• IE interfaces
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• v.17 no.spc
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• pp.103-110
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• 2004

This paper presents a two-phase method for the vehicle routing problems with time windows(VRPTW). In a supply chain management(SCM) environment, timely distribution is very important problem faced by most industries. The VRPTW is associated with SCM for each customer to be constrained the time of service. In the VRPTW, the objective is to design the least total travel time routes for a fleet of identical capacitated vehicles to service geographically scattered customers with pre-specified service time windows. The proposed approach is based on ant colony optimization(ACO) and improvement heuristic. In the first phase, an insertion based ACO is introduced for the route construction and its solutions is improved by an iterative random local search in the second phase. Experimental results show that the proposed two-phase method obtains very good solutions with respect to total travel time minimization.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.38 no.3
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• pp.457-465
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• 2018

This study proposes a novel approach to explore a "travel time budget (TTB)" using a mobile phone signaling data (MPSD), which are passively generated between a mobile phone and a base station. The data analyzied in this study were provided from KT for 8 days (from May 19 to 26 in 2016). They were about 45 million signals passively generated from users whose stay area during night was classified as three areas in Mapo-gu, Seoul and in the city of Sejong. The estmation of TTB was implemented with various pre-processing techniques on the MPSD data in a data-driven analysis. As a result, the TTBs of Mapo-gu, Seoul and Sejong were 82.94 and 80.70 minutes, respectively. The results in this study were also compared with those based on the traditional methods. The authors expect that this result will help transport experts improve the use of MPSD.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.6
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• pp.1443-1448
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• 2007

In this paper, we implement a distributed computing environment-based travel information service that can use web(internet) and speech interface at the same time and can apply location information, using voice and web browser-based VoiceXML and GPS, to escape the limitations of traditional web(internet)-based travel information services. Because of IVR(Interactive Voice Response) of traditional call center has operated to a pre-installation scenario, it takes much a service time and has the inconveniences that must repeat speech recording according to the revised scenarios in case change response contents. However, suggested VoiceXML and GPS-based travel information service system has advantages that reorganization of system setups is easy, because it consists of the method to update server after make individual conversation scenarios by file format(document), and can provide usefully various travel information in environmental restriction conditions such as the back regions environment, according as our prototype find user's present location using GPS information and then provide various travel information service by this information.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.5D
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• pp.597-604
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• 2009

The mass transit networks in Korea, such as buses, metro and subway, are co-related and the number of transfer points, in which a lot of pedestrian movement is generated, are rising. The functions of the transfer centers, in which several travel modes cross at a point, have to include convenience and comfort for pedestrians using the transfer centers, and such functions can make transit a more attractive travel option and thus eventually contribute to increases in ridership. However, the guidelines for station layouts and their assessments in transfer stations are not suggested so far. So the pedestrian pattern data (pedestrian walking distances and times, pedestrian approaching distances and times, pedestrian walking paths in the inside of stations) was collected and analyzed. Based on the results of the analysis, the ways to measure the quality of comfort for those who using transfer facilities were suggested using the times that pedestrians consume to transfer from a travel mode to another. The walking time of pedestrians at the inside of stations was also measured by pre-selected pedestrian pathways as the guidelines for station layout assessment in transfer facilities.

• Journal of Korean Institute of Industrial Engineers
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• v.27 no.2
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• pp.140-149
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• 2001

The paper discusses the problem of finding the Origin-Destination(O-D) shortest paths in internodal transportation networks with time-schedule constraints. The shortest path problem on the internodal transportation network is concerned with finding a path with minimum distance, time, or cost from an origin to a destination using all possible transportation modalities. The time-schedule constraint requires that the departure time to travel from a transfer station to another node takes place only at one of pre-specified departure times. The scheduled departure times at the transfer station are the times when the passengers are allowed to leave the station to another node using the relative transportation modality. Therefore, the total time of a path in an internodal transportation network subject to time-schedule constraints includes traveling time and transfer waiting time. In this paper, a genetic algorithm (GA) approach is developed to deal with this problem. The effectiveness of the GA approach is evaluated using several test problems.

• Journal of Korean Society of Water and Wastewater
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• v.19 no.3
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• pp.330-337
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• 2005

This study was carried out to propose the managemental improvement of the purification plants and the distribution facilities which can minimize the formation of disinfection by-products in drinking water distribution system. The disinfection by-products were highly created in the water treatment plant that the organic matters were high and the chlorine dosage was excessive. The concentration of DSPs was shown the highest value in August and the lowest value in December, because of temperature and pre-chlorine dosage effect. From the result of tracer test, the travel time from the treatment plant to the end of pipeline was around 3-4 days in summer, 5-6 days in winter, respectively, and the DSPs concentration of the reservoir(end of pipe) was 2-3 times higher than that of the beginning point. The improvement of the chlorination process and structural reformation of distribution facility was demanded to minimize the DSPs increase from purification plant to the end of pipe.

• Journal of Korean Society of Transportation
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• v.23 no.1
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• pp.21-32
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• 2005

At present automated speed enforcement system in Korea control overspeed vehicle only in the specific spot. Because the drivers generally recognize the previous stated fact, they reduce a speed only in the establishment location of systems and increase rapidly again as soon as it passes the location. we have known that the rate of traffic risk at the tunnel, bridge and curve road segment is higher than other road section. Therefore, it needs speed control in them. In such a case, it is necessary to establish the automated traffic enforcement system based on the travel time speed of an individual vehicle over a pre defined stretch of road. In this study, the application limit of existing spot overspeed enforcement system was studied through an analysis of traffic flow characteristics in the tunnel, bridge and curve section. Also we found out the optimal distance of segment and the most suitable location to an application of the overspeed vehicle by travel time speed through an analysis of the road structure, traffic condition and accident numbers in the road.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.11 no.5
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• pp.27-37
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• 2012

Even thought the firefighters have to hurry to the scene to extinguish the blaze, the fire engines could not rushed out due to the worst of traffic condition. Traffic signal control is one of the most important methods to minimize the fire engines's travel time. The focus of this paper is to develop a traffic control strategy, which is emergency vehicle preemption algorithm considering pedestrian in order to reduce travel time of emergency vehicle. This algorithm also includes recovering strategy after preemption signal to minimize the other vehicle's delay. In order to estimate the effectiveness of traffic control, traffic simulation was performed using VISSIM micro simulation tool for two different kinds of networks, which were non-coordinated corridor and coordinated corridor. The differences of travel time and average delay between emergency vehicle and ordinary vehicle were respectively estimated under pre-existed pretimed signal and preemption traffic control at two respective networks. The results of the simulation for the emergency vehicle, travel time was reduced to 36.8~43.3% under "Add or Subtract" method whereas it was reduced to 30.7~46.0% under "Dwell" method. In addition, in non-coordinated corridor case of ordinary vehicle, average control delay of "Dwell" method was increased 33.5% whereas it grew 0.5% under coordinated corridor. And "Add or Subtract" method was confirmed that average control delay of ordinary vehicle was increased 0.7% under non-coordinated corridor whereas it swelled 4.5% under coordinated corridor.

• Journal of KSNVE
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• v.11 no.3
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• pp.461-470
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• 2001

A friction-type clutch system sometimes generates spick-slip vibration during engagement, which disturbs smooth start of a car and makes a passenger uncomfortable. In this study, the spick-slip vibration in four types of friction couples was investigated at two different engagement conditions respectively of which the amount of slip time and clutch travel was varied. Results are found as follows. First, the vibration increased at the condition of small engine torque and large torque fluctuations due to higher harmonics of engine speed. Second, the friction couple without a pre-damper has advantages of reducing the vibration. This study also suggested an evaluation method of vehicle vibration in the view point of human perception by using the frequency weighting of ISO2631-1.

• Proceedings of the KSR Conference
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• 2009.05a
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• pp.1308-1317
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• 2009

The mass transit networks in Korea, such as buses, metro and subway, are co-related and the number of transfer points, in which a lot of pedestrian movement is generated, are rising. The functions of the transfer centers, in which several travel modes cross at a point, have to include convenience and comfort for pedestrians using the transfer centers, and such functions can make transit a more attractive travel option and thus eventually contribute to increases in ridership. However, the guidelines for station layouts and their assessments in transfer stations are not suggested so far. So the pedestrian pattern data (pedestrian walking distances and times, pedestrian approaching distances and times, pedestrian walking paths in the inside of stations) was collected and analyzed. Based on the results of the analysis, the ways to measure the quality of comfort for those who using transfer facilities were suggested using the times that pedestrians consume to transfer from a travel mode to another. The walking time of pedestrians at the inside of stations was also measured by pre-selected pedestrian pathways as the guidelines for station layout assessment in transfer facilities.