1. Department of Chemical and Biological Engineering, Hanbat National University, 125 Dongseodaero, Yuseong-gu, Daejeon 305-719, Republic of Korea
2. Functional Composite Materials Research Center, Korea Institute of Science and Technology (KIST), Jeonbuk Institute of Advanced Composite Materials, Wanju-gun, Jeollabuk-do 55324, Republic of Korea