Chan-Hee Jung1, In-Tae Hwang1, In-Seol Kuk1, Oh-Sun Kwon2, Kwanwoo Shin2, and Jae-Hak Choi1 3 ∗ 1Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Jeongeup-si, Jeollabuk-do 580-185, Republic of Korea 2Department of Chemistry and Institute of Biological Interfaces, Sogang University, Seoul 121-742, Republic of Korea 3Department of Polymer Science and Engineering, Chungnam National University, Yusong-gu, Daejeon 305-764, Republic of Korea