I. Introduction
Recently, the tremendous amount of information is digitalized and becoming available on the WWW (World Wide Web). These digital contents are nowadays easily accessible to a lot of Internet users due to the advent of a wide variety of web-enabled devices, such as PDAs (Personal Digital Assistants), handheld computers, and cellular phones in addition to conventional desktop counterparts. This trend, at the same time, poses a new challenge for web technology, personalized presentation for satisfying visitor's individual needs.