1. a Laboratory of New Fiber Materials and Modern Textile, Growing Base for State Key Laboratory, Qingdao University , Qingdao , 266071 , China
2. b Electronic Ceramics Center, DongEui University , Busan , 614-714 , Korea
3. c Physics Department , DongEui University , Busan , 614-714 , Korea
4. d Department of Semiconductor Physics , Korea Maritime University , Busan , 600-545 , Korea
5. e Department of Nano-medical Engineering , Pusan National University , Busan , 609-735 , Korea