1. a School of Automotive , Industrial and Mechanical Engineering, Daegu University , 15 Naeri, Jinryang, Jyungsan, Kyungbook, 712–714 Korea
2. b Department of Mechanical Engineering , Sejong University , 98 Gunja-Dong, Gwangjin-Gu, Seoul, 143–747 Korea
3. c CAD/CAM Research Center , Korea Institute of Science and Technology , Seongbuk-gu Hawolgok-dong 39-1, Seoul, 136–791 Korea