1) To check the accuracies of the GPS, the circling experiments of 50m radius by the DGPS were made on the ground. The accuracies of turning circle measured by the DGPS were found to be very high as the errors of 1.5m. 2) the turning circle by the DGPS could be measured very accurately, by the seed, rudder angle, starboard and port respectively. 3) The turning circle measured by the dumb card was found to be measured accurately as much as the DGPS, when using large rudder angle, the turning circle was large, the turning circle by the dumb car could not be measured accurately on account of large error of bearing of compass. 4) The tactical diameters by the DGPS in case of the rudder angle 35。~5。, were found to be 2.6。15.0 times the Lpp of S.T HAELIM-3 at her slow speed 2.8~16.6 times her Lpp at her half speed, 3.1~17.4 times her Lpp at her full speed. The tactical diameter by the dumb card was found to be 2.4~9.5 times, 2.6~9.6 times, 3.2~12.2 times her Lpp respectively, in the above case and speed.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.15 no.2
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• pp.67-76
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• 1979

Diurnal variation of the catch of some important species groups in the Northwestern coast of Africa were studied on the basis of fish catching data compiled by a stern trawler(G.T., 499ton 2,200ps). The experimental fishing has been conducted from September, 1975 to August, 1976. The catch of the important groups I. e. squid, cuttlefish, octopus, sole fish and sea bream revealed different fluctuation patterns. The results obtained are as follows: 1. The catch of squid caught in daytime(0900-1800) was greater than that caught in night (2100-0600). 2. The catch of cuttle fish caught in daytime was more than that caught in night. In the daytime, large size group(heavier than 300g) was caught dominately during midday (1200-1500) whereas the small size group, lighter than 300g, was caught dominately during the time of sunrise (0600-0900) and sunset (1800-2100). 3. The catch of octopus varied according to the size groups. The large sige group, heavier than 700g, was caught predominately during daytime and the small size group, lighter than 700g, was caught predominately during night. 4. The catch of sole fish caught in night was greater than that caught in daytime. 5. The catch of sea bream and miscellaneous fishes including sardin, jack-mackerel and etc. was greater in daytime.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.28 no.1
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• pp.21-26
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• 1992

Generally a navigator evaluated the maneuverability of his ship by the scale of turning circle which was described only by the largest rudder angle of the port and starboard sides. But to have the sufficient knowledge of his ship's maneuvering characteristics he should consider the data about the new course keeping test, the spiral test, and the turning circle tests in accordance with the rudder angles together. In this paper the author performed the above tests to study the maneuverability of the stern trawler M.S. Pusan 404 which is a training ship of the National Fisheries University of Pusan. The obtained results are summarized as follows: 1. When the rudder angles being 5。, 10。, 20。, 30。, 35。 the advances of the starboard side turning circles were 12.8, 8.2, 4.8, 2.9, 2.7 times as large as the length of the ship, and of the port side turning circles were 13.3, 8.7, 5.4, 3.5, 2.9, time as large as the large as it. Under the same conditions the tactical diameters were 15.1, 9.7, 5.2, 3.1, 2.8 times as large as the length of the ship, for starboard side, and 17.2, 12.4, 6.4, 3.7, 3.2 times as large as it for port side. 2. As the rudder angle being increased the ratio of the advance to the tactical diameter was nearly 1 and her obeying ability was better than that of the small angle. 3. The mean values of the rates of speed reduction during the steady turning motion were 0.96, 0.92, 0.82, 0.71, 0.65 in accordance with the rudder angles. 4. The relative formulas between the distance to the new course y and the altering course x were as follows: When rudder angles being 10。, 20。, 30。, y=52.2222+1.6133x, y=48.750+0.9383x, y=39.250+0.655x respectively. 5. There was little difference of the distance to the new course between rudder angle 20。and 30。, and so it is desirable for a navigator to a navigator to use the small rudder angles unless sudden emergencies. 6. Though her rudder angle being small her course stability was good according to the spiral tests.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.36 no.4
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• pp.281-286
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• 2000

To analyze the shape of the net mouth of bottom trawl which is composed with 6 seams net, the field experiment was carried out on the sea near Kokunsan Is, Western sea of Korea. The distance of otter board, net height, trawl speed and resistance of the fishing gear were respectively measured according to the change of warp length and towing speed. The results obtained are summarized as follows : 1. The spreading distance of the otter board has been increased straightly according to the increment of towing speed and warp length. The rate of increase by the warp length has been greatly higher than the rate of increase by the towing speed. The total variation of the spreading distance was 57.0-82.8m, and it was occupied 43-62% of the hand rope, net pendent and the length of nets. 2. The height of net mouth has been decreased straightly according to the increment of towing speed and warp length. The rate of decrease by the towing speed has been greatly higher than the decrease rate of the warp length. The total variation of the net height was 3.1-4.0m. 3. When the distance of wing tip is increased, the height of net mouth is decreased, but the ratio of the decreasing rate of the height of net mouth for the increasing rate of the distance of wing tip was gradually low according to the increment of warp length. 4. The ratio of the distance of both wing tip for the height of net mouth has been increased gradually according to the increment of towing speed and warp length, and the total variation of the ratio was 4.17-7.81 times.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.12 no.3
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• pp.125-130
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• 1979

In this paper, the noise pressure propagated in the air on account of the engine revolution of a stern trawler, Sae-Ba-Da(G. T. 2275.71) was measured at the check points No.1 through No.43 when the vessel was cruising, towing nets, and drifting. The experiment was carried out in the period from August 23 to October 22, 1978 at the locations of lat. $33^{\circ}$ 47'N, long. $127^{\circ}$ 34'E; lat. $34^{\circ}$ 24'N, long. $128^{\circ}$ 23'E; and lat. $6^{\circ}$ 01'N, long. $108^{\circ}$ 04'E. In case of cruising, noise on the weather deck came from funnel noise. The highest noise pressure was 92dB at observation point No.9 where tile noise pressure from main engine was 105dB when the engine was operated at 730rpm and $12^{\circ}$ sorely propeller pitch. The noise measured was reduced to 90dB at observation point No.9 when the screw propeller pitch was changed to $8^{\circ}$ that resulted in reduction of engine to 103dB. In case of towing net, the main engine revolution and screw propeller pitch was fixed at 730rpm and $8^{\circ}$ respectively. But the engine noise pressure was increased up to 106dB due to the towing resistance by 14 tons of the nets, and the noise pressure was 90dB at No.9 point. A hight noise was also generated from screw because of the towing reoistance and could be measurable even in the wall of the insulated freezing room. When the vessel was drifting: the noise pressure from the generator operated, at 720rpm was 100dB. This caused 87dB noise pressure at No.9 point. The noise pressure in the boarding or residence sections was 45 to 60dB in each case of cruisinrg towing net or drifting but it was so high as 82dB on the open deck that voice could hardly be heap.