• Title/Summary/Keyword: critical current

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Case Study on the Countermeasure Methods and Collapsed Sources of Segmental Retaining Wall Considering Site Conditions (시공환경을 고려한 블록식 보강토옹벽의 붕괴요인 분석 및 대책방안 사례연구)

  • Han, Jung-Geun;Cho, Sam-Deok;Jeong, Sang-Seom;Lee, Kwang-Wo;Kim, Ji-Sun
    • Journal of the Korean Geosynthetics Society
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    • v.4 no.3
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    • pp.35-43
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    • 2005
  • The geosynthetic reinforced segmental retaining walls(SRW) are improved that the disadvantage of existed retaining wall and the workability in field. Recently, the segmental retaining wall is replacing the exited wall because it is quickly advanced to using by the block in-situ. The use, therefore, is increasing. But, the trends of the large scaled construction was developed that the problems likely to crack and collapse, those are caused of careless in design and construction of SRW not considering about various surrounding conditions. In this study, the cause analysis on destructed SRW was carried out that based on the datum of measured displacement of walls, rainfall features and ground sounding conditions. Also, the analysis of the global slope stability was carried out on collapsed section and non-collapsed section using critical equilibrium method. For the rational stability and analysis of slope including SRW structure, the site conditions including situations of topography, ground and histories of construction and collapse etc should be considered. The rational countermeasure methods for non-collapsed and collapsed areas may be sustained as much as possible current state.

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A Comparative Study of Landscape Design Competitions' Guidelines and Entry Plans -The Case of Winning Design Proposals for Urban Infrastructure of the Hangdong Bogeumjari Housing District- (조경현상설계지침과 출품작의 내용관계 비교 -항동 보금자리주택지구 도시기반시설공모 입상작을 중심으로-)

  • Hong, Youn-Soon
    • Journal of the Korean Institute of Landscape Architecture
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    • v.39 no.2
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    • pp.18-28
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    • 2011
  • This study is aimed at the improvement of administrative operations of landscape design competitions and qualitative enhancement of design quality by mutually comparing the guidelines and entry plans. The case targeted for the current study is landscape design proposals for the Seoul Hangdong Bogeumjari Housing District recently launched within a greenbelt zone in the outskirts of Seoul. The study examines from a critical perspective the design guidelines and the contents of the three winning design proposals with a focus on whether or not they have reflected the guidelines. It was observed that many provisions of the principles and conceptual guidelines which serve as clues to the designs for winning designs proposals show the direction in which the project is to be headed It was also observed that the provisions and the way they are expressed are intertwined, while, at the same time, the guidelines were not organized or developed in an orderly manner. Such a structural pattern of the guidelines is linked to the aspects of the contents of the winning design proposals as described in the following. It is observed that guidelines related to the direction in which the design to be headed are so regulatory and lengthy that they are overly standardized. This could make it difficult to read the possibility of the alternative shifts in the winning design proposals. At the same time, the attributes of winning design proposals themselves, which require observable discriminatory superiority, could serve as a factor causing excess of meanings by jumping on the bandwagon of naming. On the contrary, where autonomy of design is guaranteed or no guidelines are provided for the winning design proposals, discriminatory differences were observed, thereby making it easy to measure them This illustrates well that guidelines and structural format should be provided through a separate undertaking that has taken into careful consideration environmental traits of the site in question, objectives required and so forth.

Diffusion Bonding and Property of Superconducting Coated Conductor (초전도 박막선재의 확산 접합 및 특성)

  • Ha, H.S.;Kim, H.S.;Ko, R.K.;Yoo, K.K.;Yang, J.S.;Kim, H.K.;Jung, S.W.;Lee, J.H.;Lee, N.J.;Kim, T.H.;Song, K.J.;Ha, D.W.;Oh, S.S.;Youm, D.;Park, C.;Yoo, S.I.;Moon, S.H.;Joo, J.
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2008.06a
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    • pp.299-299
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    • 2008
  • 초전도 응용기기 개발을 위해 필수적인 초전도 박막선재는 길이방향으로 임계전류밀도가 균일한 것이 요구되고 있다. 전체 길이에 대해 가장 임계전류 밀도가 낮은 지점에서 선재의 특성이 제한되기 때문이다. 한편 초전도 박막선재의 경우 높은 임계전류 밀도와 함께 과전류 등의 사고발생시를 고려하여 안정화재를 반드시 초전도층 위에 구성하여야 한다. 고가의 은(Ag)을 두껍게 증착할 수 없으므로 보통은 구리도금 또는 솔더링으로 안정화재를 덧댄다. 본 연구에서는 초전도 박막선재의 대전류화와 길이방향의 전류 균일성 향상, 안정화 특성 항상 등의 목적으로 초전도 박막선재간 확산 접합을 시도하였다. 초전도 박막선재 제조 후 안정화재인 은을 증착 후 따로 구리도금이나 솔더링 없이 선재 2가닥을 서로 포개어서 열처리를 하였다. 이때 선재간의 충분한 확산접합을 위하여 선재를 둥근 SUS 디스크에 감고 외부에 다시 SUS판재로 감아서 열처리 도중 압력을 가하였다. 아울러 포개는 방법도 초전도층의 위치에 따라 3 가지로 하였으며 열처리 후 임계전류를 측정하였다. 각 선재한 가닥에 대한 임계전류는 77K에서 50~60 A 정도의 임계전류를 나타내었으며 선재를 접합한 경우 90~120A의 특성을 나타내었으며 특히 초전도층이 설마주보는 형태에서 가장 높은 임계전류 특성을 나타내었다.

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The Improvement of Curtain Wall Design Process using Value Stream Mapping Tools (VSM기법을 활용한 커튼월 공사의 설계 프로세스 개선)

  • Kim, Chang-Duk;Lee, Sang-Hyuk
    • Korean Journal of Construction Engineering and Management
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    • v.7 no.5
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    • pp.128-137
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    • 2006
  • This paper is to develop curtain wall process life-cycle system in high-rise buildings in order to establish effective cooperation communication channels among the diverse constituents. This paper is to provide a base toward a curtain wall life-cycle management system to support decision making and the effective flow in light of information and materials. The four objectives of the research are 1) the analysis of the current curtain wall life-cycle process, 2) the analysis and development of the curtain wall design process As-Is model, and 3) the Muda analysis of the design process As-Is model and the suggestion of the improvements, 4) the development of curtain wall design To-Be model and comparative analysis of the improvement in terms of value streams. This research indicates the wastes decrease (or the values increase) from 6.7% up to 100% in different decision criteria through the improvement by the comparative analysis between the As-ls and To-Be curtain wall design process. This research suggests the potential improvement by VSM and a curtain wall life-cycle management system in curtain wall construction for diverse constituents be significant.

Distributional Patterns and the Evaluation of Hydrophytic Plants of Urban Wetlands in Seongnam City, Gyunggi-do Province, Korea (경기도 성남시 도시지역 습지의 유형 분포 및 습지식물의 특성 평가)

  • Chun, Seung-Hoon
    • Korean Journal of Environment and Ecology
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    • v.22 no.2
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    • pp.159-172
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    • 2008
  • This study was carried out to obtain ecological information necessary for a conservation plan based on the distributional patterns, wetland types, and hydrophytic characteristics of urban wetlands in Seongnam City, Kyunggi Province where representing the various patterns of land use made by rapid urbanization since 1970s. Total 162 sites of four wetland types were identified as urban wetlands during the first survey. The sites were classified into 55 forested swamps, 4 riverine wetlands, 62 abandoned paddy fields, 37 small ponds, and 4 reservoirs, etc. The second survey targeted 107 sites which were identified as good wetlands. It showed that 42 sites(about 39%) were already degraded due to drainage, landfill, and crop cultivation at 6 months intervals. Both hydrologic conditions and hydrophytic characteristics of 27 good wetlands help maintain current ecological status, but most wetlands have been degraded by artificial impacts. Among 184 species identified, only 75 species(about 40.7%) were hydrophytes. Prevalence Index of hydrophyte based on three categories of OBL(obligatory wetland plant), FAC(facultitative plant), UPL(obligatory upland plant) was 3.7, indicating that vegetation data alone is inadequate to designate as wetlands. This study revealed that as critical habitats for wildlife they playa vital role in ecotone between both terrestrial and aquatic ecosystem with its proper distributional pattern in spite of their small areas compared to the entire geographic region of the City.

The Mitochondrial Warburg Effect: A Cancer Enigma

  • Kim, Hans H.;Joo, Hyun;Kim, Tae-Ho;Kim, Eui-Yong;Park, Seok-Ju;Park, Ji-Kyoung;Kim, Han-Jip
    • Interdisciplinary Bio Central
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    • v.1 no.2
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    • pp.7.1-7.7
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    • 2009
  • "To be, or not to be?" This question is not only Hamlet's agony but also the dilemma of mitochondria in a cancer cell. Cancer cells have a high glycolysis rate even in the presence of oxygen. This feature of cancer cells is known as the Warburg effect, named for the first scientist to observe it, Otto Warburg, who assumed that because of mitochondrial malfunction, cancer cells had to depend on anaerobic glycolysis to generate ATP. It was demonstrated, however, that cancer cells with intact mitochondria also showed evidence of the Warburg effect. Thus, an alternative explanation was proposed: the Warburg effect helps cancer cells harness additional ATP to meet the high energy demand required for their extraordinary growth while providing a basic building block of metabolites for their proliferation. A third view suggests that the Warburg effect is a defense mechanism, protecting cancer cells from the higher than usual oxidative environment in which they survive. Interestingly, the latter view does not conflict with the high-energy production view, as increased glucose metabolism enables cancer cells to produce larger amounts of both antioxidants to fight oxidative stress and ATP and metabolites for growth. The combination of these two different hypotheses may explain the Warburg effect, but critical questions at the mechanistic level remain to be explored. Cancer shows complex and multi-faceted behaviors. Previously, there has been no overall plan or systematic approach to integrate and interpret the complex signaling in cancer cells. A new paradigm of collaboration and a well-designed systemic approach will supply answers to fill the gaps in current cancer knowledge and will accelerate the discovery of the connections behind the Warburg mystery. An integrated understanding of cancer complexity and tumorigenesis is necessary to expand the frontiers of cancer cell biology.

Reframing Sustainability in Consideration of Climate Change and Natural Hazards: Focusing on the U.S. Natural Hazards Mitigation Trend and Case Analysis (기후변화시대 자연재해를 고려한 지속가능개발 개념의 재정립: 미국 방재동향 및 사례 분석을 중심으로)

  • Kwon, Tae Jung
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.33 no.2
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    • pp.801-810
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    • 2013
  • The main purpose of this study is to reframe sustainability or sustainable development concept in the field of planning in consideration of climate change and natural hazards. The new concept is expected to provide a theoretical foundation for upcoming hazard mitigation measures addressing climate change. The first and main argument of the new concept is that environmental protection should be inclusive enough to address urban (or community) security from current natural hazards. The second is that the balance between structural and nonstructural mitigation measures is critical to cope more effectively with extreme natural hazards in the era of climate change and also with conflicts driven by three goals of sustainability--environmental protection, economic development, and social justice. The following studies, based on this new concept of sustainablity, are expected (1) to address new participation methods for the conflict resolution, (2) to explore detailed and substantive planning strategies and creative technical and institutional solutions for environmental protection, natural hazard mitigation, and conflict resolution. Two of APFM(the Associated Programme on Flood Management)'s three natural hazard risk criteria, Exposure and Vulnerability, may guide the exploration.

A Current Review on the Publicness of Electronic Communication Networks: Focused on the Idea of Transport Economics and Network Neutrality (전자 커뮤니케이션 네트워크의 사회적 공공성에 대한 시론: 교통 경제학과 네트워크 중립성 논의를 중심으로)

  • Lee, Young-Joo
    • Korean journal of communication and information
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    • v.36
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    • pp.7-41
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    • 2006
  • This study criticizes the wave of liberalization, privatization, thoughtless and uncontrolled over-competition in the electronic communication networks area. This criticism is based on the 'transport economics' on one side, the 'network neutrality debate' on the other side. Through these standpoints, this study insists that it needs to deal with a social agenda related to the problems such as unplanned and unbalanced development of electronic communication networks, double/tripple-investment in the communication industry, conflicts among network companies and the decline of public values. Also does this study stress on the new ideas in the electronic communication network policy and planning to manage these problems. Electronic communication networks are converging and their borders are blurred. As a result of these flows, the field of information technology, media and contents is faced with radical changes. These changes could be so critical and complicated that nobody can diagnose their multi-level implications. However, the one thing sure is that we should start from the communication networks to think and control a communication system. Therefore, we should discuss and plan the now-and-future of communication infrastructure and its management. we need not only a market mentality but also a socio-cultural mentality. In this respect, this study does insist that it requires the vision of digital democracy and democratic communication ecology to put the steps toward social communication system.

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The Other 90%, Warm Technology, and the Best Solution: A Critique of the Appropriate Technology Movement in South Korea (소외된 90%, 따뜻한 기술, 최고의 솔루션: 한국 적정기술 운동의 문제의식 비판)

  • Jeon, Chihyung
    • Journal of Science and Technology Studies
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    • v.14 no.2
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    • pp.127-164
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    • 2014
  • This essay examines the motivations, goals, and assumptions of those who are participating in the appropriate technology movement in contemporary South Korea. In addition to analyzing books, articles, presentation materials, and media reports written by or about the "appropriate technologists," I have interviewed a few of them to hear their thoughts on appropriate technologies as well as inappropriate technologies. They choose to work on appropriate technology out of their good will for people in need, their Christian faith, and their pride in Korea's rapid and successful development. As a result, the appropriate technology movement in Korea does not engage in a critical evaluation of current sociotechnical systems, but instead takes an ethical and paternalistic stance in accepting and improving the given situation. Its apolitical character is effective in drawing a large number of participants, but it also limits their imagination and the movement's potential influence. Moreover, the movement's focus on "the other 90%" leads the participants to frame appropriate technology as something for "them" or "locals" rather than as something for "all of us." This essay concludes by suggesting that the appropriate technology movement in Korea should expand its scope from an ethical pursuit of technology to a political engagement with technology.

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Attributes of a 'Good Job': Construct Formation and Validation in South Korea

  • Kim, Sang-Wook;Phang, Ha-Nam
    • Korea journal of population studies
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    • v.30 no.2
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    • pp.117-146
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    • 2007
  • The research reported in this paper suggests an index of a 'good job' and validates it in several different ways. Not much is known yet, it is emphasized, about what the defining characteristics of a good job are and what the causes and major consequences are resulting from the attainment of such job. This is not merely because relatively little attention has been paid to construct a usable index, but also because a few studies, if any, were often plagued with several limitations, some theoretical and other analytical. As a consequence, fragmented speculations and research findings tended to flourish in the shortage of an overarching conceptualization and rigorous empirical assessment. In particular, a comprehensive index that encompasses a few critical job characteristics based on some solid theoretical underpinnings was in thirsty want. To relieve this want, the current study tries to formulate such index and validate it. A covariance structure analysis of representative national sample survey (Korean General Social Survey) data in South Korea indicates that wage, occupational prestige, authority and job security are the defining characteristics of a good job and that the index consisting of these characteristics is generally valid with respect to its constituent attributes, antecedents and a consequence, thereby supporting its discriminant-convergent and construct validities. The findings are interpreted with providing a few substantive implications stemming from them.