• 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.

• 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.

• 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.

• Journal of the Korean Wood Science and Technology
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• v.52 no.4
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• pp.343-362
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• 2024

Eurycoma longifolia (pasak bumi) is a popular medicinal plant in Indonesia and is widely used in various products. Its high economic value has caused illegal harvesting and product falsification. Using molecular techniques, the authentication and traceability of E. longifolia derivatives can be controlled to ensure consumer safety. Therefore, this study aimed to authenticate the products and derivatives of E. longifolia (pasak bumi) produced, marketed, and consumed in Indonesia using molecular identification techniques. Genomic DNA from 37 leaf samples collected from the Sumatran mainland and the Riau Islands and six E. longifolia products were amplified and sequenced using trnL-trnF and internal transcribed spacer (ITS) regions. The results revealed that all leaf samples were indeed E. longifolia based on the markers used, with the six products, only the herbal tea product (sample code TCPB) was most likely derived from E. longifolia based on the two regions, suggesting that not all products labelled as E. longifolia in the market are authentic. The results also indicated that several other plants species are used as substitutes or adulterants, including Simaba spp., Simarouba spp., Homalolepis spp., Vernonia gigantea, Elephantopus scaber, Gymnanthemum amygdalinum, Cyanthillium spp., Potentilla lineata, Ailanthus altissima, Geijera paniculata, Hannoa chlorantha, and Dalbergia spp. Klebsiella pneumoniae bacteria were also identified in this study on the outer wooden cup of E. longifolia products. Therefore, this molecular approach is effective in identifying the authenticity of E. longifolia products, with trnL-trnF and ITS as the recommended DNA markers.