• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.10a
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• pp.139-142
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• 2005

Cu-Ni-Zr-Ti bulk amorphous thin strips were produced by multi-pass warm rolling of the amorphous powder at temperatures in the supercooled liquid region. Process variables for rolling of the bulk amorphous strips were properly controlled to prevent onset of crystallization and failure during rolling up to three passes. During rolling of the amorphous powder, both the deformation and densification took place and the newly developed surface on the deformed amorphous particles enhances the consolidation leading to an increase in the strength. The strain state during rolling was analyzed by FEM.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.10a
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• pp.460-462
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• 2005

Asymmetrical rolling was performed with different working roll speeds of upper and lower rolls. In order to promote the shear deformation during asymmetrical rolling, various deformation parameters of initial sheet thickness, rolling reduction, roll speed ratio and roll radius are considered. The evolution of texture during asymmetrical rolling was shown by the calculation of orientation distribution function (ODF). The effect of deformation parameters on shea. deformation were investigated by simulations with the finite element method (FEM). Asymmetrical rolling gave rise to the development of pronounced strain gradients throughout the thickness layers which resulted in the formation of strong texture gradients in the sheet.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2002.05a
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• pp.184-186
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• 2002

The evolution of texture and microstructure during warm rolling and subsequent annealing in aluminium 3004 alloy sheet was investigated by X-ray texture measurements and microstructure observations. Warm rolling at 250$^{\circ}C$ led to the development of strong through thickness texture gradients with shear textures at the surface layer and a regular rolling texture in the center of the sheets. FEM simulations indicated that these texture gradients are caused by pronounced strain gradients throughout the sheet thickness. Upon recrystallization annealing, in the sheet center the characteristic cube-recrystallization texture developed, while in the surface layers with a pronounced shear texture continuous recrystallization took place which led to the formation of a very fine grained microstructure. It is concluded that the very complex strain history in the near-surface layers together with the resulting high work-hardening rate gave rise to the formation of the ultra-fine grains with an average size smaller than 2$\mu\textrm{m}$.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1997.10a
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• pp.210-215
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• 1997

The development of rolling texture is dependent on the various rolling condition. And the geometry of rolling gab and the friction between rolls and rolled material mainly affect the type and sharpness of texture inhomogeneity through thickness. In order to follow the effect of geometry and friction various strain/pass and lubrication condition were applied during cold rolling. In this investigation various strain/pass and lubrication were applied during cold rolling in order to follow the effect rolling gap geometry and friction. More high 1/h was, more weak the ${\beta}$-fiber was and in the condition of l/h > 5 {001}<110> shear texture developed. In adition, rolling without lubrication enhanced the shear texture.

• Transactions of Materials Processing
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• v.17 no.1
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• pp.68-72
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• 2008

In order to investigate the evolution of strain states during screw rolling, the samples of copper rod were rolled in a three-roll screw rolling mill. Microstructure observations and hardness measurements were carried out for examining the deformation history during screw rolling. The finite element method(FEM) was employed to calculate the evolution of strain states during screw rolling. The strain state in the roll gap is quite inhomogeneous through the rod thickness layers. It turned out that shear strain gradients through the thickness layers are reduced by applying a higher reduction.

• Korean Architects
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• no.5 s.409
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• pp.72-77
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• 2003

도시를 온통 콘크리트로 막고 덮던 개발 전성시대의 전환점에서, 우리는 생태 도시환경의 질적 가치에 대해 생각해야 하는 새로운 시대를 맞이하고 있다. 성장과 개발이 곧 행복의 보증수표임을 믿고 달려온 어느 지점에서 그 신기루를 허무하게 체험하며, 유토피아는 현실의 환경 가운데에서만 창조될 수 있음을 고통스럽게 인식하게 된 것이다. 그렇게 개발독재 시대에 복개되었던 청계천과 고가도로는 이 시대의 새로운 화두로 등장하게 되었다. 시민단체를 중심으로 일던 청계천 복원운동은 급기야 서울시장 선거의 첫 번째 정책공방거리로 부상하고, 건설인 출신의 시장 당선과 더불어 2005년을 목표로 일사 천리한 건설을 예정하고 있다. 그러나 일각에서는 걱정의 소리도 만만치 않다. 이미 여러차례에 걸쳐 지적된 기술적, 경제적 문제들 외에도, 이 시대 도시환경의 새로운 패러다임을 짜게 될 사업이기에 심사숙고를 필요로 한다는 것이다. 이러한 여론과는 아랑곳 않고, 서울시는 사뭇 독선적이고 저돌적인 추진을 진행시키고 있다. 과연 청계천 복원사업은 어떻게 이루어져야 하는가? 비록 역사와 문화를 달리하지만, 1970년대에 있었던 프랑스 파리의 레알(Les Halles) 시장 재개발 사업은 우리의 작금의 현실과 관련하여 여러 가지 면에서 공통점을 공유하고 있으며, 교훈으로 삼기에 시사하는 바가 크다.

• YAKHAK HOEJI
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• v.8 no.3
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• pp.85-88
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• 1964

Pantothenic acid and biotin contents in Panax Ginseng roots were determined microbiologically with L. arabinosus 17-5. Detection of the vitamins was achieved by the thin-layer chromatography and PPC. Pantothenic acid and biotin were found at the Rf values of 0.42 and 0.55 respectively on the thin-layer chromatograms. In order to find out whether or not the L. arabinosus growth promoting factors contained in the respective ginseng extracts, as shown by the microbiological assay, were really the vitamins respectively, PPC was carried out. Microbiological assay of the vitamins met with results that the average pantothenic acid content in the roots was 6.6r/g, calculated as Ca-pantothenate, and the average biotin content 9.24 mr/g.

• Transactions of Materials Processing
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• v.3 no.4
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• pp.392-400
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• 1994

The formation of preferred orientations in the cold rolling texture of the Inconel 690 sheets was studied by the x-ray texture measurements and TEM observations. The increasing {220} pole intensity in the plane normal at the higher reductions was related to the {110}<112> texture component. The rolling texture of the Inconel 690 was the pure metal type which could be described by {112}<111>, {123}<634> and {110}<112> orientations. The dislocation cells were found in the near {110}<112> oriented grains. The onset of deformation twins in the {112}<111> oriented grains caused the weakening of {112}<111> and the development of {552}<115> in the rolling texture.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.05a
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• pp.256-259
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• 2009

In order to investigate the effect of strain states attributed to the lubrication during shape rolling, shape rolling for V-sectioned sheets was carried out with and without lubrication. The evolution of strain states during shape rolling was studied by three-dimensional finite element method (FEM). Shape rolling with and without lubrication produces shape-rolled samples in fairly similar outer shapes, since the distribution of normal strain components is nearly independent of the lubrication condition. In contrast, the distribution of shear strain components strongly depends on the lubrication condition.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.10a
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• pp.158-161
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• 2007

In order to investigate the evolution of strain states during screw rolling, the samples of pure copper rod were rolled in a three-roll screw rolling mill. Microstructure observations and hardness measurements were carried out for examining the deformation during screw rolling. In addition, the finite element method (FEM) was employed to calculate. The strain states reveal that the shear strain plays a dominant role in the deformation during screw rolling.