• Title/Summary/Keyword: U.J.S.

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CORRELATION BETWEEN J-INTEGRAL AND CMOD IN IMPACT BEHAVIOR OF 3-POINT BEND SPECIMEN

  • Han, M.S.;Cho, J.U.
    • International Journal of Automotive Technology
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    • v.7 no.3
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    • pp.337-343
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    • 2006

  • Numerical calculations are made in order to find a possible correlation between the J-integral and the crack mouth opening displacement(CMOD) in dynamic nonlinear fracture experiments of 3-point bend(3PB) specimens. Both elastic-plastic and elastic-viscoplastic materials are considered at different impact velocities. The J-integral may be estimated from the crack mouth opening displacement which can be measured directly from photographs taken during dynamic experiments.

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Analysis of a Two-Phases System of Mass Transfer and Electro-Reduction of Uranium(VI) in Nitric Acid-Hydrazine Media (질산-하이드라이진 매질에서 우라늄(VI)의 물질전달과 전기적 환원을 갖는 이 상계의 해석)

  • Kim, K.W.;Yoo, J.H.;Park, H.S.;Kim, J.D.;Aoyagi, H.;Yoshida, Z.
    • Nuclear Engineering and Technology
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    • v.27 no.2
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    • pp.216-225
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    • 1995

  • Simulation for a dynamic analysis of the electrolytic preparation of U(IV) in two-phases system, which consisted of mass transfer of U(VI) from TBP phase into HNO$_3$ solution and electrolytic re-duction of U(VI) to U(IV) at a cathode in aqueous phase, was carried out in order to establish the most suitable operating condition and best electrode area as basic design data for the system. It was found that maintaining an appropriate mass transfer rate was more significant rather than enlarging the surface area of the cathode for more effective production yield of U(IV). The electrode area and the operation time affected deeply the production composition of U(IV) in the resulting aqueous phase. And optimal electrode areas ore evaluated to meet production criteria of U(IV) of resulting solution in several system conditions. Though about 0.37M HNO$_3$ was preferable to prepare the solution of U(IV), nitric acid concentration should be higher than 0.5M to prevent a hydrolysis of U(IV) in the aqueous phase.

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The Development of 35kJ/s High Voltage Capacitor Charger (35kJ/s 고전압 커패시터 충전장치 개발)

  • Jang, S.R.;Ryoo, H.J.;Kim, J.S.
    • Proceedings of the KIEE Conference
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    • 2008.07a
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    • pp.988-989
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    • 2008

  • This paper describes a rapid pulsed power charging system for pulsed power application. It is capable of charging 35kJ/s energy up to 0.47uF 25kV within 3ms and maximum pulse repetition rate of 300 pps can be achieved. The charger is designed based on three-phase series resonant inverter followed by air cooled set-up transformers thus it has many advantages of lower weight, small size and high efficiency compared with large bulky traditional pulse charger system. Detail design procedure of resonant inverter and high voltage transformers is explained. Experimental results carried out at different condition and its results shows 90% efficiency at full load condition.

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