• 제목/요약/키워드: Sphere

검색결과 2,234건 처리시간 0.031초

Variable amplitude fatigue test of M30 high-strength bolt in bolt-sphere joint grid structures

  • Qiu, Bin;Lei, Honggang;Yang, Xu;Zhou, Zichun;Wang, Guoqing
    • Steel and Composite Structures
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    • 제33권3호
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    • pp.433-444
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    • 2019
  • Fatigue failure of a grid structure using bolt-sphere joints is liable to occur in a high-strength bolt due to the alternating and reciprocal actions of a suspension crane. In this study, variable amplitude fatigue tests were carried out on 20 40 Cr steel alloy M30 high-strength bolts using an MTS fatigue testing machine, and four cyclic stress amplitude loading patterns, Low-High, High-Low, Low-High-Low, and High-Low-High, were tested. The scanning electron microscope images of bolt fatigue failure due to variable amplitude stress were obtained, and the fractographic analysis of fatigue fractures was performed to investigate the fatigue failure mechanisms. Based on the available data from the constant amplitude fatigue tests, the variable amplitude fatigue life of an M30 high-strength bolt in a bolt-sphere joint was estimated using both Miner's rule and the Corten-Dolan model. Since both cumulative damage models gave similar predictions, Miner's rule is suggested for estimating the variable-amplitude fatigue life of M30 high-strength bolts in a grid structure with bolt-sphere joints; the S-N fatigue curve of the M30 high-strength bolts under variable amplitude loading was derived using equivalent stress amplitude as a design parameter.

유기발광소자의 광추출 향상을 위한 미세 반구형 유연 필름 연구 (Development of Micro-hemisphere Flexible PDMS Film for Enhancing Light Extraction in Organic Light-emitting Devices)

  • 백동현;배은정;맹형규;신지수;박영욱
    • 반도체디스플레이기술학회지
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    • 제21권4호
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    • pp.1-5
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    • 2022
  • We presented a micro hemi-sphere structure flexible film to improve the external quantum efficiency (EQE) in OLEDs. The micro hemi-sphere flexible film was fabricated with breath figure (BF) method and replica process. At 45 mg/mL of concentration, the size of the hemi-spheres was approximately 6.2 ㎛ were obtained which are the most circular shape. So, it was possible to yield the best performance with an improvement of 33 % in the EQE and the widest viewing angle ranging from 0° to 70°. As a result, the hemi-sphere film's size and distribution seem to play important roles in enhancing the EQE in OLEDs. Furthermore, the flexible hemi-sphere film based on polymeric materials could offer an effective, large-scale, mass-produced product and a simple process and approach to achieve high efficiency in flexible OLEDs.

미술의 공공성과 키스 해링(Keith Haring)의 사회적 개입에 관한 연구 (A Study on Art's Public Features and Social Intervention by Keith Haring)

  • 김지영
    • 미술이론과 현장
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    • 제8호
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    • pp.59-87
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    • 2009
  • This thesis started from the attempt to make it clear that 80's American artist Keith Haring(1958-1990) had conducted social intervention of criticism, resistance, and participation through his works, and so pursued public value. Haring of graffiti fame left popular and familiar cartoon style pictures on the street wall, the billboards, the posters and so on. Popular and playful works was explained as his unique characteristics, but Haring's creative way at the field has more value than just being grasped as artist's personal characteristics. Haring's work pieces became everyday art by joining with people's life, and are working as a social speaking place. So I think that these Haring's art works possess characteristics of 'the public sphere'. 'The Public Sphere' means that is independent and free from the government or partisan economic forces, so that is not connected with the interested relations, and that is the sphere of rational argumentation without 'disguise' or 'fabrication', and that is the sphere where general public can participate in and is inspected by them. The public sphere between the sphere of public authority such a nation and a market and the private sphere of free individual, it is mutually connected with them and works as the space forming public opinion. Private individuals communicate with this public sphere and perform a role of direct and indirect check, balance, and social criticism way off from power. Openness that should include the voice of not only leading power but also the socially weak such as citizens, women, homosexuals, minority races, and so on, and alienated class, is an index of the public characteristics. The public sphere is not working just with speech and mass media. Many artists as well as Haring open their mouth and act through an art at the center of society, and create another public sphere by an art. I understood that the real participatory and practical characteristics on the Haring's work is a phenomenon and current of a part of the art world including Haring. Such current started from 1960s is the in-depth effort to be connected with the life more closely, to communicate with people, and to improve problems of life. And it has pursued public value on the different way from the nation or public power. Artists have intervened in the society with strategic and positive ways in order to raise pushed-out value and sinked rights as the public agenda, and labored to accept the value of variety and difference at the society. The aspect of such social intervention is the notable features, findable on the Haring's works and process. Haring's works include art historical meanings and are expressed with familiar and plastic language, so they were able to communicate with various classes. And he secured various customers at the field and the street. This communicative and public approach factor raised the possibility much for his works to work as the public sphere. Haring presented critical and resistant speech toward society with his works based on this factor. He asserted his position and justice of gender identity as a sexual minority. And his such work continued to movement for alienated class and social week over his own rights. His speech and message on the wall painting, poster, T-shirts, billboard of the subway, and so on worked as a spectacle and pressed concern with social issues and consciousness shift. And he's been trying to protect and care people who is injured by HIV and drug and to realize social justice through social week protection. Haring's works planned to meet many people as much as possible performed its role of intervening in society through criticism, resistance, speech, and participation, and controlling and checking social issues. These things considered, Haring's works show his consciousness about public attributes of art, and obviously include public value seeking. And also we can find the meaning of such his work as that an art is working as the public sphere and shows the possibility to discuss and practice public issues.

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ON CONTACT THREE CR SUBMANIFOLDS OF A (4m + 3)-DIMENSIONAL UNIT SPHERE

  • Kwon, Jung-Hwan;Pak, Jin--Suk
    • 대한수학회논문집
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    • 제13권3호
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    • pp.561-577
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    • 1998
  • We study (n+3)-dimensional contact three CR submanifolds of a Riemannian manifold with Sasakian three structure and investigate some characterizations of $S^{4r+3}$(a) $\times$ $S^{4s+3}$(b) ($a^2$$b^2$=1, 4(r + s) = n - 3) as a contact three CR sub manifold of a (4m+3)-dimensional unit sphere.

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[발표취소] Gravitational Lensing by an Isothermal Sphere with a Supermassive Black Hole

  • Kim, Donghyeon;Park, Myeong-Gu
    • 천문학회보
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    • 제40권2호
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    • pp.51.2-51.2
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    • 2015
  • Gravitational lensed quasar systems are usually explained by a source quasar lensed by a galaxy that can be approximated by an isothermal sphere. But most galaxies have a supermassive black hole (SMBH) at its center. We study the lensing by an isothermal sphere with a central SMBH. The additional lensing effects of a SMBH on the number, position, and magnification of lensed images are investigated. We apply the analysis to observed lens systems including Q0957+561. We also study the lensing by an elliptical mass distribution with a SMBH.

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SCALAR CURVATURE OF CONTACT CR-SUBMANIFOLDS IN AN ODD-DIMENSIONAL UNIT SPHERE

  • Kim, Hyang-Sook;Pak, Jin-Suk
    • 대한수학회보
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    • 제47권3호
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    • pp.541-549
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    • 2010
  • In this paper we derive an integral formula on an (n + 1)-dimensional, compact, minimal contact CR-submanifold M of (n - 1) contact CR-dimension immersed in a unit (2m+1)-sphere $S^{2m+1}$. Using this integral formula, we give a sufficient condition concerning with the scalar curvature of M in order that such a submanifold M is to be a generalized Clifford torus.

GEOMETRIC CLASSIFICATION OF ISOMETRIES ACTING ON HYPERBOLIC 4-SPACE

  • Kim, Youngju
    • 대한수학회지
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    • 제54권1호
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    • pp.303-317
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    • 2017
  • An isometry of hyperbolic space can be written as a composition of the reflection in the isometric sphere and two Euclidean isometries on the boundary at infinity. The isometric sphere is also used to construct the Ford fundamental domains for the action of discrete groups of isometries. In this paper, we study the isometric spheres of isometries acting on hyperbolic 4-space. This is a new phenomenon which occurs in hyperbolic 4-space that the two isometric spheres of a parabolic isometry can intersect transversally. We provide one geometric way to classify isometries of hyperbolic 4-space using the isometric spheres.

ORTHOGONAL ALMOST COMPLEX STRUCTURES ON THE RIEMANNIAN PRODUCTS OF EVEN-DIMENSIONAL ROUND SPHERES

  • Euh, Yunhee;Sekigawa, Kouei
    • 대한수학회지
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    • 제50권2호
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    • pp.231-240
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    • 2013
  • We discuss the integrability of orthogonal almost complex structures on Riemannian products of even-dimensional round spheres and give a partial answer to the question raised by E. Calabi concerning the existence of complex structures on a product manifold of a round 2-sphere and of a round 4-sphere.