• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.36 no.11
• /
• pp.1479-1485
• /
• 2012

The development of a technique for the real-time sensing of a curve section is very important for active rolling-stocks in order to improve the curving performance. However, conventional methods using expensive track inspection equipment or various complex sensors are not practicable to be applied to commercial vehicles. Therefore, we have proposed a new method to estimate the curve radius of a curve section. This method uses the relative displacements occurring between the body and the bogie when the rolling-stock is running on a curve. To verify the validity of this method, we conducted a vehicle dynamics simulation and test using a real vehicle on a test line. The results confirmed the validity of the proposed method. We expect that this method will be effectively applied in studies of active rolling-stocks to increase the curving performance using active control technology.

• Composites Research
• /
• v.28 no.6
• /
• pp.372-377
• /
• 2015

In this study, we analyzed process numerically when a bogie frame skin is manufactured by applying resin transfer molding process using composite material instead of steel. Processing time was compared based on the various thickness of bogie frame skin and the weight variation of a skin was also considered. As a result, RTM processing time decreases and the weight of a bogie reduces as the thickness of frame skin increases with the assumption that fiber volume is constant inside the skin. By considering these results as the information to estimate the production cost, trade-off between two fields, processing time and structural properties, can be performed in design optimization to produce bogie frame.

• Journal of the Korean Society for Railway
• /
• v.16 no.1
• /
• pp.14-19
• /
• 2013

Because excessive interior noise when riding a high-speed train leads to annoyances, fatigue and stress for passengers, interior noise reduction methods should be considered. In particular, a high-speed train operated in various operation environments, and in South Korea, these include open fields and tunnels. Therefore, a specific study about changes in interior noise characteristics according to different environments is necessary. For this reason, the interior noise characteristics on a KTX train and on the KTX-Sancheon train were analyzed from noise measurements using microphones in this paper. Vibrations on the axles, bogies and floor were also measured, are these area are structural paths for interior noise. From this research, the interior noise characteristics according to the driving speed were deduced and the effects on interior noise by driving environments such as open fields and tunnels were investigated. Furthermore, the effect on interior noise by axles, bogies and floor vibrations were analyzed from a transfer function analysis.

• Journal of the Korean Society for Railway
• /
• v.20 no.5
• /
• pp.577-587
• /
• 2017

In the design process of dynamic characteristics of a railway vehicle, demand for analysis, testing and estimation methods of running stability are increasing as railway vehicle speed is increasing. Critical speed tests and estimation have been carried out using computer simulation or special test facilities, like roller rigs, because real track testing at critical speed is very dangerous. This paper introduces a test and assessment method for critical speed and estimates the validity using several roller rig tests. The test results show that it is difficult to estimate the critical speed using safety and instability assessment method in UIC 518, but that there is good agreement between the reduction of the equivalent damping ratio and the critical speed.

• Journal of the Korean Society for Railway
• /
• v.18 no.4
• /
• pp.301-308
• /
• 2015

To reduce the weight of a railroad vehicle, a bogie frame skin is considered for manufacture using an RTM process and composite material. Compared to other processes, RTM has merits in that it demands only simple manufacturing facilities and can produce a large and complex structure in a short cycle time. On the other hand, it is important to determine the proper number and locations of gates and vents to prevent void formation inside a structure. In this study, we numerically predicted the flow pattern in a bogie frame skin during the RTM process by distinguishing the permeability of a fiber mat as isotropic or anisotropic. Using the results, we analyzed the RTM process conditions of the bogie frame to predict skin void formation, mold filling time, and optimum location of vents depending on the permeability conditions.

• Journal of the Korean Society for Railway
• /
• v.16 no.2
• /
• pp.110-116
• /
• 2013

Track irregularities is one of the key factors influencing the running behavior of trains. In order to ensure safety and ride comfort of train, the criteria for track irregularities should be adequately established regarding vehicle velocity, vehicle characteristics, characteristics of the track recording car, and measurement interval. Also, track maintenance should be carried out thoroughly according to the criteria for managing track irregularities. Numerical analysis was conducted to investigate the influence of track alignment on the running behavior of Korean high speed train(KTX). Various wavelengths and amplitudes of lateral alignment were considered as parameters for this study using the Vampire program, a vehicle dynamics modeling package in railway environment. Derailment, lateral load, bogie acceleration and body acceleration of numerical analysis results due to alignment were investigated. Finally, the influence of the alignment on safety and ride comfort for the KTX was evaluated. This study indicates that alignment irregularities have significant impacts on running safety, and that the criteria used to manage alignment irregularities should be restrictive to ensure the running safety of the KTX.

• Journal of the Korean Society for Railway
• /
• v.15 no.4
• /
• pp.334-342
• /
• 2012

It is connected with various gauges existing in Euro-Asian continents. Such differences impedes the operation seriously as on the contact of railway tracks of different gauge the cargo must be either transshipped or the running assemblies of rail vehicles must be exchanged. Those operations are costly, time-consuming and require extended infrastructure together with very expensive storage and transshipment facilities at border-crossing point. Moreover, those operations extend transportation time considerably. Therefore, effectiveness of railway transportation systems significantly depends on track gauge change 1435/1520mm, which connects with complicated handling-shifting operations. The paper concerns assessment of effectiveness in strategical rail systems with gauge changing. The paper presents short description of transport system with gauge changing and initial assessment of shifting technologies. Method of system assessment comparison based on Life Cycle Cost model is described here as well.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.33 no.10
• /
• pp.1005-1013
• /
• 2009

In this paper, the performance improvement of a decentralized brake system for railway rolling stocks is investigated. In order to verify the effectiveness of the decentralized brake system, it is compared to the truck unit brake system which has only one control unit per a truck. The adaptive sliding mode control scheme is used to realize a robust anti-slip brake control system. Through computer simulations, it is verified that the decentralized brake system has better braking performance than the truck unit brake system.

• Proceedings of the KSR Conference
• /
• 2007.05a
• /
• pp.175-181
• /
• 2007

본 연구에서는 지하철용 전동차의 현가장치를 구성하는 1차 현가장치 및 2차 현가장치의 강성 및 감쇠지수 변화가 전동차의 상하진동에 미치는 영향을 분석하였다. 실제 운행 중인 전동차에 대하여 액슬박스, 대차, 객차에서 측정된 진동 데이터를 바탕으로 대차와 차체로 구성된 2자유도계 해석모델을 생성하였고, 실측된 윤축의 진동을 입력신호로 하여 수치해석을 수행하였다. 1, 2차 현가장치의 강성 및 감쇠지수의 변화에 따른 응답을 고찰한 결과, 차량의 상하진동에 지배적인 영향을 주는 설계변수는 2차 공기스프링의 강성임을 알았다. 또한 이러한 결과는 ADAMS/RAIL 전산해석을 통해서도 검증할 수 있었다.

• Journal of the Korean Society for Precision Engineering
• /
• v.18 no.3
• /
• pp.84-89
• /
• 2001

Studied in this paper was the vehicle dynamics simulation for development of single axle bogie using the multi-body dynamics simulation program(VAMPIRE). Single axle bogie vehicle is to the crew of freight vehicle. Method of analysis for dynamic behaviors of vehicle having single axle bogie was carried by UIC(International Union of Railways) code 518 and results of analysis were presented in terms of the hunting stability and the derailment ratio and the sum of wheel/rail lateral force. The results of analysis meet the criteria proposed by UIC.