1. Department of Material Science and Engineering, Korea Advanced Institute of Science and Technology, Daejeon, 305-701, Republic of Korea
2. Department of Applied Nano Mechanics, Korea Institute of Machinery & Materials, Daejeon, 305-343, Republic of Korea
3. Department of Nanomechatronics,
University of Science and Technology (UST), Daejeon 34113, Republic
of Korea
4. Graduate School of EEWS, Korea Advanced Institute of Science and Technology, Daejeon, 305-701, Republic of Korea