• International Journal of Advanced Culture Technology
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• v.10 no.4
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• pp.569-575
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• 2022

This is a research thesis on the development of a monitoring and diagnosis device that prevents the risk of an accident through monitoring and diagnosis of a modular Main Circuit Breaker (MCB) using Vacuum Interrupter (VI) for Korean high-speed rolling stock. In this paper, a comprehensive MCB monitoring and diagnosis was performed by converging vacuum level diagnosis of interrupter, operating coil monitoring of MCB and environmental temperature/humidity monitoring of modular box. In addition, to develop an algorithm that is expected to have a similar data processing before the actual field test of the MCB monitoring and diagnosis device in 2023, the cluster analysis and factor analysis were performed using the WEKA data mining technique on the big data of Korean railroad transformer, which was previously researched by Tae Hee Evolution with KORAIL.

• Journal of the Korean Society for Railway
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• v.20 no.4
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• pp.448-457
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• 2017

In this paper, for high speed railway propulsion systems, a single phase PWM Converter using discontinuous PWM (DPWM) was investigated. The conventional PWM Converter uses a low frequency modulation index of less than 10 to reduce switching losses due to high power characteristics, which results in low control frequency bandwidth and requires an additional compensation method. To solve these problems, the DPWM method, which is commonly used in three phase PWM Inverters, was adopted to a single phase PWM Converter. The proposed method was easily implemented using offset voltage techniques. Method can improve the control performance by doubling the frequency modulation index for the same switching loss, and can also bring the same dynamic characteristics among switches. Proposed DPWM method was verified by simulation of 100 kW PWM converter.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.194-200
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• 2007

The tilting train is able to tilt its body towards the center of the turning radius, preventing roll-over of the train as it runs on a curved rail at high-speed. This train, widely accepted for commercial purpose internationally is very beneficial in that the operating time is shortened without much capital investment to the infrastructure where there are many curved rails. Over several years, the Korea Railroad Research Institute(KRRI) has developed such a train. In this paper, the safety of the Korean tilting train express(TTX) is investigated using a dynamic simulation model. Since, proper safety standards have not been established for the TTX, those for the Korean train express(KTX) is employed instead to analyze the safety and ride comfort of the TTX. This study will prove useful in predicting the behavior of the TTX and ride comfort, and conforming that designed TTX measures up to the safety standards. It would be useful to recommend proper normal operating speed and determine the maximum safety speed, according to the result. Furthermore, it would be possible to provide basic reference data when analyzing the dynamic effect of the catenary system and the fatigue of the bogie.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.5
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• pp.824-829
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• 2015

The rotary type testing machine undergoes mechanical stress as an external force is applied. In case of the rotary type testing machine, even a tiny flaw results in a fatal demage because the size of the machine is huge. Therefore, when designing the rotary type testing machine, it is necessary to secure a safety factor with the mechanical stress analysis in order to prevent the machine from being destroyed due to scattering or transformation of rotating field. This thesis proposes a LSM rotary type tesitng machine which rotates at the speed of up to 600km/h. And the mechanical stress is considered in order that the safety factor remains above 1.5 at the maximum speed. In addition, because normal force as well as thrust occurs in the machine, the normal force exerted was considered through the strength analysis. Finally, a design plan which enables to weaken the normal force affecting the rotary type testing machine is introduced and its validity is proved by the results of FEM analysis.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.11
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• pp.350-356
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• 2018

The contact force, which is the dynamic interaction between the pantograph and the catenary, is an important indicator for evaluating the current collecting quality, which is a stable power supply characteristic to the vehicle. In this study, dynamic contact force characteristics of pantograph of HEMU-430X vehicle, which is a power-distributed high-speed train test vehicle, were analyzed according to the catenary tension and compared with the analytical results using the pantograph-catenary interaction model. As a result of comparing the test results with the analytical results, it was confirmed that the average contact force and the standard deviation of the contact force, which are the main dynamic contact force characteristics, coincide relatively well. Using the analytical model, the relationship between the catenary tension and the contact force is presented according to the vehicle speed, and the optimal catenary tension for each operation speed is presented and compared with the international standard. As a result, it was found that the results obtained from the analysis are comparable to those recommended by international standards.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.4
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• pp.2906-2910
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• 2015

The alignment modifications after completion of railway construction entail a lot of efforts and time as well as high additional costs. In the process of renewal of the existing railway alignment to offer higher-speed services, the effect of initial design parameters(e.g., intersection angle) on determination of allowable degree of improvement of horizontal curves under consideration of economic efficiency is investigated in this study. From the analysis results, in the case that there are obstacles at the tangent line, it was found that the larger angle of intersection has a significant effect on the permissible zone. In addition, as the intersection angle is increased, the permissible values of maximum curve radius and the length of transition curve becomes smaller and longer, respectively. It is expected that this study can contribute to the efficient and accurate prediction of the permissible zone according to the locations of obstacles and the size of intersection angle as well as improvement in the railway alignment without any additional costs.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.1427-1439
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• 2008

The quality of track-bed fills of railways has been controlled by field measurements of density (${\gamma}_d$) and the results of plate-load tests. The control measures are compatible with the design procedures whose design parameter is $k_{30}$ for both ordinary-speed railways and high-speed railways. However, one of fatal flaws of the design procedures is that there are no simple laboratory measurement procedures for the design parameters ($k_{30}$ or, $E_{v2}$ and $E_{v2}/E_{v1}$) in design stage. A new quality control procedure, in parallel with the advent of the new design procedure, is being proposed. This procedure is based upon P-wave velocity involving consistently the evaluation of design parameters in design stage and the field measurements during construction. The key concept of the procedure is that the target value for field compaction control is the P-wave velocity determined at OMC using modified compaction test, and direct-arrival method is used for the field measurements during construction. The procedure was verified at a test site and the p-wave velocity turned out to be an excellent control measure. The specifications for the control also include field compaction water content of $OMC{\pm}2%$ as well as the p-wave velocity.

• Tribology and Lubricants
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• v.30 no.6
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• pp.330-336
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• 2014

Sintered metallic brake pads and low alloy heat resistance steel disks are applied to mechanical brake systems in high energy moving machines that are associated with recently developed 200km/h trains. This has led to the speed-up of conventional urban rapid transit. In this study, we use a lab-scale dynamometer to investigate the effects of the composition of friction materials on the tribological characteristics of sintered metallic brake pads and low alloy heat resistance steel under dry sliding conditions. We conduct test under a continuous pressure of 5.5 MPa at various speeds. To determine the optimal composition of friction materials for 200 km/h train, we test and the evaluate frictional characteristics such as friction coefficients, friction stability, wear rate, and the temperature of friction material, which depend on the relative composition of the Cu-Sn and Fe components. The results clearly demonstrate that the average friction coefficient is lower for all speed conditions, when a large quantity of iron power is added. The specimen of 25 wt% iron powder that was added decreased the wear of the friction materials and the roughness of the disc surface. However when 35 wt% iron powder was added, the disc roughness and the wear rate of friction materials increased By increasing the amount of iron powder, the surface roughness, and temperature of the friction materials increased, so the average friction coefficients decreased. An oxidation layer of $Fe_2O_3$ was formed on both friction surfaces.

• Journal of the Korean Society of Safety
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• v.25 no.3
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• pp.112-117
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• 2010

This study presents a methodology to evaluate the driving safety of vehicles against localized high wind on the roads over the valleys or along the coasts. Risk level for vehicle accident is derived from the side slip caused by cross wind, and then safety criteria based on reliability for driving stability are defined. The level of safety is classified according to probability of exceeding against wind speed using the concept of extreme value statistics. To attain the safety level of vehicle on bridges, numerical simulations using Computational Fluid Dynamics(CFD) are performed. Based on this result, risk reduction and quality improvement is expected through analysis for each alternative in bridges design, construction and operation & maintenance stage with proposed process

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.1978-1983
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• 2008

With the increase in population, the area of human activities has expanded, resulting in the dramatic increase in the need for transportation system. Various infrastructures necessary for efficient logistics, however, have not been supplied enough and the logistics efficiency in Korea is in a bad situation now. As a result of the situation, the demand for the railroad transportation system that can provide large volume transportation has increased dramatically. An electric railway system is composed of high-tech subsystems, among which main electric equipment such as motors and converter are critical components determining the performance of electric vehicle. Among the on-board equipments, traction equipment is important part that has influence on safety and performances of vehicles. We is studied for high-speed train of foreign countries. From this research, we knows that axle weight of HEMU-400x is reasonable within 13ton.