1. Department of Chemical Engineering, Kongju National University, 275 Budae-dong, Seobuk-gu, Cheonan, Chungnam
331-717, Republic of Korea
2. Rare Metals Research Center, Korea Institute of Geoscience and Mineral Resources (KIGAM), Gwahang-no 124, Yuseong-gu,
Daejeon 305-350, Republic of Korea