1. Department of Materials Science
and Engineering, Yonsei University, 50
Yonsei-ro Seodaemun-gu, Seoul 120-749, Republic of Korea
2. School of Engineering, Brown University, Providence, Rhode Island 02912, United
States
3. Device Materials
Research Center, Korea Research Institute of Chemical Technology, 19
Sinseongno Yuseong-gu, Daejeon 305-600, Republic of Korea