• Journal of the Korean Society for Railway
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• v.20 no.1
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• pp.156-163
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• 2017

In the major operation sections of the urban railway, there has been habitual delay, and delay propagation; another problem is the increase of crowds and of inconvenience to passengers. The urban railway has different characteristics from rural railways, such as uncertainty of demand and irregularity of train operation. In urban railways, recently, operators manage quality indicators of service using operation results, such as the delay of train operation and the congestion of trains. However, because the urban railway has characteristics in which demand, passenger behavior, and train operation mutually affect each other, it is difficult to express the quality of service that passengers actually feel. In this paper, we suggest a quality indicator of service from the viewpoint of passengers, and present a demand responsive multi-train simulation method to predict dynamic dwell time and train operation status; we also use simulation results to consider changes in the quality indicator of service.

• Journal of the Korean Society for Railway
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• v.4 no.2
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• pp.47-54
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• 2001

Railway companies have been faced with many changes in the railway environment. To cope immediately with the influence of environment and to improve productivity, an efficient train operation system and related core technologies must be introduced. The railway system is composed of large scale infrastructures and high-cost trains. Simulation method is one of core technologies and also efficient tool for planning and analyzing these kinds of complex system. In this research, we review basic simulation programming models and present a modeling for the elements of railway system such as rail-line infrastructure, train, time table and operational route. Additionally, some considerations on the development of multi-train traffic simulator for KyongBu-line are discussed.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.5
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• pp.193-200
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• 2003

A computer simulation program to evaluate the performance of railway systems and train operation plans and the effects of new technologies is provided. The program has the functions of tracing the movements of trains on railway network following the indication of railway signalling system and obeying all kinds of operation rules. An object-oriented technique is applied to model railway system effectively, and it is expected that the program code can be reused easily for other railway simulation programs. Dedicated graphic user interface displaying the simulation outputs by animation during simulation process makes the program convenient to use. Simulation results on the train operations on Kyung-bu line show the proposed program is promising.

• Proceedings of the KIEE Conference
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• 1999.07a
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• pp.477-479
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• 1999

This paper proposed train operation simulation algorithm, algorithm to determining operational mode and algorithm for train performance program, which play a important role in multi-train operation simulation. Using railway network modelling and signalling systems modelling already developed, these algorithms was presented.

• Journal of the Korean Society for Railway
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• v.13 no.2
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• pp.222-228
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• 2010

In this paper, we propose a optimization approach for the Electric Locomotive Overhaul Maintenance Facility (ELOMF), which aims at the simulation optimization so as to meet the design specification. In simulation design, we consider the critical path and sensitivity analysis of the critical (dependent) factors and the design (independent) parameters for the parameter selection and reduction of the metamodel. Therefore, we construct the multi-objective non-linear programming. The objective function is normalized for the generalization of design parameter while the constraints are composed of the simulation-based regression metamodel for the critical factors and design factor's domain. Then the effective solution procedure based on the pareto optimal solution set is proposed. This approach provides a comprehensive approach for the optimization of Train Overhaul Maintenance Facility(TOMF)'s design parameters using the simulation and metamoels.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.9
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• pp.1699-1709
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• 2015

Moving terminals like high-speed-train undergo high Doppler frequency shift, and this leads to carrier frequency offsets that have to be compensated to avoid degradation of communication performance. In multiple access mechanism like OFDMA, base-stations need complex hardware to compensate the uplink frequency offset. In this paper, we propose a method, which can reduce burden of the base-station and makes frequency offset estimation and compensation simple. This method contains transmitting new synchronization signal, estimating frequency offsets in base-station, transmitting feedback information to terminal, and compensating the offset in uplink transmission. Simulation results show the proposed method operates well in high Doppler frequency shift conditions of 500 km/h which is the requirements of 5G mobile communication.