• Title, Summary, Keyword: transition

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Double Transition and Magnetic Phase Transition : An Electron Fluid Condensation Model for Superconductivity (이중 전이와 자화 상전이 : 초전도성에 대한 전자 유체의 응축 모델)

  • Park, Sung-Hoon;Choi, Dong-Seek;Shin, Doo-Soon;Kim, Won-Soo
    • Journal of the Korean Chemical Society
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    • v.42 no.6
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    • pp.599-606
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    • 1998
  • Since the discovery of ceramic superconductor the various theoretical developments has progressed but there are no definitive description about the superconducting transition mechanism. In special, both the double transition and the various magnetic phase transition add to the complication of the understanding of HTSC. In this paper, we presented the idea of the two-step mechanism for the superconducting transition in view of the condensation model of electron fluid for superconductivity. And these concepts are successfully applied to the double transition and the magnetic phase diagram of various types of superconductivity. Therefore, both the double transition and magnetic phase transition should be the touchstone of general theory for superconductivity.

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Energy and force transition between atoms and continuum in quasicontinuum method

  • Chang, Shu-Wei;Liao, Ying-Pao;Huang, Chang-Wei;Chen, Chuin-Shan
    • Interaction and multiscale mechanics
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    • v.7 no.1
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    • pp.543-561
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    • 2014
  • We present a full energy and force formulation of the quasicontinuum method with non-local and local transition elements. Non-local transition elements are developed to transmit inhomogeneity from the atomistic to the continuum regions. Local transition elements are developed to resolve the mathematical mismatch between non-local atoms and the local continuum. The rationale behind these transition elements is provided by analyzing the energy and force transitions between atoms and continuum under the Cauchy-Born rule. We show that breakdown of the Cauchy-Born rule occurs for slaved atoms of local elements within the cutoff of non-local atoms. The inadequacy of the Cauchy-Born rule at the transition region naturally leads to the need of atomistic treatment of transition slaved and transition representative atoms. Such an atomistic treatment together with a full or cutoff sampling allows non-local transition elements containing these transition entities to transmit inhomogeneity. Different force formulations for transition representative atoms and pure local representative atoms allow the local transition elements to resolve non-local and local mismatches. The method presented herein is validated by force calculations in an unstressed perfect crystal as well as an unrelaxed grain boundary model. A nanoindentation simulation in 3D is conducted to demonstrate the accuracy and efficiency of the proposed method.

Quantum Transition Properties of Quasi-Two Dimensional Si System in Electron Deformation Potential Phonon Interacting (전자 포텐셜 변형과 포논 상호작용에 의한 준 이차원 Si 구조의 전도 현상 해석)

  • Lee, Su-Ho;Kim, Young-Mun;Kim, Hai-Jai;Joo, Seok-Min
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.66 no.3
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    • pp.129-134
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    • 2017
  • We investigated theoretically the quantum optical transition properties of Si, in quasi 2-Dimensinal Landau splitting system, based on quantum transport theory. We apply the quantum transport theory (QTR) to the system in the confinement of electrons by square well confinement potential under linearly polarized oscillating field. We use the projected Liouville equation method with Equilibrium Average Projection Scheme (EAPS). In order to analyze the quantum transition, we compare the temperature and the magnetic field dependencies of the QTLW and the QTLS on four transition processes, namely, the intra-leval transition process, the inter-leval transition process, the phonon emission transition process and the phonon absorption transition process.

The Heterogeneity of Job Creation and Destruction in Transition and Non-transition Developing Countries: The Effects of Firm Size, Age and Ownership

  • Ochieng, Haggai Kennedy;Park, Bokyeong
    • East Asian Economic Review
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    • v.21 no.4
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    • pp.385-432
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    • 2017
  • This paper investigates how firm age, size and ownership are related with job creation and destruction, and how these patterns differ across transition and non-transition economies. The analysis finds that age is inversely related with gross job creation and net job creation in the two samples. This finding is consistent with the theory of the learning effect. The relationship between age and job destruction is indifferent in non-transition economies. On the contrary, old firms in transition economies destroy more jobs than young ones. The paper further establishes an inverse relationship between size and gross job creation in the two groups. However, there is divergence between the two samples; small firms in non-transition economies also exhibit a higher gross job destruction rate. Consequently large firms have a higher net job creation rate. In transition economies, small and large firms exhibit similar rates of job destruction. But small firms retain a higher net job creation rate. A more intriguing finding is that state owned firms do not underperform domestic private ones. This means these countries may be using soft budget constraint which allows state owned firms to overstaff. Finally, crowding out of SMEs by foreign owned firms is not evident in transition economies.

Molecular Dynamics Study on the Structural Phase Transition of Crystalline Silver Iodide

  • Jun Sik Lee;Mee Kyung Song;Mu Shik Jhon
    • Bulletin of the Korean Chemical Society
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    • v.12 no.5
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    • pp.490-494
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    • 1991
  • The ${\beta} to {\alpha}$ phase transition in silver iodide is studied with the (N, V, E) and (N, P, T) molecular dynamics (MD) method. In experiments, the phase transition temperature is 420 K. Upon heating of ${\beta}$ form, the iodine ions undergo hcp to bcc transformation and silver ions become mobile. MD simulations for the ${\beta}$ and ${\alpha}$ phases are carried out at several temperatures and the radial distribution functions (rdf) are obtained at those temperatures in the (N, V, E) ensemble. But the phase transition is not found in our calculation. Next the phase transition is studied with the (N, P, T) MD and we find some evidences of phase transition. At 3 Kbars and 2 Kbars the phase transition temperatu re is about 300 K. For 3.55 Kbars, the phase transition is higher (420 K) than the low pressure case. The phase transition temperature is somewhat dependent on the pressure in our calculations.

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Formulation Method for Solid-to-Beam Transition Finite Elements

  • Im, Jang-Gwon;Song, Dae-Han;Song, Byeong-Ho
    • Journal of Mechanical Science and Technology
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    • v.15 no.11
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    • pp.1499-1506
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    • 2001
  • Various transition elements are used in general for the effective finite element analysis of complicated mechanical structures. In this paper, a solid-to-beam transition finite element, which can b e used for connecting a C1-continuity beam element to a continuum solid element, is proposed. The shape functions of the transition finite element are derived to meet the compatibility condition, and a transition element equation is formulated by the conventional finite element procedure. In order to show the effectiveness and convergence characteristics of the proposed transition element, numerical tests are performed for various examples. As a result of this study, following conclusions are obtained. (1) The proposed transition element, which meets the compatibility of the primary variables, exhibits excellent accuracy. (2) In case of using the proposed transition element, the number of nodes in the finite element model may be considerably reduced and the model construction becomes more convenient. (3) This formulation method can be applied to the usage of higher order elements.

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Beam Transition Elements for Finite Element Analysis of Transition Regions of Coupled Wall Structures (병렬전단벽 구조물의 변화부분의 유한요소해석을 위한 보-변환요소의 개발)

  • 김호수
    • Computational Structural Engineering
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    • v.8 no.2
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    • pp.85-93
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    • 1995
  • This study presents the formulation of beam transition elements and transition zone elements for the effective finite element analysis of the transition regions of coupled wall structures. Beam transition element can be described as the quasi beam element which is replaced by an equivalent plane stress element, keeping equally, the basic behavior of beam element, based on the kinematic and force constraints between beam and wall element. These beam transition elements solve the incompatibility related to different degrees of freedom between beam and wall element in transition regions. Also, the stiffness matrices of transition zone elements which are directly connected with beam transition elements in transition regions can be derived from the equivalent constraint conditions. These elements provide the reasonable mesh grading schemes for transition regions and can be usefully applied to the transition regions of all structures that the interactions of wall and beam element are considered.

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Transition as a Theory and Practice: Transition Studies and Policies in Netherlands (이론과 실천으로서의 전환 : 네덜란드의 전환이론과 전환정책)

  • Jung, Byung Kul
    • Journal of Science and Technology Studies
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    • v.15 no.1
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    • pp.109-143
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    • 2015
  • For continuous and successful innovation, changes in innovation system are required and have been magnified as a new controversy. With high public interest in changes of innovation system, Transition theory and policy in Netherlands are now attracting attentions of many researchers and policymakers. Transition policy in Netherlands is distinguished from existing policies for fundamental system change in that take remarkably different views and methods. Typical examples of transition in Netherlands are such as sustainable energy transition, biodiversity and natural resource transition, sustainable agriculture transition, and sustainable transportation. Transitions in Netherlands are still in the early stage of it but several positive effects are witnessing. However some problems - linking theory and practice, ambiguity of transition concept, linking long-term vision and short-term, resistance of existing regime, implementation problem, diffusion of support, etc.- to be tackled are still remaining. In spite of those problems, many lessons can be drawn from them. To guide structural changes in innovation system into the right path and cope with lock-in problem by existing system and regime, we need to learn from Transition theory and policy in Netherlands.

The appropriate shape of the boundary transition section for a mountain-gorge terrain model in a wind tunnel test

  • Hu, Peng;Li, Yongle;Huang, Guoqing;Kang, Rui;Liao, Haili
    • Wind and Structures
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    • v.20 no.1
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    • pp.15-36
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    • 2015
  • Characterization of wind flows over a complex terrain, especially mountain-gorge terrain (referred to as the very complex terrain with rolling mountains and deep narrow gorges), is an important issue for design and operation of long-span bridges constructed in this area. In both wind tunnel testing and numerical simulation, a transition section is often used to connect the wind tunnel floor or computational domain bottom and the boundary top of the terrain model in order to generate a smooth flow transition over the edge of the terrain model. Although the transition section plays an important role in simulation of wind field over complex terrain, an appropriate shape needs investigation. In this study, two principles for selecting an appropriate shape of boundary transition section were proposed, and a theoretical curve serving for the mountain-gorge terrain model was derived based on potential flow theory around a circular cylinder. Then a two-dimensional (2-D) simulation was used to compare the flow transition performance between the proposed curved transition section and the traditional ramp transition section in a wind tunnel. Furthermore, the wind velocity field induced by the curved transition section with an equivalent slope of $30^{\circ}$ was investigated in detail, and a parameter called the 'velocity stability factor' was defined; an analytical model for predicting the velocity stability factor was also proposed. The results show that the proposed curved transition section has a better flow transition performance compared with the traditional ramp transition section. The proposed analytical model can also adequately predict the velocity stability factor of the wind field.

TESTING FOR SMOOTH TRANSITION NONLINEARITY IN PARTIALLY NONSTATIONARY VECTOR AUTOREGRESSIONS

  • Seo, Byeong-Seon
    • Journal of the Korean Statistical Society
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    • v.36 no.2
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    • pp.257-274
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    • 2007
  • This paper considers the tests for the presence of smooth transition non-linearity in the partially nonstationary vector autoregressive model. The transition parameters cannot be identified under the null hypothesis of linearity, and therefore this paper develops the tests for smooth transition nonlinearity, the associated asymptotic theory and the bootstrap inference. The Monte Carlo simulation evidence shows that the bootstrap inference generates moderate size and power performances.