1. Department of Electronic Information Systems Osaka City University 3‐3‐138 Sugimoto Sumiyoshi‐Ku Osaka 558‐8585 Japan
2. Institute for Materials Research (IMR) Tohoku University 2145‐2 Narita Oarai Ibaraki 311‐1313 Japan
3. Institute for Materials Research (IMR) Tohoku University 2‐1‐1 Katahira Sendai 980‐8577 Japan
4. Adamant Namiki Precision Jewel Co. Ltd. 3‐8‐22 Shinden, Adachi‐ku Tokyo 123‐8511 Japan
5. Department of Electrical and Electronic Engineering Saga University 1 Honjo‐machi Saga 840‐8502 Japan