• Korean Journal of Plant Resources
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• v.23 no.2
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• pp.179-186
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• 2010

This study was conducted to provide basic information for conservation and restoration through investigation of vegetation and soil condition of Megaleranthis saniculifolia Ohwi, Korean endemic species, in Mt. Halla, Jeju Island. Very few individuals were discontinuously distributed and restricted at 1,075 m above sea level, very steep slope ($60-70^{\circ}C$), rocky area of north face of Eorimok Valley. For investigation of environmental condition, we established two $10\;{\times}\;10\;m$ quadrats in the habitats and one control quadrat. Twenty-four species were found at site 1 under 10-12 m Carpinus laxiflora tree layer (35%) and soil conditions are pH 5.9, moisture content (field capacity) 9.39%, organic carbon 8.22% and organic matter 14.17%, respectively. Site2, 15 taxa were found under 8-12 m Platycarya strobilacea tree layer (40%) and soil conditions are pH 5.07, moisture content 4.99%, organic carbon 5.34% and 9.21 percentage of organic matter. In the control quadrat, 14 taxa were found under 10 m Carpinus laxiflora tree layer (10%) and soil conditions are pH 5.27, moisture content 6.23%, organic carbon 4.74% and organic matter 8.17%, respectively. The principal causes of threat which were investigated in this study are competition among company, very steep slopes, artificial management of valley. For restoration and conservation of habitats, it is needed to suitable plans.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.34 no.5
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• pp.263-270
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• 2021

In this study, a reliability-based design optimization of a 130-m class fixed-type offshore platform, to be installed in the North Sea, was carried out, while considering environmental, material, and manufacturing uncertainties to enhance its structural safety and economic aspects. For the reliability analysis, and reliability-based design optimization of the structural integrity, unity check values (defined as the ratio between working and allowable stress, for axial, bending, and shear stresses), of the members of the offshore platform were considered as constraints. Weight of the supporting jacket structure was minimized to reduce the manufacturing cost of the offshore platform. Statistical characteristics of uncertainties were defined based on observed and measured data references. Reliability analysis and reliability-based design optimization of a jacket-type offshore structure were computationally burdensome due to the large number of members; therefore, we suggested a method for variable screening, based on the importance of their output responses, to reduce the dimension of the problem. Furthermore, a deterministic design optimization was carried out prior to the reliability-based design optimization, to improve overall computational efficiency. Finally, the optimal design obtained was compared with the conventional rule-based offshore platform design in terms of safety and cost.

• Korean Journal of Environment and Ecology
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• v.33 no.1
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• pp.86-106
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• 2019

We investigated the environmental conditions of natural habitats of T. nuda. The species was found on rocky northern hills ($60{\sim}90^{\circ}$) near the stream where the sea level ranges 95~145m. The average annual temperature of the habitats was lower than other places of South Korea. The differences of the lowest and the highest of the year was significantly huge than any other places. Plants were growing at the edge of stream that water reached but not submerged. Most of plants were found in North, Northeast or Northwest. It is suggested that these species require moist and low sunlight for growth. The common vegetation along with the T. nuda includes Mukdenia rossii, Selaginella rossii, Calamagrostis epigeios, and Rhododendron yedoense f. poukhanense. The dominance values and sociability of T. nuda were below 3 in all studied habitats and the variance of the number of individuals among the habitats was very high. As the optimum habitats for the T. nuda are decreasing due to the extreme precipitation patterns. It is also expected that the number of T. nuda will be decreased in the future. Therefore restoration activity in situ or ex situ must be conducted to conserve this valuable plant species.

• Korean Journal of Remote Sensing
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• v.35 no.2
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• pp.327-336
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• 2019

The caldera lake "Chun-ji" is located at the summit of Baekdu volcano, which is in the border of China and North Korea. Chun-ji Lake has altitude 2,189 m above sea level. The Chun-ji is freezing in the winter when the water temperature goes down to zero for a year, and it melts in the season when the water temperature goes up again. However,since it is located at a high altitude, there are many cloudy days, and it is difficult to observe with optical images. For this reason, radar images, which are less influenced by weather than optical images, are more effective for observing the ice of heaven and earth. In this study, 75 TerraSAR-X images from chun-ji area were used for analysis from 2015 to 2017, and the calculated ice area and temperature changes were analyzed. As a result, the ice of the caldera lake formed was formed in early December and slowly melted until mid-April. During this period, temperatures in the Samjiyeon area were about $-10^{\circ}C$ when ice was produced, and the temperature was about $0^{\circ}C$ in mid-April when it was thawing. Correlation coefficients between ice surface area and temperature in winter 2015 and 2016, where global ice is produced,show a high correlation of -0.82 and -0.75. In addition to the results of this study, it can be used as an indicator to monitor the volcanic activity by comparing the result of the recent volcanic activity with the result of the increase in water temperature using various imagery.

• Journal of The Geomorphological Association of Korea
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• v.20 no.4
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• pp.1-13
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• 2013

Padori beach is one of the representative composite mixed beach in Korea and shows divert geomorphic landscape change. It belongs to the Taean National Park. The purpose of this study is to clarify movement mechanism of sediments from sediment distribution of Padori beach associated with morphology. In addition, it is to explain morphological landscape change under different wave and tide condition in the composite mixed beach consisting of a dissipative low tide terrace and a reflective beach face with a high tide range of 5 to 7m. The results of this study are: First, the mean grain size of sediments becomes smaller from the south of the beach, where there is a wide wave-cut platform, to the north because gravels are supplied from the wave-cut platform as well as sea-cliff in the south of the beach. A sedimentation pattern of the sandy gravel on the beach face and gravel on the berm, and gradation phenomena of grain size on cross-shore and alongshore direction in the beach can be explained with a pattern of sediment movement, overpassing, in the composite mixed beach. Second, micro-topography on beach face and berm were changed depending on effects of wave height and tide. As a result, in low-wave energy environments, a berm is developed in large size, and beach cusps are formed on the upper beach face, while in high-wave energy environments, a berm is built up in relatively small size, and mixture of sediments occur on the upper beach face.

• Journal of Korean Society of Forest Science
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• v.111 no.1
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• pp.100-107
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• 2022

Quercus mongolica is an important deciduous tree species in the Republic of Korea; it covers most of the total natural deciduous forest area in the country. In this study, the site characteristics and stand structure of Q. mongolica forests were investigated at sites where Q. mongolica occupied >50% of the total basal area during the 7th National Forest Inventory period (2016-2020). The total number of circular sample plots (400 m²) of Q. mongolica forests was 1,421. These forests were mainly dominant at >800 m above sea level (a.s.l). However, they were also distributed on north-facing slopes at <600 m a.s.l. and gradually on southern slopes with ascending altitudes. Quercus mongolica forests were distributed in silt loam, loam, or sandy loam soils with relatively high fertility. Dominant species distributed with Q. mongolica included Pinus densiflora, Quercus variabilis, Acer pseudosieboldianum, Fraxinus rhynchophylla, and Quercus serrata. Pinus densiflora and Q. variabilis grew in large DBH classes, Q. serrata grew in middle DBH classes, and A. pseudosieboldianum and F. rhynchophylla grew in small DBH classes. The dominant species distributed at the lower layer of Q. mongolica forests were Sasa borealis, Lindera obtusiloba, Rhododendron mucronulatum, Rhododendron schlippenbachii, Q. mongolica, and Fraxinus sieboldiana.

• Journal of the Korean earth science society
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• v.43 no.1
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• pp.23-29
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• 2022

Although tropical cyclones with wind speeds weaker than 17 ms^-1 (weak tropical cyclones: WTCs) can cause significant damage, particularly over the Seoul metropolitan area, only a few studies have focused on WTC activity over South Korea. In this study, we found that WTC activity is likely associated with the Pacific Decadal Oscillation (PDO). During the negative phases of the PDO, landfall frequency of WTCs increased significantly compared to the positive phases at 95% confidence level. When related to the negative phases of the PDO, a positive relative vorticity anomaly is found in the northern sector of the western North Pacific while a negative relative vorticity anomaly and enhanced vertical wind shear prevail in the southern sector of the WNP. These factors are favorable for the northward shift of the genesis location of tropical cyclones on average, thereby reducing the total lifetime of WTCs. Moreover, a high-pressure anomaly over the Japanese islands would shift a tropical cyclone track westward in addition to the landfall location. Consequently, the effects of the topographical friction and the Yellow Sea Bottom Cold Water on a tropical cyclone may increase. These conditions could result in a weaker lifetime maximum intensity and landfall intensity, ultimately resulting in WTCs becoming more frequent over South Korea during the negative phases of the PDO.

• Strategy21
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• s.32
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• pp.192-221
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• 2013

In order to deal with the current economic crisis, the U.S. government, as a part of its austerity fiscal policy, implemented a budget sequester. The sequester will hit the U.S. defense budget the hardest, and as a result will most likely put the security of the international community in jeopardy. The U.S. will have to cut 46 billion dollars from its original 525 billon defense spending in 2013. And by the year 2022, will have to cut 486.9 billion dollars. Such an astronomical decrease in the U.S. defense spending will inevitably burden the friendly nations. According to recent studies, pirate related incidents in Somalia, where piracy is most active, has declined from its 226 incidents to 76 incidents per year in 2012, a 66% drop from previous years'. However, piracy threats as well as those related to firearms still remain and thus participants of anti-piracy operations, namely the U.S., U.K., France, Canada, NCC, EUNAVFOR, and NATO, are facing a problem of declining forces. Considering the current situation as well as rising expectations from the international community, Republic of Korea, a supporter of NCC's maritime security operation, not to mention its foremost duty of securing its sea, is at a stage to re-examine its operational picture. Such action will be a good opportunity for Republic of Korea to build the trust and live up to the international community's expectation. To quote from the network theory, although in relation to other friendly nations participating in the anti-piracy operation, Republic of Korea currently remains at a single cell level, this opportunity will certainly develop Korea to a 'node' nation in which power and information would flow into. Through this expansion of operational capability, Republic of Korea will be able to exert more influence as a more developed nation. Currently however, not only is the single 4,500 ton class destroyer deployed in Somalia a limited unit to further expand the scale and amount of force projection in the area, but also the total of six 4,500 ton class destroyers ROK feet possess is at a high fatigue degree due to standard patrolling operations, midshipman cruise and the RIMPAC exercise. ROK fleet therefore must consider expanding the number of ships deployed along with either deploying combat support ships or constructing logistics support site in the African region. Thus, by expanding its operational capabilities and furthermore by abiding to the rightful responsibilities of a middle power nation, Republic of Korea will surely earn its respect among the members of the international community.

• Analyses & Alternatives
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• v.1 no.2
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• pp.31-43
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• 2017

The article is devoted to the theoretical and practical analysis of Chinese global leadership. The concept of leadership is applied as a methodology, which involves identifying the main factors, such as strategic power, the attractiveness of political institutions, the ability to provide acceptable ideas and the presence of allies that contribute to a comprehensive analysis of the country's leadership potential. The authors also describe the relevance of Chinese global leadership and analyze its domestic, economic and international causes. Moreover, the ''Belt and Road'' initiative is defined as the main mechanism for providing the influence of China on the global level which is now being changed its quantitative component, namely the increasing attention to the security aspects of this initiative. In addition to that, it is important to note that China maintains its economic and political positions in Africa, Central Asia and South-East Asia. Africa has a special role in the Chinese ''Belt and Road'' initiative as a recipient of Chinese investments and a site for the deployment of China's naval facilities to protect the trade routes. On the regional level, China will strive to become a leader of the trade and economic processes in the Asia-Pacific region, the South China Sea and the North Korea nuclear program issues. The American factor in modern international relations, namely so-called "Trump factor", which means the U.S. withdrawal from the Trans-Pacific Partnership and the Paris Agreement, will cause demand for Chinese leadership in the Asia-Pacific region and in the world as well. However, in this case a number of questions arise: is China prepared for this? Is Beijing able to bear greater responsibility? Does China have the potential for this? The article concludes that China will not become global leaders in the next 20-30 years, because of internal (political reforms) and foreign policy reasons (doctrinal formulation of foreign policy initiatives, military-political and economic power, international posture and relations with other states). The authors believe that the implementation of Chinese leadership is possible not on the condition of confrontation between China and the United States, but on the establishing of constructive relations between these countries. The last meeting between Trump and Xi Jinping showed a trend for creating channels for dialogue between Beijing and Washington, which can become the basis for interaction. An important place in the work is given to the analysis of development and forecasting the evolution of Russian-Chinese and U.S.-China relations. As for Russia, Moscow should conduct a policy that will not allow it to become a ''junior partner'' of China.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.11 no.2
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• pp.37-48
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• 2006

HF radar-derived current data obtained in 2002 and 2004 are analyzed to examine the effects of the completion of the Saemangeum 4th tidal dyke in June 2003, connecting Gogunsan-Gundo and Bieung-Do, on the coastal surface $M_2$ current pattern. Comparison between the currents by HF radar and current meter mooring showed good agreements. Counterclockwise rotation of the $M_2$ current in the observed area did not change with the dyke construction. Strong westward ebb jet from the gap of the dyke was observed in 2002 but disappeared in 2004. The complete closing of the dyke gap caused the current speed increase around the mouth of the Kem River estuary, decrease around Gogunsan-Gundo and the dyke, the changes in the direction of maximum current to north-ward from eastward and the delay of the maximum flood current occurrence around Gogunsan-Gundo and the dyke. Around Yeon-Do, the maximum flood current directed more clockwise and occurred rather earlier. These changes of the $M_2$ current ellipse characteristics imply that the effects of the dyke construction reached the area connecting Mal-Do and Yeun-Do.