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장욱경,장윤주,김형종 江原大學校 産業技術硏究所 2010 産業技術硏究 Vol.30 No.A
A forming limit diagram (FLD) defines the extent to which specific sheet material can be deformed by drawing, stretching or any combination of those two. To determine the forming limit curve (FLC) accurately, it is necessary to perform the tests under well-organized conditions. In this study, the influence of several geometric or process parameters such as the blank shape and dimensions, strain measuring equipments, test termination time, forming speed and lubricants on the FLC is investigated.
차량 선루프의 폴리우레탄 성형 공정에 대한 CAE 검증 및 개선에 대한 연구
장욱경,홍준호,김창희,이규웅,황순환 한국자동차공학회 2024 한국 자동차공학회논문집 Vol.32 No.4
The polyurethane molding process is used in many applications in the automobile industry. It mixes polyol and isocyanate with water, and molds it through a foaming reaction. It is also used in sunroof glass, and is produced through the processes of filling, foaming/expansion, and then hardening and ejection. Recently, sunroof products have become larger in size and more complex, due to designs that consider the openness and design aspects of the vehicle. However, this design trend has a long flow length and complex changes in shape, increasing the risk of appearance defects, such as short shots and air traps and warping defects. In this study, which used CAE, we predicted and improved the appearance defects and warping defects through flow analysis, cooling analysis, and warp analysis of sunroof polyurethane molding. In other words, we verified the consistency of CAE and the experiment by comparing flow patterns. The cause of the air trap was also identified. Furthermore, the causal factors in molding defects, depending on the air trap location, were analyzed, and improvement measures were presented. After predicting the degree of deformation based on the cooling channel, similar CAE results of 80.5 % in the vertical direction, and 90.6 % in the horizontal direction were obtained, proving the validity of the deformation analysis, which can be used as reverse engineering data.
녹색발광 β-SiAlON:Eu 세라믹 플레이트 형광체의 치밀화 소결
박영조,이성훈,장욱경,윤창번,윤철수,Park, Young-Jo,Lee, Sung-Hoon,Jang, Wook-Kyung,Yoon, Chang-Bun,Yoon, Chul-Soo 한국세라믹학회 2010 한국세라믹학회지 Vol.47 No.6
$Eu^{2+}$-doped $\beta$-SiAlONs ($Si_{6-z}Al_zO_zN_{8-z}:Eu_y$) are recognized as promising phosphor materials to build an white LED for lighting application due to its excellent absorption/emission efficiency in the long wave length region. In this research, the fabrication of $\beta$-SiAlON:Eu plate phosphor by sintering was investigated with fixed Eu content(y) and varied composition of the host lattice(z). The addition of the activator $Eu_2O_3$ lead to enhanced densification by forming the transient liquid phase. The refinement of a composition by the calculated lattice parameter indicated that the measured composition of the fabricated specimens is nearly same to that of designed one. The single phase $\beta$-SiAlON:Eu plate with relative density of 96.4% was achieved by addition of 2 wt% CaO, which implies the possibility of full densification by adjusting the processing variables.