1. Introduction
Due to advances in Internet and multimedia technologies, the Internet usage has continued
to increase rapidly and it became possible to move communication space from the real world
to virtual worlds. Therefore, Internet based communication using computers or mobile
devices has emerged as an important method of communication and there is an increasing
need for virtual communication or virtual collaboration tools which enable users to
communicate or work with others in virtual space through the Internet wherever and
whenever. Especially, for education or research area, Internet based virtual learning or virtual
collaboration may be expected as an effective method.