1. College of Information and Communication, Korea University, 1, 5-ga, Anam-dong, SungBuk-gu, 136-701, Seoul, Korea
2. Department of Information System, Hanyang University, 17, Haengdang-dong, Seongdong-gu, Seoul, 133-791, Seoul, Korea
3. Mobile Handset R&D Center, LG Electronics, 60-39, Gasan-dong, Gumchon-gu, Seoul, 153-802, Seoul, Korea