• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.65 no.3
• /
• pp.526-531
• /
• 2016

This paper presents an experimental study on the optimal settings for the selected DC fault relay (50F) to improve the operating performance for the high-speed circuit breaker on DC feeding system which ensure safety within rolling stock maintenance depot. In this study, current supplied to overhead contact wire was calculated on 1 ms interval to analyze the correction values of DC fault selective relay for the operation of current supply cutout. Particularly, standards for the accurate detection of accidents between an electric railway vehicle and the electric power facilities are shown by investigating the optimal correction values for detection of fault current, and the results indicated that it takes about 213 ms for the DC fault selective relay(50F) to fully open. In the future, the correction values of DC fault selective relay suggested in this paper will be used as the reference values of protective relay for the safe operation of DC electric railroad system such as urban railway.

• Journal of Korean Society of Transportation
• /
• v.29 no.4
• /
• pp.113-123
• /
• 2011

Traffic signal control is one of the most cost-effective means of improving urban mobility. With the recent progress of ITS (Intelligent Transportation System) and the installation of the real time traffic control systems, traffic signal control is conducted in online and real time. Normally, time-of-day (TOD) signal control is used with the system, but no definite methodology has yet been available for efficient TOD signal planing designing. Such method and process are in need to optimize the traffic signal timing plan. This paper proposes the optimization of TOD signal timings on arterials. The effects of the signal timings from the proposed method were assessed in the field. The proposed includes the methods determining the separation of the TOD break points and the TOD intervals. Those were tested on an arterial consisting of ten coordinated signalized intersections. It was found from the test results that the proposed TOD signal timing plans outperformed the previous signal timings.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.17 no.4
• /
• pp.41-53
• /
• 2018

This study developed the optimization method to correct the measured traffic volume of the expressway that minimizes the measurement error and satisfies the traffic balancing with TCS. For this purpose, the model constructed in this study was compared and verified with the true traffic volume. Verification result of the model, it was found that the measurement error is reduced when the measured traffic volume is corrected for the traffic volume balance. As a result of applying it to 40 links of the Kyoungbu expressway, the measured traffic volume was corrected by -8.1%~9.6% and the measurement error was decreased as much as the corrected traffic volume. This research is meaningful in improving the accuracy of the measured traffic volume of the expressway, while the scale and role of the expressway are increasing.

• Structural Engineering and Mechanics
• /
• v.62 no.4
• /
• pp.465-475
• /
• 2017

Photovoltaic (PV) panels are used in high-rise buildings to convert solar energy to electricity. Due to the considerable energy consumption of high-rise buildings, applying PV technology is of great significance to energy saving. In the application of PV panels, one of the most important construction issues is the connection of the PV panel with the main structures. One major difficulty of the connection design is that the PV panel connection consists of two separate components with coupling and indeterminate dimension. In this paper, the gap element is employed in these two separated but coupled components, i.e., hook and catch. Topology optimization is applied to optimize and design the cross-section of the PV panel connection. Pareto optimization is conducted to operate the optimization subject to multiple load scenarios. The initial design for the topology optimization is determined by the common design specified by the Technical Code for Glass Curtain Wall Engineering (JGJ 102-2003). Gravity and wind load scenarios are considered for the optimization and numerical analysis. Post analysis is conducted for the optimal design obtained by the topology optimization due to the manufactory requirements. Generally, compared with the conventional design, the optimized connector reduces material use with improved structural characteristics.

• Proceedings of the Korea Contents Association Conference
• /
• 2012.05a
• /
• pp.187-188
• /
• 2012

운송(transportation) 문제는 잘 알려져 있는 최적화 문제로 공급자인 생산지에서 소비자인 대리점으로 물건을 최소의 비용으로 운송시키는 문제이다. Coopr는 쉽고도 강력한 언어로 최근 각광받고 있는 파이썬 언어로 구현되었으며 최적화 모델의 해를 구할 수 있는 공용 소프트웨어 패키지이다. 본 논문에서는 몇몇 생산지에서 여러 대리점으로 물건을 운송시키는 최적화 문제를 Coopr의 한 부분인 pyomo를 이용하여 모델을 개발하고 최적화 해를 구할 수 있는 방법을 소개 한다.

• Journal of Korean Society of Transportation
• /
• v.10 no.3
• /
• pp.75-102
• /
• 1992

지난 수십년간 수많은 신호교차로제어모형이 제시되어 왔으나 과포화교차로를 특별히 다루는 기법은 거의 없었다. 본고에서는 과포화상태의 신호교차로제어를 위한 최적화모형이 제시된다. 지체도최소화나 연동폭최대화가 전통적인 제어목표로 사용되어 왔으나 혼잡교차로 제어에는 생산성최대화(maximum productivity)가 적절하며 본 모형에 사용되었다. 제시된 최적화모형은 Mixed Integer Linear Programming의 형태를 취한다. 본 모형은 두 개의 교차로 문제에 적용되었으며, 모형화 과정에 사용된 가정들의 적절함이 민감도분석에 의해 증명되었다. 최적해의 검증을 위하여 microscopic simulation model인 TRAF-NETSIM을 사용하였다.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.16 no.3
• /
• pp.250-254
• /
• 2013

Faster and cheaper transportation of the war supplies to the frontlines is essential for winning a war. This paper proposes a method to select the optimal location of the strategic military base, e.g., the Quartermaster Corps, that minimally connects three frontlines using the optimization technique. The results are also compared to the Steiner Tree theoty.

• Proceedings of the Korean Operations and Management Science Society Conference
• /
• 2006.11a
• /
• pp.273-276
• /
• 2006

At an integrated steel mill, various raw material such as coal and iron ore are unloaded from a large ship. The unloaded raw material is then transported to storage yards through a complex belt conveyer network. We propose an optimization model for scheduling the unloading operations under the limitations of available berths, unloading equipments and transportation capacity of the belt conveyer network. We show that the problem is NP-Hard and propose a heuristic approach to the problem.

• Journal of the Korean Society for Railway
• /
• v.15 no.2
• /
• pp.185-192
• /
• 2012

Line planning is to determine the frequency of trains on each line to satisfy origin-destination demand while minimizing total operation cost. However, different from the line planning in passenger transportation, it is more important at which intermediate stations each train should be stopped and shunted because the freight car handling works like drop-off or(and) pick-up can incur much time and high cost so that the delay deteriorates the quality of rail freight transportation service. We present an optimization model for constructing line plan in rail freight transportation to simultaneously minimize the train operation cost and total transportation time of freights. And we suggest a column generation approach for our problem, which can solve the real network instances in reasonable computation times.

• Asian Journal of Innovation and Policy
• /
• v.11 no.1
• /
• pp.110-147
• /
• 2022

Many megacities are exposed to natural hazards such as earthquakes, and when located in coastal regions, are also vulnerable to hurricanes and tsunamis. The physical infrastructures of transportation systems in megacities have become so complicated that very few organizations can understand their response to extreme events such as earthquakes and can effectively mitigate subsequent economic downfalls. The technological advances made in recent years to support these complex systems have not grown as fast as the rapid demand on these systems burdened by population shift toward megacities. The objective of this paper is to examine the risks imposed on and recoveries of transportation systems in megacities as the result of extreme events such as an earthquake. First, the physical damage to transportation infrastructure, loss of the transportation system performance, and the corresponding economic loss from disruptions to passenger and freight traffic is evaluated. Then, traffic flows are re-routed to reduce vehicles' delay due to earthquakes using a microscopic traffic flow simulator with an optimization model and macroscopic terminal simulator. Finally, the economic impact of the earthquake is estimated nationwide. Southern California is regarded as the region of study. The results demonstrate the effectiveness of the integrated model and provide what and how to prepare innovative resilience policies of urban infrastructure for a natural disaster occurrence.