1. a HUBO Laboratory, Humanoid Robot Research Center, Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology, 373-1 Guseong-dong Yuseong-gu, Daejeon 305-701, South Korea;, Email: garland@kaist.ac.kr
2. b HUBO Laboratory, Humanoid Robot Research Center, Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology, 373-1 Guseong-dong Yuseong-gu, Daejeon 305-701, South Korea
3. c HUBO Laboratory, Humanoid Robot Research Center, Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology, 373-1 Guseong-dong Yuseong-gu, Daejeon 305-701, South Korea