• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.44 no.2
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• pp.148-156
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• 2008

In this study it will be discussed how to solve the problem of discomfort from rolling motion on the fishing boats. Most discomfort is caused by the short cycle of rolling due to the light weight of the boats. The light weight is due to the FRP material which dries a boat. A way to improve the feeling of boarding by using fish hold was researched. The experiment was done on experimental fishing boat made by FRP in Jeju. An existing fish hold was designed and manufactured through the rolling test and that was used for a marine experiment. The rolling condition of the U-tank boat ideally designed was compared to that of an existing fishing boat using the same conditions. The experiments were carried out two times on the stop engine in the outward Sehwa fishing port, which the experimental data had analysed for effects of rolling reduction to compare the U - tank with the of exiting fish hold. The results were confirmed that the U-boat tank in the roll period and GoM were more safe than the existing fish hold and the average amplitude and significant of rolling angles were decreased relatively.

• Fisheries and Aquatic Sciences
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• v.1 no.2
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• pp.187-191
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• 1998

Chemotherapy can not be applied for the control of fish viral diseases because viruses depend on host machinery for their replication. Although new control strategies including vaccination are under development, avoidance of virus introduction by rapid and correct diagnosis is the best way of fish viral disease control. Although observation of virus particles with an electron microscope is an easy method for virus detection, it take a few days for the sample preparation. In order to shorten the sample preparation time, microwave radiation was applied in the procedure. With this method, 15 seconds was enough for fixation of virus infected fish samples or cultured cells inoculated with infectious hematopoietic necrosis virus, which takes 2-4 hours with routine methods. Also four minutes was enough for polymerization of embedding resin which takes 24-48 hours with routine methods. Samples prepared with microwave were good enough for direct electron microscopic observation and immunogold labeling assay.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.14 no.2
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• pp.107-115
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• 2011

The purpose of the study is to analyze the environmental characteristics of fish acute toxicity that is dependent on the harmfulness of ACQ (Alkaline Copper Quat)-Treated Wood and Oryzias latipes mortality in a comprehensive way, provide objective verification method on the eco-toxicity and environment-friendliness of landscaping materials and methods, and utilize it as a basic datum for evaluation criteria. The main results are summarized as follows : 1. As a result of analysis on the harmfulness characteristics, each experimental plot showed different values respectively. In particular, it has been found that in proportion to the volume of testing materials, COD and Cu increases at a constant rate, compared to the input water. In the plot C with three testing materials, COD increased 67 times more than that of the input water, and Cu increased up to 12.36mg/L. 2. In case of fish toxicity, plot C, B, A all showed a mortality rate of 100%, indicating that fish toxicity is strong. In particular, the mortality rate of each plot within the initial time of one and a half hour showed clearly, which suggests that the fish toxicity is influenced by the increased concentration of hazardous substances depending on the volume ratio of testing materials. 3. As a result of comparison and analysis on the harmfulness and fish toxicity, the harmfulness showed different values on each experimental plot but, we found that the changing rate of values of toxicity of COD and Cu is mutually similar to that of mortality in the initial hour according to the experiment of fish toxicity, which shows that COD and Cu are major factors to increase fish toxicity.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.42 no.4
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• pp.234-239
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• 2006

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.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.47 no.3
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• pp.222-233
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• 2011

This study is for the multi-dimensional analysis of diverse data sets for artificial reefs off the coast of Shimonoseki, Yamaguchi prefecture, Japan. Various data sets recorded in artificial reefs ground were integrated in new GIS software: to reveal the relationships between water temperature and fish schools; to visualize the quantitative connection between the reefs and the fish schools; and to compare the seabed types derived from two different data sources. The results obtained suggest that the application of GIS in analyzing multi-dimensional data is a better way to understand the characteristics of fish schools and environmental information around artificial reefs and particularly in the evaluation of the effectiveness of artificial reefs.

• Journal of Environmental Impact Assessment
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• v.21 no.6
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• pp.879-891
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• 2012

The objective of this study was to evaluate seasonal patterns and diel variations of fish movements in the Juksan Weir which was constructed in 2010 at the down-stream of Yeongsan-River watershed. For this study, we monitored day-and-night movement(24 Hr cycle) and seasonal fish migration(June ~ August) patterns in 2011 along with species compositions and abundances depending on the locations of the traps within the fishway. Total number of species sampled was 14 and the total number of individuals was 1,263 with only the size-fractions(as total length) of the fish < 20 cm during the study. Seasonal analysis of fish movement in the fish way showed that highest frequency in the movement occurred in June - July, which is closely associated with a spawning peak season. The most dominant species using the fishway was Squalidus chankaensis tsuchigae, and this species turned out to be 26.9% of the total in the use rate of fishway. Daily monitoring of fish movements showed that most frequent movements occurred between 18:00 PM and 21:00 PM when the fish have a feeding time generally. The migratory fish were not found in the fishway during the study. Mean current velocity during the study $0.42{\pm}0.02ms^{-1}$(n = 42), and there were no significant statistical differences(p > 0.05) among the daily and monthly velocities in the fishway. The use rate of fish passage, in terms of fish species, was 48%, compared with total sampling of fish species(29 species) at the down-river regions during the same period, indicating a low use rate. Further continuous long-term monitoring should be conducted to evaluate the impacts of the weir construction in the river.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.11 no.4
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• pp.24-36
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• 2008

The essence of a natural stream restoration project is providing habitats for various creatures in terms of the stream's environmental function. This research suggests the problems of natural stream restoration project by studying streams in terms of habitats for creatures and reviewing the national and international cases on existing natural stream restoration project. As a solution for the above, this research suggests a preservation method for biotope of upper stream areas focusing on the fish biotope area considering the ecological characteristics and preservation value of the respective stream so that the stream can be preserved as habitats for creatures. The research was carried out on Cheonglimli Baekcheon region which is an upper stream area of Buan-Dam located in the public park in Byunsanbando, Buangoon, Jeonlabookdo. We suggest the preservation method based on the habitat environment and keystone species of fish. The habitat environment evaluation was carried out mainly being divided into three groups namely, habitats and surrounding environment, reservoir's features and fish way and the diversity of fish. By improving the problematic elements discovered through such evaluation, it tries to improve the biotope of the stream and continuously preserve the stream. In addition, in order to restore the stream as habitats for various creatures, this research suggests to select keystone species which are suitable for the stream environment and restore the habitats based on the keystone species rather than restoring habitats for all species. Fish not only plays the role of a consumer of Epilithic algae and water beetles but also plays an important ecological role as a food for birds or small mammalia. If such ecologically important biotope for fish is preserved, the ecological environment of the stream will be maintained more stably.

• The Journal of Fisheries Business Administration
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• v.26 no.1
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• pp.79-104
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• 1995

Dividend Policy involves the decision to pay out earnings versus retaining them for reinvestment in the firm, and dividend policy decisions can have either favorable or unfavorable effects on the attainment of firm's objective. This paper is to examine the present status of dividend policy of the Pusan Cooperative Fish Market, and to suggest the optimal dividend policy decisions appropriate for achieving its objective, which is to promote the fishermen's benefits and protect the interest of consumers. There are two types of dividend that the Pusan Cooperative Fish Market pays to the equity owners : (1) dividend on capital and (2) equalized patronage dividend. During'90s, while the rate of dividend on capital ranged from 1.7% to 2.8%, that of equalized patronage dividend ranged from 13.9% to 22.9%. Therefore, the rate of total dividend on capital including revolving funds has been about 20%, which turns out to be much higher than those of companies listed in the stock market. According to the current dividend data, the Pusan Cooperative Fish Market focuses on the equalized patronage dividend and the dividen on capital is the secondary type of dividend. In addition, the interesting feature of equalized patronage dividend is that it is supposed to be reinvested into capital by the Articles of the Fish Market, as soon as the Fish Market pays it to its members. Finally, this paper suggests the rational dividend policy of the Fish Market that is able to help its objective to be achidved more efficiently. The overall direction of the rational dividend policy can be summarized as follows ; (1) The level of cash dividend on capital should be increased enough to reflect the market interest rate. (2) The subsidy of working capital to some member fisheries cooperatives as quasi- dividend should be cut off steadily. (3) The equalized patronage dividend should be replaced by the original patronage dividend whose level is determined by the volume of each member's purchase. (4) In the long-term, it is necessary to improve the system of revolving funds in the way that revoloving funds could serve to complement equity capital for only a fixed time, after which they ard repaid to the members.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.55 no.5
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• pp.541-548
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• 2022

Biofloc technology (BFT) systems provides an additional protein source for fish by converting waste in microbial flocs. Therefore, we aimed to determine the difference in the protein levels of the diet of Far Eastern catfish Silurus asotus reared in BFT and FW systems. We applied a two-way (six protein levels × two aquaculture systems) ANOVA design. We formulated six experimental diets to contain different protein levels (CPs)- 20%, 25%, 30%, 35%, 40% and 45%-referred to as the CP20, CP25, CP30, CP35, CP40 and CP45 diets, respectively. We randomly distributed 900 fish into 36 (18 each for BFT and FW), 300 L tanks (25 fish/tank) with three replications of each diet for 4 weeks. The weight gain (WG) and specific growth rate (SGR) considerably improved as the dietary protein level increased in the formulated diets. The BFT fish showed higher growth performance with any experimental diet than the FW fish. The growth performance of the fish fed the BFT-CP35 diet was higher than that of the fish fed the FW-CP45 diet. In conclusion, the cultivation of Far Eastern catfish (S. asotus) in BFTs can be carried out under reduced dietary protein levels.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.9
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• pp.76-83
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• 2017

Fish respond sensitively to light, so it is possible to develop fish management technology using this feature. In this study, we developed a light-based fish barrier and analyzed itsblocking effect using the difference in illuminance for the major fish species in Korea, bass and bluegill. The light was generated by a light emitting diode and the facility was installed vertically from the bottom. Considering the fish's ability to travel upstream, the flow rate was divided into three stages (0.2, 0.1, and 0.05 m/s). To prevent the learning effect, an experiment was carried out with fish that had rested for more than one day in a rearing tank. The experiment was carried out in such a way as tocompare the number of fish which travelled upstream after the introductionof the fish barrier and that of the fish which travelled upstream after itsremoval. It was also carried out after sunset to increase the effectiveness of the barrier. According to the results of the experiment, the fish blocking effect depending on the difference in illuminance was high and, overall, the blocking rate for bass was lower than that for bluegill. Based on the total size of the experimental population, the blocking rates for bass and bluegill were 96.33% and 99.00%, respectively. Based on the number of fish that travelled upstream, the blocking rates for bass and bluegill were 91.73% and 98.73%, respectively.