• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.51 no.4
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• pp.630-636
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• 2015

The study aims at analyzing a species composition of the fish live in bottom of the coastal waters off Sejon island, Korea. To reach the goal of the study, a species composition and it's seasonally fluctuation, a seasonally fluctuation of the dominant species and it's appearance type were analyzed with the fishes caught by the bottom trawl in the coastal waters off Sejon island from May, 2011 to March, 2012. The results obtained can be summarized as follows; Fish caught in this area composes 10 orders, 25 families, and 37 species. The most dominant species in an number of fish was Pennahia argentata which was occupied at 42.1% from the whole number, the second most dominant species was Konosirus punctatus which was occupied at 14.2%. The most dominant species in a biomass of fish was Pennahia argentata which was 31.3% out of the whole catch, the next dominant species was Lophius litulonwhich which was 18.2%. The first group (Trichiurus lepturus, Zeus faber, Pennahia argentata, Chelidonichthys spinosus and Lophius litulon) was appeared at May, August, October, the second group (Sphyraena pinguis) was appeared at May and November, the third group (Pampus argenteus) was appeared at August, the fourth group (Pampus echinogaster, Leiognathus nuchalis, Konosirus punctatus and Engraulis japonicus) was appeared at March.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.24 no.4
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• pp.144-149
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• 1988

The purpose of this study is to find the light intensity which induced maximum gathering rate and to observe the variation of the gathering rate both in daytime and tat night by using Striped puffer, Fugu xanthopterus (Temminck et Schlegel). An experimental tank(360L$\times$50W$\times$55H cm) was set up in a dark room. An illumination system was attached to the end of one side of the tank to control horizontal light intensity. Eight artificial light sources were prepared by combination of three light bulbs (10W, 60W, 100W) and eight filters. During the experiment water depth was maintained 50 cm level in the tank. The tank was marked into six longitudinal sections each being 60cm long to observe the distribution of fish. The fish were acclimatized in dark condition for 50 minutes prior to the main experiment. Upon turning on the light, the number of fish in each section was counted 60 times every 30 seconds, and the gathering rate was obtained from the average number of fish in each section. The light intensity inducing maximum gathering rate was 298.56 lux (188.44-444.96 lux) at daytime and 298.56 lux (188.44-444.96 lux) at night. The variation of the gathering rate of fish in illumination time was increasing trend fluctuately and did not show any distinctive difference between day and night.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.39 no.2
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• pp.92-98
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• 2003

The quantification of fish school abundance was carried out by using luminance of pixel on scanning sonar image, and compared with the indices of fish school abundance e.g. school number, school area and weighted school area. The survey was carried out in Funka Bay off southern Hokkaido, Japan using research vessel Ushio-Maru during December 1999. A 180-degree scanning sonar with a frequency of 164kHz was used. The school number was counted both left and right 40-degree radial lines from the center of own vessel mark on a scanning image. The school area was measured approximately as an ellipse from the school length and width. The weighted school area was calculated by multiplying school area and average value of inner pixel luminance. A quantification of pixel luminance was also measured to integrate squared pixel luminance value on these lines. Fish school and school bottom were discriminated by the produced sonar echogram using pixel luminance value on these lines. The relationships between the quantified luminance value and other abundance indices such as school area and weighted school area revealed a good correlation. Therefore, the quantified luminance is a useful method in estimating fish school abundance in the acoustic survey using sonar.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.16 no.1
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• pp.37-42
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• 1980

The purpose of the present study is to find the color induced maximum gathering rate and to observed'the trend of the - gathering rate by using two species of commercial fishes: rock bream, Oplegnathus fasciatus (Temminet et Schlegel) and 'grass puffer, Fugu niphobles (Jordan et Snyder). An experimental tank($360L{\times}50W{\times}55H cm$) was set up in a dark room. An illumination system was attached to the two end of tank to fix horizontal light intensity by co~bination c' one light bulb(20W) and four filters (red, blue, yellow, white) and the five regulating filters in order to fix light intensity. During the experiment water depth was maintained 50 cm lever in the tank. The tank was marked into six longitudinal sections each being 60 em long to observe the distribution of fish. The fish were acclimatized in dark condition for 40 minutes prior to the main experiment. Upon turning on the light, the number of fish in each section was counted 40 times every 30 seconds, and the gathering rates ,were obtain from the average number of fish in each secion. The color induced maximum gathering rate of rock bream appeared to be red, blue yellow and white color orderly.However, that of grass puffer appeared to be blue, white, yellow and red color orderly. Trend of the gathering rate in illumination time showed the remarkable fluctuation in the rock bream and little difference at the two color light sources. However, trend of the gathering rate in illumination time showed the little fluctuation in grass puffer and much difference at the two color light sources.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.19 no.6
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• pp.558-562
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• 1986

The purpose of this study is to find the light intensity which induces maximum gathering rate and to observe the variation of the gathering rate both in daytime and at night by using marbled sole, Limanda yokohamae (Gunther). An experimental tank ($360L{\times}50W{\times}55H\;cm$) was set up in a dark room. An illumination system was attached to the end of one side of the tank to control horizontal light intensity. Six artificial light sources were prepared by combination of two light bulbs (5W, 150W) and seven filters. During the experiment water depth was maintained 50 cm level in the tank. The tank was marked into six longitudinal sections each being 60 cm long to observe the distribution of fish. The fish were acclimatized in dark condition for 50 minutes prior to the main experiment. Upon turning on the light, the number of fish in each section was counted 40 times every 30 seconds, and the gathering rate was obtained from the average number of fish in each section. The light intensity inducing maximum gathering rate was 1.9 lux ($1.2{\sim}2.9\;lux$) in the daytime and 0.7 lux ($0.5{\sim}1.1\;lux$) at night. The variation of the gathering rate of fish in illumination time was small and comparatively fluctuated with stability.

• Korean Journal of Ichthyology
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• v.30 no.2
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• pp.119-124
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• 2018

Diversity of fish fauna and species list collected from the Imha-Dam Reservoir of the Nakdonggang River system were reviewed based on the published materials from 1992 to 2016. As a result of the present study, 46 freshwater fish species/subspecies belonging to 36 genera, 11 families, 4 orders were reported in the Imha-Dam Reservoir. Of them, Cyprinidae occupied 58.7% (27 species), Cobitidae 10.9% (5 spp.), Gobiidae 6.5% (3 spp.), and Siluridae, Centropomidae, Centrarchidae were 4.3% (2 spp.) in the number of species, respectively. The dominant species in the number of individuals was Erythroculter erythropterus (40.1%, 9,333 inds.), and the subdominant species was Opsariichthys uncirostris amurensis (9.8%, 2,281 inds.). Among 46 species/subspecies, 17 species (37.0%) were identified as endemic species to Korea. Three species were endangered fish species by the Ministry of Environment of Korea, five translocated species, and three exotic species were reported.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.19 no.1
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• pp.12-16
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• 1983

The author carried out an experiment to find out the response of cat shark, Scyliorhinus torazame(Tanaka) to the colored lights. The experimental thank (360L$\times$50W$\times$55H cm) was set up in a dark room. Six longitudinal sections with 60cm intervals are marked in the tank to observe th location of the fish. Water depth in the tank was kept 50cm level. Light bulbs of 20W at the both ends of the tank projected the light horizontally into the tank. Two different colored filters were selected from four colors of red, blue, yellow, and white, and they were placed in front of the light bulbs to make different colors of light. Light intensity were controlled by use of auxiliary filters intercepted between the bulb and the filter. The fishes were acclimatized in the dark for 50 minutes before they were employed in the experiment. Upon turning on the light, the number of fish in each section was counted 40 times in 30 second intervals, and the mean of the number of fish in each section was given as the gathering rate of the fish. The favorite color of the fish was found in the order of yellow, white, blue and red in day time, and red, blue, white and yellow at night time. The variation of the gathering rate on illumination time was very little and showed more stability in day time than at night time. The differences of the gathering rates to two selected colors out of the four colors were greater regardless of illumination time.

• Korean Journal of Ichthyology
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• v.35 no.4
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• pp.294-304
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• 2023

Seasonal variations in the community structure of larval fish assemblage in the coastal waters off Gadeok-do were investigated in May, August and November of 2019, and February in 2020. During the study period, a total of 85 larvae species belonging to 45 families were collected. The dominant species were Engraulis japonica, Gobiidae sp., Clupea pallasii, Decapterus maruadsi, and Callionymidae sp.. These five species accounted for 84.1% of the total number of larvae during the survey period. E. japonica, Gobiidae sp., D. maruadsi, and Callionymidae sp. were the dominant species in the summer, while C. pallasii was the dominant species in the winter. The Species Diversity Index was highest in the summer and lower in the fall and winter months, with the lowest values in the spring. As a result of cluster analysis using the number of individual larval fish showed that they are divided into four seasonal groups. In particular, due to seasonal changes in water temperature, an appropriate growth environment was formed in the summer, and an appropriate hatching water temperature for winter spawning fish species was formed in winter, reflecting the seasonal characteristics of the larval fish community.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.31 no.1 s.256
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• pp.36-42
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• 2007

This paper presents mechanical design, fabrication and test of a biomimetic fish robot actuated by a unimorph piezoceramic actuator, LIPCA(Lightweight Piezo-Composite curved Actuator.) We have designed a linkage mechanism that can convert bending motion of the LIPCA into the caudal fin movement. This linkage system consists of a rack-pinion system and four-bar linkage. Four types of artificial caudal fins that resemble caudal fin shapes of ostraciiform subcarangiform, carangiform, and thunniform fish, respectively, are attached to the posterior part of the robotic fish. The swimming test under 300 $V_{pp}$ input with 0.6 Hz to 1.2 Hz frequency was conducted to investigate effect of tail beat frequency and shape of caudal fin on the swimming speed of the robotic fish. At the frequency of 0.9 Hz, the maximum swimming speeds of 1.632 cm/s, 1.776 cm/s, 1.612 cm/s and 1.51 cm/s were reached for fish robots with ostraciiform, subcarangiform carangiform and thunniform caudal fins, respectively. The Strouhal number, which means the ratio between unsteady force and inertia force, or a measure of thrust efficiency, was calculated in order to examine thrust performance of the present biomimetic fish robot. The calculated Strouhal numbers show that the present robotic fish does not fall into the performance range of a fast swimming robot.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.25 no.4
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• pp.191-199
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• 1989

Research on the acoustic properties of fish has been carried out by a number of scientific workers from the earliest days of applying acoustic techniques to fish biomass estimates. This paper describes measurements of the target strength of Cyprinus Carpio, which measurements made at 50KHz in the experimental water tank. The results obtained are as follows: 1. The target strength(dB) of the fish has a directivity pattern quite similar to that of a transducer. The maximum value of target strength(dB) is obtained when the fish is insonified to its head-tail axis either from the dorsal or from the ventral side. 2. Empirical relationship between target strength(dB) and body length(cm) of the fish can be estimated as TS=20 Log L-65.4 where TS is the target strength of the fish and L is the body length of the fish. 3. The relationship between target strength(dB) and body weight(g) of the fish can be estimated as TS=6.7 Log W-53.7 where W is body weight of the fish.