• Title/Summary/Keyword: 전단 에너지

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Comparison of Shear Strength and Shear Energy for 48Sn-52In Solder Bumps with Variation of Reflow Conditions (리플로우 조건에 따른 Sn-52In 솔더범프의 전단응력과 전단에너지 비교)

  • Choi Jae-Hoon;Oh Tae-Sung
    • Journal of the Microelectronics and Packaging Society
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    • v.12 no.4 s.37
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    • pp.351-357
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    • 2005
  • Comparison of shear strength and shear energy of the 48Sn-52In solder bumps reflowed on Cu UBM were made with variations of reflow temperature from $150^{\circ}C$ to $250^{\circ}C$ and reflow time from 1 min to 20 min to establish an evaluation method for the mechanical reliability of solder bumps. Compared to the shear strength, the shear energy of the Sn-52In solder bumps was much more consistent with the solder reaction behavior and the fracture mode at the Sn-52In/Cu interface, indicating that the bump shear energy can be used as an effective tool to evaluate the mechanical integrity of solder/UBM interface.

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The Shearing Characteristics of Cornstalks for Various Knife Approach Angles and Shear Angles (진입각(進入角) 및 전단각의(剪斷角) 변화(變化)에 따른 옥수수줄기의 전단(剪斷) 특성(特性))

  • Huh, Yun Kun;Myung, Byung Soo
    • Korean Journal of Agricultural Science
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    • v.11 no.2
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    • pp.278-283
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    • 1984
  • Shearing characteristics of cornstalks were investigated under quasi-static conditions at various knife approach angles and shear angles in order to determine their importance to the cutting action of mowers. Corn variety used in this study was pioneer that was grown in the field of Chungnam National University. The results obtained were as follows: 1. The shearing process had two shearing stages in cornstalks, which was different from those of rice and other forage crops due to the hard crust. 2. Force and energy of shear were decreased progresively with height of the cornstalks. 3. The minimum shear force occured at shear angle of about $60^{\circ}$ and approach angle of about $10^{\circ}$ 4. The condition of minimum shear energy coincides with that of minimum shear force. 5. Effects of knife approach angles were more significant than those of shear angle for force and energy of shear.

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Study of the Static Shear Behaviors of Artificial Jointed Rock Specimens Utilizing a Compact CNS Shear Box (Compact CNS shear box를 활용한 모의 절리암석시료의 정적 전단 거동에 관한 연구)

  • Hanlim Kim;Gyeongjo Min;Gyeonggyu Kim;Youngjun Kim;Kyungjae Yun;Jusuk Yang;Sangho Bae;Sangho Cho
    • Tunnel and Underground Space
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    • v.33 no.6
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    • pp.574-593
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    • 2023
  • In this study, the effectiveness and applicability of a newly designed Compact CNS shear box for conducting direct shear tests on jointed rock specimens were investigated. CNS joint shear tests were conducted on jointed rocks with Artificially generated roughness while varying the fracture surface roughness coefficient and initial normal stress conditions. In addition, displacement data were validated by Digital image correlation analysis, fracture patterns were observed, and comparative analysis was conducted with previously studied shear behavior prediction models. Furthermore, the accuracy of the displacement data was confirmed through DIC analysis, the fracture patterns were observed, and the shear properties obtained from the tests were compared with existing models that predict shear behavior. The findings exhibited a strong correlation with specific established empirical models for predicting shear behavior. Furthermore, the potential linkage between the characteristics of shear behavior and fracture patterns was deliberated. In conclusion, the CNS shear box was shown to be applicable and effective in providing data on the shear characteristics of the joint.

The Estimation of Shear Stress in Uniform and Nonuniform Flow by the Entropy Concept (엔트로피 개념을 이용한 개수로에서 등류 및 부등류 흐름의 전단응력 산정)

  • Choo, Yeon Moon;Choo, Tai Ho;Yang, Da Un;Kim, Joong Hoon
    • Journal of Wetlands Research
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    • v.19 no.2
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    • pp.202-210
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    • 2017
  • Shear stress is one of the most important mechanical factors used in various fields and is important for the design of artificial channels. Current shear stresses have been used in the past, but there are factors that are difficult to actually measure or calculate, such as bed shear stress and energy slope in the equation used. In particular, the energy slope is a very difficult factor to estimate, and it is difficult to estimate the slope and flow velocity of the boundary layer although the energy slope can be used to obtain the shear stress distribution. In addition, the bed shear stress among the shear stress distribution is very difficult to measure directly, and the research is somewhat slower than the velocity. In this study, we have studied the simple calculation of the average flow velocity and the shear stress distribution using entropy M without reflecting the energy gradient, and we used existing laboratory data to demonstrate the utility of the applied equation. The stress distribution in the graphs was comparatively analyzed. In the case of the uniform flow and the non-uniform flow, the correlation coefficient was almost identical to 0.930-0.998.

Shear Deformation and Failure Characteristics of Rock-Concrete Discontinuities (암석-콘크리트 불연속면의 전단변형 및 파괴특성에 관한 연구)

  • 홍창우;전석원;황대진;최해문;박의섭
    • Proceedings of the Korean Geotechical Society Conference
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    • 2001.03a
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    • pp.57-64
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    • 2001
  • 암석-콘크리트 불연속면의 전단변형 및 파괴특성을 규명하기 위해 상부 재료를 콘크리트로, 하부 재료를 암석으로 하는 규칙.불규칙 톱니형 시료와 인공 절리시료를 제작하여 실험실 직접전단시험을 실시하였다. 전단과정 동안 하중과 변위 외에 미소파괴음의 계수와 에너지를 측정하여 전단과정의 단계별 특징을 규명하였고 미소파괴음 음원추적을 실시하여 불연속면에서의 거칠기 파괴부분의 변화를 고찰하였다. 또한 암석 불연속면과 암석-콘크리트 불연속면의 거동을 비교하고 거칠기의 불규칙성 증가에 따른 전단거동의 변화를 관찰하였다.

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The Limiting Drift and Energy Dissipation Ratio for Shear Walls Based on Structural Testing (전단벽의 최소 층변위 및 에너지 소산성능)

  • ;;N.M.Hawins
    • Magazine of the Korea Concrete Institute
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    • v.10 no.6
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    • pp.335-343
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    • 1998
  • Recently, new experimental criteria for reinforced concrete frame structures in high seismic regions have been reported in United States. The objective of the criteria is to get more reliable test data which are valid to compare with other test data done by different researchers. The criteria precribe test method of specimens, analysis method of test data, and limiting values needed to specimens like drift angle, energey dissipation ratio, stiffness, and strength. These criteria might be usefel to get objective conclusion. Shear wall structures, which belong to one of earthquake resisting systems, also need this kind of criteria. But, the general response of shear wall structures is a little bit different from that of frame structures since shear wall restrains the horizontal displacement caused by horizontal force and increases the stiffness and strength. The objective of this paper is to propose a criterion for limiting drift and energy dissipation ratio of shear walls based on structural testing. These are the most important values for presenting the capacity of shear walls. Limiting drift and energy dissipation ratios were examined for tests on shear walls having ductile type failures. Test data were analyzed and compared to the results for a suggested acceptance criteria that involve a limiting drift that is a function of aspect ratio and a limiting energy dissipation ratio that is a function of displacement ductility and damping.

Ductility Capacity of Shear-Dominated Steel Plate Walls (전단지배 강판벽의 연성능력)

  • Park, Hong Gun;Choi, In Rak;Jeon , Sang Woo;Kim, Won Ki
    • Journal of Korean Society of Steel Construction
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    • v.18 no.4
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    • pp.457-468
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    • 2006
  • An experimental study was performed to investigate the maximum energy dissipation and the ductility capacity of shear-dominated steel plate walls with thin web plates. Three specimens of three-story plate walls with thin web plates were tested. The parameters for the test specimens were the aspect ratio of the web plate and the shear strength of the column. A concentrically braced frame and a moment-resisting frme were a also tested for comparison. The steel plate walls exhibited much better ductility and energy dissipation capacity than the concentrically braced frame and the moment-resisting frame. The results showed that unlike other structural systems, the sh as well as strength, and can therefore be used as an effective earthquake-resisting system. A method of predicting the energy dissipation capacity of a steel plate wall was proposed.

Case Studies on the Experiments for Long-Term Shear Behavior of Rock Discontinuities (암반 내 불연속면의 장기 전단 거동 평가를 위한 고찰)

  • Juhyi Yim;Saeha Kwon;Seungbeom Choi;Taehyun Kim;Ki-Bok Min
    • Tunnel and Underground Space
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    • v.33 no.1
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    • pp.10-28
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    • 2023
  • Long-term shear behavior of the rock discontinuities should be analyzed and its stability should be evaluated to ensure the long-term stability of a high-level radioactive waste disposal repository. The long-term shear behavior of the discontinuities can be modeled with creep and RSF models. The shear creep test, velocity step test, and slide-hold-slide test can be performed to determine their model parameters or analyze the shear behavior by experiments under various conditions. Testing apparatuses for direct shear, triaxial compression, and biaxial shear were mainly used and improved to reproduce the thermo-hydro-mechanical conditions of local bedrock, and it was confirmed that the shear behavior could vary. In order to design a high-level radioactive waste disposal site in Korea, the long-term behavior of rock discontinuities should be investigated in consideration of rock types, thermo-hydro-mechanical conditions, metamorphism, and restoration of shear resistance.

Strength and Deformation Characteristics of Steel Fiber Reinforced Columns (강섬유 보강 기둥의 강도 및 변형 특성)

  • 장극관;이현호;양승호
    • Journal of the Korea Concrete Institute
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    • v.14 no.1
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    • pp.49-57
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    • 2002
  • As composite materials, the addition of steel fiber with concrete significant)y improves the engineering properties of structural members, notably shear strength and ductility. Flexural strength, fatigue strength, and the capacity to resist cracking are also enhanced. Especially the strengthening effect of steel fiber in shear is to prevent the brittle shear failure. In this study, shear-strengthening effect of steel fiber in RC short columns were investigated from the literature surveys and 10th specimem's member test results. From the test results, following conclusions can be made; the maximum enhancement of shear-strengthening effect can be achieved at about 1.5 % of steel fiber contents, shear strength and ductility capacity were improved remarkably in comparison to stiffness and energy dissipation capacity in steel fiber reinforced concrete.

Development of a Shear Yielding Steel Damper for Concentrically Braced Frames (중심가새골조의 내진성능향상을 위한 전단항복댐퍼의 개발)

  • Ghamar, Ali;Jeong, Seong-Hoon
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.34 no.6
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    • pp.437-443
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    • 2021
  • In this study, the use of a steel yielding damper is considered as an appropriate method to enhance the behavior of CBFs and a steel damper which is economical and straightforward to construct and replace after a severe earthquake is developed. The proposed damper was investigated experimentally and numerically. In addition, a parametric study was performed to evaluate the effect of the three types of damper mechanisms (shear, shear-flexural, and flexural) on the behavior of the proposed damper. The experimental results, as well as the numerical results, indicate that the shear damper exhibits better performance than the other dampers in terms of strength and stiffness.