• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.37 no.1 s.109
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• pp.17-24
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• 2005

The increase of using low grade ace, the unsorted mixed grade, as fibrous raw materials for the packaging paper results in the increment of fine screen reject owing to the strong tendency to reduce the slot width. Since the most of screen reject consists of undispersed fiber flake, the suitable treatment of the flake could increase the yield of ace recycling and decrease the amount of solid waste. In this work, the novel method combined the mild mechanical treatment by using Tumbling pulper with the biological treatment was developed and applied to the wet strength flake and the fine screen tail line reject originated from a packaging paper mill. The results showed the new method could provide much better efficiency for the disintegration of undispersed flake and for the recovery of fiber from the rejects. The application of the laboratory scaled-Pack pulper showed the possible separation technique for mill application by fractioning effectively the fiber from the treated solid waste.

• Korean Journal of Materials Research
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• v.7 no.4
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• pp.339-346
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• 1997

회전 불밀에 있어서 볼의 운동을 비선형 spring과 비선형 deshpot로 구성된 Kelvin모델을 사용한 DEM(Distinct Element Method;개별요소법)에 의하여 2차원으로 해석하였다. 모델에 있어서 점성계수는 볼과 밀벽사이의 반발실험 데이타로 부터 결정하였다. 각볼의 동적인 운동은 비선형 점탄성과 Newton의 운동법칙를 기초로하여 모사되었다. 밀이 회전하는 동안 볼의 궤적과 동적인 운동은 실제 실험에 의한 밀내에서의 볼의 운동고 잘 일치하였다. 본 연구에서 제안된 모델 시뮬레이션은 회전 볼밀내의 실제의 3차원인 볼의 운동에 대한 해석에 중요한 단서가 될 수 있었다. 볼의 운동고 운동에너지는 회전 볼밀의 속도와 볼의 충진율에 의해 크게 영향을 받았다.

• Journal of the Korean Geographical Society
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• v.43 no.6
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• pp.808-823
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• 2008

Sediment abrasion in rivers is caused by the interaction between bedrock channel bed and sediment particles transported through the river. Abrasion rate of sediment particles in rivers is controlled by two major factors; Sediment transport conditions including hydraulic conditions form the erosive forces and physical and chemical strengths of the particles form a resistance force against abrasion and other erosional processes. Physical experiments were performed to find the role of each variable on sediment abrasion process. Total 266 sediment particles were used in this experiment. All sediment particles were divided into 11 independent sediment groups with sediment particle size and sediment loads. Each sediment groups were abraded in tumbling mill for up to 8 hours. Changes in weight were recorded by run and total: 2,128 cases of abrasion rate were recoded. Physical strength of rock particles was measured with point load strength index. It is found that sediment abrasion rate has a negative functional relationship point load strength index ($I_{a(50)}$) ($R^2=0.22$). It was suggested that physical strength of sediment particles set the "maximum possible abrasion rate'. As sediment flux increases, abrasion rates of sediment particles with similar point load strength index were changed. It could be concluded that not only physical characteristics of sediment particles, but also sediment transport conditions control sediment abrasion rates.