1. Pusan National University, Department of Cogno-Mechatronics Engineering, 2 Busandaehak-ro 63 beon-gil, Geumjeong-gu, Busan 609-735, Republic of Korea
2. Korea Institute of Machinery and Materials, 156 Gajeongbuk-Ro, Yuseong-Gu, Daejeon 305-343, Republic of Korea