• Journal of Korean Society of Transportation
• /
• v.22 no.2 s.73
• /
• pp.121-130
• /
• 2004

In these days, multiple-path generation method is highly demanded in practice and research areas, which can represents realistically travelers behavior in choosing possible alternative paths. The multiple-path generation algorithm is one of the key components for policy analysis related to ATIS, DRGS and ATMS in ITS. This study suggested a method to generate multiple Possible paths from an origin to a destination. The approach of the suggested method is different from an other existing methods(K-shortest path algorithm) such as link elimination approach, link penalty approach and simulation approach. The result of the multi-label vine-building shortest path algorithm(MVA) by Kim (1998) and Kim(2001) was used to generate multiple reasonable possible paths with the concept of the rational upper boundary. Because the MVA algorithm records the cost, back-node and back-back node of the minimum path from the origin to the concerned node(intersection) for each direction to the node, many potential possible paths can be generated by tracing back. Among such large number of the potential possible paths, the algorithm distinguishes reasonable alternative paths from the unrealistic potential possible paths by using the concept of the rational upper boundary. The study also shows the very simple network examples to help the concept of the suggested path generation algorithm.

• Journal of Korean Society of Transportation
• /
• v.24 no.3 s.89
• /
• pp.177-187
• /
• 2006

It is known that over one million car navigation devices are being currently used in Korea. Most. if not all, route guidance systems, however, Provide only one "best" route to users, not providing any options for various types of users to select. The current practice dose not consider each individual's different preferences. These days, a vast amount of information became available due to the rapid development in information processing technology. Thus, users Prefer choices to be given and like to select the one that suits him/her the "best" among available information. To provide such options in this Paper, we developed an algorithm that provides alternative routes that may not the "least cost" ones, but ones that are close to the "least cost" routes for users to select. The algorithm developed and introduced in the paper utilizes a link-based search method, rather than the traditional node-based search method. The link-based algorithm can still utilize the existing transportation network without any modifications, and yet enables to provide flexible route guidance to meet the various needs of users by allowing transfer to other modes and/or restricting left turns. The algorithm developed has been applied to a toy network and demonstrated successful implementation of the multi-path search algorithm for multi-purpose activities.

• Proceedings of the Korean Institute of Communication Sciences Conference
• /
• 2004.11a
• /
• pp.80-80
• /
• 2004

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.23 no.4
• /
• pp.914-925
• /
• 1998

This paper considers the evaluation of the hybrid acquistion perdformance for the pilot signal in the direct sequence code division multiple access(DS/CDMA) forward link. the hybrid acquisition is introduced by the combination of two schemes, the parallel and serial acquisions. The mean acquisition time of the proposed scheme is derived to consider both the best case(the correct code-phase offsets are included i one subset) and the worst case(the correct code-phase offsets exist at the boundary of two subsets), which are cause by the distribution of the correct code-phase offsets in the subset. Expressions for the detection, false alarm, and miss probabilities are derived for the case of multiple correct code-phase offsets and multipath Rayleigh fading channel. Numerical results present the hybrid acquistion performance with repect to design parameters such as postdetectio integration length in the search and verification modes, subset size, and number of I/Q noncoherent correlators, and compare the hybrid acquistion with the parallel acquistion in terms of the minimum acquistion time under the same hardware complexity.

• Journal of Korean Society of Transportation
• /
• v.22 no.2 s.73
• /
• pp.131-143
• /
• 2004

Given a path represented by a sequence of link numbers in a graph, the vine is differentiated from the loop in a sense that any link number can be visited in the path no more than once, while more than once in the loop. The vine provides a proper idea on complicated travel patterns such as U-turn and P-turn witnessed near intersections in urban transportation networks. Application of the link label method(LLM) to the shortest Path algorithms(SPA) enables to take into account these vine travel features. This study aims at expanding the LLM to a K-th path search algorithm (KPSA), which adopts the node-based-label correcting method to find a group of K number of paths. The paths including the vine type of travels are conceptualized as drivers reasonable route choice behaviors(RRCB) based on non-repetition of the same link in the paths, and the link-label-based MPSA is proposed on the basis of the RRCB. The small-scaled network test shows that the algorithm sequence works correctly producing multiple paths satisfying the RRCB. The large-scaled network study detects the solution degeneration (SD) problem in case the number of paths (K) is not sufficient enough, and the (K-1) dimension algorithm is developed to prevent the SD from the 1st path of each link, so that it may be applied as reasonable alternative route information tool, an important requirement of which is if it can generate small number of distinct alternative paths.