1. Center for Nanometrology, Korea Research Institute of Standards and Science, Daejeon 305-340, South Korea
2. Center for Creative Convergance, Korea Research Institute of Standards and Science, Daejeon 305-340, South Korea
3. Center for Nanophotonics, Korea Institute of Science and Technology, Seoul 136-497, South Korea
4. Department of Material Science and Engineering, Pai Chai University, Daejeon 302-735, South Korea