• Title/Summary/Keyword: 화이(華夷)

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Kinetics of the Bromine-Exchange Reaction of Gallium Bromide with Isopropyl Bromide in Nitrobenzene (니트로벤젠 용액내에서의 브롬화갈륨과 브롬화이소프로필의 브롬 교환 반응)

  • Choi, Sang-Up
    • Journal of the Korean Chemical Society
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    • v.14 no.1
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    • pp.85-89
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    • 1970

  • The rate of the bromine-exchange reaction between gallium bromide and isopropyl bromide in nitrobenzene was measured at 19$^{\circ},\;25^{\circ}$ and 40$^{\circ}C$., using isopropyl bromide labelled with Br-82. The results indicated that the exchange reaction was second order with respect to gallium bromide and first order with respect to isopropyl bromide. The third-order rate constant determined at 19$^{\circ}C$. was 3.2 ${\times}10^{-2}l^2{\cdot}mole^{-2}sec^{-1}$. The activation energy, the enthalpy of activation and the entropy of activation for the exchange reaction were also determined.

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Numerical Study on Shotcrete Lining with Steel Reinforcement Using a Fiber Section Element (화이버 단면 요소를 이용한 강재 보강된 숏크리트 라이닝의 수치해석적 연구)

  • Kim, Jeong Soo;Yu, Jee Hwan;Kim, Moon Kyum
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.34 no.3
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    • pp.919-930
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    • 2014

  • In this study, the load capacities and behaviors of a shotcrete member with steel supports, as composite member, are investigated numerically by using a fiber section element. The cross section of a shotcrete lining with steel support is divided into a bundle of fibers, which are allocated nonlinear stress-strain relations and used for determining internal forces. To verify the used approach of the finite element method for shotcrete with steel supports, the load-displacement relations of shotcrete lining obtained by numerical analysis are compared with existing experimental results and are analyzed with the stress distribution of the shotcrete and steel support obtained numerically. As a result, it is shown that the proposed approach can predict the load capacities of each material and the overall nonlinear behavior of shotcrete lining with steel supports. The change of location of the neutral axis and the flexural resistance ratio of each material are also derived from the stress distribution of the cross section of the shotcrete lining with steel supports. From the results, it is concluded that the flexural resistance performance of steel support should be considered in shotcrete lining design.

  • https://doi.org/10.12652/Ksce.2014.34.3.0919 인용 PDF KSCI