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유한 차분법에 의한 Thin Slab 고속 연속주조의 동적벌징 거동해석
정영진,신건,조기현,강충길,Jeong, Yeong-Jin,Sin, Geon,Jo, Gi-Hyeon,Gang, Chung-Gil 대한기계학회 2000 大韓機械學會論文集A Vol.24 No.7
Continuous casting process has been adopted increasingly in recent years to save both energy and labor. It has experienced a rapid development in the production of semi-finished steel products, rep lacing the conventional route of ingot casting and rolling. In order to achieve this merit, however, more studies about the mechanism between roll and slab are needed. In this paper, a dynamic bulging in steel cast slabs was simulated by considering the solidification and heat transfer. This study is to prevent internal cracks of a slab in a bending and unbending zone. The value of moving strand shell bulging between two supporting rollers under the ferrostatic pressure and slab-self weight has been calculated in terms of creep and elasto-plasticity. The strain and strain rate distributions in solidified shell undergoing a series of bulging are calculated with working boundary conditions.
김덕수,김우승,조기현,Kim, Deok-Su,Kim, U-Seung,Jo, Gi-Hyeon 대한기계학회 2001 大韓機械學會論文集B Vol.25 No.3
The transport phenomena in a wedge-shaped pool of twin-roll continuous caster are affected by the various operating parameters such as the melt-feed pattern, roll-gap thickness, melt-superheat, and casting speed. A computer program has been developed for analyzing the two-dimensional, steady conservation equations for transport phenomena during twin-roll continuous casting process in order to estimate the turbulent melt-flow, temperature fields, and solidification in the wedge-shaped pool. The turbulent characteristics of the melt-flow were considered using a low-Reynolds-number K-$\xi$ turbulence model. Based on the computer program, the effects of the different melt-feed patterns, roll-gap thicknesses, and superheats of melt on the variations of the velocity and temperature distributions, and the mushy solidification were examined. The results show that the liquidus line is located considerably at the upstream region, and in the lower region appear the well-mixed melt-flow and most widely developed mushy zone. Besides, the variation of melt-flow due to varying melt-feed patterns, affects mainly the liquidus line, and scarcely has effects on the solidus line in the outlet region.
쵸크랄스키 Silicon 단결정의 Large Pit과 Flow Pattern defect의 열적 거동과 Large Pit의 소자 수율에의 영향
송영민,문영희,김종오,조기현,Song, Yeong-Min,Mun, Yeong-Hui,Kim, Jong-O,Jo, Gi-Hyeon 한국재료학회 2001 한국재료학회지 Vol.11 No.9
The thermal behavior of Flow Pattern Defect (FPD) and Large Pit (LP) in Czochralski Silicon crystal was investigated by applying high temperature annealing ($\geq$$1100^{\circ}C$) and non-agitated Secco etching. For evaluation of the effect of LP upon device performance/yield, commercial DRAM and ASIC devices were fabricated. The results indicated that high temperature annealing generates LPs whereas it decreases FPD density drastically. However, the origins of FPD and LP seemed to be quite different by not showing any correspondence to their density and the location of LP generation and FPD extinction. By not showing any difference between the performance/yield of devices whose design rule is larger than 0.35 $\mu\textrm{m}$, LP seemed not to have detrimental effects on the performance/yield.