1. Nano-Convergence Mechanical Systems Research Division, Korea Institute of Machinery & Materials (KIMM), Daejeon 305-343, Republic of Korea
2. Graduate School of Energy Environment Water and Sustainability (EEWS), Korea Advanced Institute of Science & Technology (KAIST), Daejeon 305-701, Republic of Korea
3. School
of Mechanical Engineering, Chung-Ang University, Seoul 156-756, Republic of Korea
4. Nano-Mechatronics, University of Science and Technology (UST), Daejeon 305-350, Republic of Korea