• Journal of Korean Society of Coastal and Ocean Engineers
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• v.7 no.2
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• pp.163-169
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• 1995

A two-dimensional numerical tidal model is formulated to reproduce tides in the Southwestern Sea of Korea. Tidal charts and ellipses of eight major tidal constituents (M$_2$, S$_2$, K$_1$, O$_1$, N$_2$, K$_2$, P$_1$, Q$_1$) are presented. Model results show that the semi-diurnal tides are dominant in this area. Maximum transport by tides in the Cheju Strait is about 4.2${\times}$10$\^$6/ ㎥/sec which is greater by eight times than that by residual current.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.5 no.1
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• pp.1-10
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• 1972

Studies on the circulation and water masses in the continental shelf break region of the East China Sea are Summerized as follows : 1. The main stream of the Kuroshio flowing north-east near $29^{\circ}N\;Lat\;127^{\circ}E$ tong of the East China Sea in summer is narrow in width. Moving toward east, it becomes twice as wide in Tokora Strait, Japan. 2. In the main stream area of the Kuroshio, the surface Waters in the Upper layer (0-250m) are influenced by the coastal waters of China, and the counter current submerges under the surface water. Therefore, the mixing waters are found in its intermediate layer. 3. Water mass between Amami Island and the continental shelf of the East China Sea consists of main stream water, counter current water, gyration water and mixed water with coastal waters. 4. The maximum velocity of current in this waters was 139cm/sec. The volume transport was estimated approximately as $24.2\;\times\;10^6m^3/sec$. It was less than $33\;\times\;10^6m^3/sec$ in the region between Okinawa and continental shelf of the East China Sea. 5. Surface waters east of $29^{\circ}N\;Lat\;128^{\circ}E$ Long flows toward Amami Island, Okinawa Island, and Hachi Ju San Island, while those west of the region flow toward the Korea-strait, Cheju Island, coastal waters of Kyusyu, and the Pacific Ocean through Tokora Strait. The velocity of the current was estimated approximately as $0.3\~0.5$ miles per hour. 6. The bottom waters in the continental shelf break region flow toward the Korea Strait, Cheju Island and the coastal water of Kyusyu, while that of the continental shelf flows toward the Yellow Sea, 7, The characteristics of the Kuroshio water is changed remarkably by the mixing with the coastal water of China.

• Korean Journal of Ichthyology
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• v.12 no.1
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• pp.33-37
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• 2000

A total of 28 Laemonema nana larvae, 1.4~10.5 BL (body length), were collected by bongo net and trawl-shaped fish larvae net in the coastal area of Cheju Island during 1998~1999. This species was found in around sea of Cheju Island, Korea Strait and southwestern East Sea. This paper describes morphological features of these specimens throughout their development. 1) The soft ray of fin appeared at about 4.5 mm BL and attained to a fixed number at about 6.8 mm BL. 2) There were two large pigments in the head of larvae less than 4 mm BL. 3) A large pigment in the middle of tail appeared at about 2 mm BL was spread to the caudal peduncle at about 9 mm BL. 4) Two large pigment in the base of anal fin appeared at about 2 mm BL were spread out 2/3 of anal fin to caudal fin at about 9 mm BL. 5) A new Korean name "Chal-Bun-Su-Yum-Dae-Gu" is proposed for this species.

• Animal Systematics, Evolution and Diversity
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• v.8 no.2
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• pp.243-258
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• 1992

For the systematic study of Korean Asteroidea the specimens collected from total 69 localities in the South Sea, Korea during the period from April, 1980 to Apirl, 1992 were indentified. As a result, 23 species, 18 genea, 8 families and 5 orders were identified of which two species, Mediaster brachiatus and Stellaster equestris have not been reported in Korea yet. Asterina perctinifera was the commonest species collected from 43 localities of 69 localities. Fifteen species were found in Korea Strait and Cheju Island area, respectively. Fifteen temperate species, 7 tropical species and 3 boreal species were found to be distributed in the South Sea of Korea. The asteroids known so far in Korea tuned out to be 43 species.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.21 no.1
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• pp.41-61
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• 1985

The purse-seine fishery is very important in the coastal fishery of Korea and the main fish species of this fishery are mackerals and also the main fishing grounds are Tushima Current region, To investigate the relationship between the fishing grounds of mackerels and oceanographic condition, the distribution of mean catches of mackerals of each size (1974~1982) was firstly examined and the oceanographic observation carried out in eastern and western area of Cheju island, being main fishing grounds, in July and October, 1983. The results are as follows: The main fishing grounds of mackerals were also in the Tsushima Current region in southern sea of Korea and the season of the good catches are in May and September to October. The small and medium size of mackerals of which the body lengths are 27 cm to 31 cm, about 2-3 ages, occupied about 90% but the smaller size mackerals of which body lenth is 22 cm (1 age)were about 40 to 70% in February to March. The locations of seasonal fishing grounds could founded by 15$^{\circ}C$ isotherm which indicates the Tsushima Current Water. With trace of this isotherm it was founded that the fishing grounds near the Korean Strait than that of south of Cheju island moves faster northward and/or later southward. The main fishing grounds eastward and westward of Cheju island were the front areas formed between the Tsushima Current Water and the southern coastal water of Korea or Yellow Sea Bottom Cold Water. And also the distributions of transparences, water colors and the penetration of sun light of this fishing grounds were similar to that of the temperature, the salinity or volume of planktonic organism.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.3 no.4
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• pp.175-182
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• 1998

Recently it is reported that anomalously low saline surface waters (salinity < 32) occurred at the Ulleung Basin in the East Sea-Japan Sea, during early September to November 1996. Apparent source of such a low saline watermass seems remotely linked to the Changjiang Dilute Water (CDW), which expands to the vicinity of Cheju Island during a flood season. Based on the assumption that waters passing through the Western Channel of the Korea Strait are formed by a mixing of Kuroshio Water and CDW, simplified two end-member mixing model using $^{228}Ra/^{226}Ra$ as a conservative tracer is applied to calculate the contribution of each end member for the formation of low saline surface seawater. Model calculations show CDW contributes $58{\pm}3%$ in September 1996 (S=32.17) and $10{\pm}3%$ in February 1997 (S=34.53) in the formation of surface water flowing into the Western Channel of the Korea Strait. Although results arc deduced from a simplified model with limited data, this study demonstrates that Changjiang discharge is clearly traceable to the interior of the East Sea-Japan Sea in fall season. Undergoing Three Valley Dam construction in the Changjiang River would invoke inevitable changes in the nature and discharge of CDW and its impacts on the marine environment might be significant in the northern East China Sea and even in the Ulleng Basin for coming decades.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.8 no.3
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• pp.327-339
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• 2003

During the winter in February 1998, January and April 1999, interdisciplinary research was conducted in a large area including the South Sea of Korea and northern East China Sea to examine distribution and structure. Water masses identified from the observed data are Warm Water originated from Tsushima Warm Current, Yellow Sea Cold Water (Northern or Central Cold Water) and Korean Southern Sea Cold Water. In the southern Yellow Sea, Warm Water originated from Tsushima Warm Current, flowing into the Cheju Strait after turning around the western Cheju Island, makes a front of '┍' shape, which is bounded by the Yellow Sea Central Cold Water in the southern part of Daeheuksan Island and by the Yellow Sea Northern Cold Water in the eastern part of the Yangtze Bank. This front changes its corner shape and position with strength of the warm water extension toward northwestern Yellow Sea. The position and structure of the fronts off the southwestern tip of the Korean peninsular and near the Yangtze Bank varies with observation period. In the front in the South Sea of Korea, cold coastal water which if formed independently due to local cooling, ,sinks along the sloping bottom. We explained the processes of variations in the distribution and structure of these winter fronts in terms of up-wind and down-wind flow by the seasonal monsoon, heat budget through the sea surface and density difference across the fronts.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.27 no.6
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• pp.733-753
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• 1994

Monthly mean sea levels from 103 tidal stations in Korea, Japan, and Russia are analyzed to study long-period sea level variations. Barometric adjustment are done for all the sea level data, using monthly air pressures at sea levels from meteorological stations near tidal stations. Seasonal variation is dominant in most of study area. It is the largest in the coasts along the Tsushima Current, and the smallest in the Russian coasts. The cross-correlations of seasonal variations are very high between the coasts along the Tsushima Current. In these marginal seas, seasonal variations seem to be related with the Tsushima Current. The phase of seasonal variations is generally getting late from south to north, and also from west to east. On the other hand, longer-period variations(longer than seasonal variation) have the largest amplitudes and the earliest phases in the coasts along the Pacific Ocean, which shows that they propagate from the Pacific Ocean. Shorter-period variations (shorter than seasonal variation) have generally lower cross correlations. Their values do not show any dictinct difference between areas, and show a common tendency that they are inversely proportional to distance. It implies that the shorter period waves are generated all over the study areas, and propagate in all the directions with faster dissipations. The trends of sea levels in the study area are generally negative in the coasts along the Pacific Ocean and positive in the other areas during the period of 1965 to 1985. By the trends, the mean volume transport between Cheju and Sasebo can be reduced by about 1 Sv during the period. The seasonal variation of volume transport obtained by sea level difference is about 2 Sv in the Korea Strait. The values are comparable to previous reports.

• 한국해양학회지
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• v.8 no.1
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• pp.33-45
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• 1973

Plankton samples used for the present study were collected by the NORPAC net during the CSK cruises in the Korean waters in March and August, 1967. Regional and seasonal variations in the zooplankton biomass (wet weight, mg/㎥) were noticed in the Korean waters. In March the highest biomass, 130mg/㎥ on the average, occurred in the southern part of Japan Sea, but the lowest biomass of less than 50mg/㎥ occurred in the Yellow Sea and the western sea of Cheju Island Contrally, in August, the average biomass of 120mg/㎥ was measured in the Yellow Sea, the western sea of Cheju Island and the coastal waters of southern Korea, while the biomass of Japan Sea was the lowest of the regions surveyed. In comparison with the zooplankton biomass, total number of zooplankton per cubic meter of water strained also showed regional and seasonal fluctuations. In general, variations in the number of zooplankton specimens follows the same trend as in the biomass. The largest number, up to 800mg/㎥ on the average, occurred in the southern part of Japan Sea in March and the lowest number, less than 200mg/㎥ occurred in the Yellow Sea and the western sea of Cheju Island. In August, as shown by the biomass fluctuations, the largest number of zooplankton 850mg/㎥ on the average occurred in the Yellow Sea, the western sea of Cheju Island and the coastal region of southern Korea. But the lowest number of less than 500mg/㎥ was found in the Japan Sea. Among the various groups of zooplankton examined, the following were dominant components of the zooplankton population: Copepoda, Chaetognatha, Siphonophora, Euphausiacea, Cladocera, Appendicularia, and Amphipoda. The zooplankton conposition was significantly differed between the Japan Sea and Yellow Sea. Copepods which usually occupied over 66% in the Japan Sea and thd Korean Strait samples occupied only 42% of the catches in August, while cladocerans and chaetognaths were relatively abundant, i. e., 15 and 18% of the total organisms. The most dominant species of copepods and chaetognaths were Paracalanus parvus, Oithona similis, Acartia clausi, Calanus helgolandicus, Sagitta enflata, S. bedoti, S. elegans and S. crassa.

• Journal of the korean society of oceanography
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• v.37 no.3
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• pp.91-107
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• 2002

The wintertime upwind flow in the Yellow Sea has been investigated through a series of two-dimensional numerical experiments in an idealized basin. A total of 10 experiments have been carried out to examine the effects of wind forcing, bottom friction and the presence of oceanic currents sweeping the shelf of the East China Sea. A spatially uniform steady and periodic wind stresses are considered along with comparison of linear and quadratic formulations. The wind-driven flow in the absence of oceanic current has been computed using Proudman open boundary condition (POBC), while the wind-driven current in the presence of oceanic current has been computed using Flather’s radiation condition (FOBC). The oceanic currents to be prescribed at the open boundary have been simulated by specifying uniform sea level gradients across the Taiwan Strait and the eastern ECS shelf, Calculations show that, as seen in Lee et al. (2000), oceanic flow little penetrates into the Yellow Sea in the absence of wind forcing unless a unrealistically low rate of bottom frictional dissipation is assumed. Both steady and time-periodic wind stresses invoke the upwind flow along the central trough of the Yellow Sea, independently of the presence of the oceanic current. The presence of oceanic currents very marginally alters the north-south gradient of the sea surface elevation in the Yellow Sea. Changes in the intensity and direction of the wind-induced mean upwind flow are hardly noticeable in the Yellow Sea but are found to be significant near Cheju Island where the gradient is reduced and therewith contribution of Ekman transport increases. In case of steady wind forcing circulation patterns such as two gyres on the slope sides, a cyclonic gyre on the western slope and an anticyclonic gyre on the eastern slope persist and the upwind flow composes part of the cyclonic gyre in the Yellow Sea. While in case of the time-periodic wind stress the appearance and disappearance of the patterns are repeated according to the time variation of the wind stress and the upwind flow accordingly varies with phase delay, mostly intensifying near the time when the wind forcing is approximately near the middle of the decaying stage.