1. Osaka Municipal Technical Research Institute, 1‐6‐50 Monnomiya, Joto‐ku, Osaka 536, Japan
2. Graduate School, Kansai University, 3‐3‐5 Yamate‐cho, Suita‐city, Osaka 564, Japan
3. Fuso Chemical Company, Limited, 2‐2‐6 Niitaka, Yodogawa‐ku, Osaka 532, Japan
4. Department of Materials Science and Engineering, Kansai University, 3‐3‐5 Yamate‐cho, Suita‐city, Osaka 564, Japan