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 1 keynote paper were carefully reviewed and selected during two rounds of reviewing and improvement from 640 submissions. The papers are organized in topical sections on 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.