• Journal of the Korean earth science society
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• v.40 no.4
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• pp.428-435
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• 2019

In the shallow coastal area, located off the northwestern Taean Peninsula of the eastern Yellow Sea, geoacoustic models with two layers were reconstructed for underwater acoustic experimentation and modeling. The Yellow Sea experienced glacio-eustasy sea-level fluctuations during Quaternary period. Coastal sedimentation in the Yellow Sea was characterized by alternating terrestrial and shallow marine deposits that reflected the fluctuating sea levels. The coastal geoacoustic models were based on data from piston, grab cores and the high-resolution 3.5 kHz, chirp seismic profiles (about 70 line-kilometers, respectively). Geoacoustic data of the cores were extrapolated down to 3 m in depth for geoacoustic models. The geoacoustic property of seafloor sediments is considered a key parameter for modeling underwater acoustic environments. For simulating actual underwater environments, the P-wave speed of the models was adjusted to in-situ depth below the sea floor using the Hamilton method. The proposed geoacoustic models could be used for submarine acoustic inversion and modeling in shallow-water environments of the study area.

• Journal of the Korean earth science society
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• v.40 no.1
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• pp.24-36
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• 2019

In the mid-eastern Yellow Sea, glacio-eustatic sea-level fluctuations and a regional tectonic subsidence have combined to represent an aggradational stacking pattern of sedimentary units during late Pleistocene-Holocene. The accumulated sediments are divisible into two-type units of Type-A and Type-B in high-resolution air-gun seismic profiles and the deep-drilled core of YSDP-105. Type-A unit largely comprises clast-rich coarse-grained sediments of non-marine to paralic origin, whereas Type-B unit consists mostly of tidal fine-grained sediments. Based on a bottom model of the sedimentary units, this study suggested a geoacoustic model of long-coring bottom layers at the YSDP-105 drilling site of the mid-eastern Yellow Sea. The geoacoustic model of 64-m depth below the seafloor with four-layer geoacoustic units was reconstructed in continental shelf strata at 45 m in water depth. For actual modeling, the geoacoustic property values of the models were compensated to in situ depth values below the seafloor using the Hamilton modeling method. We suggest that the geoacoustic model will be used for geoacoustic and underwater acoustic experiments of mid- and low-frequency reflecting on the deep bottom layers in the mid-eastern Yellow Sea.

• 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.

• 한국해양학회지
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• v.4 no.2
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• pp.49-67
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• 1969

A quantitative phytoplankton study in Korean waters was commenced in 1964 as a part of the primary production studies of Koreans seas, and it was continued with the cruises for Cooperative Studies of the Kuroshio(C.S.K) in 1965-1968. Phytoplankton samples were taken by dipping about 500ml of sea water from the surface, and then fixed by ading neutralized formlin. This report deals with the results obtained during 1965-1966. I examined a total of 298 samples of surface phytoplankton collected in the wate neighboring Korea in the above-mentioned period, and detected 147 species of diatoms and 22 species of dinoflagellates. Among them 123 species of diatoms and 18 species of dinoflagellates occured in the Japan Sea region, 133 species of diatoms and 11 species of dinoflagellates occured in the Korea Strait region, and 49 species of diatom and 8 species of dinoflagellates occured in the Yellow Sea region. And thd phytoplankton standing crops are dept in a fair abundance in the Japan Sea area all the year round, and are poor in the Yellow Sea area. The seas surrounding Korea are divided into seven regions by the planktological characteristics; northern and southern parts of the Japan Sea, eastern, western and southern parts of the Korea Strait, southern and northern parts of the Yellow Sea. The representative of the phytoplankton community in each sea region is generalized as follows; northern part of the Japan Sea is dominant with Chaetoceros group, southern part of the Japan Sea is dominant with Chaetoceros group and Skeletonema costaum, eastern part of the Korea Strait is dominant with Chaetoceros group and Pleurosigma sp., southern part of the Korea Strait is dominant with Chaetoceros group and Rizosolenia group, western part of the Korea Strait is most poor in phytoplankton, southern part of the Yellow Sea is dominant with Pleurosigma sp. and Coscinodiscus group, and northern part of the Yellow Sea is dominant with Pleurosigma sp. and Eucampia zoodiacus. Chaetoceros curvisetus, Leptocylindrus danicus, Pleurosigma normanii, Thalassionema nitzschioides, Thalassiothrix flauenfeldii appeared all the year round in the neighboring sea of Korea. There were 24 species (18 species of diatoms and 6 species of dinoflagellates) of the pecuriar phytoplankton in the Japan Sea, 27 species (25 species of diatoms and 2 species of dinoflagellates) of that in the Korea, and 7 species (5 species of diatoms and 2 species of dinoflagellates) of that in the Yellow Sea, respectively.

• Journal of Environmental Science International
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• v.10 no.6
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• pp.423-429
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• 2001

Satellite data, with sea surface temperature(557) by NOAA and sea level(SL) by Topex/poseidon, are used to estimate characteristics on the variations and correlations of 557 and SL in the East Asian Seas from January 1993 through May 1998. We found that there are two climatic characteristics in the East Asian seas the oceanic climate, the eastern sea of Japan, and the continental climate, the eastern sea of China, respectively. In the oceanic climate, the variations of SL have the high values in the main current of Kuroshio and the variations of 557 have not the remarkable seasonal variations because of the continuos compensation of warm current by Kuroshio. In the continental climate, SL has high variations in the estuaries(the Yellow River, the Yangtze River) with the mixing the fresh water and the saline water in the coasts of continent and 557 has highly the seasonal variations due to the climatic effect of continents. In the steric variations of summer, the eastern sea of Japan, the East China Sea and the western sod of Korea is increased the sea level about 10~20cm. But the Bohai bay in China have relatively the high values about 20~30cm due to the continental climate. generally the trends of SST and SL increased during all periods. That is say, the slopes of 557 and SL Is presented 0.29$^{\circ}C$/year and 0.84cm/year, respectively. The annual and semi-annual amplitudes have a remarkable variations in the western sea of Korea and the eastern sea of Japan. In the case of the annual peaks, there appeared mainly In the western sea of Korea and the eastern sea of .Japan because of the remarkable variations of SL associated with Kuroshio. But in the case of the semi-annual peaks, there appeared in the eastern sea of Japan by the influence of current, and in the western sea of Korea by the influence of seasonal temperature, respectively. From our results, it should be believed that 557 and SL gradually Increase in the East Asian seas concerning to the global warming. So that, it should be requested In the international co-operation against In the change of the abnormal climate.

• Journal of the Korean Society of Marine Environment & Safety
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• v.15 no.4
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• pp.339-344
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• 2009

The joint cruises of six times between Korea and China were carried out for a better understanding of the environmental and oceanographical characteristics of the Yellow Sea for 6 years from 1998 to 2003. Zooplankton samples were collected one time per year at 24 stations on 3 lines of the Yellow Sea. The aim of this study is to understand the seasonal fluctuation of zooplankton community in the Yellow Sea. There is no trend on the spatio-temporal distribution of zooplankton. Copepoda, the major taxon of the Yellow Sea, was high in distribution in the eastern part and Chaetognatha in the western part of the Yellow Sea. In this results, the dominant copepods were Calanus sinicus, Paracalanus parvus s.l., Oithona atlantica, and Corycaeus affinis during the study periods. The density fluctuation of these dominant species may be an important factor in determining the fisheries resource of the Yellow Sea.

• 한국해양학회지
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• v.27 no.4
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• pp.259-267
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• 1992

A survey of CTD casting was taken in April 1991 in the eastern Yellow Sea. The vertical structure of water column consists of the upper mixed warm, the mid cold and the lower warm layers devised clearly by a seasonal thermocline and the temperature inversion. A strongest temperature inversion is found in the southern part of the survey area. Where the low-layer water is $3^{\circ}C$ higher than the mid-layer water. The area of the temperature inversion covers about $100{\;}km{\;}{\times}{\;}100{\;}km$ and it is observed 1.5 month later. The temperature and salinity of the low-layer water shows a core structure in vertical sections and the tongue-like distribution extending from the south to the north, implying that the warm and saline water found in the oceanic front south of the survey area in early spring is advocated to the north over 150 km underneath the Yellow Sea cold water.

• The Korean Journal of Quaternary Research
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• v.16 no.1
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• pp.1-16
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• 2002

A total of 4 muddy sediment samples collected from the Central Yellow Sea were analyzed for chemical composition. The results are compared with the previously published Huanghe, Changjiang and Keum River geochemical data in order to understand provenance and sedimentation of fine-grained mud, and the sediment accumulation rates estimated. The sandy sediment facies is distributed in the eastern area, a patch of fine-grained mud exists in the western central prat, and the sandy mud and clay sedimentary facies shot. north to south zonal distribution in the central region. The content of calcium carbonate ranges from 2.8 to 10.5%, and its distributional trends to be more concentrated on the western muddy sediments near toward the China side rather than on the eastern sandy sediments. The accumulation rates obtained using Pb-210 geochronologies for the muddy sediments in the Central Yellow Sea showed ranges from 0.21 to 0.68 cm/yr or 0.176 to 0.714 g/$\textrm{cm}^2$. yr. The sedimentation rate from core CY96010 located in the eastern near side of Shandong Peninsula which is affected by the Huanghe River shows 0.68 cm/yr or 0.714 g/$\textrm{cm}^2$ . yr. The sediment cores CY96008 and CY96002 in the Central Yellow Sea, the estimated of sediment accumulation rates shows 0.21~0.23cm1yr or 0.176~0.220 9/$\textrm{cm}^2$.Vr respectively, which are much lower than above samples. These indicate that the muddy sediments in central area of the Yellow Sea may have received influence of the sediment discharge from the Huanghe River. The concentrations of Ca, Na, Sr, Ho, La, Tb, Ta and Ca/Ti ratio of the muddy sediments in the Central Yellow Sea are higher than those of the Changjiang sediments and lower than those of the Huanghe sediments. However, these element values showed similar concentration patterns than those of the Huanghe sediment. The element contents such as Fe, Ti, Nl, Co, Cr, Cu, Pb, Sc, Ce, Nd, Sm, Eu, Cd and Dy in the study area are higher than those of the Huanghe sediments and lower than the Changjiang River sediments, but these values showed close to resemblance content trends those of the Changjiang sediment. The concentration of Mn, K and Sr in sediments of the study area are similar to those of the Keum River and eastern Yellow Sea sediment. They are rich in Zn, Rb, Cd, U, Cs and Li than those of the other comparison legions. Therefore, the terrigenous materials sources of the muddy sediment in the Central Yellow Sea comes mainly from Huanghe River in the past and present, and also have party derived from the Changjiang and Keum River, while the biological deposit in this area are carried by the Yellow Sea Warm Current.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.4 no.3_4
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• pp.99-102
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• 1971

The present paper deals with secular analysis of zooplankton biomass in the eastern area of the Yellow Sea during the last seven years from 1963 to 1969. The annual variation of zooplankton biomass in the research area shows increase since October 1965, the lowest point. The increasing shape is a parabola expression, BM= 0.0146 $T^2+0.0448T+38.0436$ (BM, Biomass; T, Time, of which zero point is placed at December 1965).

• 한국해양학회지
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• v.22 no.2
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• pp.63-70
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• 1987

Existing oceanographic data indicate that tidal mixing fronts generally prevail in the Eastern Yellow Sea along the Korean coast. In the Western part, these fronts seem to be much weaker. These fronts are believed to be generated mostly by spatially different tidal mixing. The geostrophic adjustment model applied to the observed density structure gives the mixed coastal water flowing northward and the offshore waters(both surface warm and bottom cold waters) flowing southward along the Korean coast. The transport of each water amounts to O(10$\^$4/)m$\^$3//sec.