In recent years, demands for sintered ferrous material with higher strength are increasing. To satisfy these demands, studies and commercial use of the die wall lubrication method, the warm compaction method and the combination of both methods are widely carried out to achieve high density. The die wall lubrication warm compaction method makes it possible to achieve high density by reducing internal lubricant through die wall lubrication, although the method involves several issues such as prolonged cycle time due to lubricant spraying and difficulty in spraying lubricant in the case of compacting with complicated geometry. Meanwhile, the conventional warm compaction method requiring no die wall lubricant application cannot achieve such a high density as in the case of die wall lubrication warm compaction due to higher volume of internal lubricant. However, this report discloses our study result in which the possibility of improving density is exhibited by using a lubricant type with superior dynamic ejection property that can reduce volume of lubricant additive.

The outsole mold of the shoes has been manufactured using electro-discharge machining by graphite electrode or using casting etc. The study is concerned with the pattern design for the outsole of shoes by CAD, the modeling and the generation of NC data by

The injection mold industry has strong relationship with many other industries. In the injection mold industry, the harmonious collaboration of the order-making companies, the mold-making companies, and the molded-parts making companies, which are distantly located, is very important. In this study, a web-based collaboration system is developed for the purpose. It offers the criterion to select appropriate production companies. It also tries to minimize the production cost of the mold design by distributing and evaluating the design information. The developed system is constructed using various recent web-programming tools.

In the present study, the focus is on the analysis of the effect of the mold dimensions on the temperature distribution of a die during plasma activated sintering. The temperature distribution of a cylindrical mold with various dimensions was measured using K-type thermocouples. The temperature homogeneity of the die was studied based on the direction and dimensions of the die. A temperature gradient existed in the radial direction of the die during the plasma activated sintering. Also, the magnitude of the temperature gradient was increased with increasing sintering temperature. In the longitudinal direction, however, there was no temperature gradient. The temperature gradient of the die in the radial direction strongly depended on a ratio of die volume to punch area

쌀바구미와 저장 곡물 곰팡이간의 상호작용 분석의 일환으로 곰팡이 종에 대한 쌀바구미의 분포 선호성을 조사하였다. 쌀바구미는 비교 대상 4종 곰팡이(Aspergillus candidus, A. niger, A. flavus와 Penicillium spp.)에 오염된 현미를 살균된 현미보다 선호하였으며, 선호도는 A. candidus와 Penicillium spp.에 대해서 가장 높았다. 차대 쌀바구미 우화수는 A. candidus와 Penicillium 오염미에서 가장 많았으며 A. flavus 오염미에서 가장 적었다. 쌀바구미의 곰팡이 오염미에 대한 선호와 쌀바구미 적합도간 불일치 현상은 쌀바구미의 분포 및 곡물 곰팡이 선호도가 알려진바 유사 니체에서의 장기적인 공진화 과정을 거쳐 이루어진 종간 상호작용의 조정과 아울러 영양적 특성 등 단기적 서식환경의 적절성의 두 가지 측면에서 설명될 수 있음을 암시하는 것으로 생각된다.

Conidia of molds within the Asian dust were captured in the ambient air of mid-west Korea, in springtime of 2000~2002. An eight-stage Cascade impactor and 0.22 μm pore size membrane filters were used for the dust samples. Several kinds of mol

실리카 바인더 함량이 지르콘 쉘 주형의 기계적 특성에 미치는 영향을 고찰하였다. 실리카 졸/지르콘 함량비 Rw는 0.18~0.43 범위에서 변화시켰으며, 주형의 소결온도는 871˚C~1400˚C 범위에서 변화시켰다. 생형의 상온강도는 실리카 졸/지르콘 함량비 Rw에 비례하여 증가하였다. 소결온도가 1300˚C 이하인 경우, Rw가 증가함에 따라 소결된 주형의 상온강도와 치밀화는 증가하였다. 그러나 Rw가 0.43이고 1400˚C에서 3시간 동안 소결시킨 경우 주형의 상온강도와 치밀화가 오히려 감소하였다. 이는 소결 중 내화물 입자와 실리카 바인더와 열팽창계수의 차이에 기인하는 것으로 판단된다. 정밀주조용 지르콘 쉘 주형 제작을 의한 최적의 Rw 값은 0.33인 것으로 나타났다.