1. Department of Advanced Parts and Materials Engineering, Chosun University, 375 Seosuk-Dong, Dong-Gu, Gwangju 501-759, Korea
2. Department of Electronic Engineering, Chosun University, 375 Seosuk-Dong, Dong-Gu, Gwangju 501-759, Korea
3. Automotive Components & Materials R&D Group, Korea Institute of Industrial Technology, 1110-9, Oryoung-dong, Buk-gu, Gwangju, 500-480, Korea
4. Division of Electrical, Electronic and Computer Engineering, Chonnam National University, 50 Daehak-Ro, Yeosu, Jeonnam 550-749, Korea