[1] Sejong Univ, Hybrid Mat Ctr HMC, Seoul 05006, South Korea
[2] Sejong Univ, Dept Nanotechnol & Adv Mat Engn, Seoul 05006, South Korea
[3] Dankook Univ, Dept Elect & Elect Engn, Yongin 16890, South Korea
[4] Dongguk Univ Seoul, Div Elect & Elect Engn, Seoul 04620, South Korea