1. a Robotics Institute, Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, PA 15213, USA, Construction Robot and Automation Laboratory, Department of Civil and Environmental Engineering, Yonsei University 134 Shinchon-dong, Seodaemun-gu, Seoul 120-749, South Korea
2. b Construction Robot and Automation Laboratory, Department of Civil and Environmental Engineering, Yonsei University 134 Shinchon-dong, Seodaemun-gu, Seoul 120-749, South Korea;, Email: junghoon@yonsei.ac.kr
3. c Hubo-Lab, Department of Mechanical Engineering, KAIST, 335 Gwahangno, Yeseong-gu, Daejeon 307-701, South Korea