• Journal of the Korean Society for Precision Engineering
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• v.31 no.9
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• pp.783-790
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• 2014

Railway wheels and axles are the most critical parts of the railway rolling stock. The wheel carry axle loads and guide the vehicles on the track. Therefore, the contact surface of wheel are subjected to wear and fatigue process. The wheel damage can be divided into three types; wear, contact fatigue failure and thermal crack due to braking. Therefore, in the contact surface between the wheel and the rail, the materials are heat treated to have a specific hardness. The manufacturing quality of the wheel have a considerable influence on the formation of tread wear and damage. Also, the residual stress on wheel is formed during the manufacturing process is one of the main sources of the damage. In this paper, the mechanical characteristic and the residual stress according to wheel material have been evaluated by applying finite element analysis and conducting mechanical tests.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.12
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• pp.1729-1734
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• 2018

Recently, interest in environmentally friendly transportation systems has been increasing, and study on railway systems has been aggressively conducted. Therefore, lots of studies have been done in railway advanced countries to improve performance of PWM converter. The research on the PWM converter for railway vehicle was mainly carried out on the converter mounted on railway vehicle such as the high-speed railway and metropolitan railway. In also, a lot of study has been carried out to improve converter performance installed in the ground. The high-capacity transform used in this paper converted from AC 22.9kV to AC 590V. The converter changed from AC 590V to DC 950V. In general, in the case of rectifier, the DC power supply system has a negative impact on inverter control characteristics because it can not avoid the pulsating component. In this study, it was performed current control for high-capacity converter using Matlab Simulink. The PWM converter is normally performed through the voltage and current at starting mode, powering mode, and braking mode. In the light-load test and the on-line test, we have studied for the PWM converter characteristics. Using this research, we have founded that the converter has excellent performance.

• Proceedings of the KIPE Conference
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• 1996.06a
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• pp.43-46
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• 1996

The carborne Automatic Train Control(ATC) system keeps automatically optimum train speed code signals from wayside(track) circuit equipment. If there is no response for braking against the over speed detected, the driver will be noticed instantly by visual and audible warning signals. And then the ATC processes into braking mode for safe train operations to prevent any hazards by over speed limit. In this paper we are introduced the novel ATC system which has triple constructed structure made by 32 bit floating point DSP(ADSP21020-20) and process dealed with frequency domain and time domain for detecting signals. Owing to these reason it is no needed several band pass filters used in conventional ATC systems to detect the speed limit frequency. Also system's reliability and tolerance are incremented by adopt to 2 out of 3 logic to the outputs decision.

• Proceedings of the KSR Conference
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• 2011.05a
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• pp.173-180
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• 2011

Recently, many railway stations are built under the railway line in urban area. The passage of railway vehicles generates mechanical vibrations of a wide range of frequency. Thus, it is required to place structural vibration isolation systems to reduce vibration and noise originating from surrounding environments. This study is to investigate the maximum floating slab length based on track/floating slab interaction analyses. Actions to be taken into account include temperature, braking/acceleration, bending of the deck, and creep/shrinkage. The additional rail stress has been chosen for the criterion for the maximum slab length. In addition, further analyses are performed to include the stopper which restrict the in-plane movement of the floating slab track. Several alternatives for stopper positions were thoroughly studied in this study.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.1909-1915
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• 2008

The brake systems of the rolling stocks are generally consisted of electrical and mechanical brake systems. Because of its inherent structure of the each brake system, the electrical brake system is mainly used at the high speed range while the mechanical brake system is used at the relatively lower speed range. It is desirable for the rolling stocks to apply the entire electrical brake system. However, since the brake force from electric brake system is not enough to stop the rolling stock within the legal stop distance. Therefore, the mechanical brake system is indispensable to rolling stocks. In general, the vast majority of the world trains are equipped with mechanical braking systems which use compressed air as the force to push block on to wheels or pads on to discs. These mechanical systems are known as air brake or pneumatic brakes. For the air brake system, basically huge scale air compressor is equipped and the long pipe line is complexively connected. Since mass of these air brake components, it is difficult to be a light weight equipment and the long pipe line raise the maintenance problem. In order to overcome these problems of air brake system, the hydraulic brake system is proposed in this research. The hydraulic brake system makes the whole weight of brake equipment be light and large braking force can be applied. Therefore, in this research, the validity and advantages of applying the hydraulic brake system are reviewed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.12
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• pp.237-246
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• 2019

The Electro-Mechanical Brake (EMB) is the next generation braking system for automobiles and railway vehicles. Current brake systems for high-speed trains generate a braking force using a pneumatic cylinder, but EMB systems produce that force through a combination of an electric motor and a gear. In this study, an EMB operation mechanism capable of generating a high braking force was proposed, and structural and vibration analyses of the gears and shafts, which are the core parts of the mechanisms, were performed. Dynamic structural analysis confirmed that the maximum stress in the analysis model was within the yield strength of the material. In addition, the design that maximizes the diameter of the motor shaft was found to be advantageous in strength, and large shear stress could be generated in the bolt fixing the gear and eccentric shaft. In addition, a test apparatus that can reproduce the mechanism of the analytical model was fabricated to measure the strain of the fixed bolt part, which is the most vulnerable part. The strain measurement results showed that the error between the analysis and measurement was within 10%, which could verify the accuracy of the analytical model.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.11
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• pp.545-551
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• 2016

In this study, we evaluate the braking performance of an urban railway vehicle to verify its basic safety condition. The braking performance evaluation methods, deceleration measurement and braked weight percentage, were compared for trains with different numbers of cars, in order to assess the advantages of each method and their compatibility. With a probabilistic braking model, the effect of the adhesion coefficient distribution was analyzed in accordance with the train composition. A train with many cars has a narrower deceleration distribution width than one with few cars. The braked weight percentage method is expected to be useful in the design of train signal systems, because it allows the braking distance to be calculated for various initial brake velocities. The deceleration distribution model and its results are expected to be useful as a basis for precise train signal design.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.2203-2206
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• 2005

A load flow and short circuit fault simulation of AC electrified railway distribution systems is presented with DIgSILENT PowerFactory software. Load flow of electrified railways distribution system with concerning multi train lines and dynamic characteristics of train load is studied for different time laps. The dynamic characteristics of train load in starting and braking conditions with different starting and stopping times and its moving positions makes the load flow complicated so there is a great need in studying the effects of electrified railways on load flow. Short circuit fault transients is also studied and simulated for both power system or traction distribution system and their effects on the operation of the train sets is investigated.

• Journal of the Korean Society for Railway
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• v.20 no.1
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• pp.31-42
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• 2017

Many studies have been performed to reduce electric consumption in railway systems. Due to its low conduction loss and high regenerative braking efficiency characteristics, the ESS powered railway system is chosen as a promising candidate for future railway systems. This paper introduces the ESS powered railway system and analyzes current power charge calculation methods that have been set up by KEPCO (Korea Electric Power Corporation). Based on the analysis, this paper proposes two different power charge reduction methods for the railway system. One is to smooth the peaks of traction energy consumption by supplying additional energy to the grid. The other is to save electric charge by reducing electric energy consumed by the railway during the energy peak time, 2 p.m.~5 p.m., which has highest 'Won/kWh' rates. To verify the effectiveness of the proposed method, the power charge of Seoul Metro Line 2 is recalculated using the method.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.1461-1466
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• 2004

Recently Domestic EMU's on board signal systems are gradually changed form Cab signal(Fix Block) to Distance-to-go. Interfaces with on board signal system, TCMS Redundancy structure is mainly required. This paper suggest Manaul/Automatic Driving based on TCMS-ATC interface and design of backup system which is operated by Stan-by Computer when one of it's Local Interface Unit(LIU) is out of oder. For the purpose of Precision Train Stop, Distance-to-go signal system require accuracy speed. Free-axle structure is required for this system This paper suggest Free-axle braking system that lack of brake-force is compensated by the distributed brake-force using TCMS. And one of braking system has out of order, compensation of brake-force for Free-axle system. Then we prove our design to Complete Car Test