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마이크로 머플러를 이용한 ODD 소음 저감에 관한 연구
문병기 ( Byeong G. Moon ),차성운 ( Sung W. Cha ),이병희 ( Byoung H. Lee ) 정보저장시스템학회 2005 추계학술대회논문집 Vol.2005 No.-
Current Optical Disk drive is dominating high share gradually in information storage device market through development of great skill. These technologies can achieve not only improvement of transmission speed but also elevation of recording/reproduction technology. However, these present state cause not only the increase of vibration in structural viewpoint but also problem of serious noise while the ODD becomes high speed/high performance. Specially, air-born noise is being bigger than structural-born noise as disk rotation speed increases gradually. The object of this research is that reduce the air-born noise in optical disk drive by reducing a quantity of flow by using a miniaturized muffler. The micro muffler is a miniaturized muffler. The muffler is used widely by solution to reduce air-born noise which is generated by flow. According to frequency band ofthe noise source, it can be applied by muffler of various forms. In this research, we examined the noise characteristics of the micro muffler and applied it by noise reduction solution of the ODD. It could get an excellent noise reduction in high frequency band by using the micro muffler than the opened case through the decrease of an inner flow. But it could not get a noise reduction in low frequency band through the decrease of an inner flow.
Polypropylene 의 중합 구조가 초미세발포에 미치는 영향
서정환(Jung-hwan Seo),차성운(Sung W. Cha) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.11
Polypropylene is the most widely used resin. PP has good mechanical performance compared to the low resin price. PP is the representative resin, and there are many kind of PP according to the characteristics of polymerization. Microcellular plastics are polymer foams with a cell size smaller than 10㎛, comparatively much smaller that of conventional foams. Microcellular foam processing requires a cell population density greater than 10?cells/㎤ so that the fully grown cells are smaller than 10㎛. On polymerization process of PP, many kinds of PP depending on different co-monomer union could be produced easily. That is because of structure changes from arrangement of co-monomer to kinds of co-monomer. Therefore, there are so many kind of PP according to different kinds of monomer arrangement. And each kind of PP has distinctive properties that affect MCPs.
현창훈(Chang Hoon Hyun),차성운(Sung W Cha),윤재동(Jea Dong Yoon) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.6
Micro-cellular foamed plastics formed by injection molding create a sensation in polymer industrial use for their following characteristics: lighter weight, less warp, reduced cycle time, less sink marking, and so on. This is due to the fact that the cells are nucleated in the Polymer matrix during the injection. Although foamed plastics produced by an injection molder have many merits as listed above, the MCPs are not destroyed completely in hole plastic industry and offer some problems. There are few studies designed to make recommendations for the solution of the MCPs products surface quality. This research is surface problem improvement research of MCPs product that use polymer film.