• Journal of the Korean Society for Precision Engineering
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• v.29 no.6
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• pp.621-625
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• 2012

Conventionally, to measure derailment coefficient of a railway wheel, strain gauges for lateral force measurement are attached to both side of the wheel. But narrow gap between railway wheel and traction motor makes it difficult to attache the strain gauges at the inner side of wheel. In this study, to overcome the hard accessibility to the strain gauge points by narrow gap, a new Wheatstone bridge connection method is presented by attaching all the strain gauges at the outer side of wheel with a new bridge connection. We evaluate the running safety of railway vehicles in accordance with railway safety regulations. The experimental results obtained shows higher sensitivity than conventional methods and the derailment coefficient measurement procedure becomes simpler.

• Journal of the Korean Society for Nondestructive Testing
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• v.34 no.5
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• pp.390-396
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• 2014

A study on smart seats for railroad vehicles was conducted using piezoelectric (PZT) sensors. For this purpose, the concept of passenger friendly smart seats was defined, and a PZT sensor was selected as the optimum sensor based on this concept. Using PZT sensors, simulation tests were performed using a sub-scale model railroad vehicle. In these tests, the main functions of the smart seats were extracted and simplified to improve the effectiveness of the simulation tests. Based on the test results, the system for smart seats proposed in this paper was successfully verified using PZT sensors and the dedicated operation software for the system. This paper will contribute to the improvement of services in high-speed rail systems through advances in ticket checking tasks.

• Journal of the Korean Society for Precision Engineering
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• v.32 no.7
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• pp.603-609
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• 2015

Railway vehicles driven by wheels obtain force required for propulsion and braking by adhesive force between wheels and rails, this adhesive force is determined by multiplying adhesion coefficient of the friction surface by the applied axle load. Because the adhesion coefficient has a peak at certain slip velocity, it is important to determine the maximum values of the friction coefficient on the contact area. But this adhesive phenomenon is not clearly examined or analyzed. Thus we have developed new test procedure using the scaled adhesion test-bench for analyzing of the adhesion coefficient between wheel and rail. This adhesion test equipment is an experimental device that contacts mutually with twin disc which are equivalent to wheels and rails of railway vehicles.

• The Journal of Korean Society for School & Community Health Education
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• v.17 no.2
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• pp.31-44
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• 2016

Objectives: This study was aimed at finding out the current smoking situation of workers in the field of railroad electricity and vehicles and changes of their smoking behaviors after the raise of price of tobacco in 2015. Methods: With a self-administered questionnaire conducted from February 9 to March 6 2015, one-way ANOVA and crosstabs(PASW Statistics Ver. 18.0) were conducted on the data of 626 people. Results: As the result, the smoking rate was 39.1% and 90.5% of the smoking experienced group showed some changes including cutting down on smoking due to raise of price of tobacco. Factors related to smoking included stress, the number of times of drinking, awareness of harmfulness of smoking, the number of days with hard exercise per week and the marital status. Conclusion: Therefore, it is assumed that there is necessity of top-down intervention using these factors to cut down the smoking rate.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.1442-1444
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• 2000

High speed switching action of PWM inverter is being further advanced for electric motor vehicles. Due to this high speed switching action, extensive high frequency electromagnetic noise emerges. Therefore counterm-easures against electromagnetic interference of electric motor vehicles become increasingly important. This paper describes the theory and countermeasure principle of EMI prevention and EMI test method for Korean Standard EMU.

• Proceedings of the KIEE Conference
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• summer
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• pp.1370-1372
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• 2004

At present. distance relay and ${\Delta}I$ current increment relay are used as primary and secondary protection in the AC feeder system. However. electric railway vehicles according to power electronic's development had developed resistance control, thyristor phase control and PWM control system. and operation of train is increasing in a feeder section. Therefore this paper analyzes the load characteristics and situation of relay's maloperation caused by load current increase, harmonics, regenerative braking current and operation of the different vehicles in same feeder section. Based on this analysis. this paper proposes consideration items for relay correction and advanced adaptive relay that can change operation area according to load current.

• Journal of Electrical Engineering and Technology
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• v.5 no.2
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• pp.228-238
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• 2010

There is an increasing interest in research to help overcome the energy crisis that has been focused on energy storage applications in various parts of power systems. Energy storage systems are good at enhancing the reliability or improving the efficiency of a power system by creating a time gap between the generation and the consumption of power. As a contribution to the various applications of storage devices, this paper describes a novel algorithm that determines the power and storage capacity of selected energy storage devices in order to improve upon railroad system efficiency. The algorithm is also demonstrated by means of simulation studies for the Korean railroad lines now in service. A part of this novel algorithm includes the DC railroad powerflow algorithm that considers the mobility of railroad vehicles, which is necessary because the electric railroad system has a distinct distribution system where the location and power of vehicles are not fixed values. In order to derive a more accurate powerflow result, this algorithm has been designed to consider the rail voltage as well as the feeder voltage for calculating the vehicle voltage. By applying the resultant control scheme, the charging or discharging within a specific voltage boundary, energy savings and a substation voltage stabilization using storage devices are achieved at the same time.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.477-482
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• 2004

New materials are being considered for insulator of railroad vehicles. Because people want more environmental material than glass fiber, there are certain needs of finding safe and economical insulating material. We checked the flammability of some kinds insulators such as PE foam, neoprene rubber foam. melamine foam and glass fiber. You could find out the characteristics such as oxygen index. optical smoke density, toxicity index of that insulators.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.8
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• pp.3610-3616
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• 2011

Electrical Railroads provide electric power, which can operate vehicles, via feeder wires. And the supplied current returns to the transformer substation through lines and ground net. The used load current depending on the operation of rail vehicles in the electric railway sections returns to the substation through a track which is a return circuit. The load current contains harmonics because of the power conversion equipment used in rolling stocks and such harmonic currents should not affect train control system. In this paper we present the test result in order to verify that the harmonics produced by the operation of rail vehicles in the newly built electric railway sections can affect interlocking systems. The test in question was performed in a linking section that trackside equipment under railway operating conditions and interlocking are linked in order to identify whether or not the interlocking fitted in a signal machine room can be affected by harmonics according to railway operation.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.9
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• pp.955-960
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• 2011

This study was aimed at investigating the applicability of energy harvesting technologies, which are regarded as new and renewable energy sources for real-time/wireless monitoring of intelligent railroad vehicles. The surrounding energy generated in a normal operating environment was monitored using a high-speed railroad vehicle in operation. This monitoring was performed in an attempt to evaluate the effectives of energy harvesting and the applicability of energy-harvesting-monitoring technologies under the conditions in which thermal energy and vibration energy are generated.