1. Department of Textile System Engineering, Kyungpook National University, 1370 Sankyuk‐dong Buk‐gu, Daegu 702‐701, Korea
2. Department of Functional Materials Engineering, Kyungpook National University
3. James Robinson Ltd., Huddersfield HD1 6BU, UK
4. Department of Applied Chemistry, Sejong University, 98 Gunjadong, Gwangjingu, Seoul, Korea