1. a Division of Mechanical and Industrial Engineering , Pohang University of Science and Technology , San 31, Hyoja-Dong, Nam-Gu, Pohang, Kyungbuk 790-784, Republic of Korea
2. b Department of e-Management Information Systems , Cheju Halla College , 38 Halladaehakno, Jeju-si, Jeju Special Self-Governing Province, 690–708, Republic of Korea