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Mould filling analysis of aluminium extrusion dies
A.J. Koopman,H.J.M. Geijselaers,J. Huetink 한국소성가공학회 2010 기타자료 Vol.2010 No.6
During trial pressings of an aluminium extrusion the shape of the first extrudate (nose piece) tells the correctors how to change the die geometry to obtain an acceptable product. In this paper the initial filling of an aluminium extrusion die is analyzed with the objective to predict the shape of the nose piece. The calculation domain is discretized using P1+P1 tetrahedral elements. The analysis is executed as an Eulerian analysis, where the material flows through the mesh. The whole domain is divided in an aluminium domain and an air domain, where the air is modeled as a pseudo material. The interface between the aluminium and the air is tracked by convection of the initial material coordinates. After the aluminium leaves the die, the free surface of the extrusion is calculated by an ALE method. The formulation of the element, the convection of the initial coordinates, the handling of the boundary conditions, the modeling of the air domain and the reconstruction of the free surface after extrusion are treated in this paper. The results of the simulations are compared to results of real extrusions.
Analysis of Activated Sludge Process Upset Due to Filamentous Bulking and Nitrification
金昌元,Ben Koopman 부산대학교 공과대학 1987 硏究報告 Vol.33 No.-
활성 슬러지 공법을 사용하는 하폐수 처리장에서 공장설계 목적 및 운전상황에 비추어 유출수의 BOD_(5) 측정치가 과대히 높은 경우가 있어 그 원인을 규명하고 해결책을 제시하고자 하였다. 하나의 유의한 원인인 팽화 현상은 Type 1701, Thiothrix spp. 및 Type 0041 사상균의 과대성장으로 인하여 발생하였음을 발견하였다. 이러한 사상균들에 의한 팽화현상의 제어를 위하여 장기적인 대책 수립의 필요성과 함께 단기적으로 반송슬러지 염소 주입법이 제안되었다. 유출수의 높은 BOD_(5) 측정치에 관련된 다른 하나의 원인은 BOD 실험시에 발생된 질산화 반응임이 Nitrite 및 Nitrate 농도의 측정으로 확인되었다. 질산화 박테리아의 근원을 찾아내기 위하여 2회에 걸쳐 각 1주씩 유의한 몇 개의 시료 채취 장소에서 유출수 시료를 채취하여 BOD_(5) 측정치를 비교하였다. 그 결과 질산화 박테리아의 근원은 현장에 설치된 유출수의 시료 채취시설임을 발견하였다. BOD 실험시 질산화 박테리아가 시료와 함께 유입되는 것을 방지하기 위하여 현장 시료 채취시설의 정기적인 소득 및 세척의 필요성이 제안되었다.
김인배,안진선,Kim Inbae,Koopman Ben.,An Jinsun 한국환경보건학회 2004 한국환경보건학회지 Vol.30 No.5
Seaweed waste(SWW) was used to improve the liner effect in recycling of dredged soil as the landfill liner. It was found that the compressive strength became somewhat lower when SWW was added than that was when Ordinary Port-land Cement(OPC) only was added. The permeability coefficient, however, became lower in this case which showed the lowest permeability coefficient when the addition of SWW was one percent. Hence, to comply with the regulations for the compression strength and permeability coefficient of landfill liner, the addition of OPC should be over eight percent and that of seaweed waste one percent. The results of leaching test showed that the solidified material was not against the laws of waste control, so it is possible to use as the landfill liner and to expect sufficient economic effects because wastes such as dredged soil and seaweed can be recycled.