• Title/Summary/Keyword: Expansion factor

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The Method for Determining the Effectiveness Factor(k value) of Concrete Expansion Anchors in accordance with ACI 355.2 (ACI 355.2에 의한 콘크리트 확장앵커의 유효계수(k값) 결정방법)

  • Lee, Byung Soo
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2020.06a
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    • pp.151-152
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    • 2020
  • Recently, concrete expansion anchors which are a type of post-installed mechanical anchors are widely used in reinforcement concrete structures. In order to be used in the reinforced concrete structures designed in accordance with ACI 318-19 or ACI 349-13, the structural performance tests of the concrete expansion anchors should be conducted in accordance with ACI 355.2. The effectiveness factor(k) of concrete expansion anchors should be determined through the reference tests and used for the design of anchorage to concrete according to ACI 318-19 or ACI 349-13. In this study, we will look into the method for determining the effectiveness factor(k) of concrete expansion anchors and anchorage design process of concrete expansion anchors by using the effectiveness factor(k) in accordance with ACI 349-19.

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Biomass Expansion Factors for Pinus koraiensis Forests in Korea

  • Li, Xiaodong;Yi, Myong-Jong;Jeong, Mi-Jeong;Son, Yo-Whan;Park, Pil-Sun;Lee, Kyeong-Hak;Son, Yeong-Mo;Kim, Rae-Hyun
    • Journal of Korean Society of Forest Science
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    • v.99 no.5
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    • pp.693-697
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    • 2010
  • Biomass expansion factors that convert the timber volume (or dry weight) to biomass are used to estimate the forest biomass and account for the carbon budget on a national and regional scale. This study estimated the biomass conversion and expansion factors (BCEF), root to shoot ratio (R), biomass expansion factors (BEF) and ecosystem biomass expansion factor (EBEF) of Korean pine (Pinus koraiensis) forests based on direct field surveys and publications in Korea. The mean BCEF, BEF, and R was 0.6438 Mg $m^{-3}$ (n = 7, SD = 0.1286), 1.6380 (n = 27, SD = 0.1830), and 0.2653 (n = 14, SD = 0.0698), respectively. The mean EBEF, which is a simple method for estimating the understory biomass in Korean pine forest ecosystems, was 1.0218 (n = 6, SD = 0.0090). The values of the biomass expansion factors in this study estimated the Korean pine forest biomass with more precision than the default values given by the IPCC (2003, 2006).

The Relation Between Magnetic Field Configuration And The Flux Expansion Factor

  • Lee, Hwan-Hee;Magara, Tetsuya;An, Jun-Mo;Kang, Ji-Hye
    • The Bulletin of The Korean Astronomical Society
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    • v.37 no.1
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    • pp.85.1-85.1
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    • 2012
  • In this study we use three-dimensional magnetohydrodynamic simulations of flux emergence from solar subsurface layer to corona. In order to study the twist parameter of magnetic field we compare the simulations for strongly twisted and weakly twisted cases. Based on the results, we derive a flux expansion factor of selected flux tubes which is a ratio of expanded cross section to the one measured at the footpoint of the flux tube. To understand the effect of flux expansion factor, we make a comparison between magnetic field configuration and the expansion factor. By using a fitting function of hyperbolic tangent we derive noticeable correlations among the strength of the vertical magnetic field, current density and expansion factor. We discuss what these results tell about the relationship between the twist of emerging field and the mechanism for the solar wind.

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Study on Optimum Shape of Expansion Joint (신축조인트의 최적화형상에 대한 연구)

  • Han, Moonsik;Ahn, Junghyun;Yang, Chulho
    • Transactions of the Korean Society of Automotive Engineers
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    • v.21 no.2
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    • pp.154-158
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    • 2013
  • Expansion joint has been utilized in many areas including automotive bellows for exhaust system. Usage of expansion joint has been increased due to its inherent flexibility and excellent anti-vibration property. Simple shape of expansion joint is modeled to understand the behavior of joint system. 27 design cases using 3 design factors with 3 levels are constructed by design of experiment. Each case is simulated to find the most influential design factors. Response for this study, maximum stress in the expansion joint, has been used to determine main design factors of joint. Among the 3 design factors, factor B has affected greatly a response in the formation of optimum shape of joint. Also, interaction factor, $A{\times}B$, has also showed its influence to the response of joint. This study showed that design of experiment combined with finite element analysis could be used in the design decision process effectively in the design of expansion joint.

Expansion Factors of Cement Mortar Containing Expanding Admixture (팽창재를 포함한 시멘트 모르터의 팽창 요인)

  • 황인동;염희남;정윤중
    • Journal of the Korean Ceramic Society
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    • v.37 no.6
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    • pp.576-582
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    • 2000
  • Two type of expanding cement generally referred to as CSA with Hauyne(3CaO 3Al2O3 CaSO4) and Quick lime(CaO). Hauyne is formed to ettringite when there are presented with CaO and CaSO4, and CaO reacts wtih water to form Ca(OH)2. REcently, the mechanism of compensation and expand mortar or concrete tend to same and it has been used improving on its shrink property. The volume of cement paste varies with its water content shrink with drying and re-wetting. Concrete and mortar works are required shrinking compensation and expansion properties to reduce of potential crack. The use of expansion cement may improve on its shrinking volume changes. CSA dosages for shrinking compensation limited by cement weight, but obtained difference expansion rate with varied W/C or inorganic admixture. This paper studies expansion rate according to expansion cement dosages, water and inorganic admixtures as Silica fume. Therefor, the expansion factor has to considered before the application.

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Analysis of the Residual Stress due to Cold Expansion and Stress Intensity Factor in CT specimen Using Finite Element Method (유한요소법을 이용한 CT 시편의 홀확장 잔류응력 및 응력확대계수 해석)

  • Jang, Jae-Soon;Yang, Won-Ho;Kim, Cheol;Ko, Myung-Hoon;Cho, Myoung-Rae
    • Proceedings of the KSME Conference
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    • 2001.06a
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    • pp.603-608
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    • 2001
  • Recently, cold expansion of fastener holes is commonly used in the aerospace industry to increase the fatigue endurance of airframes. Cold expansion process is used as the retardation of crack initiation in the hole. This treatment leads to an improvement of fatigue behavior due to the compressive residual stresses developed on the hole surface. The residual stress profile depends on the cold expansion ratio. In the present paper, it is shown that residual stress is redistributed due to the application of cold expansion process for CT specimen. It is further shown that residual stress increases in proportion to cold expansion ratio. It is thought that crack growth rate increases as cold expansion ratio.

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Angular Momentum Effect of Electron Scattering with Reduced Angular Momentum Expansion (축약 각운동량 전개(Reduced Angular Momentum Expansion) 방법으로 해석한 전자 산란의 각 운동량 효과)

  • Kang, J.H.
    • Journal of the Korean Magnetics Society
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    • v.18 no.1
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    • pp.36-38
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    • 2008
  • We calculate the electron scattering amplitude with reduced angular momentum expansion(RAME) and compare it with the plane wave approximation. By using WKB approximation it is shown that the curvature correction factor given by RAME is originated from the source wave centrifugal potential energy. The factor also can be understood as an effective wave number correction factor in plane wave approximation. Angular momentum and its relationship with scattering amplitude is explicitly shown.

Analysis of the Residual Stress due to Cold Expansion and Stress Intensity Factor in CT Specimen Using Finite Element Method (유한요소법을 이용한 CT 시편의 홀확장 잔류응력 및 응력확대계수 해석)

  • Jang, Jae-Soon;Yang, Won-Ho;Kim, Cheol;Ko, Myung-Hoon;Cho, Myoung-Rae
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.26 no.5
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    • pp.890-895
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    • 2002
  • Cold expansion method is retarded of crack initiation due to the compressive residual stress developed on the hole surface. Previous research has just been study about residual stress distribution in the hole surrounding. But, The purpose of this study was to improve the understanding of the residual stress effect in hole surrounding as crack growth from another hole. In this paper, it is shown that residual stress is redistributed due to the application of cold expansion process for CT specimen using finite element method. It is further shown that tensile stress increases in proportion to cold expansion ratio in the vicinity of crack. It is thought that stress intensity factor increases with cold expansion ratio.

Analysis of Fatigue Strength in Expansion Joint Weldment of Bridge (교량 신축이음창치 용접부의 피로강도 해석)

  • 이용복;정진성;박영근;김태윤;김호경;박상흡
    • Journal of Welding and Joining
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    • v.16 no.4
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    • pp.73-82
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    • 1998
  • This paper is especially concerned with the weldment between support beam and square bar that plays important roles in control box of Expansion Joint as a brdige structure. Fatigue strength ({TEX}$$\sigma$_{ult}${/TEX}) of the weldment is dependent on notch factor ({TEX}$K_{f}${/TEX}) become important factors to predict fatigue life. The fatigue notch sensitivity (η) for metals can be divided into two types ; high and low notch sensitivity. In this work, the Expansion Joint weldment was found to have low notch sensitivity. The maximum strain distribution during static loading is similar to the FEM analysis. Fatigue test of real structure was performed up to {TEX}$10^{6}${/TEX} cycles to be compared with predicted endurance limit.

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Notes on the biomass expansion factors of Quercus mongolica and Quercus variabilis forests in Korea

  • Li, Xiaodong;Son, Yeong-Mo;Lee, Kyeong-Hak;Kim, Rae-Hyun;Yi, Myong-Jong;Son, Yo-Whan
    • Journal of Ecology and Environment
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    • v.35 no.3
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    • pp.243-249
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    • 2012
  • Biomass expansion factors, which convert timber volume (or dry weight) to biomass, are used for estimating the forest biomass and accounting for the carbon budget at a regional or national scale. We estimated the biomass conversion and expansion factors (BCEF), biomass expansion factors (BEF), root to shoot ratio (R), and ecosystem biomass expansion factor (EBEF) for Quercus mongolica Fisch. and Quercus variabilis Bl. forests based on publications in Korea. The mean BCEF, BEF, and R for Q. mongolica was 1.0383 Mg/$m^3$ (N = 27; standard deviation [SD], 0.5515), 1.3572 (N = 27; SD, 0.1355), and 0.2017 (N = 32; SD, 0.0447), respectively. The mean BCEF, BEF, and R for Q. variabilis was 0.7164 Mg/$m^3$ (N = 17; SD, 0.3232), 1.2464 (N = 17; SD, 0.0823), and 0.1660 (N = 8; SD, 0.0632), respectively. The mean EBEF, as a simple method for estimating the ground vegetation biomass, was 1.0216 (N = 7; SD, 0.0232) for Q. mongolica forest ecosystems, and 1.0496 (N = 8; SD, 0.0725) for Q. variabilis forest ecosystems. The biomass expansion factor values in this study may be better estimates of forest biomass in Q. mongolica or Q. variabilis forests of Korea compared with the default values given by the Intergovernmental Panel on Climate Change (IPCC).