• Journal of the Society of Disaster Information
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• v.14 no.3
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• pp.288-295
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• 2018

Purpose: The paper aims to compare the effectiveness of the two types of transport demand management measures, namely pull measures and push measures. Method: Case studies of two metropolitan areas in the developing world assess the extent to which increases in fuel prices can contribute to reducing automobile use and increasing the public transport use and the potential of urban rail transit to cause mode shift from automobiles. Within the case studies, a stated response survey of current car users has been conducted for Cairo and an on-line survey of rail transit users in Algiers. Results: There was a major proportion of car drivers who intend to switch to public transport, depending on the range of fuel prices in Cairo and a considerable proportion of rail users who have switched from automobiles resulting in a measurable reduction in CO2 emissions in Algiers. Conclusion: Investments in urban rail can be highly effective where there are demands for better public transport, but this type of pull measures can be much more effective if combined with push measures which significantly raise driving costs.

• Journal of the Korean Society of Systems Engineering
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• v.17 no.2
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• pp.122-128
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• 2021

Despite various economic crises, the domestic parcel delivery market handled 3.37 billion parcels in 2020 while maintaining annual growth due to the activation of e-commerce. In particular, in the case of the metropolitan area, which accounts for about 70% of the nation's parcel throughput, the increase in parcel delivery volume is directly related to the increase in freight vehicles in central area of Seoul,. And it leads to an increase of unnecessary social and environmental costs such as traffic congestion, road damage, and environmental pollution in the city. Therefore, in this paper we proposed the underground urban logistics system utilizing the existing urban rail infrastructure, and establish a conceptual design by operational scenario. In order to establish conceptual design of underground urban logistics system, we use order picking system process, which is use in warehouse, produce result combined ISO/IEC 26702. The results of this study can be usefully used before the underground urban logistics system is introduced.

• Journal of Power Electronics
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• v.16 no.2
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• pp.542-552
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• 2016

Central 60° synchronous modulation is an easy pulse-width modulation (PWM) method to implement for the traction inverters of urban rail trains at a very low switching frequency. Unfortunately, its switching patterns are determined by a Fourier analysis of assumed steady-state voltages. As a result, its transient responses are not very good with over-currents and high instantaneous torque pulses. In the proposed solution, the switching patterns of the conventional central 60° modulation are modified according to the dynamic error between the target and actual stator flux. Then, the specific trajectory of the stator flux and current vector can be guaranteed, which leads to better system transients. In addition, stator flux control is introduced to get smooth mode switching between the central 60° modulation and the other PWMs in this paper. A detailed flow chart of the control signal transmission is given. The target flux is obtained by an integral of the target voltage. The actual PMSM flux is estimated by a minimum order flux state observer based on the extended flux model. Based on a two-level inverter model, improved rules in the α-β stationary coordinate system and equations of the switching patterns amendment are proposed. The proposed method is verified by simulation and experimental results.

• Journal of the Korean Society for Railway
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• v.7 no.4
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• pp.412-417
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• 2004

In urban rail transit systems, ground faults in the DC traction power supply system are currently detected by the potential relay, 64P. Though it detects the fault it cannot identify the faulted region and therefore the faulted region could not be isolated properly. Therefore it could cause a power loss of the trains running on the healthy regions and the safety of the passengers in the trains could be affected adversely. Two new ground fault protective relay schemes that can identify the faulted region are presented in this paper. A current limiting device, called Device X, is newly introduced in both system, which enables large amount of ground fault current flow upon the positive line to ground fault. One type of the relaying schemes is called directional and differential ground fault protective relay which uses the current differential scheme in detecting the fault and uses the permissive signal from neighboring substation to identify the faulted region correctly. The other is called ground over current protective relay. It is similar to the ordinary over current relay but it measures the ground current at the device X not at the power feeding line, and it compares the current variation value to the ground current in Device X to identify the correct faulted line. Though both type of the relays have pros and cons and can identify the faulted region correctly, the ground over current protective relaying scheme has more advantages than the other.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.9
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• pp.1374-1379
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• 2012

Urban rail transit tends to global grounding system in order to control ground potential rise and potential differences between electric equipments. In addition, global grounding system can discharge the large capacity surge current to the ground safely. Since some railway electric equipments are installed all section of line, the global grounding system connected with the connecting grounding wire is more effectively. However, if the fault occurred in the connecting grounding wire area, some dangerous voltage is generated. So, the installation of additional grounding rod will be required. In this study, the global grounding system is simulated using CDEGS program to analyze the divergence spacing of additional ground rod depending on dangerous electric potential characteristics. Grounding net of the each station is modelled in depending on the size of the platform, and the spacing of the connecting grounding rod are compared 50m, 100m, 250m and 400m. Simulation results considering of earth resistivity and underground condition of the connecting grounding wire, spacing of the connecting grounding rod is that less than 250m to spacing of the ground rod was appropriately confirmed.

• Proceedings of the KSR Conference
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• 2011.05a
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• pp.1080-1084
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• 2011

Urban maglev should have such characteristics as not only environmentally friendliness and excellent driving capability but also curve negotiation performance because its routes have many sharp curves. Due to normal mechanism of urban maglev its relative displacements of secondary spring are bigger than conventional railway vehicle and the centering force of levitation magnet is smaller than wheel-on-rail system. These features of maglev affect the curving negotiation and so the additional steering device is to be required on Urban maglev to improve the running performance at sharp curve of less than about R50m. Some developed urban maglev had the passive steering device which consists of mechanical linkage or hydraulic cylinder and closed-route piping. But it has drawback as complexity of layout of understructure of vehicle and functional limitation of passive mechanism regarding transient curve. These demerits could be solved by using active steering system. But it has a weak point that an active device should have actuators and additional inverter or hydraulic power source. In this paper, the semi-active steering system for urban maglev is to be introduced.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.59 no.3
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• pp.268-274
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• 2010

Urban rail transit brings the benefits of various aspects of society. With the advent of fast and large trains, however, risk and scale of accidents have increased. Despite the fact that there is various safety features built into the modern metros, train faults happen from time to time. Especially, as urban railway vehicles in Korea have become deterioration rapidly, more advanced diagnosis methods are required to prevent various accidents. In this paper, we present diagnosis method for electrical wires to guarantee secure driving and authenticity more accurately in urban railway vehicles. Although there are kinds of conventional methods based on insulation resistance measurement and withstand test, it is extremely difficult to effectively diagnose obsolete equipments such as electrical wires and cables not new ones. This study is focused on development of diagnosis method and establishment of evaluation standard for electrical wires in urban railway vehicles.

• Proceedings of the KSR Conference
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• 2006.11b
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• pp.791-795
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• 2006

Urban transit is one of the most effective ways for efficient operation and construction of an urban transit by composition system which is liked originally such as rolling-stock, power, signal and infrastructure. Urban rail transit system is running in domestic, imports major equipments from advanced countries and setup for maintenance. But it takes long time because it does each organizations and lines. Also, signal, power and track system apply different standard by each construction organizations it causes an increasing construction of cost accordingly it desperately needs a systematic countermeasure. Therefore standard specification of urban transit have been establishing and operatingfor efficient operation of urban transit and base technology security that is populace ride to become a base of state economy. After track, power and signal system will be announced. Standard specification become more, the importance of administrationof standards is emphasized more. Specification administrator’s the importance which use a computing support tool recently in railroad part in embossed and is predicted to be more such forward. Therefore we propose the effective method of management with track, power signal system by constructed data-base system.

• Journal of The Korean Society For Urban Railway
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• v.6 no.4
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• pp.259-268
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• 2018

To reduce conducted a survey on human error risk factors and related experience frequency to drivers of Seoulmetro and Korail. The human error arising from systems operating urban railway aimed at eliminating and reducing the fundamental causes of urban rail accidents is based on research from a factorial point of view, since it contains problems dealing with the types and situations of accident generation. It is required to contribute to reducing human error so that urban railway accidents may be reduced and safe operation will be continuedly seared.

• Journal of the Korea institute for structural maintenance and inspection
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• v.16 no.6
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• pp.143-154
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• 2012

The wireless low-floored tram is an innovative transportation system which is environment-friendly and highly energy-efficient. In addition, the system has various advantages such as low construction cost, improvement of urban landscape, revitalization of surrounding commercial area, elevated convenience for passengers, etc. Therefore, more than ten local governments have proposed tram construction projects in Korea. Accordingly, many research and development projects are ongoing funded by government including the developments of tram vehicle, tram trackway, signal system, etc. The embedded rail system are commonly used in order to provide leveled roadway surface in urban area. It is effective to reduce the noise and vibration, caused at the interface between the wheel and track, to minimize the construction period, and to lower the maintenance cost. This paper investigated the design and construction processes for tram trackway and figured out the constructability for the test track with embedded rail system for the first time in Korea. The performance to reduce the noise and vibration were quantitatively measured in the test track with embedded rail system. In addition, the results were compared to the ones for track with conventional rail system.