In order to develop the biodegradable monofilament gill net for the protection of marine ecosystem and reduction of ghost fishing, enpol monofilament gill net was made for Chionoecetes opilio using polybutylene succinate as a biodegradable chip. Catching efficiency on 2 type monofilament gill net, PA and Enpol, were carried out using 2 commercial fishing boats around the fishing ground of Wang-dol rock from January 2004 to May 2006. Enpol monofilament gill net spun polybutylene succinate as a biodegradable chip was appeared high practicality for Chionoecetes opilio gill net. Target fishing ratio were 98% and 98.3% for the PA and enpol monfilament gill net, respectively. In addition, CPUE ratio of female and male(CL < 90mm) to Chionoecetes opilio caught in the enpol gill net were 25.3-40.3%, 14.0-22.1% less than PA gill net, respectively. However, CPUE ratio of male(CL > 90mm) to Chionoecetes opilio caught in the enpol gill net were 2.5-11.3% more than PA gill net. There was no difference in CPUE of female and male to Chionoecetes opilio caught using 2 gill nets as a result of the significance level of 5% by T-test.

This fundamental studies on for the productivity improvement and laborsaving of purse seine fishery. Given the difficulty posed from the distortion of net shape caused by the external forces, such as tide, at the time of shooting and pursing, we set the 4 steps of 0, 2, 4 and 6cm/sec in flow velocity in the flume tank for the experiment in order to examine those characteristics. We used two model seines designed on the scale of 1 to 180 based on the power block seine, which is the mackerel purse seine generally used in the near sea of Jeju Island and triplex seine, which is the mackerel purse seine of one boat system fishing expected in the future, for the experiment, and interpreted the characteristics of several motion in water, such as the shape of seine, the change in tension and area during pursing and its the analysis results are as follows. Though the experiment could be conducted up to 6cm/sec of flow velocity that was defined, the experiment could not go on because of the severe distortion in the seine at the flow velocity in excess of 6cm/sec. As for the depth of leadline and reduction rate of side area of seine when the pursing is connected, P seine turned out to be slightly higher than T seine, and the hauling speed and reduction rate of upper area of seine were found similar to each other. The correlation between the hauling time (Ht) and depth of lead line (Dhp, Dht) of P seine and T seine can be expressed by the equation, that is, Dhp=(0.99Pt-7.63)Pt+69.01, Dht=(1.03Pt-7.73)Pt+66.74. The correlation between the hauling time and hauling velocity (Hpp, Hpt) can be expressed by the equation, that is, Hpp=-0.06Ht2+0.88Ht+0.78, Hpt=-0.05Ht2+0.81Ht+0.98 here, Pt is pursing time. And the correlation between the pursing time and the reduction rate of side area (sArp, sArt) can be expressed by the equation, that is, sArp=-0.48Pt2+14.79Pt-16.74, sArt=-0.45Pt2+14.56Pt-16.48. The reduction rate of upper area of seine (tArp, tArt) can be expressed by the equation, that is, tArp=0.34Pt2-0.66Pt-0.74, tArt=0.34Pt2-0.27Pt-1.80. In addition, the correlation between the pursing time and tension of purse line (Tep, Tet) can be expressed by the equation, that is, Tep=2.79Pt2+2.26Pt-0.60, Tet=2.14Pt2+8.08Pt-27.50.

It is the basic studies for productivity improvement and laborsaving of purse seine fishery. Because the seine shape is apt to be transformed in seine shooting process due to the effect of tide, this study is intended to establish 4 steps, whose flow velocity are 0, 2, 4 and 6cm/sec, in flume tank and perform the experiment to review the character. We used two model seines designed on the scale of 1 to 180 based on the power block seine, which is the mackerel purse seine generally used in the near sea of Jeju Island and triplex seine, which is the mackerel purse seine of one boat system fishing expected in the future, for the experiment, analyzed of the sinking movements on the two seines and its results are as follows. In the setting over the flow velocity 6cm/sec, experiment was impossible because of flying and transformation of seine were severe. The sinking movements of P seine and T seine generally showed linear phenomenon and the sinking speed showed gentle curve shape. Sinking tendency was distinguished by existence of flow velocity. When there is flow velocity, it showed the phenomenon that it sinking by similar type. Although sinking depth and sinking speed did not show distinguished classification, P seine shows bigger than T seine. When there was in flow velocity, the elapsed time(Et) and sinking depth (PDp, TDp) of P seine and T seine can be shown such experimental equations as PDp=(0.21V+4.96)Et-(0.62V-0.10) and TDp=(0.19V+4.95)Et-(0.72V+0.34). When there was in flow velocity, the elapsed time and siking speed (PSp, TSp) of P seine and T seine can be shown such experimental equations as PSp=-0.11Et2+1.42Et+1.75 and TSp=-0.11Et2+1.41Et+1.37.

In this study, the 2-way condensation system was designed applying air-to-air heat pump to dry a marine product such as squid in the winter. And to be made the drying apparatuses by this system, there are two kinds of type, A type, was set a compressor outside of the drying apparatus, B type, was set a compressor in the drying room. And then the variations of temperature in drying room were measured to compare the heating performance of the drying apparatuses between A type and B type at -6.5℃, outdoor temperature. The temperature of the drying room for B type was increased to 36℃ but the temperature of the drying room for A type was not increased to 36℃, to be increased to 20℃.

The potential of ecosystem-based fisheries management is recently recognized to be very important to improve the sustainability of fisheries resources. Under the depressed condition of many fisheries resources, this recognition has been expanded and more effort has been taken to improve this approach. Taking ecosystem concept includes the use of other tools of management in addition to fisheries regulation, such as stock and productivity enhancement, provision of physical structure, or marine protected areas. In the ecosystem-based fisheries management approach, it would require to holistically consider ecological interactions of target species with predators, competitors, and prey species, the effects of climate on fisheries ecology, the complex interactions between fishes and their habitat, and the effects of fishing on fish stocks and their ecosystem. Fisheries management based upon the understanding of these factors can prevent significant and potentially irreversible changes in marine ecosystems caused by fishing. A useful approach for analyzing tropho-dynamic interactions and mass-balance in marine ecosystems is introduced to demonstrate the complexity and usefulness of the ecosystem approach, which was applied to a small ecosystem in Korea. Korea should seriously consider to take the ecosystem-based approach to fisheries management, since most major fish stocks are currently depleted due to many reasons such as overfishing, land reclamation and coastal pollution.

This paper introduces an auto-feeding system to exactly control the feeding time and the amount to cultured fishes in aquaculture industrial field. To reduce expensive costs or labors in this field, it was designed by the concept of controlling feed quantity exactly on the basis of fish's feeding behavior pattern in water tank. A feed control method of this system was developed for controlling feed amount by rotor capacity and motor rotated number. Moreover, a scattering section was selected by rotate way of propeller wing to scatter dried feed to designated site, and then, the diameter of its wing was 250mm and maximum scattering distance was 7.6m for 600rpm. Furthermore, the scattering ways were embodied 2 types such as a simplified way and a multistage shift way looks like a manual scattering. As a results, the multistage shift way is more effective to discharge the dried feed widely than the simple way in the water tank.

The transmittance properties of fishing lamp of the squid jigging vessel was investigated during nighttime operations in the Northwest Pacific on 21 and 29 September 2005. The metal halide lamps of white color(2.0kW×168) in the air and metal halide lamp of white color(10.0kW×1) in the underwater were used as a fishing lamp for gathering squids. The relative irradiance of metal halide lamp in the air showed peak in 850nm of wave length. The relationship between underwater illuminance(Y) and water depth(X) of metal halide lamp light in the observation areas is represented, Y=84.137e-0.1105X, R2=0.9974. The distribution of underwater illuminance of measure points St. 1-5 showed low value of 0.11x in 80m depth.

This research aims at establishing the application of canvas kite to the fishing gear through the analysis of the lift/drag tests of the kites have been performed in our previous finding. Now that several methodologies were designed to find the most effective triangular model as a buoyancy device applied to the fishing gear. Comparisons of drag/lift were made by installing the model in an installation frame instead of the prototype. Also, we have considered the application of canvas kite to the prototypic fishing gear by calculation using the result of this test. The results obtained from the above approaches are summarized as follows, where attack angle, lift coefficient, maximum lift coefficient and drag coefficient are denoted as B, CL, CLmax and CD respectively. The camber showed a gradual increase with an increase of fluid velocity. There was a big discrepancy in B=20 unlike B=30. Even if the kite retreats along the fluid flow, there is little relationship with the velocity variation. Lifts calculated with the kites were bigger and drags were smaller than those of the calculations with the float only. The kite as the buoyancy device will be very useful when the appropriate applications and the stability are met.

The circle hook experiments were conducted to compare the catch rates of target and bycatch species between J hook and circle hooks in the tuna longline fishery of the eastern Pacific Ocean between 1˚48'S-7˚00'S and 142˚00'-149˚13'W from July 15 to August 12, 2005. In the target species group no significant differences among 3 types hook, between size 4.0 traditional tuna hooks(J-4) and size 15 circle hooks(C15), and between C15 and size 18 circle hooks(C18) were revealed, but significant differences were found between J-4 and C18. In the bycatch species group significant differences were found among 3 types hook, between J 4 and C15, and between J-4 and C18, but no significant differences were revealed between C15 and C18. Large circle hook(C18) had the lowest catch rate for tunas and for other fishes, and the small circle hook(C15) had lowest rate for billfishes and sharks. The length distributions for bigeye tuna are very similar for the 3 hook types. There were very slight differences in length size between hook types in the bycatch species.

This paper described the experimental squid jigging fishery conducted by a commercial fishing vessel in the Northwest Atlantic Ocean from August to October 2005. Author carried out experimental jiggings of 65 times during 57 days by three type of jigs which were pick jig, soft jig and soft luminous jig. The total catch, effort/day and catches/line-day of northern shortfin squid (Illex illecebrosus) were 12,726kg, 35 auto jigging machine and 3.5kg, respectively. Higher CUPE was observed in September, August and October. Catch ratio of pick jig was higher by 57-86% than those of soft jig and soft luminous jig. Higher catch was recorded at the 42˚55'N, 62˚10'W with surface temperature ranging 18-21℃. The range of the dorsal mantle length was from 13.5cm to 23.0cm with average 17.2cm for female and from 13.0cm to 20.0cm with average 17.0cm for male. Sex ratio showed 55.4% of female.

To determine the relative efficiency and mesh selectivity of gill net for the Pacific saury, Cololabis saira, a series of fishing experiments was carried out in the Northwest Pacific Ocean from August 13 to October 13 in 2002, using gill nets of different mesh size(30, 33, 35, 37, 39 and 42mm) constructed from two kinds of twine material(monofilament, twisted multifilament nylon web). The relative efficiency of two material gears was expressed as the ratio obtained by dividing monofilament catch by multifilament catch in number. The master selection curve of each material gear was estimated by applying the extended Kitahara's method. The catch of experimental gears is mostly Pacific saury(98.6%), Cololabis saira. The kinds of bycatch are common squid(0.7%), Pacific mackerel(0.6%), etc. Catch comparisons in the two gears showed that monofilament nylon nets are 1.7 times more efficient. The optimum values in monofilament and multifilament gill net for Pacific saury are 8.28 and 8.23, respectively.

In order to efficiently manage the coastal and offshore fishing ground, the applicability of real-time monitering was also investigated through a wide-area network of automatic identification system(AIS). The experiment of efficiently managing coastal and offshore fishing ground with a wide-area network of AIS required, on the headquarter's screen, a synthetic display of vessel information transmitted from three different distant stations. This experiment tested the applicability of real-time monitoring with the shown display. The maximum range of detection of the first station in Busan was 24 nautical miles while those of the second and third stations in Yeosu and Jeju were 26 and 52 nautical miles, respectively.

This research aims at establishing the fundamental characteristics of the kite through the analysis of the flow field around various types of kites. The approach of this study were adopted for the analysis; visualization by CFD(computational fluid dynamics). Also, the lift/drag and PIV(particle image velocimetry) tests of kites had been performed in our previous finding. For this situation, models of canvas kite were designed by solidworks(design program) for the CFD test using the same conditions as in the lift/drag tests. And we utilized FloWorks as a CFD analysis program. The results obtained from the above approach are summarized as follows: According to comparison of the measured and analyzed results from mechanical tests, PIV and CFD test, the results of all test were similar. The numerical results of lift-coefficient and drag-coefficient were 5-20% less than those of the tests when attack angle is 10˚, 20˚ and 30˚. In particular, it showed the 20% discrepancy at 40˚. The numerical results of the ratio of drag and lift were 8-13% less than those of the tests at 10˚ and 10% less than those of the tests at 20˚, 30˚ and 40˚. Pressure distribution gradually became stable at 10˚. In particular, the rectangular and triangular types had the centre of the high pressure field towards the leading edge and the inverted triangular type had it towards the trailing edge. The increase of the attack angle resulted in the eddy in order of the rectangular, triangular and inverted triangular type. The magnitude of the eddy followed the same order. The effect of edge-eddy was biggest in the triangular type followed by the rectangular and then the inverted triangular type. The action point of dynamic pressure as a function of the attack angle was close to the rear area of the model with the small attack angle, and with large attack angle, the action point was close to the front part of the model.

A study on the species composition and seasonal variations of fishery creatures caught by a funnel net was carried out in the coastal water off Dolsan Island, Yeosu from 2002 to 2003. During the study period, a total of 23 fishery creatures species were caught. Seabream(Acanthopagrus schlegeli), sea bass(Lateolabrax japonicus), mullet(Mugil cephalus), puffer(Takifugu niphobles) and rockfish(Sebastes inermis) predominated. These five species accounted for 85.1% of the total number of fishery creatures caught. Seasonal peaks of number of species occurred in summer, while those of number of individuals occurred in autumn. The lowest number of species and individuals were observed in winter. The large annual variation of diversity indices were observed from May to August. These large annual variation of diversity indices were mainly due to predominance of seabream, sea bass and mullet which accounted for most of all fishery creatures caught. The seasonal variations of fishery creatures showed that sea bass and mullet were caught mainly from spring to summer, seabream and puffer were caught mainly in autumn, and rockfish and brotula(Hoplobrotula armata) were caught mainly in winter.

A model experiment, simulation test using personal computer and real sea trial fishing were carried out to investigate the basic efficiency of bottom trawl net which can be used in the sea mount of North West Pacific, and experimental values were analyzed as the values of full-scale bottom trawl net. Hydrodynamic resistance for the full-scale trawl net according to the Koyama equation was 2.1 times higher than that of simulation and 2.4 times higher than that of model experiment at the average towing velocity. At the 3.5kt's of towing speed, net width of the full-scale trawl net was 2.5% smaller than that of simulation and 8.2% larger than that of model experiment. On the fishing experiment of the full-scale trawl net for the 3.5kt's of average towing speed, average net height of A group(same direction with external force) was 423.5% higher than that of model experiment and 457.1% higher than that of simulation and that of B group(opposite direction with external force) were 283.8% and 306.3% higher than in case of model experiment and Simulation respectively. Net mouth of the full-scale trawl net was 338.1-504.6% higher than those of model experiment and simulation in A group, and 525.2-745.3% higher in B group.

A model experiment using circulation water channel was carried out to investigate the dynamic characteristics of bottom trawl net which can be used in sea mount of North Pacific. Hydrodynamic resistance and shape variation according to the flow velocity and angle of hand rope transformation for net were measured, and experimental value was analyzed as the value of full-scale bottom trawl net. The results summarized are as follows; At the 30˚ of angle of hand rope to net, hydrodynamic resistance varied from 0.5kgf to 2.68kgf as the flow velocity increased between 0.31m/s and 0.92m/s, and formula of hydrodynamic resistance for the model net was Fm=3.04 · r1.53. At the fixed angle of hand rope, Net height was low and Net width was high according to the increase of flow velocity, and in addition, vertical opening was low and Net width was high by the increase of angle of hand rope at the fixed flow velocity. At the 30˚ of angle of hand rope to net, net opening area was 0.214m2 as flow velocity was 0.61m/s, and formula of net opening area for the model net was Sm=-0.22r+0.35. At the 30˚ of angle of hand rope to net, catch efficiency seemed to be highest as 0.319m3/s of filtering volume at the 0.76m/s(51kt's) of flow velocity. Shape variation of net showed the gradual laminar transform for the variation of flow velocity but there needed some improvements due to the occurrence of shortening at the ahead of wing net.

An estimation of the headline height of a bottom trammel net set across under uniform current was achieved numerically from a differential equations describing the forces of the net and compared with the measured value in a flume tank experiment. The analysis on the shape of the bottom trammel net with the headline free was based on the equilibrium equation of the bottom gill net which was modified and slack of the trammel net was varied with net depth as shown in the tank experiment. The differential equations were solved by a forth-order Runge-Kutta method. The estimated headline heights with varied slack was found to be closer than that with constant slack when compared with the actual values.

It is indispensable to grasp the turning ability of a ship to operate her effectively. For this purpose, the author measured the turning ability of training ship, A-RA by use of bow thruster and stem rudder. The turning ability of this ship, in case of using both of stem rudder and bow thruster at the same time, caused by increase of steering angle provides more influence to the size of tactical diameter than it caused by the power of bow thruster. But the influence of bow thruster on the turning ability is available only within rudder angle 5˚ - 10˚, so it is possible to grasp that the effect of bow truster is reduced as rudder angle become bigger. In case of the influence of bow thruster by her speed, the ability of bow thruster is very effective at low speed, but it is almost not available in normal turning speed. Therefore, the using both of stem rudder and bow thruster can be useful in case of low speed proceeding at entrance or departure of the narrow waterway or inside port which sea traffic is congest for collision avoidance.

The 3D visualization of seafloor topography(ST) was realized to discuss the effective use by the 3D visualization of ST on the integrated navigation system(INS) for fishing boat. The software was to actually display the 3D visualization of ST using triangular irregular network, helical hyperspatial codes and stereo projection. The INS for fishing boat which applied the 3D visualization of ST will be utilized for safety voyage and the effective fishing work on the fishing ground.

The integrated navigation system(INS) for fishing boat which organized the marine radar, global positioning system(GPS) compass, automatic identification system(AIS), echo sounder, GPS and electronic nautical chart(ENC) was manufactured to reduce the marine accidents of fishing boats occurred frequently at coastal and offshore. The application possibility of INS for fishing boat was examined for basic experiments in the sea. Integration display of various information, such as other vessel's behavior, depth, own vessel's position etc. was done to help the operate user who understood the circumstance around own boat. Therefore, the system will be utilized as a useful equipment for safety voyage and fishing work on the fishing ground.