• Journal of Korean Society of Transportation
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• v.26 no.3
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• pp.97-108
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• 2008

Like always selecting anything in everyday lives, We must choose a travel mode to achieve its purposes driven by diverse factors such as travel distance and accessibility of public transit. Assuming that they are differentiated depending on whether a travel purpose is commuting, shopping or leasure, the study investigated their distinguished impacts on travel mode choice by using binary logit models by travel purpose and mode. Identifying that travel time has an important role in choosing a travel mode whether its purpose is any, the results show that longer travel time tends to increase the possibilities of taking public transit, transfer and rail transit rather than bus. In addition, the easy use of a car and its parking to travelers is more important in their choosing an automobile as a travel mode than other factors. In the models of identifying the probability of mode choice between bus and rail transit, we find that its choice tends to be decided by travelers depending on whether any public transit mode is more accessible to them. When comparing the results among travel purposes, we identify that the easy use of a car and parking in their destination is more important for commuting, while accessibility of public transit in their origination increases the probability of taking a transit mode.

• Journal of the Economic Geographical Society of Korea
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• v.10 no.1
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• pp.44-63
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• 2007

The purpose of this study is to propose mining processes in the large trip-transaction database of the Metropolitan Seoul area and to analyze the spatial characteristics of travel behavior. For the purpose. this study introduces a mining algorithm developed for exploring trip patterns from the large trip-transaction database produced every day by transit users in the Metropolitan Seoul area. The algorithm computes trip chains of transit users by using the bus routes and a graph of the subway stops in the Seoul subway network. We explore the transfer frequency of the transit users in their trip chains in a day transaction database of three different years. We find the number of transit users who transfer to other bus or subway is increasing yearly. From the trip chains of the large trip-transaction database, trip patterns are mined to analyze how transit users travel in the public transportation system. The mining algorithm is a kind of level-wise approaches to find frequent trip patterns. The resulting frequent patterns are illustrated to show top-ranked subway stations and bus stops in their supports. From the outputs, we explore the travel patterns of three different time zones in a day. We obtain sufficient differences in the spatial structures in the travel patterns of origin and destination depending on time zones. In order to examine the changes in the travel patterns along time, we apply the algorithm to one day data per year since 2004. The results are visualized by utilizing GIS, and then the spatial characteristics of travel patterns are analyzed. The spatial distribution of trip origins and destinations shows the sharp distinction among time zones.

• The Transactions of the Korea Information Processing Society
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• v.5 no.4
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• pp.1033-1043
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• 1998

In this paper, we present an improved multicasting path assignment algorithm based on the minimum cost spanning tree. In the method presented in this paper, a multicasting path is assigned preferentially when a node to be received is found among the next degree nodes of the searching node in the multicasting path assignment of the constrained steiner tree (CST). If nodes of the legacy group exist between nodes of the new group, a new path among the nodes of new group is assigned as long as the nodes may be excluded from the new multicasting path assignment taking into consideration characteristics of nodes in the legacy group. In assigning the multicasting path additionally, where the source and destination nodes which can be set for the new multicasting path exist in the domain of identical network (local area network) and conditions for degree constraint are satisfied, a method of producing and assigning a new multicasting path is used. The results of comparison of CST with MCSTOP, MCSTOp algorithm enhanced performance capabilities about the communication cost, the propagation delay, and the computation time for the multicasting assignment paths more than CST algorithm. Further to this, research activities need study for the application of the international standard protocol(multicasting path assignment technology in the multipoint communication service (MCS) of the ITU-T T.120).

• Journal of Korea Multimedia Society
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• v.15 no.1
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• pp.32-39
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• 2012

In this paper, the implementation of location based services (LBS) using S-DMB (satellite-digital multimedia broadcasting) system was proposed. In S-DMB System, the frequency of transmitted signal is about 2 GHz which has a characteristics of strong straightness but weak diffraction so that there are many shade areas such as indoors and underground spaces. Therefore the signal transmitted from the satellite should be retransmitted by the earth repeaters called as gap filler. Because each gap filler has its own identification value, the gap filler ID introduces the area in which the gap filler was installed. Generally, the 51st data symbols of S-DMB pilot signal transmitted from the satellite are padded by dummy value and gap filler ID is embedded in this pilot symbol by the gap filler when S-DMB signals are retransmitted by gap fillers. So using gap filler ID of S-DMB system, LBS such as region registration, distance and time to destination, alarm of local area information could be implemented. In the experiment to prove the performance of the proposed LBS system using the gap filler ID of the S-DMB system, the firmware of S-DMB chip composing of RF and baseband parts was lightly modified so that application processor was able to manipulate the gap filler ID and the its related regional information.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.2
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• pp.618-633
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• 2014

Relay technology is becoming more important for mobile communications and wireless internet of things (IoT) networking because of the extended access network coverage range and reliable quality of service (QoS) it can provide at low power consumption levels. Existing mobile multihop relay (MMR) technology uses fixed-point stationary relay stations (RSs) and a divided time-frame (or frequency-band) to support the relay operation. This approach has limitations when a local fixed-point stationary RS does not exist. In addition, since the time-frame (or frequency-band) channel resources are pre-divided for the relay operation, there is no way to achieve high channel utilization using intelligent opportunistic techniques. In this paper, a different approach is considered, where the use of mobile/IoT devices as RSs is considered. In applications that use mobile/IoT devices as relay systems, due to the very limited battery energy of a mobile/IoT device and unequal channel conditions to and from the RS, both minimum energy consumption and QoS support must be considered simultaneously in the selection and configuration of RSs. Therefore, in this paper, a mobile RS is selected and configured with the objective of minimizing power consumption while satisfying end-to-end data rate and bit error rate (BER) requirements. For the RS, both downlink (DL) to the destination system (DS) (i.e., IoT device or user equipment (UE)) and uplink (UL) to the base station (BS) need to be adaptively configured (using adaptive modulation and power control) to minimize power consumption while satisfying the end-to-end QoS constraints. This paper proposes a minimum transmission power consuming RS selection and configuration (MPRSC) scheme, where the RS uses cognitive radio (CR) sub-channels when communicating with the DS, and therefore the scheme is named MPRSC-CR. The proposed MPRSC-CR scheme is activated when a DS moves out of the BS's QoS supportive coverage range. In this case, data transmissions between the RS and BS use the assigned primary channel that the DS had been using, and data transmissions between the RS and DS use CR sub-channels. The simulation results demonstrate that the proposed MPRSC-CR scheme extends the coverage range of the BS and minimizes the power consumption of the RS through optimal selection and configuration of a RS.

• Journal of the Korean Association of Geographic Information Studies
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• v.13 no.4
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• pp.78-90
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• 2010

This research tried to suggest a method of DB construction in the field using evaluation variables and Mobile GIS focusing on Changwon City as a leading study to encourage walking and biking in everyday life. First, twenty evaluation variables of WEs(walking environments) were selected through the literature review, and also scored separately. Second, the field survey-DB of each variable was built effectively using Mobile GIS. Finally, WEs were evaluated synthetically based on the obtained data. The results of this research are summarized as follows. While the WE of the zones located in the fringe of Changwon square were generally got a high score as over 42, other zones located in detached or row house area were evaluated relatively highly bad. Findings from this research will help in determining the zone required improvement of WEs or easy access to main destination such as a park, shopping center, school, etc. and also selecting variables of WEs, needed an intensive improvement, in the selected zone after comparing the results of field and questionnaire survey. Furthermore, those will be used as a means of decision making support for planing, designing and maintaining of WEs to promote people's physical activity in their daily lives.

• The Journal of Society for e-Business Studies
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• v.21 no.2
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• pp.47-59
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• 2016

Parcel service is to deliver goods from one place to the designated destination requested according to user request. Parcel operations such as sorting, distributing, etc. or the managed information are heterogeneous by the companies. Additionally, it is impossible to support interoperability between companies with unformatted data of manual processing. Most parcel package boxes attached to paper typed waybill is attached is delivered to consignee. So, security problems such as personal information leaking are occurred, or extra processing time and logistics costs are needed due to wrong or the damaged information. Business environment of parcel service is rapidly changed as introducing unmanned delivery or the advanced technology such as Internet of Things. User want to know the accurate status or steps from parcel service request to delivery. To provide these requirements, the unified and integrated waybill information for reliable transportation of parcel service is needed. This information will provide to pickup or delivery carrier, warehouse or terminal, and parcel service user per pickup, transport, and delivery stage of parcel delivery service. Therefore, this paper defines the simplified and unified information model for parcel service waybill by analyzing information systems used for logistics unit processes that is occurred to parcel service, and manual work processes, and developing the relevant information of work flows occurred between business processes or transactions with the collected or processed information by from parcel service's stages. It is possible to share these standard model between business entities, and replacing paper typed waybill will improve national life safety as preventing security threats by paper typed waybill. As a result, it will promote the public interest from the stakeholder's perspective.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.5 no.1 s.9
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• pp.1-12
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• 2006

In order to estimate a dynamic origin and destination demand between on and off-ramps in the freeways, a traffic flow theory can be used to calculate a link distribution proportion of traffics moving between them. We have developed a dynamic traffic estimation model based on the three-phase traffic theory (Kerner, 2004), which explains the complexity of traffic phenomena based on phase transitions among free-flow, synchronized flow and moving jam phases, and on their complex nonlinear spatiotemporal features. The developed model explains and estimates traffic congestion in terms of speed breakdown, phase transition and queue propagation. We have estimated the link, on and off-ramp volumes at every time interval by using traffic data collected from vehicle detection systems in Korea freeway sections. The analyzed results show that the developed model describes traffic flows adequately.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.11 no.5
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• pp.46-55
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• 2012

This study proposes an estimate method of willingness to pay(WTP) for real-time route guidance systems using contingent valuation method(CVM) under double bounded dichotomous choice question(DBDCQ) and analysis for impact factors of WTP estimation. This study assumed that provided real-time traffic information service is optimal route concepts dealing with traffic conditions on origin-destination. Analysis targets were classified into two groups as short distance path and middle distance path for estimating WTP for realtime route guidance system in a year using the survival analysis method and the regression model with personal information, actual condition and satisfaction of information usage and users' awareness and usage of facilities. As a result, mean WTP of realtime route guidance system is 4,034won/year in short distance path, and 4,884won/year in middle distance path. Therefore real-time route guidance system for longer distance path is recognized as more valuable than shorter distance path. Moreover, the necessity of information was required on a higher income group and higher WTP was estimated on owners of vehicle group and lower awareness of a route group.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.11 no.5
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• pp.38-45
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• 2012

Finding shortest paths on time dependent networks is an important task for scheduling and routing plan and real-time navigation system in ITS. In this research, one-to-one time dependent shortest path algorithms based on link flow speeds on urban networks are proposed. For this work, first we select three general shortest path algorithms such as Graph growth algorithm with two queues, Dijkstra's algorithm with approximate buckets and Dijkstra's algorithm with double buckets. These algorithms were developed to compute shortest distance paths from one node to all nodes in a network and have proven to be fast and efficient algorithms in real networks. These algorithms are extended to compute a time dependent shortest path from an origin node to a destination node in real urban networks. Three extended algorithms are implemented on a data set from real urban networks to test and evaluate three algorithms. A data set consists of 4 urban street networks for Anaheim, CA, Baltimore, MD, Chicago, IL, and Philadelphia, PA. Based on the computational results, among the three algorithms for TDSP, the extended Dijkstra's algorithm with double buckets is recommended to solve one-to-one time dependent shortest path for urban street networks.