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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korean society of Fisheries Technology
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Journal DOI :
The Korean Society of Fisheries Technology
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Volume & Issues
Volume 39, Issue 4 - Nov 2003
Volume 39, Issue 3 - Aug 2003
Volume 39, Issue 2 - May 2003
Volume 39, Issue 1 - Feb 2003
Selecting the target year
A Study on the Performance Index of Automatic Steering System of Fishing Boat Using Frequency Response Analysis
Journal of the Korean society of Fisheries Technology , volume 39, issue 1, 2003, Pages 1~7
DOI : 10.3796/KSFT.2003.39.1.001
When a ship is course-keeping in the open seas, autopilot system is adapted. The design of autopilot system is very important for improvement of ship′s element research. Automatic steering system consists of autopilot device, power unit, steering gear, magnetic or gyro compass and ship dynamics. In order to evaluate automatic steering system of ships in open seas. we need to know the characteristics of each component of the system, and also to know the characteristics of disturbance to ship dynamics. In this paper, I provide evaluation method of autopilot navigation system of the fishing ship. Prediction method based on the principle of linear superposition is introduced for irregular disturbance. For the evaluation of automatic steering system of a ship, "performance index" is introduced from the viewpoint of energy saving and calculation method is frequency response analysis. Finally, I carried out calculation of sensitivity of control constants of autopilot with various conditions of ocean environments.
The Characteristics of Fishing Ground in the Adjacent Sea of Naro Island (1) - Oceanic Condition of Fishing Ground -
Journal of the Korean society of Fisheries Technology , volume 39, issue 1, 2003, Pages 8~18
DOI : 10.3796/KSFT.2003.39.1.008
In order to investigate the oceanic condition of fishing ground in the adjacent sea of Naro Island, the oceanographic observation were carried out by the training vessel of Yosu National University on winter, spring, summer, and autumn in 2000. Main features in the observation are as follows; 1) the ranges of temperature, salinity, and chlorophyll-a were from 4.
, from 33.1 psu to 34.9 psu, and from 0.1
in winter, from 8.
, from 33.1 psu to 34.3 psu, and from 0.1
in spring, from 14.
, from 30.5 psu to 34.1 psu, and from 0.1
in summer, and from 14.
, from 30.1 psu to 34.0 psu, and from 0.1
in autumn, respectively, 2) the temperature in the coastal region was higher than that in the open ocean while salinity was lower, and the convection was identified between the surface and the bottom during in winter and autumn, and the thermocline were made between surface and 20m layer with vertical gradients of 4.
/7m in summer, 3) the chlorophyll-a in the this region was varied in each season, being highly distributed in spring, on bottom and coastal region, and 4) an evidence of sea water intrusion toward Sori Island was observed, and of inner water intrusion from Yeoja Bay was observed.
The Characteristics of Fishing Ground in the Adjacent Sea of Naro Island (2) - Seasonal Variation of Watermass -
Journal of the Korean society of Fisheries Technology , volume 39, issue 1, 2003, Pages 19~26
DOI : 10.3796/KSFT.2003.39.1.019
In order to investigate the seasonal variation of watermass in the adjacent sea of Naro Island, oceanographic observation on the fishing grounds were carried out by the training vessel of Yosu National University on winter, spring, summer, and autumn in 2000. The results obtained are summarized as follows ; 1) the watermass in the fishing ground were divided into the coastal water (30.0∼31.4psu), mixing water (31.5∼32.9psu) and the offshore water (33.0∼35.0psu) according to the distribution of salinity from T-S diagram plotted all salinity data observed on winter, spring, summer, and autumn in 2000. 2) the ranges of temperature and salinity were from 4.
and from 33.1psu to 34.9psu in winter, from 8.
and from 33.1psu to 34.3psu in spring, from 14.5
and from 30.5psu to 34.1psu in summer, and from 14.
and from 30.1psu to 34.0psu in autumn, respectively. 3) the distribution of watermass in the fishing ground varied largely each seasons, but a general tendency on the distribution was obtained. That is, in winter and spring the offshore water was distributed most widely and in summer the coastal and mixing water occupied the fishing ground but in autumn the mixing water prevailed. 4) variation of temperature and salinity were appeared between the surface and 20m layer in the sea aduacent to Naro Island. Therefore, in the summer the thermocline were made between surface and 20m layer with vertical gradients of 4.
Calculation of Nonlinear Interactions between Hydrofoil and Free-Surface by the High-Order Spectral/Boundary-Integral Method
Journal of the Korean society of Fisheries Technology , volume 39, issue 1, 2003, Pages 27~32
DOI : 10.3796/KSFT.2003.39.1.027
Under the assumption of potential flow, free-surface flow around a hydrofoil is calculated by the high-order spectra1!boundary-integral method, This method is one of the most efficient numerical methods by which the nonlinear interactions between hydrofoil and free-surface can be simulated in time-domain. In this method. the wave potential which represents the nonlinear evolution of free-surface is solved by the high-order spectral method and the body potential which provides the effects of hydrofoil and shed vortex is solved by the boundary-integral method. The calculated free-surface profiles which are generated by a uniformly translating hydrofoil are compared with other experimental results. And they show relatively good agreements each other. As another example, free-surface flow generated by a heaving and translating hydrofoil is calculated and discussed.
Development for Fishing Gear and Method of the Non-Float Midwater Pair Trawl Net(I) - Opening Efficiency of Model Net according to the Length of Lower Warp -
Journal of the Korean society of Fisheries Technology , volume 39, issue 1, 2003, Pages 33~43
DOI : 10.3796/KSFT.2003.39.1.033
The midwater pair trawl which is being used at present in Korea have several problems. Firstly, it is difficult to control the net height on high towing speed. Secondly, net breaking often occurs owing to floats and thirdly, the volume of net on the net drum is so large. This study is aiming for examining the possibility of application for the Korean midwater pair trawl through the model experiment of non-float midwater pair trawl. The model of non-float midwater pair trawl was manufactured as 1/100 of the full scale net which is being used in bottom pair trawl for 850ps class considering the Tauti`s Similarity law. The model experiment was carried out to analyze the opening efficiency according to the variation of lower warp length and the opening efficiency was investigated between th proto type and non-float type. The results obtained can be summarized as follows ; 1. The hydrodynamic resistance of non-float type was about 10~20% smaller than that of the proto type and it increased about 1ton according to the increase of dL at the condition of the same flow speed. The resistance acting on the lower warp decreased about 5% but that of the upper warp increased according to the increase of lower warp length (dL) at the condition of the same flow speed. 2. The net height of the non-float type decreased almost linearly according as the increased of flow speed and it increased in a logarithmic functional form with the increase of the lower warp length at the condition of the same flow speed. On the decreasing rate of the net height, the non-float type was lower than the proto type and the difference of the decreasing rate was about 12% at 3.0 knot, 25% at 4.0 knot, 25% at 4.0 knot respectively when dL was 30m. 3. The net width of non-float type was not varied so much as only 2m range and was larger than that of proto type. 4. The mouth area of non-float type decreased in a exponential functional form. On the decreasing rate of the mouth area, the non-float type was lower than the proto type. The filtering volume increased in a logarithmic functional form with increasing flow speed and the filtering volume of proto type decreased steeply over 3.0knot, but that of non-float type increased until 4.0knot. 5. The optimal length of lower warp was when the value of dL was about 30m and the optimal position of front weight was at the connection point of four net pendants.
Variations of Secchi Depth in Coastal Water, Masan Bay in Korea
Journal of the Korean society of Fisheries Technology , volume 39, issue 1, 2003, Pages 44~49
DOI : 10.3796/KSFT.2003.39.1.044
Masan Bay is one of the most heavily polluted bay in Korea owing to the large industrial complex and urban area. Water transparency, Secchi depth in meter, was observed 33 times totally at four sites during 1995 through 2002 and analysed statistically. The range was 0.2∼7.2m, mean 204m, and variation coefficient 60% in totally. Roughly speaking, monthly mean showed lower value April or July than other months. Seasonal mean showed lower in spring or summer than other seasons. Yearly mean was lowest in `95 and `98 during 7 years. Each sampling site showed a different patterns by the monthly, seasonal or yearly transparencies. Inner bay area, S1 site, showed lowest transparency and highest variation coefficient owing to the streamlets and urban area. And it was supposed that one of the important factor affecting different transparency distribution of most seaward site, S4 site, among four sites in the Masan Bay may be the underwater effluents of urban sewage water treated
Study on the Improvement of Gill Nets and Trap Nets Fishing for the Resource Management at the Coastal Area of Yellow Sea -On the Present States of Gill Nets and Trap Nets Fishing and Body Length Distribution of Main Catch at the Coastal Area of Yellow Sea-
Journal of the Korean society of Fisheries Technology , volume 39, issue 1, 2003, Pages 50~55
DOI : 10.3796/KSFT.2003.39.1.050
In order to study on the improvement of gill nets and trap nets fishing for the management of fisheries resource in the coastal area of Yellow Sea, we have investigated the general present condition of those fishing, and the actual fishing operation of gill nets for croaker and trap nets for rock shell which is called the the other trap nets, and then measured the body length of croaker and blue shell caught by their fishing vessels. The results are as follows ; 1. The total number of permission for coastal fishing are 12,944 cases, but the number of operation for coastal fishing are 7,558 cases in the coastal area of Yellow Sea. Among the total number of permission, the gill nets fishing are 5,154 cases with 39.8% but even so the number of operation are 3,724 cases, the trap nets fishing are 1,025 cases with 7.6% but even so the number of operation are 662 cases. On the fishing ratio, the gill nets and trap nets fishing are comparatively higher than the other fishing with 72.3% and 64.6%, respectively. 2. The main fishing period of gill nets for croaker is from the middle of July to early of September, and the main fishing grounds are sandymud bottom of 15-50m in depth around the islands of southern parts of western coastal area, and the fishing operation carry out 1∼2 times per day in flood tide and nets hauling conduct in 1∼2 hours after drifting with current. 3. The distribution range of body length of 139 croakers, which are caught in the gill nets, are 43.0∼120.0㎝ and the mode is 85.0㎝. 4. The main fishing period of trap nets for rock shell which is called the other trap nets is all the year round except the catching period of blue crab from early of September to the middle of October, and the main fishing ground are the sandymud bottom of 10∼20m in depth, and nets hauling conduct in next day after nets casting. 5. The distribution range of maximum carapace of 5,372 rock shells are 4.5∼8.5㎝ and the mode is 7.5㎝.
Study on the Improvement of Gill Nets and Trap Nets Fishing for the Resource Management at the Coastal Area of Yellow Sea - On the Entrapping Behavior of Fishes into Trap Nets in the Water Tank Experiment -
Journal of the Korean society of Fisheries Technology , volume 39, issue 1, 2003, Pages 56~62
DOI : 10.3796/KSFT.2003.39.1.056
To investigate the entrapping behavior of blue crab, rock shell and green ling, which are mainly caught with the other trap nets in the coastal area of Yellow Sea, by the using duration of trap nets through the water tank experiment. We select the three kinds of trap nets which have different using duration such as new, 6 months and 12 months used one, and observe the entrapping ratio into the trap nets, respectively. In the mean while, in order to obtain the basic data for the estimate of mesh selectivity of the other trap nets, the entrapping behavior into the trap nets for green ling which has high activity compared to blue crab and rock shell, are examined to the three kinds of mesh size (35mm, 50mm and 65mm). The results are as follows ; 1. The mean entrapping ratio of blue crab by the using duration of trap nets in high with 4.4 fishes (44.0%) in the 6 months used one, become lower with 2.9 fishes (28.0%) in the new one, and with 2.0 fishes (20.0%) in the 12 months used one. 2. The mean entrapping ratio of rock shell by the using duration of trap nets in high with 7.3 fishes (36.7%) in the new one, and become lower with 7.2 fishes (35.8%) in the 6 months used one, and with 5.7 fishes (28.3%) in the 12 months used one. 3. The mean entrapping ratio of green ling by the using duration of trap nets in high with 3.4 fishes (34.0%) in the 6 months used one, and become lower with 3.0 fishes (30.0%) in the new one, and with 2.8 fishes (28.0%) in the 12 months used one. 4. The mean residual ratio of green ling by the mesh size of trap nets is high with 2.4 fishes (24.0%) in the 35mm mesh size, and become lower with 2.2 fishes (22.0%) in the 50mm mesh size and 2.0 fishes (20.0%) in the 65mm mesh size.
Species Composition and Seasonal Variations of the Shrimp Beam Trawl Fisheries in the Adjacent Waters Geomundo, Korea
Journal of the Korean society of Fisheries Technology , volume 39, issue 1, 2003, Pages 63~76
DOI : 10.3796/KSFT.2003.39.1.063
Species composition and seasonal variations of shrimp caught in the adjacent waters Geomundo, Korea were studied using the monthly catch of beam trawl fishery from November 1998 to October 1999. During in the study period, a total of 700,765 shrimps consisting 36 species, 27 genus and 11 families were collected. The community was dominated by Palaemon gravieri, Parapenaeopsis tenellus, Solenocela melantho and Plesionika izumiae. The peak abundance of shrimp occurred in summer, and low abundance in winter and spring. Major species occurred in area A, B and C was P. gravieri, and P. tenellus, and P. izumiae and S. melantho, respectively. The number of individual and abundance showed in July, and low in November. It was noted that values of species diversity, dominance and evenness indices were high in adjacent water Geomundo and lower in adjacent water Chodo and Chodo-Sonjukdo. Analysis of dendrogram of the clustering showed that there were two distinct groups; Geomundo group and Chodo-Sonjukdo group.
Design of a Web-based Autonomous Under-water Mobile Robot Controller Using Neuro-Fuzzy in the Dynamic Environment
Journal of the Korean society of Fisheries Technology , volume 39, issue 1, 2003, Pages 77~83
DOI : 10.3796/KSFT.2003.39.1.077
Autonomous mobile robots based on the Web have been already used in public places such as museums. There are many kinds of problems to be solved because of the limitation of Web and the dynamically changing environment. We present a methodology for intelligent mobile robot that demonstrates a certain degree of autonomy in navigation applications. In this paper, we focus on a mobile robot navigator equipped with neuro-fuzzy controller which perceives the environment, make decisions, and take actions. The neuro-fuzzy controller equipped with collision avoidance behavior and target trace behavior enables the mobile robot to navigate in dynamic environment from the start location to goal location. Most telerobotics system workable on the Web have used standard Internet techniques such as HTTP, CGI and Scripting languages. However, for mobile robot navigations, these tools have significant limitations. In our study, C# and ASP.NET are used for both the client and the server side programs because of their interactivity and quick responsibility. Two kinds of simulations are performed to verify our proposed method. Our approach is verified through computer simulations of collision avoidance and target trace.