• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.62.1-62.1
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• 2011

The wind can be stronger and steadier further from shore, but water depth is also deeper. Then bottom-mounted towers are not feasible, and floating turbines are more competitive. There are additional motions in an offshore floating wind turbine, which results in a more complex aerodynamics operating environment for the turbine rotor. Many aerodynamic analysis methods rely on blade element momentum theory to investigate aerodynamic load, which are not valid in vortex ring state that occurs in floating wind turbine operations. So, vortex lattice method, which is more physical, was used in this analysis. Floating platform's prescribed positions were calculated in the time domain by using floating system RAO and waves that are simulated using JONSWAP spectrum. The average value of in-plane aerodynamic force increase, but the value of out-of-plane force decrease. The maximum variation aerodynamic force abruptly increases in severe sea state. Especially, as the pitch motion of the barge platform is large, this motion should be avoided to decrease the aerodynamic load variation.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.5 no.4
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• pp.357-362
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• 2000

Stable isotope ratios of oxygen and hydrogen were investigated in southern Yellow Sea in August 1997. Salinity showed good positive correlation with ${\delta}^{18}$O and ${\delta}$. The correlation between ${\delta}^{18}$O and ${\delta}$D is good. From the relationship between these parameters, we obtained two lines of conclusion: 1) seawater of study area I in summer is a mixture of Changjiang Water and modified Kuroshio Water; 2) stable isotopes are very useful tracers in studying property and behavior of water masses in the study area. In case when water masses can not be easily distinguished by T-S analysis, the stable isotopes seem to be powerful tools for this purpose.

• Strategy21
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• s.30
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• pp.286-311
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• 2012

한국은 세계 유일의 분단국가로서 대륙으로는 북한과 대치 중에 있으며, 해양으로는 세계 강대국인 중국, 일본, 러시아 등에 의해서 둘러 쌓여 있다. 이러한 안보환경에서 최근 북한은 김정은 후계세습을 위해 천안함 피격사건과 연평도 포격도발 사건을 감행하였으며, 이러한 북한의 도발위협은 김정일 사후 지속되고 있다. 그러나 한국은 북한이라는 현존 위협에 대비함과 동시에 주변국으로 상정할 수 있는 잠재적 위협에도 대비해야 한다. 특히 잠재적 위협의 경우 해상에서 한국과 국가이익이 상충되고 있으며, 이들 모두 한국보다 강한 해군력을 보유하고 있을 뿐만 아니라 최근 들어 해군력을 강화하고 있다. 따라서 최근의 안보정세는 한국해군이 향후 어떠한 해양전략을 추구해야 하는지에 대한 재정립을 요구하고 있다고 할 수 있다. 본 논문은 한국의 잠재적 위협인 러시아와 일본 간에 발생한 러일전쟁을 통해 미래 위협에 대비한 최정예해군(Post modern navy)으로 도약하기 위한 한국해군의 발전방향을 도출하고, 이를 달성하기 위한 4가지 핵심개념을 제시하였다. 구체적으로 이는 최정예해군으로서 해양통제와 거부를 균형적으로 갖추고, 원정작전 수행능력을 보유하며, 해양경찰과 결속력이 있는 유대관계를 형성 및 북한의 비대칭전력에 대한 대응능력을 갖춘 해군이라고 설명할 수 있다. 결국 한국해군은 대륙세력인 북한의 위협에 대비하고 동시에 미래 잠재적 위협에 대비함과 동시에 해양에서의 국가이익을 보호해야 한다고 할 수 있다. 한국은 해양국가이다. 한국은 결코 바다를 포기할 수 없으며, 한국해군이 추구하는 해양전략은 국가의 운명을 결정짓는다고 해도 과언이 아닐 것이다. 이러한 측면에서 본 논문은 향후 한국해군이 어떠한 해양전략을 추구해야 하는지에 대해 하나의 방향을 제시하고 있다.

• The KIPS Transactions:PartD
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• v.8D no.1
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• pp.1-9
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• 2001

The SQL CLl (Call Level Interface) is a database application programming interface (API) that fits the client-server environment, and its de facto standards such as ODBC and JDBC are widely employed in various applications. The current SQL CLl standards, however, do not specify enough features for efficient retrieval of large objects (LOBs) that constitute the multimedia data. In this paper, we propose the LOB caching through the SQL CLl and describe the extension of the SQL eLl to achieve such a goal. We implement our proposal by extending the SQL CLl library for BADA - II DBMS developed at ETRI, and evaluate the performance of LOB retrieval through the cache compared to that of LOB retrieval conducted solely with the functions specified in the current SQL CLl standards.

• The Journal of Fisheries Business Administration
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• v.43 no.3
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• pp.1-22
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• 2012

This study is to survey the Japanese investigations for Korean sea during Meiji period. Meiji government was eager to develop new fishing ground to provide the marine products to their people, to offer the job for their people and to accumulate the starting capital. They found that the Korean sea was abundant in shark, sea cucumber and ear shell. These products were valuable for Chinese foods. From 1870's, Japan Navy investigated Korean sea for military purpose and subsequently for fishery. The first investigation for Korean maritime products was The Circumstances for Catching Fish in Korean Sea by Sekizawa Akikiyo in 1893. He was the most famous specialist in fishery and insisted that Japanese fishermen must go to Korean sea and catch fishes. Meiji government accepted his opinion and pushed the policy sending fishermen to Korean sea. Meiji government enlarged the investigations and backed up the activities of fisherman and the organization for fishery in Korean sea. Especially, the investigations by The Association for Korean Sea Fishery were repeated and detailed(1897~1900). The Association intervened the conflicts between Korean and Japanese fishermen. At the same time, The Association investigated the attitudes of Korean people to Japanese. The Guidelines for Fishery in Korean Sea by Kuzuu Syuzo was also very detail, especially in the kinds of fishes in Korean sea. These investigations were supported by Meiji government or organizations helped by government.

• Spatial Information Research
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• v.11 no.4
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• pp.371-389
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• 2003

This study aims at defining the concept of a cyber-geospace and proposing how to establish a cyber-geospace fir the entire country in detail. The study defined the cyber-geospace as 'the dynamic second territory of Korea not only to manage the land systematicality and deal with administrative services for the people in aspect of public sector, but also to contain economic activities of corporations and the citizen's everyday lives in aspect of private sector, in a 3D virtual reality made by digitizing various facilities and buildings as well as the entire toterritory including ground, underground and even sea'. In order to establish such a cyber-geospace, the project should be pursued on the national level fir around ten-year period.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.5
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• pp.13-18
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• 1993

The purpose of this study is to analyze the seismic effects of Lead Rubber Bearing base isolators on bridges. Base isolation is the tool to minimize the effect of earthquake before the seismic force is transfered to the structure. Currently, many structures including the buildings, power plants, and bridges, were built and planned with base isolation method. The simple model is developed for bridges with Lead Rubber Bearings. Equations of motion are solved by Newmark ${\beta}$ method. Springs representing the base isolators are assumed as bilinear springs and piers are modeled as nonlinear springs implementing Q-HYST model. Analysis is performed for the selected bridge. El Centro (N-S) earthquake(1940) is used. Deck displacement, pier ductility and pier shear force are calculated for the various Lead Rubber Bearings.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.1 no.1
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• pp.32-45
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• 1996

Analyses of surface sediment textures and recent benthic foraminifera were carried out to understand the change of sedimentary depositional processes in the eastern part of Kwangyang Bay. Echo-sounding images revealed that topographic change of the delta front sheet sand was caused by POSCO (Pohang Steel Company)'s dredging and reclaiming. The sand body prograded toward southeast. Fine sediments are distributed in the northeastern part of the study area. Identification of benthic foraminifera was conducted for the two selected cores from the sand body for the first time. Dominant species are Ammonia beccarii, Elphidium excavatum and Quinqueloculina lamarckiana. No abrupt change of benthic foraminiferal assemblage was observed from the sedimentary sequences.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.1 no.1
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• pp.13-19
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• 1996

Toxicity of surface seawater in Ulsan Bay on a sea urchin, Hemicentrotus pulcherrimus was assessed to investigate the correlation between the concentrations of five heavy metals (Fe, Co, Cu, Cd, and Ni) and the impairments during the developmental stage of the sea urchin eggs. The tests during the six developmental stages of the eggs, are fertilization rate, cell 4, cell 4, polyspermic cleavage, permanent blastula and exogastrula. Highly positive correlations were found between the concentrations of Cu, Co and Ni and the toxicities on the eggs. Such tests will be useful as an indicator of seawater quality.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.11
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• pp.2397-2404
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• 2012

Underwater acoustic communication has multipath error because of reflection by sea-level and sea-bottom. The multipath of underwater channel causes signal distortion and error floor. In order to improve the performance, it is necessary to employ an iterative coding scheme. Among the iterative coding scheme, turbo codes and LDPC codes are dominant channel coding schemes in recent. This paper concluded that turbo coding scheme is optimal for underwater communications system in aspect to performance, coded word length, and equalizer combining. Also, decision directed phase recovery was used for correcting phase offset induced by multipath. Based on these algorithms, we confirmed the performance in the environment of oceanic experimentation.