a
Department of Polymer Science, Kyungpook National University, 1370 Sankyuk-dong, Buk-gu, Korea
E-mail: gkwak@knu.ac.kr
;
Fax: +82-53-950-6623
;
Tel: +82-53-950-7558
b
Graduate School of Materials Science, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Japan
c
Advanced Photonics Research Institute, Gwangju Institute of Science and Technology, 1 Oryong-dong, Buk-gu, Korea