This book constitutes the thoroughly refereed postproceedings of the First International Conference on Ubiquitous Convergence Technology, ICUCT 2006, held in Jeju Island, Korea in December, 2006. The 29 revised full papers presented together with one keynote paper cover multimedia, applications, mobile, wireless, and ad-hoc networking, smart sensors and sensor networks, privacy and security, as well as Web-based simulation for natural systems.