• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.19 no.3
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• pp.215-222
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• 2014

Paralarvae of the common squid, Todarodes pacificus Steenstrup were sampled with the bongo net (diameter: 60 cm, mesh: $333{\mu}m$) by using oblique tow method with the oceanographic research vessel (Tamgu 12) at 21 stations along the southwestern coastal waters of the East Sea in August and September, 2013. Paralarvae were collected 16 ind./$10m^3$ in August and 7 ind./$10m^3$ in September at approximately, and bottom depth was from 70 m to 500 m. Mantle length of paralarvae was from 1.7 to 6.0 mm. Paralavae were distributed mainly in offshore stations in August and near by Cape Janggi in September. Optimum embryo survival temperature ($18-24^{\circ}C$) was formed shallower than 35 m depth for almost stations where paralarvae were existed, and survival temperature ($15-24^{\circ}C$) for embryo stage was located shallower than 75 m.

• Journal of the Society of Naval Architects of Korea
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• v.31 no.3
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• pp.65-79
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• 1994

In the present paper, An emphasis is laid upon effects of stern bulb on hydrodynamic property and manoeuvring performance. We carried out captive model tests in circulating water channel with two ship models of which the frame lines of aft bodies are different. such as normal stern form and stern form with bulb, but of which the other parts are exactly same. The tests conducted consist of hull resistance test, effective thrust measurement, oblique tow test, and measurements of factors related to rudder force. From the results of model tests, we discussed effects of stern bulb on hull forces and on hull-propeller-rudder interactions, comparing with normal stern form. Furthermore, we also discussed effects of stern bulb on course stability. turning ability. spiral characteristics and zig-zag manoeuvre by computer simulation. As a result, it is clarified that the adoption of stern bulb makes course stability the worse and turning ability the better. The difference of the hydrodynamic derivatives of naked hull between two ship forms cause the worse course stability of the ship with stern bulb. The differences of the effective inflow velocity to rudder and hull forces induced by steered rudder cause the better turning ability of the ship with stern bulb.

• 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.

• Korean Journal of Environmental Biology
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• v.36 no.2
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• pp.140-149
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• 2018

Seasonal variations in the community structure of larval fish assemblage in Jinhae Bay were investigated in February, May, August and November of 2015, and in the same months in 2016. During the study period, a total of 28 larvae species belonging to 24 families were collected. The dominant species were Clupea pallasii, Liparis tanakae, Callionymidae sp., Sillago japonica, Ernogrammus hexagrammus and Engraulis japonica. These six species accounted for 77.6% of the total number of larvae during the survey period. The larvae of C. pallasii and L. tanakae were exclusively caught in February 2015 and 2016, while those of Apogon lineatus and Sillago japonica were exclusively caught in August 2015 and 2016. Overall, species diversity of the fish larvae was highest in February and August, although it was relatively low in May. The results of the non-metric multidimensional scaling (nMDS) analysis using the number of individual larval fish showed that they are divided into four seasonal groups. Our results showed that the community of larval fish in Jinhae Bay was affected by seasonal changes in temperature and the emergence of spawning fish species. Additionally, we suggest that the high abundance of larval fish came from around Jam-do and the northern part of Chilcheon-do; these locations are the main spawning grounds of Jinhae Bay.