• Journal of the korean society of oceanography
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• v.39 no.1
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• pp.72-95
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• 2004

The Yellow Sea is characterized by relatively shallow water depth, varying range of tidal action and very complex coastal geometry such as islands, bays, peninsulas, tidal flats, shoals etc. The dynamic system is controlled by tides, regional winds, river discharge, and interaction with the Kuroshio. The circulation, water mass properties and their variability in the Yellow Sea are very complicated and still far from clear understanding. In this study, an effort to improve our understanding the dynamic feature of the Yellow Sea system was conducted using numerical simulation with the ROMS model, applying climatologic forcing such as winds, heat flux and fresh water precipitation. The inter-annual variability of general circulation and thermohaline structure throughout the year has been obtained, which has been compared with observational data sets. The simulated horizontal distribution and vertical cross-sectional structures of temperature and salinity show a good agreement with the observational data indicating significantly the water masses such as Yellow Sea Warm Water, Yellow Sea Bottom Cold Water, Changjiang River Diluted Water and other sporadically observed coastal waters around the Yellow Sea. The tidal effects on circulation and dynamic features such as coastal tidal fronts and coastal mixing are predominant in the Yellow Sea. Hence the tidal effects on those dynamic features are dealt in the accompanying paper (Kim et at., 2004). The ROMS model adopts curvilinear grid with horizontal resolution of 35 km and 20 vertical grid spacing confirming to relatively realistic bottom topography. The model was initialized with the LEVITUS climatologic data and forced by the monthly mean air-sea fluxes of momentum, heat and fresh water derived from COADS. On the open boundaries, climatological temperature and salinity are nudged every 20 days for data assimilation to stabilize the modeling implementation. This study demonstrates a Yellow Sea version of Atlantic Basin experiment conducted by Haidvogel et al. (2000) experiment that the ROMS simulates the dynamic variability of temperature, salinity, and velocity fields in the ocean. However the present study has been improved to deal with the large river system, open boundary nudging process and further with combination of the tidal forcing that is a significant feature in the Yellow Sea.

• Korean Journal of Environmental Biology
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• v.37 no.3
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• pp.389-395
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• 2019

In this study, we aimed to assess the toxicity of biocide present in antifouling paint on embryos of sea urchin, Mesocentrotus nudus. Three types of biocide (Sea-nine 211, Diuron, and Irgarol 1051) were selected for the exposure experiment. The EC₅₀ of Sea-nine, Diuron, and Irgarol on the fertilization rate of sea urchin were 32.8 ㎍ L^-1, 7,975 ㎍ L^-1 and 6,995 ㎍ L^-1, respectively. The EC₅₀ of Sea-nine, Diuron, and Irgarol on the development rate of sea urchin were 31.6 ㎍ L^-1, 3,044 ㎍ L^-1, and 2,267 ㎍ L^-1, respectively. The highest toxicity was observed in the presence of Sea-nine.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.40 no.2
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• pp.102-107
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• 2007

A remarkable sea surface cooling (SSC) event was observed in the eastern sea of Korean peninsula based on new generation sea surface temperature (NGSST) satellite images in September 2005, when typhoon Nabi passed over the East Sea. The degree of SSC ranged from $1^{\circ}C\;to\;4^{\circ}C$, and its maximum was observed in the southeastern sea area. Daily variations in sea surface temperature at a longitudinal line $(35^{\circ}-41^{\circ}N,\;132^{\circ}E)$, derived from satellite data for September 1-13, 2005, showed that the SSC lasted about 3 days after the typhoon passed in the south of $39^{\circ}N$, whereas it was unclear in the north of$39^{\circ}N$. Water temperature measured by a mooring buoy suggested that the SSC was caused mainly by a vertical mixing of the water column driven by the typhoon, rather than by coastal upwelling.

• Ocean and Polar Research
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• v.30 no.3
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• pp.277-287
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• 2008

We collected information on seasonal and interannual variability of surface chlorophyll a concentration between 1997-2007 from the Northwest Pacific Ocean. Satellite data were used to acquire chlorophyll a and sea surface temperature from six regions: East Sea/Ulleung Basin, East China Sea, Philippin Sea, Warm Pool region, Warm Pool North region, and Warm Pool East region. Mixed layer depth (MLD) was calculated from temperature profiles of ARGO floats data in four of the six regions during 2002-2007. In the East Sea/Ulleung Basin, seasonal variability of chlorophyll a concentration was attributed to seasonal change of MLD, while there was no significant relationship between chlorophyll a concentration and MLD in the Warm Pool region. Interannual anomaly in sea surface temperature were similar among the East Sea, East China Sea, Philippin Sea, and Warm Pool North region. The anomaly pattern was reversed in the Warm Pool East region. However, the anomaly pattern in the Warm Pool region was intermediate of the two patterns. In relation to chlorophyll a, there was a reversed interannual anomaly pattern between Warm Pool North and Warm Pool East, while the anomaly pattern in the Warm Pool region was similar to that of Warm Pool North except for the El $Ni\tilde{n}o$ years (1997/1998, 2002/2003, 2006/2007). However, there was no distinct relationship among other seas. Interestingly, in the Warm Pool and Warm Pool East regions, sea surface temperature showed a pronounced inverse pattern with chlorophyll a. This indicates a strong interrelationship among sea surface temperature-MLD-chlorophyll a in the regions. In the Warm Pool and Warm Pool East, zonal distribution of chlorophyll a concentration within the past 10 years has shown a good relationship with sea surface temperature which reflects ENSO variability.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.47 no.3
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• pp.255-263
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• 2014

We investigated the reproductive characteristics of Lycodes tanakae in the coastal waters of the middle East Sea to elucidate the species' population structure. We investigated Lycodes tanakae maturation and spawning based on samples collected by Danish seine and gill nets from January 2012 to December 2013. We analyzed monthly changes in maturity stage, gonadosomatic index (GSI), egg diameter, fecundity, and total length at 50% group maturity. The spawning period was December to February, while fecundity ranged from 1,677 eggs at 57.3 cm (total length;TL) to 6,445 eggs at 75.7 cm. The relationship between TL and fecundity (F) was $F_e=6E-05TL^{3.127}$ ($R^2$ = 0.516), and F increased with increasing TL. We estimated the TL at 50% group maturity as 60.4 cm for females and 59.8 cm for males. This study is the first report of Lycodes tanakae reproductive characteristics in the coastal waters of the middle East Sea.

• Strategy21
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• s.42
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• pp.154-195
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• 2017

This paper is to analyse conflict between the US and China over the South China Sea and Korea's responses. To this end the paper is composed of 6 chapters titled instruction; the current status of South China Sea sovereignty disputes; changes in US and Chinese maritime security strategies and the strategic values of the South China Sea; key issues and future prospects for US-China conflicts in the South China Sea; South Korea's security and diplomatic responses; and conclusion. The recent East Asian maritime security issue has evolved into a global issue of supremacy between the US and China, beyond conflicts over territorial disputes and demarcation among the countries in the region. China is pursuing offensive ocean policy to expand economic growth. The core of the maritime order that the United States intends to pursue is the freedom of navigation in the oceans and the maintenance of maritime access. China is making artificial islands in the South China Sea, claiming the sovereignty of these islands, building strategic bases in East Asia, and securing routes. The United States has developed several "Freedom of Navigation Operations" to neutralize the declaration of the territorial sea surrounding Chinese artificial islands. We can not be free from marine conflicts in the South China Sea and the East China Sea. Regarding the South China Sea dispute, it is expected that the strategic competition and conflict between the two countries will intensify due to China's failure to make concessions of core interests and adherence to the US compliance with international norms. In the midst of conflict over the South China Sea, we need a harmonious balance between our alliance security and economic diplomacy. We must continue our efforts to strengthen the ROK-US alliance but not to make China an enemy. Considering the significant impacts of the oceans on the survival and prosperity of the nation, we must continue to develop our interest in the oceans, appropriate investments and tactical strategies.

• Journal of the Korean Society of Marine Environment & Safety
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• v.22 no.1
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• pp.145-151
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• 2016

Temperature variability at the upper layer related to climate regime shifts in the Korean waters was illustrated using water temperature, climate index. Three major climate regime shifts (CRS) in 1976, 1988 and 1998 in north Pacific region had an significant influence on the major marine ecosystems structure pattern. Three marginal seas around Korean peninsula; East Sea, East China Sea and Yellow Sea also got important impact from this kind of decadal shift. We used 10m sea water temperatures in four regions of Korean waters since 1950 to detect major fluctuation patterns both seasonally and also decadal shift. 1988 CRS was occurred in all of the study areas in most seasons however, 1998 CRS was only detected in the Yellow Sea and in the southern part of the East Sea. 1976 CRS was detected in all of the study area mainly in winter. After 1998 CRS, the water temperature in the southern part of the East Sea, East China Sea and Yellow Sea were going into decreased pattern; however, in the northern part of the East Sea, it was further shifted to increasing pattern which was started from 1988 CRS period.

• Journal of the Korean earth science society
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• v.26 no.6
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• pp.541-550
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• 2005

Molluscan shells were sampled from the continental shelf of South Sea: 19 stations in the southeast continental shelf and 5 in the southwest sea, in order to understand characteristics of sea level changes and time-averaging since the last glacial age. Radiocarbon dates were made on 42 dominant and specific species which were sampled from 24 stations. Time-averaging was observed and showed to be 11,939 years in age difference. The sea-level ranged from 150 to 160 m below sea level during the LGM (about 15,000 yrs B.P). The sea-level significantly rose to 60 m at around 9,000 yrs B.P. and became stable at 50 to 60 m between periods between 4,000 and 5,000 yrs B.P. Between 3,000 and 4,000 yrs B.P, the sea-level rapidly rose to a depth of $10\~20m$ below today’s present sea level.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.44 no.5
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• pp.516-523
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• 2011

To compare four populations of sea squirt Halocynthia roretzi adults, their egg quality and larval development were investigated in the hatchery. The populations were: south sea wild (SSW), south sea cultured (SSC), east sea wild (ESW) and Iwate Japan cultured (IJC). Egg quality and larval development were compared using 13 factors (fertilization rate and diameter, proximate composition, amino acid and fatty acid contents of eggs, hatching rate and various sizes of tadpole larvae) which were obtained from each population. Fertilized egg diameter, hatching rate and size of tadpole larvae were significantly different among the four populations (P<0.05). Eggs were produced with higher crude protein ($5.20{\pm}0.00%$ SSW, $4.71{\pm}0.01%$ ESW, $4.66{\pm}0.01%$ SSC and $3.96{\pm}0.01%$ IJC) and lipid ($1.22{\pm}0.01%$ ESW, $1.01{\pm}0.00%$ SSW, $0.77{\pm}0.01%$ SSC and $0.69{\pm}0.00%$ IJC,) contents from domestic wild populations than from Japanese or cultured populations. Also amino acid and fatty acid contents were different. The extent of similarity between domestic and Japanese populations (30.5% IJC:SSW, 34.3% IJC:SSC and 40.7% IJC:ESW) was relatively low but was very high between SSW and SSC (73.9%). These results may have been due to differences in the abundance of food types and environmental conditions in the four localities and consequent differences in the diets of the sea squirts.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.18 no.4
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• pp.374-380
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• 1985

The annual variations of sea surface temperature (SST), air temperature (AT), and sea-air temperature separation (SST-AT) in the East Sea (Japan Sea) are studied by harmonic analysis of the monthly data in 2 by 2 degree rectangles. In the Tsushima Current region of the Japan Sea, the annual means of SST and AT are high due to warm water advection by the current, and the annual amplitudes of SST and AT are small because the annual variations of heat advection the the current and of the incoming solar radiation are almost out of phase each other. In summer the SST and the AT in the Japan Sea are almost the same, but in winter the SST is $6{\sim}10^{\circ}C$ higher than the AT. The physical processes responsible for the observed SST-AT in the Japan Sea and their consequences in the sea-air thermal interactions are discussed in this paper.