• 한국수산과학회지
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• 제36권3호
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• pp.306-316
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• 2003

We conducted a time-series analysis of temperature and salinity of sea water around Jeju Island, Korea. Monthly mean temperature and salinity was influenced by precipitation and weather conditions on Jeju as well as by oceanographic conditions of the open sea such as the Tsushima Warm Current and sea water in coastal areas. Salinity of Jeju coastal waters was the highest in April, and it was always over 34.00 psu with tiny fluctuation between December and June. Due to the effects of the Tsushima Warm Current, Jeju coastal waters maintained high salinity and stability. Low salinity and its large fluctuations during summer were closely associated with the China Coastal Water and precipitation in Jeju. The place of the lowest water temperature was the northeast coasts of Jeju (Gimneong, Hado, Jongdalri). In winter, as warmer water of the Tsushima Warm Current appeared in western area of Jeju dwindled flowing along the northern coasts of Jeju area and becoming cool, the lowest water temperature often appeared locally in Gimnyeong and its vicinitly in summer. The Tsushima Warm Current flows into the east entrance of Jeju Strait, but its influence is weak because of geometry and strong vertical mixing due to fast tidal currents.

• Ocean Science Journal
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• 제43권1호
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• pp.25-30
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• 2008

Potentially toxic diatoms Pseudo-nitzschia calliantha and P. fraudulenta were found in bottle samples of phytoplankton collected in Amurskii Bay (East/Japan Sea) and in the coastal waters of Sakhalin Island (East/Japan Sea and Sea of Okhotsk) in different seasons during 2002-2006. The mass development of these species occurred in October and November 2002 at water temperatures of $6-16^{\circ}C$ and salinities of 28.8-33.5 PSU. The highest concentrations of P. calliantha and P. fraudulenta were about $2{\times}10^5\;cells\;L^{-1}$ and $1.5{\times}10^5\;cells\;L^{-1}$, respectively. P. fraudulenta was found for the first time in the Russian waters of the East/Japan Sea. Morphological descriptions of these species based on observation with light and electron microscopy and information on their ecology are presented. Data on the geographical distribution of these species are supplemented.

• 한국수산과학회지
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• 제51권2호
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• pp.187-198
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• 2018

The monthly salinity maps from Aquarius satellite covering the entire East Sea were produced to analyze the low-salinity water appearing in fall every year. The low-salinity water in the northern East Sea began to appear in May-June, spreading southward along the coast and eastward north of the subpolar front. Low-salinity water from the East China Sea entered the East Sea through the Korea Strait from July to September and was mixed with low-salinity water from the northern East Sea in the Ulleung Basin. The strength of the low-salinity water from the East China Sea was dependent on the strength of the southerly wind of the East China Sea in July-August. The salinity reaches a minimum in September with a distribution parallel to the latitude of $37.5^{\circ}N$. In October, low salinity water is distributed along the mean current path and subpolar front and the entire East Sea is covered with the low salinity water in November. Water with salinity larger than 34 psu starts to flow into the East Sea through the Korea Strait in December and it expands gradually northward up to the subpolar front in January- February.

• 한국수산과학회지
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• 제50권6호
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• pp.818-823
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• 2017

The diet composition of juvenile gold-eye rockfish, Sebastes thompsoni (40-50 mm SL), was examined based on 121 individuals collected in the Yellow Sea Bottom Cold Water in August 2016. The Yellow Sea Bottom Cold Water is characterized a by water mass of <$10.0^{\circ}C$ and 33 psu. The juvenile gold-eye rockfish fed on Amphipods [57.3% index of relative importance (IRI)] and Euphausiacea (32.9%). Most of the point in the prey-specific abundance plot indicated a high between-phenotype component (BPC).

• 한국수산과학회지
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• 제53권4호
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• pp.486-491
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• 2020

This study was investigated the survival and hatching rate of fertilized eggs in olive flounder Paralichthys olivaceus at water temperature, salinity, duration of transport and different stock densities during commercial transport. The observed optimal temperature during transport was 17.5℃ similar to the natural environmental conditions. The proper salinity was observed to be at 33 psu (practical salinity unit) in both surviving and hatching rate. In terms of the duration of transport, there were no differences until 12 hours between survival and hatching rate, but shorter time of transport would be better. With the best conditions during transport, 20,000 eggs/L were handled in both survival and hatching rate. These results can be essential in the production and transport of healthy olive flounder seeds.

• 한국수산과학회지
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• 제53권4호
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• pp.650-655
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• 2020

Chilsan-do Island, South Korea, has previously been identified as one of the biggest spawning sites of the small yellow croaker Larimichthys polyactis in the Yellow Sea. To determine whether Chilsan-do still serves as a spawning site for L. polyactis, three to five stations around Chilsan-do Island were surveyed for eggs from April to June (the main spawning season of L. polyactis) in 2019, using an RN80 net. For the first time, three L. polyactis eggs were identified at two stations, located just in front of Chilsan-do Island and between Chilsan-do and the coastline, only in May. The diameter of L. polyactis eggs (1.26-1.34 mm) was very similar to those of Collichthys niveatus (1.30-1.37 mm) and Setipinna tenuifilis (1.34-1.35 mm). During the survey period, the sea surface salinity remained constant (32.0-32.1 psu), but the sea surface temperature (SST) rapidly rose from 13.6-13.7℃ in April to 22.1℃ in May. Our findings suggest that L. polyactis still spawns near Chilsan-do Island today, but on a very small scale, and that changes in SST promote spawning of L. polyactis.

• 한국수산과학회지
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• 제53권5호
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• pp.688-693
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• 2020

Vibrio vulnificus is a Gram-negative marine bacterium known to cause septicemia. This study was conducted to investigate the distribution of V. vulnificus along the coast of Gadeok Island in Korea and to determine the molecular characteristics of isolated strains sampled between March and November 2019 from seawater. The strains were mostly detected between July and September, when the average water temperature and average salinity were 22.2-26.2℃ and 14.2-29.9 psu, respectively. V. vulnificus was not detected in seawater below 15℃. In September, the highest population of V. vulnificus was observed at 2,100 MPN (most probable number)/100 mL, attributable to decreased salinity from heavy rains. In addition, the detection rate of V. vulnificus was higher at the sampling station near the Nakdong River. Virulence-related genes were also identified among the isolates, such as vvhA (97.1%), viuB (44.1%), and vcgC (57.4%). In particular, viuB and vcgC were only observed in V. vulnificus isolated from June to September, when the detection rate was high and water temperature was above 20℃, suggesting the role of seasonal characteristics.

• Ocean and Polar Research
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• 제31권4호
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• pp.283-296
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• 2009

Oceanographic survey data were analyzed to understand the characteristics of a warm eddy observed in the Ulleung Basin in July 2005. The temperature distribution at 200 db and vertical sections provided evidence of the warm eddy in the Ulleung Basin (UWE05). Based on the 5$^{\circ}C$ isothermal line on 200 db temperature, the major axis was 160 km from southwest to northeast, and the minor axis was 80 km from southeast to northwest. The homogeneous layer in the thermocline of UWE05 had mean values of 10.40$^{\circ}C$ potential temperature, 34.35 psu salinity, and 26.37 kg/m$^3$ potential density (${\sigma}_{\theta}$) and provided evidence that UWE05 also existed during the winter of 2004-2005. A warm streamer initially flowed along the circumference of UWE05 and mixed with the upper central water. Two northward current cores were found on the western side of the measured current section at the central latitude of UWE05. One was the East Korean Warm Current (EKWC) and the other was the main stream of the western part of UWE05. Geostrophic transport of the upper layer (from the surface to the isopycnal surface of 26.9 ${\sigma}_{\theta}$) was approximately 2.5 Sv in the eastern side of UWE05. However, the measured transport was twice as large as the geostrophic transport. Mass conservation of geostrophic transport was well satisfied in the upper layer. The direct current measurements and geostrophic transport analysis showed that the EKWC meandered around UWE05.

• 전력전자학회논문지
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• 제14권4호
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• pp.299-306
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• 2009

최근 대기전력저감기능을 갖는 PWM IC를 적용한 플라이백 컨버터는 대기전력 모드 시 Burst 스위칭 동작에 의해 전력소모를 최소화 할 수 있지만 경 부하 및 대기전력모드 시 변압기를 통해 흐르는 큰 자화전류에 의해 여전히 낮은 효율특성을 가지는 문제점이 있었다. 본 논문에서는 경 부하 및 대기전력모드 동작 시 자화전류를 최 소화함으로 효율을 개선한 회로를 제안하였으며 50인치 PDP TV PSU (Power Supply Unit)에 있어서 대기전력 및 보조전원으로 사용된 70W 플라이백 컨버터에 적용 실험하여 보았다.

• 한국수산과학회지
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• 제36권5호
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• pp.549-561
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• 2003

Behavior of the Nakdong River plume was studied by the analysis of the observed CTD data and numerical simulations using three-dimensional Princeton Ocean model (POM) in which the river discharge, tides and winds were considered. During the flood season of summer the 30 psu isohaline expands northward to Daebyeon and southwestward to Samcheonpo. The model results show that the isohalines are approximately parallel to the bottom slope, which suggests the possibility of upwelling induced by the topographic effects. Northwesterly wind expands the river plume to the offshore direction so that the inflow of fresh plume water into Jinhae Bay through the Gaduk Channel is constrained, then the coastal upwelling seems to be caused by the wind-driven current at the southern edge of Gaduk Island. Southwesterly wind expands the river plume toward Daebyeon, and the inflow of fresh water into Jinhae Bay is also constrained.