• Journal of Korean Society of Coastal and Ocean Engineers
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• v.9 no.2
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• pp.63-73
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• 1997

The tidal propagation for the Southeast Asian Seas is described via a high-resolution, two-dimensional hydrodynamic model by the equilibrium tide and co-oscillating tide at the Straits. Computed tidal distributions of four major semidiurnal tides (M$_2$, S$_2$, $K_2$, $N_2$) and four major diurnal tides (K$_1$, $O_1$, P$_1$, Q$_1$) are presented and results are also compared with coastal observations archived in IHO global tidal data base (Canadian Marine Environmental Data Service) and existing tidal charts including Schwiderski GOTD(Global Ocean Tidal Data) maps.

• Journal of the Korean Society for Marine Environment & Energy
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• v.12 no.4
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• pp.296-301
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• 2009

The ENCs, which is a database for the use of maritime navigation within the ECDIS on the ships are recently being utilized in wide marine applications. But, even though official ENCs have been produced according to the IHO S-57 and S-52 standards, current ENCs are limited to their static characteristics of contents and structures being inherited from the analog media style of the traditional paper charts. Thus these limitations are often recognized as barriers to the full use of high resolution and advanced digital technologies. This paper presents prototype development results which demonstrate dynamic ENC features using high density ENCs and simulated tidal information to support various marine GIS fields as well as efficient and safe navigation purpose.

• Journal of Environmental Science International
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• v.13 no.5
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• pp.479-488
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• 2004

Five sediment cores from the tidal flat of artificial Lake Shihwa are analyzed in terms of sedimentology and geochemistry to evaluate the heavy metal contamination and redox condition of surficial sediment following the Shihwa seawall construction. The variability of concentrations of various elements depends on the depositional environment, and reflects the various redox conditions and sediment provenances. The amounts of Ti and Al and their ratio of Ti/ Al with respect to Li clearly indicate that there is an anthropogenic contribution to the surficial sediment. The high concentrations of heavy metals suggest an anthropogenic contribution at ST. 34 and ST. 22. Concentrations of most elements (Cr, Cu, Zn and Pb) are higher near the Shihwa-Banwol industrial complex than in the central part of Lake Shihwa. Concentrations of heavy metal in surficial sediment near the Shihwa-Banwol industrial complex are two to eight times higher than in the center of Lake Shihwa. Enrichment factors (EF), which are normalized by the unpolluted shale, suggests a significant metallic contamination near the Shihwa-Banwol industrial complex (SBIC). The redox condition is divided into two anoxic and mixed oxi $c_oxic zones based on the carbon:sulfur (C/S) ratios of organic matter and elemental relationships. Correlations among geochemical elements Mn, U and Mo are significantly different from site to site, and may therefore be an indicator of the spatial redox condition. Controlling factors for switching anoxic/oxic conditions are thought to be water depth and the differences in industrial effluent supply. The variations of the Cu/Mn ratio in the sediments confirms above mentioned spatial differences of a redox condition in part, and therefore shows a location-dependence redox condition in sediments at four other sites. The redox condition of the surficial sediment characteristics of the Shihwa Lake are controlled by its geographic location and water depth.th.

• Journal of the Society of Naval Architects of Korea
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• v.43 no.3 s.147
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• pp.351-361
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• 2006

The fatigue strength analysis of VLFS is carried out by using a 3-dimensional plate finite element model with a zooming technology which performs the modeling of wide portions of the structure by a coarse mesh but the concerned parts by a very fine mesh of t by t level. And a stepwise substructure modeling technique for global loading conditions is applied which uses the motion response of the global structure from 2-D plate hydroelastic analysis as the enforcing nodal displacements of the concern 3-D structural zooming model. Seven incident wave angles and whole ranges of frequency domains of wave spectrum are considered. In order to consider the effect of breakwater, the modified JONSWAP wave spectrum is used. Applying the wave data of installation region, the longterm spectrum analysis is done based on stochastic process and the fatigue life of the structure is estimated. Finally some design considerations from the view point of fatigue strength analysis of VLFS are discussed.

• Ocean and Polar Research
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• v.32 no.1
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• pp.85-95
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• 2010

There is increasing consensus that global warming is seriously affecting the Arctic region. Sea Ice decreases and sea level rise have led to environmental change in Arctic Ecosystems, while also making the Arctic sea route more accessible to humans. There are complicated international governance dynamics in play, in addition to commercial and scientific interests in the Arctic region. This provides a unique opportunity for Korea to lead the future direction of Arctic policy in response to the global issues such as climate change and economic or scientific interests. Korea acquired Ad-hoc Observer status of the Arctic Council(AC) in 2008, which is the only pan-Arctic intergovernmental organization. It consists of six working groups: ACAP, AMAP, CAFF, PAME, EPPR, SDWG that implement research, survey, and monitoring. AC's Observer country has the opportunity to participate in a diverse range of activities such technical and expertise support, research and monitoring, financial support and conference organization. In order for Korea to expand its activities in the Arctic region, we suggest the following approach: First, Korea should become more actively engaged with the Arctic Council and its activities; Second, Korea should construct organized collaborative networks of national experts to respond to Arctic issues; Third, Korea should develop collaborations with Arctic states; Finally, Korea should intensify its research on international relations and international laws related to the Arctic region.

• Bulletin of the Korean Chemical Society
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• v.35 no.8
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• pp.2335-2341
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• 2014

Chemical investigation on the methanol extract of the starfish Ctenodiscus crispatus resulted in the isolation of five steroids, (22E,$24{\zeta}$)-26,27-bisnor-24-methyl-$5{\alpha}$-cholest-22-en-$3{\beta}$,5,$6{\beta}$,$15{\alpha}$,25-pentol 25-O-sulfate (1), (22E,24R,25R)-24-methyl-$5{\alpha}$-cholest-22-en-$3{\beta}$,5,$6{\beta}$,$15{\alpha}$,25,26-hexol 26-O-sulfate (2), (28R)-24-ethyl-$5{\alpha}$-cholesta-$3{\beta}$,5,$6{\beta}$,8,$15{\alpha}$,28,29-heptaol-24-sulfate (3), (25S)-$5{\alpha}$-cholestane-$3{\beta}$,5,$6{\beta}$,$15{\alpha}$,$16{\beta}$,26-hexaol (4), and ${\Delta}7$-sitosterol (5). Their structures were identified by extensive spectroscopic analyses, including 1D, 2D NMR and MS and chemical methods. Compound 4 showed cytotoxicity against human hepatoma HepG2 and glioblastoma U87MG cells via inhibition of cell growth and induction of apoptosis. Induction of apoptosis by 4 was demonstrated by cell death, DNA fragmentation, increased Bax/Bcl-2 protein ratio and the activation of caspase-3, caspase-9 and poly (ADP-ribose) polymerase (PARP).

• Journal of the Society of Naval Architects of Korea
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• v.47 no.1
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• pp.20-29
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• 2010

The complicated flow characteristics of upper propeller wake influenced by hull wake are investigated in detail in the present study. A two-frame PIV (particle image velocimetry) technique was employed to visualize the upper propeller wake region. As the upper hull wake affects strongly propeller inflow, upper propeller wake shows much unstable vortical behavior, especially in the tip vortices. Velocity field measurements were conducted in a cavitation tunnel with a simulated hull wake. Generally, the hull wake generated by the hull of a marine ship may cause different loading distributions on the propeller blade in both upper and lower propeller planes. The unstable upper propeller wake caused by the ship's hull is expressed in terms of turbulent kinetic energy (TKE) and is identified by using the proper orthogonal decomposition (POD) method to characterize the coherent flow structure in it. Instabilities appeared in the eigen functions higher than the second one, giving unsteadiness to the downstream flow characteristics. The first eigen mode would be useful to find out the tip vortex positions immersed in the unstable downstream region.

• Ocean and Polar Research
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• v.31 no.4
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• pp.327-338
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• 2009

Zooplankton community structure was investigated in the Saemangeum region in March, May, July and October of 2007 and 2008 in order to understand the potential effect of post construction of Saemangeum dyke on their temporal and spatial distribution. Mean abundance of zooplankton in the inner and outer area of the dyke, except for dinoflagellate Noctiluca scintillans, ranged from 173 to 15,830 ind.m$^{-3}$, showing higher variability in the inner area compared to the outer area. Zooplankton abundance was higher in the outer area than the inner area in 2007, and vice versa in 2008. In the inner area of the dyke, zooplankton abundance was the highest in May 2007 and March 2008. In the outer area of the dyke, abundance was the highest in October 2007 and July 2008. Brackish species such as Tortanus derjugini and Pseudodiaptomus inopinus were dominant prior to construction of the dyke, and appeared less frequently in the inner area. Marine zooplankton taxa such as juvenile hydromedusa, and calanoid copepods Acartiahongi and Paracalanus parvus s.l. dominated both areas of the dyke. In CCA analysis, zooplankton community structure in the inner and outer area was similar in March and May, but different in July and October. Temperature, salinity and COD were important environmental factors affecting zooplankton community structure. These results suggest that zooplankton community structure in the inner and outer area of Saemangeum dyke are significantly affected by whether the sluice gates are closed or open.

• Ocean and Polar Research
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• v.28 no.3
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• pp.273-285
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• 2006

As the political arguments on international power concept has gradually been deepened, the role of international regimes, defined as principles, norms, rules, and decision-making procedures around which nation-actors' expectations converge in a given issue-area, has also been reinforced. There are many ways of understanding about international regimes. In terms of realistic theories, international regimes are one of methods of maintaining hegemonic power order of hegemonic nation and in terms of liberalistic theories, international regimes are understood as the products of mutual inter-dependence of nations in changing international society. As a matter of fact, if we take structural causes and regime consequences into severe consideration, we can find not a few characteristics of international regimes, such as security regime, world trade and fiance regime, ocean regime, environmental regime, human right regime, etc. This paper will examine the changing concept of power after World War II in three categories of hard power (military power), meta power (regime creating power), and soft power (advanced in cultural, diplomatical, and technological power). This paper will provide the evidence of why the changing power concepts will be strongly related with the emergence of international regimes. The UN convention on the law of the sea will chosen as a standard case of the ocean regime and it's regime structure and role will also be analysed in both realistic :md liberalistic theories. Futhermore, the nations' interests involved in the UN convention on the law of the sea will be analytically classified and finally a future prospectus of the UN convention on the law of the sea as an ocean regime will be tested.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.39 no.spc1
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• pp.214-222
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• 2006

Dominant species of macrobenthos were analyzed based on differentiation of three distinct methods: the density based method, the biomass based method and LeBris method, by considering the frequency of occurrence using quantitative data collected over 5 years (1993-1998) at 21 stations in Chonsu Bay. Sedimentary environments as well as species composition and diversity showed the spatial and temporal distribution patterns. The ranks of dominant species as determined by the density based method were more similar to the results by the LeBris method than to those from the biomass based method. Considering the temporal variation, LeBris method were more efficient than any other methods for the determination of dominant species in Chonsu Bay. Lumbrineris longifolia, Theora fragilis, and Moerella jedoensis were recognized by all three methods. A one-way analysis of variance indicated spatial distributions patterns among most of the dominant species. These species showed positive correlations to sedimentary parameters such as mean grain size. However, T. fragilis and Paraprinospio pinnata showed the temporal patterns in their distribution, and were also correlated to the benthic environment, organic content and dissolved oxygen. Some dominant species, e.g., T. fragilis, S. scutata, G. gurjanovae proved to be useful benthic indicators based on the environmental variations determinated by long-term benthic ecological monitoring in Chonsu Bay.