• Title, Summary, Keyword: 세장비

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Evaluation and Test of Slenderness Ratio Effect on Buckling Characteristics of Thin Cylindrical Structures Subjecting the Shear Loads (전단하중을 받는 얇은 원통구조물의 세장비에 따른 좌굴특성 평가 및 시험)

  • 구경회;김종범;이재한
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.15 no.3
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    • pp.535-543
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    • 2002
  • The purpose of this paper is to investigate the slenderness ratio effect on buckling characteristics of thin cylindrical structures subjecting the shear loads in detail. To do this, the buckling strength evaluations were carried out with using the evaluation formulae proposed by J. Okada. From the results of the buckling strength evaluations, the three types of staled cylindrical test specimen, which have L/R=3.1, 1.6, and 1.0, are determined for the numerical analyses and tests. From results, target slenderness ratio over L/R=3 results in dominant bending buckling mode, smaller slenderness ratio under L/R=1 results in dominant shear buckling mode, and near L/R=1.6 region shows the mixed buckling mode which has the bending and shear buckling mode simultaneously. Most results of buckling characteristics obtained by the numerical analyses and the evaluation formulae we in good agreement with those of tests.

탈이온수를 절연액으로 사용한 깊은 구멍 가공

  • 서동우;이상민;주종남
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.244-244
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    • 2004
  • 다양한 산업 분야에서 세장비가 높은 구멍 가공의 필요성이 증가하고 있다. 방전 가공은 세장비가 높은 미세 구멍을 가공하는데 매우 효과적인 방법이다. 그러나 일반적인 방전 가공으로는 세장비가 5이상 되는 깊은 구멍을 가공하기가 쉽지 않다 구멍을 가공할 때에 일정 깊이 이상으로 가공이 진행되면 가공 부스러기가 쉽게 배출되지 못하여 방전 집중 현상과 아크 방전이 일어나게 된다. 이로 인해 깊은 구멍 가공이 불가능하게 된다. 그러나 절연액에 초음파를 부가하여 가공을 하면 공구와 가공물 사이의 기공 부스러기가 분산되어 방전 집중 현상과 아크 방전 현상이 사라지고 가공이 원활히 이루어진다.(중략)

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A Study on the Buckling Strength and Effective Length of Tubular Member with Gusset Plate Considering End Restraints (단부구속효과를 고려한 관통 가셋트 부착 강관부재의 좌굴내력 및 유효세장비 산정에 관한 연구)

  • Kim, Woo Bum
    • Journal of Korean Society of Steel Construction
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    • v.15 no.2
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    • pp.159-165
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    • 2003
  • A tubular member with through-gusset plate is often used to transmit axial compression in an electric transmission towers. In current code, the strength of tubular member is evaluated with an effective length factor k=0.9 without considering the deformation of boundary element. A buckling strength of member with end gusset plate is affected by stiffness ratio($\beta$) and the length ratio(G) between main tubular member and end gusset plate. In this study theoretical mechanism based on the elastic buckling behavior was investigated, and finite element analysis was performed to propose a formula for the buckling strength and effective length factor of tubular member in elsatic and inelastic ranges.

차세대 반도체 세정장비 기술동향

  • Jo, Jung-Geun
    • Proceedings of the Korean Society Of Semiconductor Equipment Technology
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    • pp.42-54
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    • 2007
  • ${\blacksquare}$ 매엽실 세정장비의 양산적용 확대 ${\centerdot}$ 역오염 감소로 수율개선, 짧은 TAT ${\centerdot}$ Throughput 개선필요 : Process Module + Wafer Transfer ${\blacksquare}$ 향후 $2{\sim}3$년 동안 세정기술의 패러다임 변화 예상 ${\centerdot}$ 초미세 패턴에서의 입자 제거 대책 (${\sim}22.5nm$), 신재료에 따른 케미컬 대응 (에칭, 부식, 물성변화). ${\blacksquare}$ 세정기술의 통합 솔루션 필요 ${\centerdot}$ 초임계 유체세정 : 극미세 패턴까지도 대응 가능 ${\centerdot}$ 장비와 공정 측면에서 많은 연구 필요

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Flow Variation Analysis of Cavity Depending on Aspect Ratio using EDISON_CFD (EDISON_CFD를 이용한 세장비에 따른 공동의 유동 변화 분석)

  • Ha, Heon-U
    • Proceeding of EDISON Challenge
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    • pp.349-353
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    • 2013
  • 공동주위의 유동에 대한 연구결과를 보면 개방형 공동(L/D<10)과 밀폐형 공동(L/D>13)으로 구별하는 데 개방형 공동은 앞전에서 발생한 자유전단층이 뒷전 부근에 재부착하여 공동을 완전히 연결하므로, 자유전단층과 외부유동과의 상호작용으로 발생하는 심한 압력변화에 의해 진동현상이 나타나게 된다. 이것은 큰 소음을 유발하고, 구조물의 고장 혹은 파괴의 원인이 되기도 하고, 공력 성능 및 안정성에 해를 주고 민감한 계기를 손상 시킬 수도 있다. 본 논문에서는 공동을 연구하기 위해 EDISON_CFD를 사용하여 공동의 시뮬레이션하기 위해 격자를 구성하고 세장비를 각각 1/5, 1/3, 1/2, 1, 2, 5 로 변화를 주어 M=1.5 일 때 밀도, 압력, 마하수와 유동구조를 세장비에 따라 결과를 비교, 분석한다.

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Hysteretic Behavior of Compressive Braces upon Repeated Cyclic Loading Based on the Review of Existing Data (기존 실험 자료를 통한 압축 철골가새의 반복 이력거동에 관한 고찰)

  • Lee, Kangmin
    • Journal of Korean Society of Steel Construction
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    • v.15 no.4
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    • pp.359-368
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    • 2003
  • Design and detailing requirements of seismic provisions for Concentrically Braced Frames (CBF) were specified based on the premise that bracing members with large KL/r and low b/t have superior seismic performance. However, relatively few tests have been done to investigate the cyclic behavior of CBF. Therefore, the question lies on whether the compression member of CBF plays as significant a role as what has been typically assumed by design providers. In this paper, existing experimental data were reviewed to quantify the extent of hysteretic energy achieved by bracing members in past compression tests as well as the extent of degradation of the compression force given repeated cycling loading.

Fluid-Structure Interaction Analysis of High Aspect Ratio Wing for the Prediction of Aero-elasticity (유체-구조 연계 해석기법을 이용한 세장비가 큰 비행체 날개의 공탄성 해석)

  • Lee, Ki-Du;Lee, Young-Shin;Lee, Dae-Yearl;Lee, In-Won
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.38 no.6
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    • pp.547-556
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    • 2010
  • For the safety of aircraft and accuracy of bombs, many companies have researched the new concept of adaptive kit to flying-bombs. For the long distance flying, it's normally used deployed high-aspect ratio wing because of limited volume. The probabilities of large elastic deformation and flutter are increased due to decreased stiffness of high-aspect ratio wing. In this paper, computational fluid dynamics and computational structure dynamics interaction methodology are applied for prediction of aerodynamic characteristics. FLUENT and ABAQUS are used to calculate fluid and structural dynamics. Code-bridge was made base on the compactly supported radial basis function to execute interpolation and mapping. There are some differences between rigid body and fluid-structure interaction analysis which are results of aerodynamics characteristics due to structural deformation. Small successive vibration was observed by interaction.

Determination of True Modulus of Elasticity and Modulus of Rigidity for Domestic Woods with Different Slenderness Ratios Using Nondestructive Tests (서로 다른 세장비에 대한 비파괴실험으로 국산재의 실질탄성계수와 전단탄성계수 결정)

  • Cha, Jae Kyung
    • Journal of the Korean Wood Science and Technology
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    • v.43 no.1
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    • pp.36-42
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    • 2015
  • This study examined true modulus of elasticity (MOE) and modulus of rigidity (G) for domestic woods with different slenderness ratios (L/D) using the static bending and stress wave tests. Bending properties of small clear wood specimen of three domestic wood species were determined at 12% moisture content. The results of this study indicated that both MOR and MOE of domestic woods were affected by the slenderness ratio. As the slenderness ratio increased, MOR and MOE increased. G and true MOE of domestic timber beams were obtained at different slenderness ratios by flexure test and stress wave test. The values reported here can be useful if these species woods are used for structural purposes. However, the reported values are only indicative and do not represent the true average of wood species due to the limited number of specimens tested.