1. Automative Components and Meterials R&BD Group, Korea Institute of Industrial Technology, 6 Cheomdan-gwagiro, Buk-gu, Gwangju, 500-480, Korea
2. Department of Control Engineering and Robotics, Mokpo National University, 1666, Youngsan-ro, Cheonggye-Myeon, Muan-gun, Jeonnam 534-729, South Korea