• 한국철도학회논문집
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• 제9권3호
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• pp.298-304
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• 2006

An active application of concrete track is being expected for the future constructions of Korean railroad. For the successful concrete track construction and design in earthwork areas, the roadbed behavior should be reasonably estimated using the proper analysis method. In this paper, behaviors of concrete track on the reinforced roadbed constructed with the standard stiffness and depth were estimated thorough numerical analyses and field measurements. A three dimensional finite difference method was employed to model the concrete tracks and subground. The settlement and vertical pressures caused by train load were estimated by the numerical method and compared with the field measurement results. The bearing characteristics of roadbed were presented and the proper method for the analysis of concrete track was proposed.

• 한국군사과학기술학회지
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• 제10권3호
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• pp.173-180
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• 2007

In this paper, we have proposed a simple finite element model for separation mode analysis on the roadwheel and track assembly of main battle tank and established a contact stress-based mechanism which could explain the initiation and growth of separation defect occurred during the test of padreplacable track. It was proved that the longitudinal contact shear stress component on the pin hole region of the track shoe body which is parallel to the driving direction is consistent with the crack initiation at the bonding surface between track shoe and wheel-side rubber. The longitudinal shear stress increased locally near the separated region after the separation initiated. So we could assume that the local stress concentration accelerates the separation growth according to the shear mode.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 추계학술대회 논문집
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• pp.1169-1177
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• 2008

The system of the railway signaling using the track transmits the approved speed to the location of a train and it. Referring to the way of transmitting train control information, there are the one transmitting it to the on-board system of a train using the direct track, the another transmitting it establishing an instrument, and the other transmitting an instrument by a railway track. The one is the method using the direct track as a conductor for composing the part of the track and attaining the information controlling a train by transmitting a signal to the track. It is used for the high-speed railway and the subway. The method using the track attains information by transmitting it to returned information, and the on-board system of a train attains it by magnetic coupling. Because many reinforcing bars on the concrete slab track are used, interaction between a rail and a reinforcing bar that is not produced on ballast track is made. Due to the interaction, the electric characteristic of rail is changed. In the current paper, we numerically computed the coupling coefficient between the rail and the reinforcing bar based on the concrete slab track throughout the model related to the rail and the reinforcing bar using the concrete slab track that is used in the second interval of the Gyeongbu high-speed railway, and we defined the coupling coefficient not changed in the electric characteristic of rail in the condition that there is no interaction between the rail and the reinforcing bar.

• Wind and Structures
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• 제27권4호
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• pp.255-267
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• 2018

This paper investigated the wind-snow flow around the bogie region of a high-speed train under crosswinds using a coupled numerical method of the unsteady Realizable $k-{\varepsilon}$ turbulence model and discrete phase model (DPM). The flow features around the bogie region were discussed and the influence of bogie fairing height on the snow accumulation on the bogie was also analyzed. Here the high-speed train was running at a speed of 200 km/h in a natural environment with the crosswind speed of 15 m/s. The mesh resolution and methodology for CFD analysis were validated against wind tunnel experiments. The results show that large negative pressure occurs locally on the bottom of wheels, electric motors, gear covers, while the positive pressure occurs locally on those windward surfaces. The airflow travels through the complex bogie and flows towards the rear bogie plate, causing a backflow in the upper space of the bogie region. The snow particles mainly accumulate on the wheels, electric motors, windward sides of gear covers, side fairings and back plate of the bogie. Longer side fairings increase the snow accumulation on the bogie, especially on the back plate, side fairings and brake clamps. However, the fairing height shows little impact on snow accumulation on the upper region of the bogie. Compared to short side fairings, a full length side fairing model contributes to more than two times of snow accumulation on the brake clamps, and more than 20% on the whole bogie.

• Wind and Structures
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• 제20권4호
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• pp.509-525
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• 2015

A three-dimensional aerodynamic model and a vehicle dynamics model are established to investigate the effect of noise barrier on the dynamic performance of a high-speed train running on an embankment in crosswind in this paper. Based on the developed model, flow structures around the train with and without noise barrier are compared. Effect of the noise barrier height on the train dynamic performance is studied. Then, comparisons between the dynamic performance indexes of the train running on the windward track and on the leeward track are made. The calculated results show that the noise barrier has significant effects on the structure of the flow field around the train in crosswind and thus on the dynamic performance of the high-speed train. The dynamic performance of the train on the windward track is better than that on the leeward track. In addition, various heights of the noise barrier will have different effects on the train dynamic performance. The dynamic performance indexes keep decreasing with the increase of the noise barrier height before the height reaches a certain value, while these indexes have an inverse trend when the height is above this value. These results suggest that optimization on the noise barrier height is possible and demonstrate that the designed noise barrier height of the existing China Railway High-speed line analysed in this article is reasonable from the view point of the flow field structure and train dynamic performance although the noise barrier is always designed based on the noise-related standard.

• 한국지반신소재학회논문집
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• 제13권3호
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• pp.39-47
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• 2014

호남고속철도에 부설된 동일한 궤도노반시스템을 실제 열차하중이 가능한 실대형 가진시험을 통해 성능을 평가하였다. 실험결 과 Odemark 등가깊이 이론에 의한 노반압력과 매우 유사한 것을 확인하였다. 콘크리트궤도에서 정적하중 330 kN을 재하시 노반 상부의 토압은 50 kPa 이내로 발생하였고, 정적하중시험과 반복하중시험 결과는 비교적 큰 차이가 없었다. HSB의 탄성변위는 증속시험 시 관리기준값 1 mm에 비해 약 1/100 수준이며, 노반의 탄성변위량과 비교해볼 때 1/175 정도로 매우 작은 변위가 발생하였다. 가진주파수의 크기에 따라 궤도노반의 동적거동은 가진주파수가 35 Hz이하에서는 모든 측정값이 거의 선형적으로 증가하였으나, 35 Hz이상에서는 윤중, 변위, 지반가속도 등이 감소하였다.

• 한국철도학회논문집
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• 제18권5호
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• pp.447-456
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• 2015

본 연구에서는 궤도틀림 측정용 트롤리의 사용성을 증진하기 위한 방편의 하나로 트롤리의 정지시 뿐만 아니라 이동시 계측방안과 이에 따른 계측오차의 최소화 방안에 대하여 논의하였다. 이를 위하여 트롤리의 완화곡선 및 원곡선내 주행에 따른 궤도틀림 측정의 정밀도를 향상시키기 위한 운동학적 관계식을 새롭게 제안하였으며 비선형 확장 칼만필터를 도입하여 계측오차를 최소화하였다. 제안한 모형의 적용성 파악을 위하여 이론적인 궤도상태를 가정한 후 이산형 및 연속형 궤도틀림 측정에 따르는 표준편차를 산정하였으며 이 결과, 제안한 모형의 효용성을 입증하였다. 또한 기존 궤도 틀림 모형과의 비교를 통해 제안한 운동학적 관계식의 우월성을 입증하였다.

• 한국소음진동공학회논문집
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• 제13권5호
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• pp.393-399
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• 2003

Hydraulic mounts show strong1y frequency-dependent stiffness and damping characteristics in low frequency range, which result from so called inertia track dynamics. A lumped mass has been incorporated in several mechanical models of the literature to take the inertia effect of the fluid in the track into consideration. Although complex s%illness by the mechanical model showed good agreements with the measured values, there exists a critical pitfall. In this paper, the shortcomings of mechanical models with lumped mass for hydraulic founts are clearly identified by illustrating actual measurements of the stiffness parameters for a hydraulic mount. It is conclusively discussed that the inertia effect of the fluid flow through the circular track is significant but latent. As an alternative to the mechanical model, a hydraulic model is claimed to be used for further dynamic analysis of engine/mount system or whole car system.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2003년도 가을 학술발표회 논문집
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• pp.97-102
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• 2003

A real train load fluctuates along the track because of complicated movements(Bouncing, Rolling, Pitching and Yawing) and rail conditions. This research has for its object in development of a numerical real train load model including fluctuation characteristics of lateral forces. It is based on Klingel movement theory of a wheelset on straight track it presents a propriety of application by comparison between a 3D-Numerical analysis result using this train load model and a measured data. And this paper presents further study subject to improve a method about the train load modeling.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2005년도 추계학술대회 논문집
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• pp.1130-1137
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• 2005

This paper addresses the mathematical model of the long-term track tamping scheduling problem in the railway system. The proposed model is analyzed in problem size, then three solution approaches (relaxation, decomposition, and heuristic) are presented at the sketch level.