1. Division of Advanced Materials Engineering; Kongju National University; 1223-24, Cheonan-daero Cheonan Chungnam 331-717 Korea
2. Department of Chemical & Biological Engineering; Hanbat National University; 125, Dongseodaero Yuseong-gu Daejeon 305-719 Korea
3. Power Control Device Research Team; Electronics and Telecommunications Research Institute (ETRI); 218, Gajeongno Yuseong-gu Daejeon 305-700 Korea