• Journal of information and communication convergence engineering
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• v.2 no.1
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• pp.58-60
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• 2004

Sea level variations and sea surface circulations in the Korean seas were observed by Topex/Poseidon altimeter data from 1993 through 1997. In sea level variations, the West and South Sea showed relatively high variations with comparison to the East Sea. Then, the northern and southern area in the West Sea showed the range of 20∼30cm and 18∼24cm, and the northern west of Jeju island and the southern west of Tsushima island in the South Sea showed the range of 15∼20cm and 10∼15cm, respectively. High variations in the West Sea were results to the inflow in sea surface of Yellow Sea Warm Current (YSWC) and bottom topography. Sea level variations in the South Sea were due to two branch currents (Jeju Warm Current and East Korea Warm Current) originated from Kuroshio Current (KC). In sea surface circulations, there existed remarkably three eddies circulations in the East Sea that are mainly connected with North Korea Cold Current (NKCC), East Korea Warm Current (EKWC) and Tushima Warm Current (TWC). Their eddies are caused basically to the influence of currents in sea surface circulations; Cyclone (0.03 cm/see) in the Wonsan bay off shore with NKCC, and anticyclone (0.06 cm/see) in the southwestern area of Ulleung island with EKWC, and cyclone (0.01 cm/see) in the northeastern area of Tushima island with TWC, respectively.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.879-881
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• 2003

Sea level variations and sea surface circulations in the Korean seas were observed by Topex/Poseidon altimeter data from 1993 through 1997. In sea level variations, the West and South Sea showed relatively high variations with comparison to the East Sea. Then, the northern and southern area in the West Sea showed the range of 20${\sim}$30cm and 18${\sim}$24cm, and the northern west of Jeju island and the southern west of Tsushima island in the South Sea showed the range of 15${\sim}$20cm and 10${\sim}$15cm, respectively. High variations in the West Sea was results to the inflow in sea surface of Yellow Sea Warm Current (YSWC) and bottom topography. Sea level variations in the South Sea was due to two branch currents(Jeju Warm Current and East Korea Warm Current) originated from Kuroshio Current (KC). In sea surface circulations, there existed remarkably three eddies circulations in the East Sea that are mainly connected with North Korea Cold Current (NKCC), East Korea Warm Current (EKWC) and Tushima Warm Current(TWC). Their eddies are caused basically to the influence of currents in sea surface circulations; Cyclone (0.03 cm/sec) in the Wonsan bay off shore with NKCC, and anticyclone (0.06 cm/sec) in the southwestern area of Ulleung island with EKWC, and cyclone (0.01 cm/sec) in the northeastern area of Tushima island with TWC, respectively.

• Ocean and Polar Research
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• v.32 no.4
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• pp.351-359
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• 2010

This study examined extensive patches of floating green macroalgal (Ulva prolifera) mats in the northern East China Sea (ECS) using satellite images from mid May through July 2008 and field observation made during early August 2008 cruise. It was previously reported that the massive macroalgal blooms occurred in the coastal areas of Qingdao in China. During our field survey, researchers noticed widely distributed floating patches of macroalgal mats ranging in size from tens of centimeters to a few hundred meters in diameter. Meteorological data in the northern ECS showed high irradiance, high air-temperature, and predominant southerly winds in summer. In the study area during the survey period, surface waters were characterized by the Changjiang Diluted Water (CDW) mass, which contained high concentrations of nitrate and phosphate. The internal transcribed spacer (ITS) sequence of U. prolifera found in the northern ECS was the same as those of U. prolifera sampled from Qingdao blooms, suggesting a possibility that U. prolifera found in two regions would be derived from the same origin. We suggest that U. prolifera in the nearshore Jiangsu Province drifted into the northern ECS and proliferated under favorable meteorological and oceanographic conditions during the summer of 2008.

• Journal of the Korea Institute of Military Science and Technology
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• v.18 no.2
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• pp.201-211
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• 2015

Acoustic propagation in shallow water with changing environments is a major concern of navy. Temporal and spatial variability of acoustic propagation in the northern East China Sea (ECS) is studied, using the 11 years hydrographic data and the Bellhop acoustic model. Acoustic propagation in the northern ECS is highly variable due to extensive interaction of various ocean currents and boundaries. Seasonal variations of transmission loss (TL) with various source depths are highly affected by sharp gradient of sound speed and bottoms interaction. Especially, various bottom sediment types lead to severely degrading a waterborne propagation with bottom loss. In particular, the highly increased TL near the ocean front depends on the source position, and the direction of sound propagation.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.36 no.2
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• pp.178-186
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• 2003

Seasonal variation of phytoplankton was investigated with surface mixed layer ecosystem model in the East Sea. The model consisted of four compartments (phytoplankton, zooplankton, nutrient, detritus) forced by mixed layer depths, photosynthetically available radiation and nutrient concentrations. From model results we estimated entrainment rate $2.5-4.0\;m{\cdot}day^{-1}$ to reproduce the two annual blooms, and reproduced seasonal variation of phytoplankton at southern and northern regions by the difference of surface winter mixed layer depth (MLD) using the entrainment rate value $3.0\;m{\cdot}day^{-1}$. The spring blooms in the southern and northern regions closely related to deepening of a winter surface MLD. In the southern region where MLD was shallow and phytoplankton spring bloom occurs one month in advance to the northern region where MLD was deep. The amount of light increases within the MLD during the onset of stratification and water temperature increases faster in spring in the southern region than the northern region. Decrease of phytoplankton was mainly affected by zooplankton grazing in the southern region and by nutrient exhaustion in the northern region. The fall bloom in the two regions was caused by the nutrient availability and entrainment on the phytoplankton.

• Korean Journal of Remote Sensing
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• v.20 no.3
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• pp.153-162
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• 2004

In the summer of 1998-2001, a huge flood occurred in the Yangtze River in the eastern China. Low salinity water less than 28 psu from the river was detected around the southwestern part of the Jeju Island, which is located in the southern part of the Korean Peninsula. We studied how to detect low salinity water from the Yangtze River, that cause a terrible damage to the Korean fisheries. We established a relationships between low salinity at surface, turbid water from the Yangtze River and digital ocean color remotely sensed data of SeaWiFS sensor in the northern East China Sea, in the summer of 1998, 1999, 2000 and 2001. The salinity charts of the northern East China Sea were created by regeneration of the satellite ocean color data using the empirical formula from the relationships between in situ low salinity, in situ measured turbid water with transparency and SeaWiFS ocean color data (normalized water leaving radiance of 490 nm/555 nm).

• Ocean and Polar Research
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• v.31 no.2
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• pp.219-229
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• 2009

In order to establish annual variations in the marine ecosystem of the East China Sea, suspended solids (SSs) and particulate organic carbon (POC) were extensively investigated in the northern part of the East China Sea from August 2003 to April 2008. Surface SS concentrations showed large spatial variations in spring and fall, but not in summer. Surface SS concentrations in spring were lower than those in summer and fall. In summer, SSs discharged from Changjiang were mostly deposited in the coastal areas and did not reach our study area which was located about 260 km from the river mouth. High SS concentrations were observed near the bottom, which resulted from resuspension of bottom sediments by the bottom currents. Surface POC concentrations did not exhibited large seasonal variations. Phytoplankton biomass was a main factor controlling surface POC concentrations. POC/chlorophyll ratios showed large seasonal variations, with maximum numbers in summer. POC/PON ratios were higher in summer than the Redefied ratio (6.6), while they were lower in spring and fall. In summer, higher POC/chlorophyll and POC/PON ratios were probably attributed to the high phytoplankton mortality caused by nutrient depletion in surface waters.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.56 no.2
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• pp.259-264
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• 2023

Day-night vertical euphausiid distribution was investigated at three stations in the East Sea using a Multiple Opening/Closing Net and Environmental Sensing System (MOCNESS). Three euphausiid species were recognized. Euphausia pacifica was more dominant than Thysanoessa longipes. Euphausiids were collected at Station 1 at night, Station 2 at sunset, and Station 3 during the daytime. At Station 1, calyptopis and furcilia stages were concentrated from the surface to 30 m and 20-40 m, respectively. Juveniles and E. pacifica were distributed in strata shallower than 30 m. At Station 2, calyptopis and furcilia stages were dominant in strata from the surface to 40 m. Juveniles were not recorded in strata at 30-100 m. However, E. pacifica occurred in these strata. At Station 3, calyptopis and furcilia stages occurred in the upper 40 m of strata. E. pacifica was distributed deeper than 100 m and rarely occurred above 100 m. The furcilia stages weakly migrated, whereas the calyptopis stages did not. Juveniles and E. pacifica showed a clear migration pattern. Vertical distribution of euphausiids in the northern East Sea varied by life stage and time of day.

• Journal of Environmental Science International
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• v.12 no.9
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• pp.943-948
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• 2003

Variation of the polar front in the East Sea is studied using temperature and dissolved oxygen data obtained from Japan Meteorological Agency from 1972 to 1999. Variation of the polar front in the East Sea has a close relation to the variation of the Tsushima Warm Current (TWC). When the TWC spreads widely in the East Sea, polar front moves northward. The spatial variation of the polar front is greater in the southwestern area of the East Sea and the northern area of Tsugaru Strait where the variation of the TWC's distribution area is greater than those in others of the East Sea. Hence, in the southeastern area of the East Sea, that is, between near Noto peninsula and Tsugaru Strait, the spatial variation of the polar front is not so wide as in the southwestern area because the flow of TWC is stable.

• Proceedings of the KSRS Conference
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• 2002.10a
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• pp.649-654
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• 2002

In summer season of 1998, a huge flood occurred around the Yangtze River in the eastern China. The low salinity water less than 28 psu from the river was detected around the southeastern part of the Jeju Island which is located in the southern part of the Korean peninsula. We studied how to detect low salinity water from the Yangtze River, which gives terrible damages to the Korean fisheries. We got the relationships between low surface salinity, turbid water from the Yangtze River and digital ocean color using remote sensing of SeaWiFS satellite in the northern East China Sea in summer seanson of 1998, 1999, 2000 and 2001. The charts of salinity in the northern East China Sea were made by the regenerating of the satellite ocean color data with the formula from the relationships between low salinity, in situ turbid water (transparency) and satellite ocean color.