1. a Department of Robotics and Intelligent Machinery, Nano Convergence and Manufacturing Systems Research Division, Korea Institute of Machinery and Materials, 171 Jang-dong, Yuseong-gu, Daejeon 305-343, South Korea, Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology, 373-1 Guseong-dong, Yuseong-gu, Daejeon 305-701, South Korea;, Email: chpark@kimm.re.kr
2. b Department of Robotics and Intelligent Machinery, Nano Convergence and Manufacturing Systems Research Division, Korea Institute of Machinery and Materials, 171 Jang-dong, Yuseong-gu, Daejeon 305-343, South Korea
3. c Department of Robotics and Intelligent Machinery, Nano Convergence and Manufacturing Systems Research Division, Korea Institute of Machinery and Materials, 171 Jang-dong, Yuseong-gu, Daejeon 305-343, South Korea
4. d Department of Robotics and Intelligent Machinery, Nano Convergence and Manufacturing Systems Research Division, Korea Institute of Machinery and Materials, 171 Jang-dong, Yuseong-gu, Daejeon 305-343, South Korea
5. e Department of Robotics and Intelligent Machinery, Nano Convergence and Manufacturing Systems Research Division, Korea Institute of Machinery and Materials, 171 Jang-dong, Yuseong-gu, Daejeon 305-343, South Korea
6. f Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology, 373-1 Guseong-dong, Yuseong-gu, Daejeon 305-701, South Korea