• Title/Summary/Keyword: global circulation

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Sediment Particulate Motions Over a Ripple Under Different Wave Amplitude Conditions (파랑에 의한 해저 사련 위에서의 유사입자의 거동 특성)

  • Chang, Yeon S.;Ahn, Kyungmo;Hwang, Jin H.;Park, Young-Gyu
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.25 no.6
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    • pp.374-385
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    • 2013
  • Sediment particle motions have been numerically simulated over a sinusoidal ripple. Turbulent boundary layer flows are generated by Large Eddy Simulation, and the sediment particle motions are simulated using Lagrangian particle tracking method. Two unsteady flow conditions are used in the experiment by employing two different wave amplitudes while keeping other conditions such as wave period same. As expected, the amount of suspended sediment particles is clearly dependent on the wave amplitude as it is increasing with increasing flow intensity. However, it is also observed that the pattern of suspension may be different as well due to the only different condition caused by wave amplitude. Specially, the time of maximum sediment suspension within the wave period is not coincident between the two cases because sediment suspension is strongly affected by the existence of turbulent eddies that are formed at different times over the ripple between the two cases as well. The role of these turbulent eddies on sediment suspension is important as it is also confirmed in previous researches. However, it is also found the time of these eddies' formation may also dependent on the wave amplitude over rippled beds. Therefore, it has been proved that various flow as well as geometric conditions under waves has to be considered in order to have better understanding on the sediment suspension process over ripples. In addition, it is found that high turbulent energy and strong upward flow velocities occur during the time of eddy formation, which also supports high suspension rate at these time steps. The results indicate that the relationship between the structure of flows and bedforms has to be carefully examined in studying sediment suspension at coastal regions.

A Study on the Timing of Spring Onset over the Republic of Korea Using Ensemble Empirical Mode Decomposition (앙상블 경험적 모드 분해법을 이용한 우리나라 봄 시작일에 관한 연구)

  • Kwon, Jaeil;Choi, Youngeun
    • Journal of the Korean Geographical Society
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    • v.49 no.5
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    • pp.675-689
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    • 2014
  • This study applied Ensemble Empirical Mode Decomposition(EEMD), a new methodology to define the timing of spring onset over the Republic of Korea and to examine its spatio-temporal change. Also this study identified the relationship between spring onet timing and some atmospheric variations, and figured out synoptic factors which affect the timing of spring onset. The averaged spring onset timing for the period of 1974-2011 was 11th, March in Republic of Korea. In general, the spring onset timing was later with higher latitude and altitude regions, and it was later in inland regions than in costal ones. The correlation analysis has been carried out to find out the factors which affect spring onset timing, and global annual mean temperature, Arctic Oscillation(AO), Siberian High had a significant correlation with spring onset timing. The multiple regression analysis was conducted with three indices which were related to spring onset timing, and the model explained 64.7%. As a result of multiple regression analysis, the effect of annual mean temperature was the greatest and that of AO was the second. To find out synoptic factors affecting spring onset timing, the synoptic analysis has been carried out. As a result the intensity of meridional circulation represented as the major factor affect spring onset timing.

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Long-term and Real-time Monitoring System of the East/Japan Sea

  • Kim, Kuh;Kim, Yun-Bae;Park, Jong-Jin;Nam, Sung-Hyun;Park, Kyung-Ae;Chang, Kyung-Il
    • Ocean Science Journal
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    • v.40 no.1
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    • pp.25-44
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    • 2005
  • Long-term, continuous, and real-time ocean monitoring has been undertaken in order to evaluate various oceanographic phenomena and processes in the East/Japan Sea. Recent technical advances combined with our concerted efforts have allowed us to establish a real-time monitoring system and to accumulate considerable knowledge on what has been taking place in water properties, current systems, and circulation in the East Sea. We have obtained information on volume transport across the Korea Strait through cable voltage measurements and continuous temperature and salinity profile data from ARGO floats placed throughout entire East Sea since 1997. These ARGO float data have been utilized to estimate deep current, inertial kinetic energy, and changes in water mass, especially in the northern East Sea. We have also developed the East Sea Real-time Ocean Buoy (ESROB) in coastal regions and made continual improvements till it has evolved into the most up-to-date and effective monitoring system as a result of remarkable technical progress in data communication systems. Atmospheric and oceanic measurements by ESROB have contributed to the recognition of coastal wind variability, current fluctuations, and internal waves near and off the eastern coast of Korea. Long-tenn current meter moorings have been in operation since 1996 between Ulleungdo and Dokdo to monitor the interbasin deep water exchanges between the Japanese and Ulleung Basins. In addition, remotely sensed satellite data could facilitate the investigation of atmospheric and oceanic surface conditions such as sea surface temperature (SST), sea surface height, near-surface winds, oceanic color, surface roughness, and so on. These satellite data revealed surface frontal structures with a fairly good spatial resolution, seasonal cycle of SST, atmospheric wind forcing, geostrophic current anomalies, and biogeochemical processes associated with physical forcing and processes. Since the East Sea has been recognized as a natural laboratory for global oceanic changes and a clue to abrupt climate change, we aim at constructing a 4-D continuous real-time monitoring system, over a decade at least, using the most advanced techniques to understand a variety of oceanic processes in the East Sea.

Evaluation System of Environmental Safety on Marine Geological Sequestration of Captured Carbon Dioxide (이산화탄소의 해양지중저장과 환경 안전성 평가 방안)

  • Gim, Byeong-Mo;Choi, Tae Seob;Lee, Jung-Suk;Park, Young-Gyu;Kang, Seong-Gil;Jeon, Ei-Chan
    • Journal of the Korean Society for Marine Environment & Energy
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    • v.16 no.1
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    • pp.42-52
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    • 2013
  • Carbon Capture and Storage (CCS) is a mitigation technology essential in tackling global climate change. In Korea, many research projects are aimed to commercialize CCS business around 2020. Public acceptance can be a key factor to affect the successful proceeds of CCS near future. Therefore this paper provides a concise insight into the application of environmental impact assessment and risk assessment procedures to support the sustainable CCS projects. Futhermore, bottlenecks regarding the environmental impacts assessment and related domestic and foreign legislation are revised. Finally, suggestions to overcome these bottlenecks and recommendations for future research are made in conclusion.

Vertical Variations of Water Environments and Phytoplankton Community during the 2009 Autumn in the Coast of Dokdo, Korea (2009년 추계 독도연안의 수환경과 식물플랑크톤 군집의 수심별 변화)

  • Kim, Yun-Sam;Park, Kyung-Woo;Park, Jung-Won;Jeune, Kyung-Hee;Kim, Mi-Kyung
    • Korean Journal of Environmental Biology
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    • v.28 no.4
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    • pp.202-211
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    • 2010
  • The variations of physico-chemical factors and the species compositions of phytoplanktons were investigated to analyze the marine ecosystem at the depths during summer in the coast of Dokdo (stations DOK 1-3). The mean values of conductivity (48.9 mS $cm^{-1}$), salinity (32.9 psu) and total suspended solids (57.9 mg $L^{-1}$) were the highest in DOK 1. The biomass (Chl-a) of phytoplanktons was the highest in the surface of DOK 1 (2.61 ${\mu}gL^{-1}$). By the means of physicochemical factors (salinity, turbidity, Chl-a, TN, TP and Si), the water estimated in the coast of Dokdo was more eutrophicated than that in 2008. The phytoplanktons were a total of 42 species in Dokdo, which were composed of 33 species (78.6%) for Bacillariophyceae and 9 species (21.4%) for Dinophyceae. The standing crops of phytoplanktons were the highest ($18{\times}10^3$ cells $L^{-1}$) in the surface of DOK 2 and in the surface of DOK 3, while they were the lowest ($2{\times}10^3$ cells $L^{-1}$) at depth of 40 m of DOK1 and at depth of 30 m of DOK 3. The dominant species of phytoplanktons were Chaetoceros castracanei ($6{\times}10^3$ cells $L^{-1}$) in the surface, Rhizosolenia alata f. gracillima ($3{\times}10^3$ cells $L^{-1}$) at depth of 20 m and Protocentrum compressum ($4{\times}10^3$ cells $L^{-1}$) at the depth of 30 m of DOK 1. At the surface of DOK 2, the dominant species was Bacillaria paxillifer ($6{\times}10^3$ cells $L^{-1}$), while it was Hemiaulus indicus ($12{\times}10^3$ cells $L^{-1}$) at the surface of DOK 3. The DOK 1, which is affected by upwelling, whirlpool and circulation due to the East Korean Warm Current, was the most eutrophicated water body among three stations. The monitoring of marine ecosystem in the coast of Dokdo should be continued to propose the alternatives for water quality and species conservation and to purify the eutrophicated water body due to artificial pollutants as well as natural effectors by the global warming, the climatic change, etc.

Consideration on the Operation of water level management and Environmental Change Associated with Inner Dike Constructions in Saemangeum Reservoir (새만금호 방수제 공사에 따른 관리수위 운영과 환경변화에 관한 고찰)

  • Choi, Jung-Hoon;Oh, Chan-Sung;Cho, Young-Kweon;Ahn, Chi-Ho
    • Journal of the Korean Society for Marine Environment & Energy
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    • v.16 no.4
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    • pp.290-298
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    • 2013
  • A Saemangeum Development Project, which is a national project in South Korea, has started with the objective of developing the reclaimed area mainly agricultural land use since the mid'80s. To develop a model of the global eco-reclamation, constructions of the eco-friendly counter facilities such as sluice gates and inner dikes, as well as environmental preservation measures for an estuary reservoir, have been carried out. However, reasonable measures of the water quality management for the Saemangeum area are required. Thus, the purpose of this study is to rigorously analyze and quantitatively evaluate the environmental problems due to the water level management associated with inner dike constructions. To achieve these objectives, the affecting factors on determination of water level management are described and a series of calibrated transient-state numerical simulations was performed to demonstrate the salinity distribution difference in the estuary before and after the construction of inner dikes. The overall salinity reduced about 2~5 psu, and the seawater intrusion was weakened by a well-regulated waterway after construction of the inner dikes compared to before construction of them.

Art and Collectivity (미술과 집단성)

  • Kwok, Kian-Chow
    • The Journal of Art Theory & Practice
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    • no.4
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    • pp.181-202
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    • 2006
  • "When it comes to art, nationalism is a goodticket to ride with", says the title of a report in the Indian Express (Mumbai, 29 Oct 2000). The newspaper report goes on to say that since Indian art was kept "ethnic" by colonialism, national liberation meant opening up to the world on India's own terms. Advocacy, at the tail end of the 20th century, would contrast dramatically with the call by Rabindranath Tagore, the founder of the academy at Santiniketan in 1901, to guard against the fetish of nationalism. "The colourless vagueness of cosmopolitanism," Tagore pronounced, "nor thefierce self-idolatry of nation-worship, is the goal of human history" (Nationalism, 1917). This contrast is significant on two counts. First is the positive aspect of "nation" as a frame in art production or circulation, at the current point of globalization when massive expansion of cultural consumers may be realized through prevailing communication networks and technology. The organization of the information market, most vividly demonstrated through the recent FIFA World Cup when one out of every five living human beings on earth watched the finals, is predicated on nations as categories. An extension of the Indian Express argument would be that tagging of artworks along the category of nation would help ensure greatest reception, and would in turn open up the reified category of "art," so as to consider new impetus from aesthetic traditions from all parts of the world many of which hereto fore regarded as "ethnic," so as to liberate art from any hegemony of "international standards." Secondly, the critique of nationalism points to a transnational civic sphere, be it Tagore's notion of people-not-nation, or the much mo re recent "transnational constellation" of Jurgen Habermas (2001), a vision for the European Union w here civil sphere beyond confines of nation opens up new possibilities, and may serve as a model for a liberated sphere on global scale. There are other levels of collectivity which art may address, for instance the Indonesian example of local communities headed by Ketua Rukun Tetangga, the neighbourhood headmen, in which community matters of culture and the arts are organically woven into the communal fabric. Art and collectivity at the national-transnational level yield a contrasting situation of, on the idealized end, the dual inputs of local culture and tradition through "nation" as necessary frame, and the concurrent development of a transnational, culturally and aesthetically vibrant civic sphere that will ensure a cosmopolitanism that is not a "colourless vagueness." In art historical studies, this is seen, for instance, in the recent discussion on "cosmopolitan modernisms." Conversely, we may see a dual tyranny of a nationalism that is a closure (sometimes stated as "ethno-nationalism" which is disputable), and an internationalism that is evolved through restrictive understanding of historical development within privileged expressions. In art historical terms, where there is a lack of investigation into the reality of multiple modernisms, the possibility of a democratic cosmopolitanism in art is severely curtailed. The advocacy of a liberal cosmopolitanism without a democratic foundation returns art to dominance of historical privileged category. A local community with lack of transnational inputs may sometimes place emphasis on neo-traditionalism which is also a double edged sword, as re kindling with traditions is both liberating and restrictive, which in turn interplays with the push and pull of the collective matrix.

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A Study on the Landscape plan to the Cheongdo Saemaeul Movement Memorial Park (청도새마을운동 기념공원 기본계획)

  • Kwon, Jin Wook;Park, Chan Yong
    • Journal of Korean Society of Rural Planning
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    • v.20 no.3
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    • pp.179-189
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    • 2014
  • The Saemaeul Movement, which is the representative national campaign of Korea aimed at the development of local communities, has drawn a great deal of attention from home and abroad and formed an element of Korea's national brand since 2000. Accordingly, this research was conducted for the purpose of constructing a memorial park in Shindo Village, Cheongdo County, North Kyoungsang Province, which is a home to the Saemaeul Movement. As the Saemaeul Movement is benchmarked by many countries around the world today, this research aims to communicate the spirit and social value of the movement and disseminate its effects of local community development in rural areas through the construction of a memorial park. In this study, the design motive of the memorial park was conceived through the historical review and case studies of the Saemaeul Movement. In parallel, theoretical study was also conducted on design techniques as the basis of this research. In consideration of the characteristics of a technical article, this research was conducted in several phases. In the first phase, the conditions of the site where the park construction was planned were analyzed and the direction of its development was set. In the second phase, the main theme and the basic principles of planning were established, and the contents of the park construction project were devised in detail. In the last phase, a comprehensive plan was established, including a space layout to accommodate activities, facilities and programs to be introduced to the park. The park construction site ($106,000m^2$) was divided into four zones (memorial zone, historical theme park, education zone and experience zone) based on circulation planning aimed at creating memorial space, and was linked to eco-friendly ecological space in consideration of environmental features. At a time when the Saemaeul Movement is being propagated across the world, the result of this study will help create a place for its memorial and play a pivotal role to boost international movements aimed at promoting co-prosperity across the global village. It will also bear significance as an example of theme-based park construction in a rural area and the invigoration of a local community.

Measurement of Mutual Solubility of High-pressure Gaseous Fire Extinguishing Agents(HFCs) and Nitrogen (고압가스계 소화약제(HFCs계열)와 질소의 상호용해도 측정)

  • 임종성;박지영;이병권;김재덕;이윤용
    • Fire Science and Engineering
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    • v.16 no.3
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    • pp.26-31
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    • 2002
  • Bromotrifluoromethane(halon-1301) and bromochlorodifluoromethane(halon-1211) have been widely used as a clean fire extinguishing agents due to their outstanding properties. However, production and use of halon are currently being phased out under an international agreements Montreal Protocol because of global environmental concerns and HFCs have been considered as promising alter-natives for the replacement of halon since their ozone depletion potentials are low. The vapor-liquid equilibrium data are required as important basic information in evaluating the solubility of clean fire extinguishing agents and determining their optimal compositions. In this work, we chose HFCs such as HFC-22 HFC-125, and HFC-l34a for gaseous fire extinguishing agents and nitrogen as a pressurization gas for a proper jet velocity of these agents. Phase equilibria for binary mixtures of nitrogen/HFC-22, nitrogen/HFC-125, and nitrogen/HFC-l34a were measured in the temperature range from 283.15K to 303.15K. For equilibrium measurement, we used a circulation type apparatus in which both vapor and liquid phases were continuously recirculated. The experimental data were relatively well correlated with the Peng-Robinson equation of state with Wong-Sandier mixing rules.

A High-resolution Study of Isotopic Compositions of Precipitation (고해상도 강우동위원소변동에 대한 연구)

  • Lee, Jeonghoon;Kim, Songyi;Han, Yeongcheol;Na, Un-Sung;Oh, Yoon Seok;Kim, Young-Hee;Kim, Hyerin;Ham, Ji-Young;Choi, Hye-Bin;Koh, Dong-Chan
    • Economic and Environmental Geology
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    • v.48 no.5
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    • pp.371-377
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    • 2015
  • Isotopic compositions of precipitation have been used to understand moisture transport in the atmosphere and interactions between precipitation and groundwater. Isotopic compositions of speleothems and ice cores, so called, ''paleoarchives'', can be utilized to interpret climate of the past and global circulation models (GCMs). The GCMs are able to explain the paleoarchives, can be validated by the precipitation isotopes. The developments of stable isotope analyzers make high-resolution isotopic studies feasible. Therefore, a high-resolution study of precipitation isotopes is needed. For this study, precipitation samples were collected for every 5 to 15 minutes, depending on precipitation rates, using an auto-sampler for precipitation isotopes near coastal area. The isotopic compositions of precipitation range from -5.7‰ (-40.1‰) to -10.8‰ (-74.3‰) for oxygen (hydrogen). The slope of ${\delta}^{18}O-{\delta}D$ diagram for the whole period is 6.8, but that of each storm is 5.1, 4.2, 7.9 and 7.7, respectively. It indicates that evaporation occurred during the first two storms, while the latter two storm did not experience any evaporation. The isotopic fractionations of precipitation has significant implications for the water cycle and high-resolution data of precipitation isotopes will be needed for the future studies.