1. Graduate School of Interdisciplinary Program of E-Commerce, Chonnam National University, Yongbong-dong, Buk-gu, Gwangju 500-757, Republic of Korea
2. School of Electronics and Computer Engineering, Chonnam National University, Yongbong-dong, Buk-gu, Gwangju 500-757, Republic of Korea
3. Department of Digital Contents, Korea Nazarene University, Cheonan 331-718, Republic of Korea