• Title, Summary, Keyword: derived cup product

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DERIVED CUP PRODUCT AND (STRICTLY) DERIVED GROUPS

  • Lee, Dae-Woong
    • Bulletin of the Korean Mathematical Society
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    • v.35 no.4
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    • pp.791-807
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    • 1998
  • The purpose of this paper is to construct a ring with unity under the derived cup product on the cochain groups of the inverse system and an isomorphism which is useful as the computation of a derived group by deleting the suitable terms in the directed set D. Moreover we apply these results to the K-theory.

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A CAE Approach for Net-Shape Automobile Stamping Components of Aluminum Alloy (자동차용 알루미늄 합금 정형의 스탬핑 부품 성형을 위한 CAE 기법 개발)

  • Choi, Han-Ho;Ku, Tae-Wan;Hwang, Sang-Moon;Kang, Beom-Soo
    • Journal of the Korean Society for Precision Engineering
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    • v.16 no.10
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    • pp.164-171
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    • 1999
  • An optimum blank design technology is required for near-net of net-shape cold forming using sheets. Originally, the backward tracing scheme has been developed for preform design in bulk forming, and applied to several forming processes successfully. Its key concept is to trace backward from the final desirable configuration to an intermediate preform of initial blocker. A program for initial blank design in sheet forming which contains the capabilities of forward loading simulation by the finite element method and backward tracing simulation, has been developed and proved the effectiveness by applying to a square cup stamping process. In the blank design of square cup stamping, the backward tracing program can produce an optimum blank configuration which forms a sound net-shape cup product without machining after forming. Another general application appears in the blank design of a cup stamping with protruding flanges, one of typical automobile components. The blank configurations derived by backward tracing simulation have been confirmed by a series of loading simulations. The approach or decision of an initial blank configuration presented in this study will be a milestone in fields of sheet forming process design.

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Development of the Backward Tracing Scheme of FEM and Its Application to Initial Blank Design in Sheet Metal Forming (유한요소법을 이용한 역추적기법 개발 및 판재성형의 초기블랭크 형상설계에 적용)

  • 최한호;강경주;구태완;임학진;황상문;강범수
    • Transactions of Materials Processing
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    • v.9 no.4
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    • pp.348-355
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    • 2000
  • The backward tracing scheme(BWT) of the finite element method has been extended lot the design of sheet blank in three-dimensional deformation. Originally the scheme was developed for preform design in bulk forming, and applied to several forming processes successfully. Its key concept is to trace backward from the final desirable configuration to an intermediate preform or initial blocker. A program for initial blank design in sheet forming which contains the capabilities of forward loading simulation by the finite element method and backward tracing simulation, has been developed and proved the effectiveness by applying to a square cup stamping process. In the blank design of square cup stamping, the backward tracing program can produce an optimum blank configuration which forms a sound net-shape cup product without machining after forming. For the confirmation of the analytic result derived from the backward tracing simulations as well as forward loading simulations, a series of experiment were carried out. The experiments include the first trial sheet forming process with a rectangular blank, an improved process with a modified blank preform and the final process with an optimum blank resulted from the backward tracing scheme. The experiments show that the backward tracing scheme has been implemented successfully in blank design of sheet metal forming.

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