1. Department of Mechanical System Engineering, Jeonbuk National University, Jeonju 54896, Republic of Korea
2. Advanced Transportation Machinery Research Center, Jeonbuk National University, Jeonju 54896, Republic of Korea
3. Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
4. Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA