1. Department of Mechanical Engineering, Soongsil University, 369 Sangdo-ro, Donjak-gu, Seoul, 156-743, Korea
2. Department of Organic Materials and Fiber Engineering, Soongsil University, 369 Sangdo-ro, Donjak-gu, Seoul, 156-743, Korea
3. Molds and Dies Technology R&BD Group, Korea Institute of Industrial Technology, SongDo-Dong, Yeonsu-Gu, Incheon, 420-734, Korea