• Journal of Korean Society of Transportation
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• v.36 no.3
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• pp.169-183
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• 2018

Aggressive driving leads to a greater crash potential because it threatens surrounding vehicles. This study conducted traffic simulation experiments using driving behavior data obtained from multi-agent driving simulations. VISSIM traffic simulator and surrogate safety assessment model (SSAM) were used to identify the impacts of aggressive driving on traffic stream in terms of safety and operational efficiency. Market penetration rates (MPR) of aggressive driving vehicle, coupled with various traffic conditions, were taken into consideration in analyzing the impacts. As expected, it was identified that aggressive driving vehicles tended to deteriorate the traffic safety performance. From the perspective of operational efficiency, interesting results were observable. Under level of service (LOS) A, B, and C, it was observed that the average travel speed increased with greater MPRs. Conversely, the average travel speed decreased with under LOS D and E conditions. The outcome of this study would be effectively used for developing safety-related policies for reducing aggressive driving behavior.

• Industrial Engineering and Management Systems
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• v.16 no.1
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• pp.44-51
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• 2017

In today's competitive environment, supply chain management is a major concern for a company. Two of the key issues in supply chain management are transportation and inventory management. To achieve significant savings, companies should integrate these two issues instead of treating them separately. In this paper we develop a framework for modeling stochastic programming in a supply chain that is subject to demand uncertainty. With reasonable assumptions, two stochastic programming models are presented, respectively, including a single-period and a multi-period situations. Our assumptions allow us to capture the stochastic nature of the problem and translate it into a deterministic model. And then, based on the genetic algorithm and stochastic simulation, a solution method is developed to solve the model. Finally, the computational results are provided to demonstrate the effectiveness of our model and algorithm.

• IE interfaces
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• v.11 no.1
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• pp.55-66
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• 1998

Fleet sizing and distribution of empty equipments are two of the most critical problems in managing transportation system. This paper develops a cost model for sizing a fleet and establishing decentralized redistribution polices of empty equipments by building from inventory theory of multi-echelon system in hub-and-spoke network. An analytical approach to determine control variables of redistribution policies in each terminal and fleet size of the transportation system is proposed and its results are validated by simulation model. Numerical experiments are conducted with respect to parameters of the model and test results for assumptions of the model are discussed.

• Journal of Ocean Engineering and Technology
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• v.21 no.3 s.76
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• pp.16-25
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• 2007

A comparative study on the turbulent flaw simulation and the potential flaw analysis has been performed. A law Mach number preconditioned Navier-Stokes solver, using the multi-block grid method and a panel method based on the velocity potential, have been developed and validated by comparison to the experimental data. The present numerical analysis methods are applied to the ground effect problem around the NACA 4412 airfoil. It has been confirmed that the potential flaw analysis on the ground effect, using the image method, is consistent, to some degree, with the viscous calculations for high Reynolds number flows.

• Journal of the Korean Society of Safety
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• v.14 no.1
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• pp.66-72
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• 1999

Local heating transportation pipe has sensor and return lines to detect water-leakage. There are impulse and resistance comparison measurement types for a water-leakage detection. The impulse type shows large detection error within a measurement range. Since the resistance comparison type can find a comparative accurate single water-leakage point in the measurement range of heating pipe, it has been used to detect water-leakages these days. However if the multi water-leakages are happened in the measurement range of transportation pipe. the resistance comparison type shows a detection error point by the parallel resistance between a detection sensor line and ground. But the detection error will be minimized by the divided transportation pipe loops. In this research, it suggests the design of remote controlled detection system which can divide a large pipe loop and a possible single water-leakage measurement process in each divided loops.

• Proceedings of KOSOMES biannual meeting
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• 2017.04a
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• pp.166-166
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• 2017

Nowadays, container transport services play a substantial role in global cargo transportation by serving as an intermodal between the exporter and importer. Container shipping has become increasingly important over the past few decades due to its obvious advantages. However, Vietnam's container market has shown severely ongoing competition among numerous domestic and foreign shipping lines resulting in serious consequences occurring such as the freight rates substantially decreasing within the last ten years. In fact, Vietnam's sea lanes have become more defensive to cover the losses of shipping companies. Selection of criteria for competitive evaluation of container transport companies is necessary to help recognize the problems within the enterprise especially relating to its position in the market and from here, business management are able to put strategic plans in place and reasonable policy in order to be able to survive and grow.

• Journal of the Korea Safety Management & Science
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• v.12 no.3
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• pp.315-320
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• 2010

Recently, there are environmental issues for sustainable transportation system to pursue the energy-efficient and environment-friendly public urban transit. These transportation system needs to offer demand-oriented high-quality service being on the same level with cab service for urban space. PRT(Personal Rapid Transit), small track-guided vehicle, is repeatedly mentioned as a possible alternative for the new urban public transportion system, but but there are not many researches on the operational optimal routing for PRT network. In this paper, the concept of PRT and general optimal routing methods are reviewed. And we suggest the optimal routing method for city-wide PRT network with multi-vehicles and stations, junctions and directional arcs. Futher research directions for PRT routing are presented.

• Proceedings of the KOR-KST Conference
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• 1998.09a
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• pp.65-70
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• 1998

Economic evaluation methodologies for railway investments of China and Korea are comparatively analyzed. Chinese procedures specified in the new economic evaluation manual of 1997 were compared with those of Korea based on the economic evaluation manual of 1982. As expected those procedures reflect general economic requirements of the respective countries. Several differences in the specification are also noted. Details of the specification of Chinese procedure far exceed Korean specification, while Korean manual is rich of explanation on the fundamental theory. Differences in the procedure of calculating benefits of investments are most conspicuous, and specific requirements of carrying out a optimum opening year analysis in Korean procedure is notable. Despite of these differences in the procedure, two methodologies share same objective of ensuring selection of economically and financially sound railway projects. Both procedures of China and Korea, however, limit their evaluation scope on railways alone. Therefore, they are needed to expand scope of evaluation to encompass the idea of multi-modal or inter-modal evaluation, which will eventually contribute to build truly efficient national comprehensive transportation system.

• Geomechanics and Engineering
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• v.17 no.4
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• pp.385-392
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• 2019

The present fractional-order plasticity models for granular soil are mainly established under the triaxial compression condition, due to its difficult in analytically solving the fractional differentiation of the third stress invariant, e.g., Lode's angle. To solve this problem, a three dimensional fractional-order elastoplastic model based on the transformed stress method, which does not rely on the analytical solution of the Lode's angle, is proposed. A nonassociated plastic flow rule is derived by conducting the fractional derivative of the yielding function with respect to the stress tensor in the transformed stress space. All the model parameters can be easily determined by using laboratory test. The performance of this 3D model is then verified by simulating multi series of true triaxial test results of rockfill.

• Proceedings of the Korean Society of Computer Information Conference
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• 2022.07a
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• pp.289-292
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• 2022

본 논문에서는 실제 철도 건널목(교차로)에서 발생하는 소음 및 진동, 차량 및 보행자 사고와 같은 위험 요소로부터 발생하는 위험 상황들을 분류하고, 철도 건널목(교차로) 운행 상황을 구현한 모형 철도 주변에 센서를 부착하여 철도 건널목에서 발생하는 위험 요소들을 아두이노 센서로 감지해 데이터를 수집한다. 또한 수집된 데이터들을 활용하여 사용자의 상황에 맞는 철도데이터 운영시스템을 제안한다.