1. Department of Chemical Engineering, Research Institute of Nano Technologies, Daegu University, Gyeongbuk 712-714, Korea
2. Department of Polymer Science, Kyungpook National University, Daegu 702-701, Korea
3. Department of Physics, Kyungpook National University, Daegu 702-701, Korea
4. Advanced Display Manufacturing Research Center, Kyungpook National University, Daegu 702-701, Korea