• Title/Summary/Keyword: 임계하중

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Rescue Lift Development Using Structural Analysis (구조해석을 통한 구조용 인양기 개발)

  • Son, In-Soo;Kim, Chang-Ho;Bae, Sung-Ho;Lee, Joon-Yong
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.14 no.1
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    • pp.111-116
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    • 2015
  • There has been a string of negligent accidents at the seaside. In addition, there is a shortage of professional equipment to deal with these negligent accidents at present. The purpose of this paper is to assess the development of a rescue lift using a structural analysis. The critical load of a support pipe on the rescue lift is investigated in this paper. The stability of the rescue lift is also determined in a structural analysis. In the critical load analysis, the effects of variations in the pipe length and the ratio of the moment of inertia are investigated. The total weight of the developed rescue lift is approximately 20.7kg, and the lift passed the load tests.

Buckling and Limit Width-Thickness Ratios of Steel Columns under Compression at Elevated Temperatures (온도 상승에 따른 압축강재의 좌굴 및 한계 판폭두께비)

  • Kang, Seong-Deok;Kim, Jae-Uk;Choi, Hyun-Sik
    • Journal of Korean Association for Spatial Structures
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    • v.12 no.3
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    • pp.55-62
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    • 2012
  • 본 연구는 온도 증가에 따른 압축을 받는 H형 강재의 플랜지와 웨브의 국부 및 전체좌굴응력 내화해석 프로그램 개발과 플랜지와 웨브가 항복파괴전에 국부좌굴이 일어나지 않을 한계 판폭두께비의 상관값을 구하는 프로그램을 개발하는 것이다. 고온에서의 강재의 응력-변형도 관계식은 EC3:Part 1.2를 근거로 하였으며, 비교, 검토를 위하여 영국 BS5950의 강재를 대상으로 온도 증가에 따른 압축을 받는 강재의 플랜지와 웨브의 파괴온도와 하중을 본 연구의 내화해석 프로그램으로 예측하였다. 본 연구는 좌굴 및 항복에 대한 내화해석 프로그램을 개발하는 것을 목적으로 하고 적용 예를 통하여 좌굴 및 한계 판폭두께비를 분석하고 개발 프로그램의 타당성을 검토하였다.

Buckling of Composite Cylindrical Shells Sugjected ot Torsion of Lateral Pressure (비틀림 및 횡압럭을 받고 있는 복합재 원통쉘의 좌굴)

  • Han, Byeong-Gi;Lee, Seong-Hui;Yu, Taek-In
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.20 no.5
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    • pp.1436-1444
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    • 1996
  • The problem ofinstability of laminated circular cylindrical shell under the action of torsio or lateral pressure is investigated. The analysis is based on the Sander's theory for finite deformations of thin shell. The buckling is elastic for thin compoisite shell nad the geometry is assumed to be free of initial imperfections. The equilibrium equations are obrained by usitn the p[erturbation technique. Solution procedure is based on the Galerkin mehtod. The computer program for numerical results is made for several stacking sequence, length-to-radius ratio, and radius-to-thickness ratio. The numerical results of buckling load are present.

The study of bending and buckling behavior of sandwich structure according to design parameter variation (설계변수 변화에 따른 샌드위치 구조물의 굽힘 및 좌굴 거동에 관한 연구)

  • 한근조;안성찬;안성찬;김진영
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.841-844
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    • 1997
  • Sandwich structure is widely used in various fields of industry due to its excellent strength and stiffness compared with weight. We studied the buckling and bending behavior with respect to the variation of design parameters such as length, height, and thickness of honeycomb sandwich core. We found that as the density and the thickness of core become higher, the value of critical bucking load increased significantly. We found that the effect of bending stress due to critical buckling load resulted in high bending stress and the value of bending stress decreased in half according to the increase of length of core. The effect by bending stress is dominant above the portion of the intersection line between bending stress and the effect of buckling is dominant below the potion of it. We could get proper thickness ratio and density of core according to applied load conditions.

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The Eigenvalues and Their Relationships for the Rectangular Frame (4각형 골조의 고유치와 고유치 간의 관계)

  • Lee, Soo-Gon;Kim, Soon-Cheol;Song, Chang-Young;Song, Sang-Yong
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.9 no.3
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    • pp.139-150
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    • 2005
  • Finite element method is applied to the determinations of the two eigenvalues(the elastic critical load and the natural frequence of lateral vibrations) of single story-3 equal bay rectangular frame. The analysis parameters are taper parameter ${\alpha}$ for column, and beam span to column height ratio, ${\beta}$ and second moment area ratio of beam to column, ${\Upsilon}$. Support condition at the column base and sway condition at the column top are also considered in the stability analysis of frame. The changes in the coefficient of eigenvalue are represented by algebraic function of analysis parameter. The coefficients estimated by the proposed algebraic function show good agreement with those determined by finite element method, which suggest the design aid role of the proposed function. By increasing the column axial forces step by step, the corresponding frequencies are also determined, which makes one examine or confirm the relationship suggested by other studies.

Fracture Toughness Evaluation and Influence Parameter Analysis by Numerical Simulation of Brazilian Test (Brazilian시험의 수치해석 시뮬레이션을 통한 파괴인성 산정 및 영향변수 분석)

  • Synn, Joong-Ho;Park, Chan;Shin, Hee-Soon;Chung, Yong-Bok;Lee, Hi-Keun
    • Proceedings of the Korean Society for Rock Mechanics Conference
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    • pp.67-75
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    • 2000
  • The numerical simulation of Brazilian fracture toughness test is carried out using PFC code and the influence parameters are analyzed such as shape of loading plane, size of Brazilian disc and unit panicle of model, loading angle and loading rate. The flattened Brazilian disc is adopted for applying uniform load. The range of loading angle(2$\alpha$) necessary to induce the tensile crack at disc center and to obtain the load-displacement curve giving the critical load for the stable crack propagation is shown as 20$^{\circ}$~40$^{\circ}$. In condition that the loading angle is 20$^{\circ}$, the mode-I fracture toughness is evaluated almost constant in the range of particle size less than I mm and loading rate less than 0.01 mm/s. This range of influence parameters seems appropriate condition for the tensile crack initiation at disc center and the control of stable crack propagation, which can give the reliance in evaluation of fracture toughness by Brazilian test.

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Fracture Toughness Evaluation and Influence Parameter Analysis by Numerical Simulation of Brazilian Test (Brazilian 시험의 수치해석 시뮬레이션을 통한 파괴인성 산정 및 영향변수 분석)

  • Synn, Joong-Ho;Park, Chan;Shin, Hee-Soon;Chung, Yong-Bok;Lee, Hi-Keun
    • Tunnel and Underground Space
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    • v.10 no.3
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    • pp.320-328
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    • 2000
  • The numerical simulation of Brazilian fracture toughness test is carried out using PFC code and the influence parameters are analyzed such as shape of loading plane, size of Brazilian disc and unit particle of model, loading angle and loading rate. The flattened Brazilian disc is adopted for applying uniform load. The range of loading angle(2$\alpha$) necessary to induce the tensile crack at disc center and to obtain the load-displacement curve giving the critical load for the stable crack propagation is shown as 20°∼40°. In condition that the loading angle is 20°, the mode-I fracture toughness is evaluated almost constant in the range of particle size less than 1 mm and loading rate less than 0.01㎜/s. This range of influence parameters seems appropriate condition for the tensile crack initiation at disc center and the control of stable crack propagation, which can give the reliance in evaluation of fracture toughness by Brazilian test.

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Design of Steel Frames using Plastic Hinge Analysis (소성힌지해석을 이용한 강골조 시스템의 설계)

  • Chang, Chun-Ho
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.8 no.3
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    • pp.131-140
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    • 2004
  • The main objective of the research is to develop an algorithm for the optimum design of two dimensional steel frames using refined plastic hinge analysis which considers material and geometrical nonlinearities. Using developed algorithm, an optimum design was perform without calculating an effective length factor of the column (K-factor). A multi-level discrete optimization technique with two parameters has been developed and employed in the optimum design algorithm. The optimization algorithm is applied to structural design with the objective of minimizing the weight of a structure and with constraints on load limit, frame drift, ductility. Various application example is provided to demonstrate the feasibility, validity and efficiency of the developed program.

Variation of Electrical characteristics of the Ni/SiC interface with annealing effect (열처리효과에 따르는 Ni/sic 계면의 전기적 특성)

  • 금병훈;강수창;도석주;제정소;신무환
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.493-496
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    • 1999
  • Ni/3C-SiC 옴믹 접합에 대한 미세구조적-접합 특성과의 상관관계를 규명하였다. 3C-SiC 웨이퍼 위에 저저항 전면 옴믹 적합층을 형성하기 위하여 Ni(t=300$\AA$)을 thermal evaporator를 사용하여 증착하고, 50$0^{\circ}C$, 80$0^{\circ}C$, 103$0^{\circ}C$ 온도에서 30분간(Ar 분위기) 열처리 한 후, scratch test를 실행하여 Ni/3C-SiC의 접착력 특성을 조사하였다. 여러 다른 온도에 따른 Ni/3C-SiC 층의 표면과 계면의 미세구조는 X-ray scattering 법을 사용하였다. 50$0^{\circ}C$ 에서 열처리된 Ni/3C-SiC 층은 가장 낮은 계면 평활도와 가장 높은 표면 평활도를 나타내었다. Ni/3C-SiC 접착력 분석에서 500 $^{\circ}C$ 열처리된 시편의 측정된 임계하중 값은 As-deposited 시편(12 N~ 13 N)보다 훨씬 낮은 2 N~3 N 범위의 값을 보였으나, 열처리 온도가 증가함에 따라 다시 높아지는 경향을 보였다. 미세구조 특성에서는 열처리 온도가 500 $^{\circ}C$ 이상에서는 NiSi$_2$silicides의 domain size는 결정성의 향상에 따라 증가되었다. 결정성 향상이 3C-SiC와 silicides 사이의 격자상수의 낮은 불일치를 완화시키는데 기여 하였 다.

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Geometrically Nonlinear Analysis of Eccentrically Stiffened Plate (편심 보강평판의 기하학적 비선형 해석)

  • Jae-Wook Lee;Kie-Tae Chung;Young-Tae Yang
    • Journal of the Society of Naval Architects of Korea
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    • v.28 no.2
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    • pp.307-317
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    • 1991
  • A displacement-based finite element method is presented for the geometrically nonlinear analysis of eccentrically stiffened plates. The nonlinear degenerated shell and eccentric isobeam(isoparametric beam) elements are formulated on the basis of total Lagrangian and updated Lagrangian descriptions. To describe the stiffener's local plate buckling mode, some additional local degrees of freedom are used in the eccentric isobeam element. The eccentric isobeam element can be affectively employed to model the eccentric stiffener just like the case of the degenerated shell element. A detailed nonlinear analysis including the effects of stiffener's eccentricity is performed to estimate the critical load and the post buckling behaviour of an eccentrically stiffened plate. The critical buckling loads are found higher than analytic plate buckling load but lower than Euler buckling load which are the buckling strength requirements of classification society.

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