1. Department of Mechanical Engineering Yonsei University Seoul 03722 Korea
2. Tribology Research Lab Yonsei University Seoul 03722 Korea
3. ZJU‐UIUC Institute Zhejiang University Haining Zhejiang 314400 China
4. Department of Mechanical Science and Engineering University of Illinois at Urbana‐ Champaign Urbana IL 61801 USA