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정태훈(Taehoon Chung) 한국생산제조학회 2005 한국공작기계학회 추계학술대회논문집 Vol.2005 No.-
By the use of a similar numerical method as that in the previous paper, the forming limit strain by coating method of clad sheet metals is investigated, in which the FEM is applied and J2G(]2-Gotoh's comer theory) is utilized as the plasticity constitutive equation. Functionally Gradient Material are stretched in a plane-strain state, with various work-hardening exponent n-values and thicknesses of each layer. Processes of shear-band formation in such composite sheets are clearly illustrated. It is concluded that, in the bonded state, the higher limiting strain of one layer is reduced due to the lower limiting strain of the other layer and vice versa, and does not necessarily obey the rule of linear combination of the limiting strain of each layer weighted according thickness.
정태훈 한국공작기계학회 2004 한국공작기계학회 춘계학술대회논문집 Vol.2004 No.-
By the use of a similar numerical method as that in the previous paper, the forming limit strain by coating method of clad sheet metals is investigated, in which the FEM is applied and J2G(J₂-Gotoh's corner theory) is utilized as the plasticity constitutive equation. Declined Multilayer Metals Materials are stretched in a plane-strain state, with various work-hardening exponent n-values and thicknesses of each layer. Processes of shear-band formation in such composite sheets are clearly illustrated. It is concluded that, in the bonded state, the higher limiting strain of one layer is reduced due to the lower limiting strain of the other layer and vice versa, and does not necessarily obey the rule of linear combination of the limiting strain of each layer weighted according thickness.
정태훈 한국공작기계학회 2002 한국공작기계학회 추계학술대회논문집 Vol.2002 No.-
In this paper, Compression in the case where dissimilar blocks arc twinned variously are carried out in the condition of lubricated interface. The degree of growth is experimentally investigated. Moreover, numerical simulations are carried out by the elastic-plastic FEM for the case of the dissimilar blocks with the initial sawtooth angle of 60°. The dissimilar blocks are twinned, larger difference between material properties leads smaller growth, and the degreased interface leads smaller growth than that in the lubricated one. Furthermore, by the simulation of compression where dissimilar blocks are twinned, it is confirmed that the tendency of the general deformation pattern is very similar to the experiment.
정태훈,이경전 한국경영과학회 2000 經營 科學 Vol.17 No.3
This paper performs a case study on an Internet business networking company, oneQ.com. We define the functions of Internet business networker and discuss its characteristics such as network effect, lock-in effect, and increasing returns etc. Through reviewing the business models, strategies, and implemented technologies of the oneQ.com, we investigate the applicability and effectiveness of the Internet business networker as well as its research implications.
정태훈 한국공작기계학회 2003 한국공작기계학회 춘계학술대회논문집 Vol.2003 No.-
By the use of a similar numerical method as that in the previous paper, the forming limit strain by coating method of clad sheet metals is investigated, in which the FEM is applied and J₂G(J₂-Gotoh's corner theory) is utilized as the plasticity constitutive equation. Clad two-layer sheets and sheets bonded with dissimilar sheets on both surface planes are stretched in a plane-strain state, with various work-hardening exponent n-values and thicknesses of each layer. Processes of shear-band formation in such composite sheets are clearly illustrated. It is concluded that, in the clad state, the higher limiting strain of one layer is reduced due to the lower limiting strain of the other layer and vice versa, and does not necessarily obey the rule of linear combination of the limiting strain of each layer weighted according thickness.
정태훈 한국공작기계학회 2004 한국공작기계학회 추계학술대회논문집 Vol.2004 No.-
In press forming of sheet metals, the material sheet is usually subjected to very large plastic strain under in-plane stressing. Moreover, the sheet also very often is subjected to out-of-plane compressive force between tools such as the upper and lower dies, the blank holder and the die, and so forth. In this paper, it is clearly demonstrated theoretically that out-of-plane stress may notably raise the forming limit strain and thus it can be effectively utilized to avoid earlier fracture of the sheet in press forming.
정태훈 한국공작기계학회 2001 한국생산제조학회지 Vol.10 No.1
By the use of a similar numerical method as that the forming limit strain by coating method of coated sheet metals is investigated, in which the FEM is applied and J2G(J2-Gotoh's corner theory) is utilized as the plasticity constitutive equation. Circular bonded sheet metals with dissimilar sheets on both surface planes are stretched in a plane-strain state, with various work-hardening exponent n-values and thicknesses of each layer. Processes of shear-band formation in such composite sheets are clearly illustrated. It is concluded that, in the bonded state, the higher limiting strain of one layer is reduced due to the lower limiting strain of the other layer and vice versa, and does not necessarily obey the rule of linear combination of the limiting strain of each layer weighted according thickness.