• 한국철도학회:학술대회논문집
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• 한국철도학회 2003년도 춘계학술대회 논문집
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• pp.561-566
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• 2003

Research and development project for the gearboxes of Korea High Speed Train is being run as one of the 'G7 Project' to achieve the Technical Independency in the area for the High Speed - High Load Gearboxes. Executing this project we domesticate the technologies for Design, Analysis, Manufacturing and Testing. Acquired high-technologies can be applied not only to the Rolling Stocks, but also to other Industrial Areas including the Cars and Aerovehicles. The prototypes had been tested on the roller rig and are being tested on the railway.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2005년도 추계학술대회 논문집
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• pp.811-815
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• 2005

Traditional passive suspension has limitations to meet the required specifications of high level trains, and so Active suspension system is proposed to meet the requirements with active components which could be controlled by external signal for optimized behavior of train. Active suspension is to be divided by Full active suspension and Semi-active suspension whether using the external power source or not, and though the performance of Semi-Active suspension is worse than Full one. Semi-active suspension is focused with its effectiveness per cost. Semi-Active suspension system consists of sensors, ECU (electrical control unit), and variable damper, which are to be designed to be fit for train system. And the software of ECU is to be developed for to be suited to its dynamic behavior through simulation result calculated by proven model. In this experimental study, the hardware and software of semi-active suspension system is to be realized and its performance for improvement of ride quality to be confirmed through roller rig test.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2008년도 제31회 추계학술대회논문집
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• pp.424-426
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• 2008

초소형 가스터빈에 사용되는 소형 고속 구름베어링의 연료윤활 특성을 실험적으로 조사하였다. 윤활유로는 항공용 가스터빈에서 사용되는 MIL-PRF-7808 터빈오일과 항공용 가스터빈의 추진연료로 사용되는 JP-8 연료를 사용하여 운용특성을 비교하였고, 시험용 베어링으로는 내경 17 mm의 깊은 홈(deep groove) ball bearing과 내경 20 mm의 원통형(cylindrical) roller bearing을 사용하였다. 베어링의 연료윤활에 따른 특성을 비교하기 위하여 오일 및 연료를 공급하며 고속베어링 시험을 수행할 수 있는 시험 장치를 개발하여 하중, 냉각공기 온도, 윤활유량 및 회전속도를 변화시키면서 시험을 수행하였다. 30,000 rpm에서 70,000 rpm까지 회전속도를 변화시키면서 시험한 결과 깊은 홈 볼베어링은 축하중과 회전속도가 증가하는 경우 베어링 케이지에 마모가 발생하였으며 마모상태는 오일윤활보다 연료윤활시 마모가 더 많이 발생하였고 본 베어링의 속도한계인 59,000 rpm까지는 연료 윤활로 운용이 가능하다는 것을 확인할 수 있었다. 연료윤활의 경우가 오일윤활의 경우보다 베어링 온도가 더 낮은 것을 알 수 있었는데 이는 베어링의 냉각특성이 연료윤활인 경우가 오일윤활의 경우보다 더 좋기 때문이라 판단된다. 본 실험을 통하여 소형 항공용 가스터빈의 주축 베어링 윤활방식으로 연료윤활 방식이 적용 가능함을 확인할 수 있었다.

• 한국철도학회논문집
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• 제19권1호
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• pp.20-28
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• 2016

스킬 소음은 곡선부에서 레일과 차륜 사이에 발생하는 순음의 큰 소음이다. 차륜과 레일 사이의 접촉은 점착-미끄러짐(stick-slip)현상을 보이면서 스킬 소음이 발생한다고 알려져 있다. 본 논문에서는 이러한 스킬 소음의 발생 메커니즘을 규명하기 위해 차륜, 레일의 주파수 관점에서의 접촉력 특성을 파악하고자 했다. 스킬 소음을 실험실 조건에서 발생시키기 위하여 축소 스킬소음 시험장치를 제작하였다. 접촉력을 구하기 위하여 레일 롤러를 지지하는 서브 프레임 진동 데이터와 응답특성을 측정하여, 접촉력을 예측하였다. 계산된 접촉력 결과를 검증하기 위해서, 레일 롤러의 접촉점 변위를 계산된 접촉력을 이용하여 계산하고 레이저 변위센서로 측정한 변위 실험결과와 비교하였다. 또한 시험장치를 유한요소로 모델링하여, 계산된 접촉력에 의한 음향 방사 해석을 수행하였고, 그 음압 결과를 반무향실 조건에서 축소 스킬소음 시험장치 운영시 발생되는 소음의 크기와 비교하였다. 변위와 음압 결과가 실험 결과와 유사한 경향을 나타내었다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 춘계학술대회 논문집
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• pp.1085-1091
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• 2011

The dynamic stability of railway vehicle has been one of the important issues in railway safety. The dynamic simulator has been used in the study about the dynamic stability of railway vehicle and wheel/rail interface. Especially, a small scale simulator has been widely used in the fundamental study in the laboratory instead of full scale roller rig which is not cost effective and inconvenient to achieve diverse design parameters. But the technique for the design of the small scale simulator for the fundamental study about the dynamic characteristics of the wheel-rail system and the bogie system has not been well developed in Korea. Therefore, the research about the development of the small scale simulator and the bogie has been conducted. This paper presents the design of the small-scaled derailment simulator and the example design case of a small scale bogie. The simulator could be used in the study about the effect of diverse parameters such as attack angle, wheelbase and cant on dynamic behavior of the bogie and the safety parameter such as derailment coefficient and critical speed.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.2600-2608
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• 2011

The dynamic stability of railway vehicle has been one of the important issues in railway safety. The dynamic simulator has been used in the study about the dynamic stability of railway vehicle and wheel/rail interface. Especially, a small scale simulator has been widely used in the fundamental study in the laboratory instead of full scale roller rig which is not cost effective and inconvenient to achieve diverse design parameters. But the technique for the design of the small scale simulator for the fundamental study about the dynamic characteristics of the wheel-rail system and the bogie system has not been well developed in Korea. Therefore, the research about the development of the small scale simulator and the bogie has been conducted. As this paper, To predict the dynamic behavior of railway vehicle, we studied running stability test of 1/5 scaled bogie that similarity laws is applied using small scale derailment simulator. For the operation of the small scale derailment simulator, it is required to investigate the performance and characteristics of the system. This could be achieved by a comparative study between an analysis and an experiment. This paper presented the analytical model which could be used for verifying of the test results and understanding of the physical behavior of the dynamic system comprising the small scale bogie and the simulator.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2003년도 추계학술대회 논문집(I)
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• pp.125-130
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• 2003

Korean High Speed Train (KHST) designed to operate at 350km/h has been tested on high speed line in JungBu site since it was developed in 2002. The dynamic performances of railway vehicle are generally stability, safety and ride comfort. The stability performance of KHST was proved that it is stable at 400Km/h through Roller Rig test. The safety and ride comfort need to be predicted the capability of it at 350km/h by the on-line test because KHST is testing at 300km/h up to now. Therefor, in this paper, the safety and ride comfort at 350km/h are predicted the performance using the acceleration results at 300kw/h and these results show that the KHST's dynamic performances are very good. Also, it illustrate the two cases occurred the abnormal vibration of KHST during some on-line tests. The first case is that the variation of vertical acceleration of wheel is analyzed when an abrasion occur on wheel. The second case is that the lateral acceleration of wheel, bogie and body are analyzed when the KHST is unstable at high speed. The occurrences of these special phenomena were due to the some faults of the suspension and braking systems and the faults were improved. In present, it is testing with safety.

• International Journal of Railway
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• 제3권2호
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• pp.60-67
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• 2010

This paper deals with an experimental study on the wheel flange climbing of railway vehicles, which is a major factor leading to derailment. An experiment is carried out on a 1/5-scale model wheelset of a truck used on a standard-gauge track, which is placed on a roller rig. The lateral external force acting on the wheelset is ramped up until derailment occurs under the condition of a fixed attack angle and wheel-load unbalance ratio. Three parameters, the height of wheel lift, the lateral force, and the wheel load acting on the outer rail, are measured until derailment occurs. From these measurements, it is possible to observe the behavior of the wheelset and to elucidate how the attack angle, the wheel-load unbalance ratio and the lateral external force affect flange-climb derailment. Then, a numerical simulation is carried out using an analytical model based on a single wheelset. As a result, the flange-climb behavior observed in the experiment can be explained theoretically on the bases of the analytical results, although further improvement of the model is desired.

• 한국철도학회논문집
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• 제10권3호
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• pp.257-263
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• 2007

The critical speed above which the vehicle become unstable is one of the items that should be verified in the development of a new train. In the case of a high speed tilting train, which requires both higher critical speed and higher curving speed, the critical speed should be more carefully treated because the both requirements are in conflict with each other in the conventional train design. The main purpose of the present work is to estimate the linear and non-linear critical speeds of 200km/h Korean Tilting Train 'Hanbit200' under development. The newly developed self-steering mechanism was attached to the tilting train to ensure that the critical speed falls under the lower yaw stiffness which is needed to secure higher curving performance. The simulation for predicting the critical speed was done by a commercially available vehicle dynamics software. A full scale roller rig test was carried out to validate the numerical results and to verify the effectiveness of the self-steering mechanism.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 추계학술대회 논문집
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• pp.606-612
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• 2008

Creep force is one of the only appeared at conventional train which used to be driven by metallic wheel and rail contact. Due to the elastic deformation of wheel/rail contact patch by the weights of wheel and all the components related to it, creep force generates and becomes to the decision factor of critical speed of bogie(or railway vehicle) which is the criteria of avoiding vehicle to be unstable. There are many kind of factors which affect generation of creep force at a wheel/rail contact surface such as viscosity of contact patch, velocity, wheel and rail geometric profile, mechanical properties of wheel and rail. This paper concentrates on a wheelset simple 2 DOF Equation of Motion being exerted. From the simple numerical analysis using linear solution about getting creep force some factors could find roughly. Among the factors geometric parameter could be the one of most important for this study. In the future we'll prolong the range of study to find out method of measuring creep force easily.