Human Computer Interaction -- A Rule-Based Publish-Subscribe Message Routing System for Ubiquitous Computing -- Exploiting Eye Gaze Information for Operating Services in Home Network System -- A Methodology for Assessing the Level of U-Transformation of Ubiquitous Services -- 3D Space Handwriting Recognition with Ligature Model -- Scenario-Based Design of Ambient Intelligence -- Ubiquitous Multimedia Access with a Multidimensional Information Browser -- OPF: A Distributed Context-Sensing Framework for Ubiquitous Computing Environments -- Modeling and Social Aspects -- Implementation of Telematics Services with Context-Aware Agent Framework -- Clock Offsets in TDOA Localization -- Context-Dependent Task Computing in Pervasive Environment -- Semantic Information Retrieval in the COMPASS Location System -- A Formal Characterization of Vagueness and Granularity for Context-Aware Mobile and Ubiquitous Computing -- An Inference Engine for Personalized Content Adaptation in Heterogeneous Mobile Environment -- Context-Based Cooperation Architecture for Ubiquitous Environment -- Affordance-Based Design of Physical Interfaces for Ubiquitous Environments -- Systems -- Dynamic Clustering for Object Tracking in Wireless Sensor Networks -- An Ultra Low Power Medium Access Control Protocol with the Divided Preamble Sampling -- A Service Conflict Resolution Algorithm Based on Virtual Personal World -- Experimental Evaluation of Decision Criteria for WLAN Handover: Signal Strength and Frame Retransmission -- Buffer Feedback Scheduling: Runtime Adaptation of Ubicomp Applications -- Exploiting Passive Advantages of Sentient Artefacts -- Scenario-Based Programming for Ubiquitous Applications -- JSense - Prototyping Sensor-Based, Location-Aware Applications in Java -- Communications I -- Estimation of the Number ofCompeting Stations Applied with Central Difference Filter for an IEEE 802.11 Network -- An Emergency Message Propagation Method in Highway Traffic -- UbiComm: An Adaptive Vertical Handoff Decision Scheme for Heterogeneous Wireless Networks -- Reducing Location Update Cost using Multiple Virtual Layers in HMIPv6 -- Design and Emulation of Integration Framework for Heterogeneous Wireless PAN Networks -- Heterogeneous Routing Protocol Coordinator for Mobile Ad Hoc Networks -- Communications II -- DynaMoNET: Dynamic Multi-homed IPv6 Mobile Networks with Multiple Mobile Routers -- Fast IPv6 Address Auto-configuration Using Proxy for Mobile Environment -- Parametric Routing for Wireless Sensor Networks -- Analyzing the Effect of a Block FEC Algorithm's Symbol Size on Energy Consumption in Wireless Sensor Networks -- Minimum Dominating Sets for Solving the Coverage Problem in Wireless Sensor Networks -- A Simple Scheme with Low Energy consumption for Coverage Maintenance in Wireless Sensor Networks -- Spectrum Sensing Method for Increasing the Spectrum Efficiency in Wireless Sensor Network -- Smart Devices and Security -- Algorithm for the Predictive Hibernation of Sensor Systems -- Encapsulation and Entity-Based Approach of Interconnection Between Sensor Platform and Middleware of Pervasive Computing -- Feature Selection and Activity Recognition from Wearable Sensors -- Portable Device for Bi-emotional State Identification Using Heart Rate Variability -- An Optimizing Authenticated Key Exchange Protocol for Self-organizing Sensor Networks.

We cordially welcome you to the proceedings of the 2006 International Symposium on Ubiquitous Computing Systems (UCS) held in Seoul, Korea. UCS has been a symposium for dissemination of state-of-the-art research and engineering practices in ubiquitous computing with particular emphasis on systems and software. 2006 UCS was the third of this series of international symposia, and its importance is increasing as information technology industries are recognizing ubiquitous systems to be one of their top priorities. This year the symposium was organized by u-Korea Forum, Su- kyunkwan University, The Electronic Times, and UCN, Korea. It was also sponsored by the Korea Ministry of Information and Communication, KISS, KIPS, KICS, NCA from Korea and IPSJ SIGUBI, IEICE URON, and UNF from Japan. This year we attracted 359 high-quality paper submissions from all over the world. Among them, 41 papers representing 11 countries were selected to be included in the technical program. This very low acceptance rate of about 11% clearly demonstrates the high quality of the conference, and this tradition will continue in the upcoming years. Three distinguished speakers were also invited for keynote speeches, who enlightened the audience on ubiquitous computing theory and application.