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A Study on Post-Tensioned Reinforced Concrete Slab by the Beam Theory (포스트텐션된 철근콘크리트 슬래브의 보 이론에 의한 연구)

  • Han, Bong-Koo;Kim, Duck-Hyun
    • Composites Research
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    • v.22 no.5
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    • pp.24-29
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    • 2009
  • In this paper, a post-tensioned reinforced concrete slab was analyzed by the specially orthotropic laminates theory. Both the geometrical and material property of the cross section of the slab was considered symmetrically with respect to the neutral surface so that the bending extension coupling stiffness, $B_{ij}=0$, and $D_{16}=D_{26}=0$. Reinforced concrete slab behave as specially orthotropic plates. In general, the analytical solution for such complex systems is very difficult to obtain. Thus, finite difference method was used for analysis of the problem. In this paper, the finite difference method and the beam theory were used for analysis. The result of beam analysis was modified to obtain the solution of the plate analysis.

Efficient Thermal Stress Analysis of Laminated Composite Plates using Enhanced First-order Shear Deformation Theory (일차전단변형이론을 이용한 복합재료 적층평판의 효율적 열응력 해석)

  • Han, Jang-Woo;Kim, Jun-Sik;Cho, Maenghyo
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.25 no.6
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    • pp.505-512
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    • 2012
  • In this paper, an efficient yet accurate method for the thermal stress analysis using a first order shear deformation theory(FSDT) is presented. The main objective herein is to systematically modify transverse shear strain energy through the mixed variational theorem(MVT). In the mixed formulation, independent transverse shear stresses are taken from the efficient higher-order zigzag plate theory, and the in-plane displacements are assumed to be those of the FSDT. Moreover, a smooth parabolic distribution through the thickness is assumed in the transverse normal displacement field in order to consider a transverse normal deformation. The resulting strain energy expression is referred to as an enhanced first order shear deformation theory, which is obtained via the mixed variational theorem with transverse normal deformation effect(EFSDTM_TN). The EFSDTM_TN has the same computational advantage as the FSDT_TN(FSDT with transverse normal deformation effect) does, which allows us to improve the through-the-thickness distributions of displacements and stresses via the recovery procedure. The thermal stresses obtained by the present theory are compared with those of the FSDT_TN and three-dimensional elasticity.

Das Problem des Selbstbewußtseins Zwischen Vernunft und Existenz: Im Zentrum auf die Transformationen von Kants Selbstbewußtseinstheorie in Heideggers Analytik vom Dasein, Apels Lehre von diskursiver Vernunft, und Ebelings Lehre von Widerstandsbewußtsein (이성과 실존 사이에서 자기의식의 문제: 하이데거의 현존재 분석론, 아펠의 담론적 이성 이론, 그리고 에벨링의 저항의식 이론에서칸트의 자기의식 이론에 대한 변형들을 중심으로)

  • Kim, Chungjoo
    • Journal of Korean Philosophical Society
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    • no.120
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    • pp.217-250
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    • 2018
  • Subjekt oder $Selbstbewu{\ss}tsein$ ist ein grundlegendes Prinzip neuzeitlicher Philosophie. Das $Selbstbewu{\ss}tsein$ ist bei Kant $Selbstbewu{\ss}tsein$(analytische Einheit der Apperzeption als klare Selbstbeziehung) in Objekts $bewu{\ss}tsein$(synthetischer Einheit der Apperzeptuion). Dabei zeigt er ein Reflexionsmodell des $Selbstbewu{\ss}tseins$. Aber er $erkl{\ddot{a}}rt$ nicht systematisch ein $Verh{\ddot{a}}ltnis$ zwischen synthetischer Einheit und analytischer Einheit der Apperzeption, und auch $l{\ddot{o}}st$ er nicht theorienimmanente und formale Schwierigkeiten von Zirkelargument bzw. unendlicher Iteration in der Reflxionsstruktur des $Selbstbewu{\ss}tseins$. Aufgrund der Voraussetzungen seiner eigenen Fundamentalontologie kritisiert der $fr{\ddot{u}}he$ Heidegger, $da{\ss}$ Kants $traditionsabh{\ddot{a}}ngige$ $Subjektivit{\ddot{a}}tstheorie$ Symptome der Seins vergessenheit zeigt, transformiert Kants $Selbstbewu{\ss}tseinstheorie$, interpretiert Kants transformierte Theorie als $subjektivit{\ddot{a}}tstheoretische$ $Begr{\ddot{u}}ndung$ der traditionellen Ontologie von Vorhandenheit, und versteht sie als ersten Schritt und erstes phlosophisches Modell seiner Fundamentalontologie. Durch kritische Interpretation von Kants Lehre von Selbstaffektion und $Selbstbewu{\ss}tsein$ deutet er ein Modell des $Selbstbewu{\ss}tseins$ als des $ph{\ddot{a}}nomenologischen$ $Horizontsbewu{\ss}tseins$ an. In diesem Modell der vorreflexiven und unmittelbaren Selbstbeziehung entstehen Schwierigkeiten von Zirkelargument bzw. unendlicher Iteration nicht. Apel kritisiert Kants $selbstbewu{\ss}te$ Apperzeptionstheorie in dem Sinne, $da{\ss}$ sie solipsistisch sei, und in seiner Transzendentalpragmatik $vervollst{\ddot{a}}ndigt$ er Kants transzendentalphilosophische $G{\ddot{u}}ltigkeit$ in der Dimension von $Intersubjektivit{\ddot{a}}t$ diskurierender Menschen. Hierbei ersetzt die Kommunikationsgemeinschaft Kants Apperzeption oder $Bewu{\ss}tsein$ ${\ddot{u}}berhaupt$. In der transzendentalpragmatischen Sicht, die auf den sprachlichen Bezug des Denkens und Erkennens und die Kommunikationsgemeinschaft geht, beruht das $Selbstbewu{\ss}tsein$ oder die Reflexion des Subjekts wesentlich auf seinem sprachlich vermittelten sozialen Bezug. Also geht es nicht um Zirkelargument und unendliche Iteration in denkender Selbstbeziehung des Subjekts. Ebeling hebt Heideggers Daseinsanalytik auf das Niveau von Apels Transzendentalpragmatik an und entwickelt Fundamatalpragmatik ${\ddot{u}}ber$ $Widerstandsbewu{\ss}tsein$ gegen allgemeinen Tod. Dieser $Widerstandsbewu{\ss}tsein$ ist fundamentalpragmatische Transformation von Kants $Selbstbewu{\ss}tsein$. Der $Widerstandsbewu{\ss}tsein$ der Vernunft bleibt in der solipsistischen Dimension nicht und ist ein $Bewu{\ss}tsein$, das in der Widerstandsgemeinschaft durch Argumentation universalisiert werden kann. Hierbei geht es nicht um Zirkelargument und unendliche Iteration.

Development of Landscape Urbanism in Practice (랜드스케이프 어바니즘의 실천적 전개 양상)

  • Kim, Youngmin;Jeong, Wookju
    • Journal of the Korean Institute of Landscape Architecture
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    • v.42 no.1
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    • pp.1-17
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    • 2014
  • The Practice of Landscape Urbanism has been criticized on two aspects; Landscape Urbanism does not yet provide differentiated forms of planning and design neither able to fill the gap between theory and practice. In response to these criticisms, Landscape Urbanists have tried to provide additional cases that can exemplify achievements of Landscape Urbanism in practice. There has been another type of effort to suggest distinct planning and design strategies of Landscape Urbanism from theoretical texts. However, these approaches overlooked the fact that professional practice actually gave huge influence on the theoretical framework of Landscape Urbanism. Based on this observation, the study examined the development process of Landscape Urbanism by verifying the correlation between its practice and theory. Through an extensive literature review, the study suggested horizontality, infrastructure, process, ecology, media, hybrid, site, and scale as eight major concepts of Landscape Urbanism. Afterwards, the study classified 51 projects cited in major essays and articles of Landscape Urbanism into four categories: Archetypal projects, precedent projects, exemplary projects, and progressive projects. The correlation between strategies of the selected projects and main theoretical concepts was analyzed. The study found out that the early stage of the theory was focused on defining and explaining the new design and planning approaches of contemporary design projects related with landscape. However, these days, Landscape Urbanism became a more productive in providing diverse types of practice sharing the direction and vision proposed by the theory. Various projects influenced in constructing theoretical structure of Landscape Urbanism as well as proved that the suggestions of Landscape Urbanism could be effective to reorganize contemporary cites in the form of design and planning strategies. The observation of this study can contribute to provide proper answers to the criticism on practice of Landscape Urbanism and be helpful in understanding the limits and unrealized potentials of Landscape Urbanism as a practical theory.

Analysis of Normal Shock-Wave Oscillation in a Supersonic Diffuser (초음속 디퓨져에서 발생하는 수직충격파 진동의 이론해석)

  • 김희동
    • Journal of the Korean Society of Propulsion Engineers
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    • v.2 no.3
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    • pp.36-46
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    • 1998
  • Shock-wave in a supersonic diffuser flow cannot be stable even in the given pressure ratio which remains constant over time, and oscillates around a certain time-mean position. In the present study, oscillation of a normal shock-wave in a supersonic diffuser was analyzed by a small perturbation method. Upstream pressure perturbation was applied to a supersonic diffuser flow with a normal shock-wave. Stability of shock-wave was investigated by considering the diffuser pressure recovery and frequency of the pressure perturbation. The results obtained show that a stable oscillation of weak normal shock-wave is obtainable for the flow with the Mach number over 1.74. The ratio of sound pressures downstream to upstream of the shock wave increases with increase of the Mach number. The present results agree well with other analytical and experimental results.

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A Study on the Arching Effect due to Embankment Piles (성토지지말뚝에 의한 아칭효과 연구)

  • Lee, Seung-Hyun
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.18 no.7
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    • pp.375-381
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    • 2017
  • A full-scale field test was conducted to investigate the arching effect of an embankment pile. The arching effect calculated from the test results was compared with theoretical values. Measurements obtained from a load cell and an earth pressure cell during the field test reflected the arching effect of the embankment pile well. The arching effect measured by load cells for an embankment height of 3m or less was smaller than the theoretical value with the assumption of plain strain.The measured effect for a height of 4 m or more was larger than the theoretical value. In contrast to the consistent decrease of the theoretical arching effect, the arching effect obtained from the field test shows continually increasing trends. The arching effects calculated from the earth pressure cells were greater than those from the theory under the plain strain assumption, but the trend was similar to the theoretical one. The arching effects measured by the earth pressure cells an embankment heights of 2, 3, 4, 5, and 6 m were 1.05, 1.23, 1.29, 1.28, and 1.29 times greater than those from the theory under the assumption of plain strain. The arching effects from the field test were much greater than those from the theory under the installation of a pile grid.

A Potential-Based Panel Method for the Analysis of A Two-Dimensional Super-Cavitating Hydrofoil (양력판(揚力板) 이론(理論)에 의(依)한 2차원(次元) 수중익(水中翼)의 초월(超越) 공동(空洞) 문제(問題) 해석(解析))

  • Y.G. Kim;C.S. Lee;J.T. Lee
    • Journal of the Society of Naval Architects of Korea
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    • v.28 no.2
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    • pp.159-173
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    • 1991
  • This paper describes a potential-based panel method formulated for the analysis of a super-cavitating two-dimensional hydrofoil. The method employs normal dipoles and sources distributed on the foil and cavity surfaces to represent the potential flow around the cavitating hydrofoil. The kinematic boundary condition on the wetted portion of the foil surface is satisfied by requiring that the total potential vanish in the fictitious inner flow region of the foil, and the dynamic boundary condition on the cavity surface is satisfied by requiring thats the potential vary linearly, i.e., the tangential velocity be constant. Green's theorem then results in a potential-based integral equation rather than the usual velocity-based formulation of Hess & Smith type. With the singularities distributed on the exact hydrofoil surface, the pressure distributions are predicted with improved accuracy compared to those of the linearized lilting surface theory, especially near the leading edge. The theory then predicts the cavity shape and cavitation number for an assumed cavity length. To improve the accuracy, the sources and dipoles on the cavity surface are moved to the newly computed cavity surface, where the boundary conditions are satisfied again. This iteration process is repeated until the results are converged. Characteristics of iteration and discretization of the present numerical method are much faster and more stable than the existing nonlinear theories. The theory shows good correlations with the existing theories and experimental results for the super-cavitating flow. In the region of small angles of attack, the present prediction shows and excellent comparison with the Geurst's linear theory. For the long cavity, the method recovers the trends of the Wu's nonlinear theory. In the intermediate regions of the short super-cavitation, the method compares very well with the experimental results of Parkin and also those of Silberman.

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A study on the perspective of relationship between Confucianism and Taoism of Yuan-hong & Ge-hong (원굉(袁宏)과 갈홍(葛洪)의 유도(儒道)관계론 연구)

  • Lee, Jin-yong
    • The Journal of Korean Philosophical History
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    • no.27
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    • pp.293-326
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    • 2009
  • Confucianism and Taoism is the most representative schools in the Chinese philosophy. Through getting down to earth, they not only solved the social problem, but also accomplished a complete ideological system of their own philosophy. While examining closely the history of Chinese philosophy, some philosophers paid attention to the relationship between Confucianism and Taoism, and they will unite the different ideological system. Xuanxue(玄學) in the Wei-jin dynasty, typically, carried their research on the relationship between naturalness(自然) and Confucian ethical code(名敎). Against these theory, the scholars of Dongjin(東晋) dynasty tended to maintain the forming philosophical ideology of the relationship between naturalness(自然) and Confucian ethical code(名敎). Furthermore, they directly discussed the relationship between Confucianism and Taoism. This thesis is about a philosophical study of Yuan-hong and Ge-hong who was the typical scholar of the relationship between Confucianism and Taoism in the Donjin dynasty. Yuan-hong emphasized the utility and value of the Confucian ethical code, and he tried to find a basis of Confucian ethical code. Thus, he succeeded to the theory of the relationship between naturalness and Confucian ethical code, he at last advanced a new theory about the relationship between Confucianism and Taoism, which is called 'Taoist foundation Confucian utility(道本儒用)'. Ge-hong, from the point of view of the Taoist, accomplished the perspective on the relationship between Confucianism and Taoism, which is called 'Taoist foundation Confucian branch(道本儒末)'. Yuan-hong and Ge-hong, from the view of the relationship between foundation and utility & branch, advanced the new theory about the relationship between Confucianism and Taoism. In addition, we can correctly estimate their contribution to the development of the Chinese philosophy.