I. Introduction
Recently, with the development of satellite systems and the penetration of mobile technologies, a variety of services such as real-time traffic information, car accident alarm, and efficient path planning were made available, particularly by way of telematics networks. Those services are provided on top of location histories obtained from GPS receivers typically equipped within an in-vehicle telematics device. There exist a great volume of previous and ongoing researches in this area, and not a few of them attempted to search and cluster similar trajectories [2] [17] [1] [22] [23] [15]. Also, they made an effort to analyze the applicability of these schemes for the road network environment in terms of road traffic distribution and user's preference for driving route, aiming at providing such information as the location of moving objects or user's behavior patterns.