• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.1
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• pp.148-158
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• 2011

As critical infrastructure, bridges play an indispensable role in facilitating the distribution of goods. When bridges reach their end of useful life or get damaged by natural disasters such as earthquakes or storms, they have to be removed and reconstructed. When bridges in service need to be reconstructed, user costs occur from vehicle detours and traffic congestions, and social costs occur from noise and dust during construction periods. However, these user and social costs are not considered during reconstruction and the evaluation methods of those costs are vague. Thus, there is lack of appropriate bridge types that consider these costs. Therefore, this paper identifies the social overhead costs that occur during bridge reconstruction, which is also called, users' socioeconomic values. Next, it proposes a method to evaluate user costs during bridge reconstruction, and appraises the method. User costs are evaluated based on traffic information, social and material volumes including the bridge's daily traffic volume, peak hours, detour distance and time. In addition, time delay costs due to traffic operational costs and bridge reconstruction are also taken into consideration.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.1731-1737
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• 2007

This paper considers subway routing problem. Given a schedule of train to be routed by a railway stock, the routing problem determines a sequence of trains while satisfying turnaround time and maintenance restrictions. Generally, the solution of routing problem is generated from set partition formulation solved by column generation method, a typical integer programming approach for train-set. However, we find the characteristics of metropolitan subway which has a simple rail network, a few end stations and 13 departure-arrival patterns. We reflect a turn-around constraint due to spatial limitations has no existence in conventional railroad. Our objective is to minimize the number of daily train-sets. In this paper, we develop two basic techniques that solve the subway routing problem in a reasonable time. In first stage, we formulate the routing problem as a Min-cost-flow problem. Then, in the second stage, we attempt to normalize the distance covered to each routes and reduce the travel distance using our heuristic approach. Applied to the current daily timetable, we could find the subway routings, which is an approximately 14% improvement on the number of train-sets reducing 15% of maximum traveling distance and 8% of the standard deviation.

• Journal of Korean Society of Transportation
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• v.25 no.5
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• pp.91-100
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• 2007

This study suggests direct connection service which has advantage of high-speed operation of KTX and access convenience of general train, and Pre-feasibility studies on the direct connection service. And analyze transportation demand change by the method as follows; It is to analyze the demand change of before and after KTX operation by previous transport data of Gyeongbu line, and calculate the coefficient of utilization using triggering demand by opening the 2nd phase of Gyeongbu line (Dongdaegu${\sim}$Busan). Through Pre-feasibility analysis, reduction $70{\sim}100$ minutes of train travel time and total revenue will increase about $100 thousand per day. Also, there will be environment-friendly effects of decreasing $CO_2$ emissions. But, Direct connection service need to highly cost ; Buying and Operation cost of KTX train. Therefore, we will be get more correct result of Pre-feasibility study on direct connection service, if there are concrete on buying the KTX action plans.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 2010.09a
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• pp.363-368
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• 2010

본 논문은 레미콘 차량의 관제 및 관리, 레미콘 플랜트의 효율적 운영을 위해 시행되고 있는 레미콘차량 관제 시스템의 최적 좌표 전송 주기를 평가하고자 하였다. 이를 위해 실제적으로 레미콘차량 관제 시스템을 운영 중인 레미콘회사를 사례로 2010년 5월 한달 간 운행된 20대의 차량에 30초, 1분, 3분, 5분 간격으로 수신 된 좌표 주기별 거리와 실제로 운행 된 거리를 비교하였다. 또한 최적 좌표전송주기를 평가하기 위해 30초, 1분, 3분, 5분 간격으로 전송되는 주기별 Packet 계산표에 따라 데이터 요금제를 비교 환산하여 비용 대비 최적의 좌표전송주기를 평가 하였다. 그 결과 1분 간격의 송신주기가 오차율이 2.34%, 1일 8시간 운행기준 월 송신요금이 10,000원으로 나타나 가장 합리적으로 분석되었다. 그러나 좌표전송에서 비정상적인 값이 수신 될 경우 그에 대한 방안이내 처리 절차 등의 추가적인 연구의 필요성이 제기된다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.11 no.6
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• pp.131-142
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• 2007

The road user cost in indirect costs as well as direct costs such as the inspection/ diagnosis cost and the repair/reinforcement cost should be considered as one of the important items in the life-cycle cost-effective design and maintenance of the bridges. To estimate the road user cost, this paper formulates the road user cost as a sum of the user delay cost and the vehicle operating cost considering the detour effect. A numerical traffic simulation and a regression analysis are performed to develop a regression model due to a time delay. The proposed regression model is applied to the generation of the maintenance strategy based on the life-cycle cost and performance, and its effectiveness and applicability is investigated. The road user cost has a great influence on establishing the maintenance strategy, and the proposed regression model could be successfully utilized to estimate the road user cost of a bridge.

• Proceedings of the KOR-KST Conference
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• 2007.11a
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• pp.97-103
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• 2007

• Journal of Energy Engineering
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• v.8 no.1
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• pp.95-100
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• 1999

대우자동차는 1992년 이래로 전기자동차 개발사업을 추진하고 있으며 1996년에는 전기자동차의 Fleet 운영시험을 위해 10대의 씨에로 개조형 전기자동차를 제작하였다. 이 씨에로 전기자동차에는 고성능 연축전지, 교류유도전동기, 탑재형 충전기 및 전동조향배력장치 등이 장착되어 있으며 고등기술연구원에서는 전기자동차의 Fleet 운영시험의 일환으로 시외 일반도로 운행조건에서 전기자동차의 에너지비용을 조사하기 위한 연구를 수행하였다. 두 대의 씨에로 전기자동차를 용인시와 안성군 지역의 일반도로에서 1998년 4월부터 운행하였으며 이 운행시험 결과를 바탕으로 일반도로 주행조건에서 씨에로 전기자동차의 에너지비용과 동급의 가솔린자동차인 씨에로 1.5DOHC A/T 차량의 에너지비용을 계산하였다. 두 대의 전기자동차중 한 대의 연비는 5.7 km/kWh이었으며, 다른 한 대의 연비는 5.8 km/kWh이었다. 이에 비해 가솔린자동차의 연비는 13.7 km/l로 년간 20,000 km를 주행한다고 가정할 때 가솔린자동차의 년간 주행비용은 전기자동차의 3.4∼18.0배가 되는 것으로 나타났다. 이 시험을 통해 향후 전기자동차의 개발을 위해 유용하고 가치있는 많은 데이터를 얻었다.

• Journal of Korean Society of Transportation
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• v.27 no.6
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• pp.147-156
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• 2009

We present a methodology for modeling and solving the transit frequency design problem with variable demand. The problem is described as a bi-level model based on a non-cooperative Stackelberg game. The upper-level operator problem is formulated as a non-linear optimization model to minimize net cost, which includes operating cost, travel cost and revenue, with fleet size and frequency constraints. The lower-level user problem is formulated as a capacity-constrained stochastic user equilibrium assignment model with variable demand, considering transfer delay between transit lines. An efficient algorithm is also presented for solving the proposed model. The upper-level model is solved by a gradient projection method, and the lower-level model is solved by an existing iterative balancing method. An application of the proposed model and algorithm is presented using a small test network. The results of this application show that the proposed algorithm converges well to an optimal point. The methodology of this study is expected to contribute to form a theoretical basis for diagnosing the problems of current transit systems and for improving its operational efficiency to increase the demand as well as the level of service.

• Spatial Information Research
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• v.18 no.3
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• pp.63-72
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• 2010

The vehicle routing problem with simultaneous pick-up and delivery (VRPSPD) is a variant of the vehicle routing problem (VRP) that customers require simultaneously a pick-up and delivery service. The main objective of VRPSPD is to minimize a cost of routes satisfying many constraints. Traditional VRPSPD have been dealt with a static environment. The static environment means that a routing data and plan cannot be changed. For example, it is difficult to change a vehicle's routing plan so that a vehicle serves the pick-up demands of new customers during the delivery service. Therefore, traditional approach is not suitable for dynamic environments. To solve this problem, we propose a novel approach for finding efficient routes using a real-time re-routing heuristics based on the Location Based Service (LBS). Our re-routing heuristics can generate a new route for vehicle that satisfies a new customer's demand considering the current geographic location of a vehicle. Experimental results show that our methodology can reduce the traveling cost of vehicles comparing with other previous methods.

• Journal of Korean Society of Transportation
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• v.20 no.2
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• pp.27-38
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• 2002

This study estimates the social cost of the traffic congestion of the Express highway from Seoul to Pusan during the New Year holiday in 1999. Considering inelastic demand and the hyper congestion, we show the congestion cost can be estimated as externalities caused by traffics which exceed the road capacity. Due to the congestion, it is estimated that it took about 12.40 hours more from Seoul to Pusan. The congestion is also estimated to have caused fuel cost of 0.6 billion won. time cost of 43.6 billion won and environmental cost of 0.5 billion won. The total cost reached up to 44.8 billion won.