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귀중품 포장 블록용 폴리우레탄 소재의 NC 가공조건 결정에 관한 연구
은수인(Suin Eun),임창혁(Changhyuk Lim),맹희영(Heeyoung Maeng) 한국생산제조학회 2020 한국생산제조학회지 Vol.29 No.3
Polyurethane is used for packaging valuables. However, it is challenging to cut polyurethane while maintaining the exact form of the workpiece because of its high elasticity. Therefore, it is essential to precisely determine the machining parameters for maintaining the form accuracy rather than the processing speed. In this study, the machining conditions that could maintain the contact surface accuracy were determined so that the packaging block could stably support the contents. Based on the characteristics of the Taguchi technique and experimentally applied initial machining conditions, the optimum machining conditions such as the spindle speed, feed rate, step over, and tool path pattern, considering the machining stability and machined surface integrity, were determined.
Lee, Woomin,Kihm, Kenneth David,Kim, Hong Goo,Shin, Seungha,Lee, Changhyuk,Park, Jae Sung,Cheon, Sosan,Kwon, Oh Myoung,Lim, Gyumin,Lee, Woorim American Chemical Society 2017 Nano letters Vol.17 No.4
<P>Manipulation of the chemical vapor deposition graphene synthesis conditions, such as operating P, T, heating/cooling time intervals, and precursor gas concentration ratios (CH4/H-2), allowed for synthesis of polycrystalline single layered graphene with controlled grain sizes. The graphene samples were then suspended on 8 mu m diameter patterned holes on a silicon-nitride (Si3N4) substrate, and the in-plane thermal conductivities k(T) for 320 K < T < 510 K were measured to be 2660-1230, 1890-1020, and 680-340 W/m center dot K for average grain sizes of 4.1, 2.2, and 0.5 mu m, respectively, using an opto-thermal Raman technique. Fitting of these data by a simple linear chain model of polycrystalline thermal transport determined k = 5500-1980 W/m center dot K for single-crystal graphene for the same temperature range above; thus, significant reduction of k was achieved when the grain size was decreased from infinite down to 0.5 mu m. Furthermore, detailed elaborations were performed to assess the measurement reliability of k by addressing the hole-edge boundary condition, and the airconvection/radiation losses from the graphene surface.</P>