1. Radiation Research Division for Industry & Environment, Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, 1266 Sinjeong-dong, Jeongeup-si, Jeollabuk-do 580-185, Republic of Korea
2. Division of Semiconductor and Chemical Engineering, Nanomaterials Processing Research Center, Chonbuk National University, Jeonju-si, Jeollabuk-do 560-756, Republic of Korea