Abstract:The polycarbonate (PC)-based optical diffusers for direct-lit LED backlight unit were prepared by using extrusion compounding followed by compression molding process. The application of inorganic porous silica particles as a diffusing agent in addition to conventional poly(methyl methacrylate) (PMMA) beads was attempted, and the optical, thermal, and mechanical properties of the prepared diffusers were investigated. The morphological observations revealed that the diffusing agents could be uniformly dispersed in the PC matrix without agglomeration by high shear stress generated during extrusion process. The incorporation of the porous silica particles mixed with PMMA beads remarkably enhanced the luminance uniformity with respect to both location and view angle for the diffuser, while minimizing the reduction in the absolute luminance, as compared with the diffuser containing only PMMA beads. In addition, thermal and mechanical properties of the diffusers were shown to be improved upon addition of the porous silica particles.
The purpose of this study was to explore the direction of Korea's future mathematics education in preparation for the future age represented by the Fourth Industrial Revolution. In this study, investigation was done on future competences proposed by international organizations, such as OECD, UNESCO, WEF and P21, and the emphasis of recent mathematics curriculum for Japan, Singapore, China, Finland, Germany, Australia, UK and US. As a result, we have developed a framework for future mathematics education, which entails Mathematics Core Content, Future Mathematical Theme, Mathematical Competence, and Social and Emotional Competence as the main areas for future mathematics education. The direction of the future mathematics education proposed in this study will serve as a basis for establishing a systematic mathematics education policy for future generations in Korea.
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