1. Dept. of Materials Science and Engineering, Seoul National Univ., Seoul 08826, South Korea.
2. Research and Development Center, MK Electron, Yongin 17030, South Korea.
3. Dept. of Mechanical Engineering, Univ. of Colorado at Boulder, Boulder, CO 80300-0427.
4. Analytical Research Division, Korea Basic Science Institute, Jeonju, Jeollabuk-do 54907, South Korea.
5. Professor, Dept. of Materials Science and Engineering, Seoul National Univ., Seoul 08826, South Korea.
6. Professor, Dept. of Mechanical Engineering, Univ. of Colorado at Boulder, Boulder, CO 80300-0427 (corresponding author).