• 한국정밀공학회지
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• 제20권6호
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• pp.113-122
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• 2003

Topology optimization is begun with layout optimization that is attributed to Rozvany and Prager of the 1960's. They claimed that structure was transformed into truss connecting all the nodes of finite element and optimized by control of its sectional modulus. But, this method is partial topology optimization. General layout optimal design appliable to continum structure was proposed by Bendsoe and Kikuchi in 1988. Topology optimization expresses material stiffness of structure into function of arbitrary variable. If this variable is 1, material exists but if this variable is 0, material doesn't exist. Therefore, topology optimization searches the distribution function of material stiffness for structure. There are a few researchs for simple engineering problem such as topology optimization of square plane structure or truss structure. So, This study applied to topology optimization of table liner for vertical roller mill that is the largest scale in the world. After table liner decreased by 20% of original weight, the structure analysis for first optimized model was performed.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2008년도 추계 학술발표회 제20권2호
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• pp.525-528
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• 2008

고에너지 소비형인 시멘트의 대체 재료로써 고로슬래그의 활용성을 높이기 위해 분쇄 방법과 입자의 분말도 그리고 알칼리 자극제의 종류에 따른 50wt.%의 고로슬래그를 치환한 고로 슬래그 시멘트의 수화 및 물리적 특성을 조사하였다. 알칼리 자극제로써 Ca(OH)$_2$, NaOH, Na$_2$SO$_4$,사용하였고 이런 특성들을 비교하기 위해 자극제를 넣지 않은 무첨가 슬래그 시멘트를 함께 실험하였다. 압축강도 실험에서의 분쇄방법에 차이로는 알칼리 자극제에 관계없이 롤러밀로 분쇄한 슬래그가 대체적으로 높은 강도를 나타내었으며 자극제에 따라서는 재령 7일 이내의 초기강도에서는 분말도와 분쇄방법에 관계없이 Na$_2$SO$_4$>Ca(OH)$_2$>None>NaOH 순으로 나왔으며 28일의 장기강도에선 Ca(OH)$_2$가 가장 높게 나타났다.

• 대한기계학회논문집A
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• 제31권12호
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• pp.1214-1220
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• 2007

The vertical roller mill, which performs the grinding and partly blending of raw material, is the one of the important machine to produce ordinary portland cement. It has been reported that an unexpected fatigue failure occurred in a table liner in the course of grinding portland cement. The life of table liner is estimated to $4{\times}10^7$ cycles in the design stage, but at the field, when its operating time reaches to $2{\times}10^6{\sim}8{\times}10^6$ cycles, the fracture of table liner begins to be found. The fracture of table liner is initiated from the outside edge of grinding path contacting with the grinding roller. Its maintenance normally take 30 % of the total maintenance costs of the roller mill. Therefore, this study shows the clarification of the reasons occurring the fatal destruction of the table liner by fatigue fracture analysis utilizing fracture mechanics and by the finite element method. And, the results from Goodman diagram illustrate relationship of including information on the transition between tensile and bending fatigue strength in the fatigue characterization of table liner.