1. Materials R&D Center, Samsung Advanced Institute of Technology, San #14, Nongseo-dong, Giheung-gu, Yongin-si, Gyeonggi-do, 446-712, Korea
2. School of Electrical Engineering, Kookmin University, Jeongneung-dong, Seongbuk-gu, Seoul,
136-702, Korea
3. Department of Organic
Materials and Fiber Engineering, Soongsil University, Sangdoro 369, Dongjak-gu, Seoul, 156-743,
Korea