• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.13 no.1
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• pp.53-60
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• 2014

Redundant handovers cause degraded quality of service to passengers in vehicle. This paper proposes a handover scheme suitable for users traveling in vehicles, which enables continuous learning of the handover process using a discrete-time Markov chain (DTMC). Through AdaBoost machine learning algorithm, the proposed handover scheme avoids unnecessary handover trials when a short dwell time in a target cell is expected or when the target cell is an intermediate cell through which the vehicle quickly passes. Simulation results show that the proposed scheme reduces the number of handover occurrences and maintains adequate throughput.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.1D
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• pp.71-80
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• 2012

Metropolitan transport demand has increased in Seoul Metropolitan Area (SMA) due to the expansion of its role and land use. Various public transport modes have to be supplied to relieve road congestions for the convenience of users. During the constructions of theses infrastructures some conflicts between the central government and local governments arise for sharing financial resources. In this study finance sharing criteria is developed for the metropolitan BRT, transfer facility, and public garages. Finally, a case study has been done for the metropolitan BRT between Cheongra and Hwagok area in SMA.

• Journal of the Korean Society for Railway
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• v.12 no.6
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• pp.1067-1075
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• 2009

The Bimodal Tram being developed in Korea is a new transit system that provides both benefits of rail and bus systems in terms of accessibility and fixed time schedule. This study accomplished a feasibility study for introducing the Bimodal Tram system by considering the travel demand and existing transit system at a city level based on its population. The feasibility of Bimodal Tram system varies depending on cities with respect to demographic scale, mode shares, and operational distances. The strategies introduced here will help any cities where transport agencies are trying to introduce the Bimodal Tram as a new transit system.

• Proceedings of the KSR Conference
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• 2009.05a
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• pp.1805-1816
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• 2009

The Bimodal Tram being developed in Korea is a new transit system that provides both benefits of rail and bus systems in terns of accessibility and fixed time schedule. The Bimodal Tram will change the role of transit system in Korea. This study developed a strategy of introducing the Bimodal Tram system by considering the travel demand and existing transit system at a city level. The transport/transit system varies depending on cities with respect to demographic characteristics, financial capabilities, etc. The strategies introduced here will help any cities where transport agencies are trying to introduce the Bimodal Tram as a new transit system.

• Proceedings of the Korea Information Processing Society Conference
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• 2019.05a
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• pp.371-374
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• 2019

PDA나 휴대폰 단말로 여러 속성의 데이터를 이용하여 사용자에게 필요한 정보를 제공하는 위치기반 서비스는 물류/운송 정보 서비스, 버스/지하철 노선 안내 서비스 등에 사용된다. 여기에서 제공하는 데이터들을 최적 경로를 구하는 외판원 순회문제 (Traveling Salesman Problem)에 사용한다면 더 정확한 경로 서비스 제공이 가능하다. 하지만 데이터의 수가 많아질수록 비교 횟수가 기하급수적으로 늘어나는 외판원 순회 알고리즘의 특성상 일반 단말기에서 활용하기에는 배터리의 제약이 따른다. 본 논문에서는 이와 같은 단점을 해결하기 위해서 최적 경로의 후보군을 줄일 수 있는 스카이라인 질의를 이용하여 n차원 속성에 대한 최적 경로 알고리즘을 제안한다. 실험에서 정확도와 오차율을 통해 제안한 방식의 유용성을 보였으며 기존방식과 연산시간 차이를 비교하여 다차원방식의 효율성을 나타내었다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.1
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• pp.251-259
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• 2014

Securing publicness and efficiencies are the two core goals for implementing quasi-public bus system. However, researches for evaluating the quasi-public bus system with respect to the two goals have been very limited. This study represents an attempt to evaluate the system performance in these two aspects. To achieve this, a framework for performance evaluation is developed. Utilizing the framework, the 5-year performances of the quasi-public bus system in Busan are evaluated. Acess, agency and public interests are employed as criteria for publicness evaluation. Financial aspects of operators, labor, vehicle utilization, productivity and operational costs are selected as indicators for efficiency evaluation. The results show that the publicness of bus services has been vastly improved, while the efficiency has been also improved in most areas except in cost and vehicle utilization aspects. The results of this study will be of use for planners and policy-makers developing strategies for system improvement. It is hoped that this study can be further refined by adding and adjusting indicators which this study may neglect or ignore.

• Informatization Policy
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• v.27 no.2
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• pp.66-83
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• 2020

Local issues that occur in cities typically garner great attention from the public. While local governments strive to resolve these issues, it is often difficult to effectively eliminate them all, which leads to complaints. In tackling these issues, it is imperative for local governments to use big data to identify the nature of complaints, and proactively provide solutions. This study applies the LDA topic modeling technique to research and analyze trends and patterns in complaints filed online. To this end, 9,625 cases of online complaints submitted to the city of Busan from 2015 to 2017 were analyzed, and 20 topics were identified. From these topics, key topics were singled out, and through analysis of quarterly weighting trends, four "hot" topics(Bus stops, Taxi drivers, Praises, and Administrative handling) and four "cold" topics(CCTV installation, Bus routes, Park facilities including parking, and Festivities issues) were highlighted. The study conducted big data analysis for the identification of trends and patterns in civil affairs and makes an academic impact by encouraging follow-up research. Moreover, the text mining technique used for complaint analysis can be used for other projects requiring big data processing.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.36 no.1
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• pp.105-114
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• 2016

With approximately 20 million transportation card data entries of the metropolitan districts being generated per day, application of the data to management and policy interventions is becoming an issue of interest. The research herein attempts a model of the possibility of dynamic demand change predictions and its purpose is thereby to construct a Dynamic Passengers Trip Assignment Model. The model and algorithm created are targeted at city rail lines operated by seven different transport facilities with the exclusion of travel by bus, as passenger movements by this mode can be minutely disaggregated through card tagging. The model created has been constructed in continuous time as is fitting to the big data characteristic of transport card data, while passenger path choice behavior is effectively represented using a perception parameter as a function of increasing number of transfers. Running the model on 800 pairs of metropolitan city rail data has proven its capability in determining dynamic demand at any moment in time, in line with the typical advantages expected of a continuous time-based model. Comparison against data measured by the eye of existing rail operating facilities to assess changes in congestion intensity shows that the model closely approximates the values and trends of the existing data with high levels of confidence. Future research efforts should be directed toward continued examination into construction of an integrated bus-city rail system model.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.1D
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• pp.17-23
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• 2009

Due to the rapid increase of vehicles on the street, Korean society is facing worsening traffic congestions and air pollutions. Also, the oil price pickup has led to increasing need for the use of public transportation. In particular, transfering among public transportation may be a main factor for riders who are commuting for a long distance journey. In order to ensure such connectivity, transfer stations have been actively built in Korea. However, it would be necessary to shift those vehicles, from cars to public transportations by enhancing the users' satisfaction with public transportation through strategies for minimizing the users' waiting cost by building an efficient connective system between transportation modes as well as the preparation of aforementioned transfer stations. Therefore, this study aimed to develop an algorithm for minimizing transferring passengers' waiting costs based on service intervals of linked buses within the transfer facilities. In order to adjust the service interval, we calculated the total costs, involving the wait cost of transfer passengers and bus operation costs, and produced an allocation interval, that would minimize the costs. We selected a KTX departing from Seoul station, and a No. 6014 bus route in Gwangmyeong city where it starts from the Gwangmyeong station in order to for verifying the model. Then, the transfer passengers' total waitting cost was reduced equivalent to the maximum of 212 minutes, and it revealed that the model performed very effectively.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.15 no.3
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• pp.60-67
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• 2016

In cumulative transfer functions, as number of transfer increase, the impact of individual transfer to transfer cost increase linearly or non linearly. This function can effectively explain various passengers's travel behavior who choose their travel routes in integrated transit line networks including bus and railway modes. Using the function, it is possible to simulate general situations such that even though more travel times are expected, less number of transfer routes are preferred. However, because travel cost with cumulative transfer function is known as non additive cost function types in route search algorithms, finding an optimal route in integrated transit networks is confronted by the insolvable enumeration of all routes in many cases. This research proposes a methodology for finding an optimal path considering cumulative transfer function. For this purpose, the reversal phenomenon of optimal path generated in route search process is explained. Also a heuristic methodology for selecting an optimal route among multiple routes predefined by the K path algorithm. The incoming link based entire path deletion method is adopted for finding K ranking path thanks to the merit of security of route optimality condition. Through case studies the proposed methodology is discussed in terms of the applicability of real situations.