1. Nippon Steel Corporation Amagasaki Research and Development Center 1 , 1-8 Fuso-Cho, Amagasaki, Hyogo 660-0891, Japan
2. Nippon Steel Corporation RE Center 2 , 20-1 Shintomi, Futtsu, Chiba 293-8511, Japan
3. Department of Electronic and Photonic Systems Engineering, Kochi University of Technology 3 , Tosayamada-cho, Kami, Kochi 782-8502, Japan