• Title/Summary/Keyword: 구조적 안정도

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GAP요소를 이용한 접촉 알고리즘

  • 정기택
    • Computational Structural Engineering
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    • v.10 no.1
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    • pp.52-61
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    • 1997
  • 본 논문에서는 기존의 gap 요소의 단점을 보완하여 간단하면서도 효율적인 접촉 알고리즘을 개발하였다. 다양한 수치 예제를 통하여, 제안된 접촉 알고리즘의 효율성 및 정확도를 검증하였다. 새로운 gap 요소는 일반적인 유한요소와 결합되어, 마찰이 포함되지 않은 삼차원 탄소성 접촉 문제의 해를 구하는데 이용될 수 있다. 개발된 접촉 알고리즘은 최적화기법을 도입하지 않고 시행착오기법에 기반을 두면서도 접촉문제에 대한 반복해의 수렴성 및 안정성을 보장한다. 또한 gap요소를 이용한 접촉 알고리즘은 코드화가 용이하므로, 기존의 복잡한 알고리즘에 대한 좋은 대안이 될 것이다.

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BIAS POINT CONTROL IN SYNTHETIC ANTIFERROMAGNET-BASED SPIN-VALVES

  • Park, J.S.;Lee, S.R.;Kim, Y. K.
    • Proceedings of the Korean Magnestics Society Conference
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    • 2002.12a
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    • pp.52-53
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    • 2002
  • 스핀밸브 구조는 현재 고기록밀도 자기저장 분야에서 그 응용범위가 넓다. 이런 고기록밀도를 달성하기 위해서는 자기저항곡선의 비대칭성 문제가 중요하다. 그러므로 비대칭성 문제를 해결하여 센서의 민감도를 높이기 위해서는 고정층에서 나오는 정자기장을 제어하는 것이 필요하다. 이런 문제를 해결하기 위해 IBM에서 최초로 합성형 스핀밸브 구조가 도입하였다 [1]. 이런 합성형 스핀밸브는 기존의 스핀밸브에 비해 열적으로나 또는 자기적으로 매우 안정한 장점을 가지고 있다. (중략)

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Mesh slide for preventing fall(building, APT etc.) (추락방지 매쉬형 슬라이드)

  • Yang, Seung_gyu;Kwon, Young_hyuk
    • Proceedings of the Korean Society of Disaster Information Conference
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    • 2015.11a
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    • pp.270-271
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    • 2015
  • 본 논문은 추락 방지장치가 형성된 창문에 관한 것으로, 일반적인 형태의 공동주택 여닫이 창문은 사각틀 형태로 된 창틀의 내 창문이 슬라이드 가능하게 끼워져 있고, 창문을 개방 시, 창틀에 해충방지용 방충망이 설치되어 있지만, 종래의 방충망은 구조적으로 매우 취약하여 찢어지거나 휘면서 창틀로부터 쉽게 이탈되어 쉽게 추락사고가 발생하였다. 이러한 문제점을 해소하기 위해서 본 기술을 적용한 창문 설치 시, 개방했을 경우에만 체인 안전망이 형성되고, 창문을 닫았을 경우에는 체인 안전망이 창틀 또는 창문틀에 수용되어 보이지 않게 되어 미관을 해치지 않으면서도 추락 사고를 방지하여 안정성을 보장하는 효과를 거두었다.

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Characterization of Working Electrode Using by Hydrothermal and Electrophoretic Deposition for Dye Sensitized Solar Cells

  • Gong, Jae-Seok;Choe, Yun-Su;Park, Min-Ho;Jeong, Su-Chang;Choe, Hyeon-Gwang;Jeon, Min-Hyeon
    • Proceedings of the Korean Vacuum Society Conference
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    • 2013.02a
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    • pp.308-308
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    • 2013
  • 본 연구에 염료감응형 태양전지(Dye Sensitized Solar Cells; DSSCs)의 광전변환효율을 높이기 위해 작업전극에 새로운 구조의 광투과층 및 산란층을 도입하였다. DSSCs 작업전극의 빛을 투과시키는 투과층에 크기가 10 nm 이하의 nanoparticle $TiO_2$를 적용하고, 투과된 빛이 산란되어 많은 전자가 여기 될 수 있도록 기존의 큰 입자 사이즈였던 산란층을 이용하는 대신 $TiO_2$ nanorod 및 nanotube 형태의 구조를 도입하여 기존의 작업전극과 비교하였다. 산란층에서 방향성을 가지는 rutile 상의 $TiO_2$는 저온에서 안정적인 anatase 상의 $TiO_2$보다 화학적으로 안정하며, 높은 산란율을 가지고, 광에 의해 여기된 전자를 직접적으로 집전전극에 전달해 줌으로서 소자의 효율을 증가시킨다고 보고되고 있다. Rutile 상의 $TiO_2$ 층 제작 시 수열합성법을 이용하면 nanorod 모양의 $TiO_2$층을 형성할 수 있고, 이와 같은 방법으로 성장시킨 산란층에 전기영동법의 식각 효과를 사용하면 nanotube 모양의 $TiO_2$층을 성장시킬 수 있어 산란효과의 극대화 및 전극의 표면적을 넓히는 장점이 있다. 각각의 방법을 이용하여 만든 구조 위에 입자 크기 10 nm의 $TiO_2$를 Dr blade 방법으로 도포하여 double layer (산란층+흡수층)로 구성된 작업 전극을 이용한 DSSCs를 제작한 후 I-V curve와 EIS (Electrochemical Impedance Spectroscopy)를 측정하여 효율 및 전기화학적 특성을 분석하였다.

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A Study on the Development of Force Limiting Devices of Cross-Section Cutting Types (단면절삭형 응력제한 장치의 개발에 관한 연구)

  • Kim, Cheol Hwan;Chae, Won Tak
    • Journal of Korean Society of Steel Construction
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    • v.27 no.1
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    • pp.77-85
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    • 2015
  • This paper describes the development of force limiting device(FLD). The FLD could induce compressive yield before occurring elastic buckling for slender member under compressive load. Therefore, it might prevent reduction of load carrying capacity by elastic buckling and the structures with the devices would behave stable. A new type of FLD reduced cross area is proposed in this study different to existing studies like as out of plane type, slit type and folded plate type. The parameters of specimens are depth, width and number of cutting. The structural capacity and characteristics of proposed types were verified by experiment and FEM analysis. The FLD of cutting type is efficient in compressive member.

Rapid Theraml Annealing Effect on the Magnetic Tunnel Junction with MgO Tunnel Barrier (MgO 절연막을 갖는 자기 터널 접합구조에서의 급속 열처리 효과)

  • Min, Kiljoon;Lee, Kyungil;Kim, Taewan;Jang, Joonyeon
    • Journal of the Korean Magnetics Society
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    • v.25 no.2
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    • pp.47-51
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    • 2015
  • To achieve a high tunneling magneto resistance (TMR) of sputtered magnetic tunnel junctions (MTJs) with an MgO barrier, the annealing process is indispensable. The structural and compositional changes as consequences of the annealing greatly affect the spin-dependent transport properties of MTJs. Higher TMR could be obtained for MTJs annealed at higher annealing temperature. The diffusion of Ru, Mn and/or Ta in the MTJs may occur during annealing process, which is known to be detrimental to spin-dependent tunneling effect. The rapid thermal annealing (RTA) process was used for annealing the MTJs with synthetic antiferromagnets. To suppress the diffusion of Mn, Ru and/or Ta in the MTJs, the process time and temperature of RTA were minutely controlled.

A Development of NURBS-Based Pre and Post Processor for Structural Analysis of Free-Shaped Beam (자유형상 보요소 해석을 위한 NURBS기반의 전·후처리 모듈 개발)

  • Jung, Sung-Jin;Park, Se-Hee
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.16 no.10
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    • pp.6673-6678
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    • 2015
  • Recently, the free form buildings are constructed frequently. Exterior and interior components of these buildings have the free cross-section and a curved shape. So, There are many usages of classical finite element having tapered section and free-style shape. Some general commercial applications like ETABS, SAP2000, MIDAS are usually used for the safety evaluation of the free form structures. However, there are some limits in the accuracy of structural analysis and the length of analysis time because a very complicated finite element mesh have to be used. Therefore, In this study, a pre and post program module was developed to take advantage of general 3-D curved beam element which has a free-style curved shape and mathematical backgrounds. Pre-post processing module has been developed in this study was developed to control the curvature of the curved members by the NURBS control points. As a result, fast geometric modeling than was possible commercial applications. In addition, realistic depiction of the shape and behavior patterns were possible because of the free-form building allows visual check of the free form.

A Study on Ground Response Curve for Tunnel Design (터널 설계를 위한 지반응답곡선)

  • Lee, Song;Ahn, Sung-Hak;Ahn, Tae Hun
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.7 no.1
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    • pp.181-190
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    • 2003
  • The convergence-confinement method is an attempt to evaluate tunnel stability conditions by means of a mathematical model and a ground response curve. In this study, the convergence-confinement method by numerical model was examined. This method don't need the basic assumptions for a mathematical model. Also This is applicable to general tunnel. According to the results of this study, the change of shotcrete stiffness and the load-distribution ratio used for 2-Dimension numerical analysis are not signficant factors. The ground response curve and the support reaction curve are mutually dependent. Especially the support reaction curve depends upon the ground response curve. The mechanism of tunnel must be analyzed by the interaction between support and ground. Consequently the stability of tunnel must be qualitatively investigated by a ground response curve and quantitatively adjudged by a numerical analysis for the reasonable design of tunnel.

A Study on the Nonlinear Structural Analysis of Barrel Vault-Typed Membrane Roof Structures Considering the Orthotropic Material (직교이방성을 고려한 Barrel Vault형 지붕 막구조물의 비선형 구조해석에 관한 연구)

  • Kim, Seung-Deog;Jeong, Eul-Seok;Baek, In-Seong
    • Journal of Korean Association for Spatial Structures
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    • v.5 no.1 s.15
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    • pp.91-98
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    • 2005
  • Membrane structures, a kind of lightweight soft structural system, are used for spatial structures. The material property of the membrane has strong axial stiffness, but little bending stiffness. Therefore membrane structures are unstable structures initially. These soft structures need to be introduced initial stresses first because of its initial unstable state, and it happens large deformation phenomenon. To find the structural shape after large deformation caused by initial stiffness introduced, we need the shape analysis considering geometric nonlinearity in structural design procedure In this study, we analyze the soft spatial structures by the NASS which is the program for nonlinear analysis. The analytic model is a roof membrane structures of Barrel Vault-Type. We have done the shape analysis and the stress-deformation analysis considering the orthotropic material, and then study the safety.

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A Experimental Study on the Structural Performance of Precast Bracket under Precast Road Deck Slab of Double Deck Tunnel (복층터널에서 도로용 중간슬래브와 연결되는 조립식 브라켓의 구조성능에 관한 실험연구)

  • Kim, Bo Yeon;Lee, Doo Sung;Kim, Tae Kyun;Kim, Young Jin
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.37 no.4
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    • pp.647-657
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    • 2017
  • The main purpose of this study is to investigate the static & dynamic behavior of a precast bracket under precast road deck slab of double deck tunnel. In order to improve the construction speed, the field prefabricated bracket to connect the intermediate slab to the precast shield tunnel lining structure has been developed in the 'SPC (Steel Precast Concrete) bracket'. The experiments were performed for the full scale model in order to evaluate the performance of the 'SPC bracket', the structural stability was verified through the FEM analysis. The result of static loading test, no deformations or cracks of the bracket undergo the ultimate load was investigated. In addition, no pulling or deformation of the chemical anchor for fixing the bracket was measured. As a result of dynamic loading test, it was investigated that there is no problem in the chemical anchor for fixing the bracket. FEM analysis showed similar behavior to static load test and it was determined that there is no problem in serviceability and structural safety.