• Journal of the Korean Society for Precision Engineering
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• v.18 no.3
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• pp.99-106
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• 2001

Model trains should have very similar motion characteristics to real trains in order to provide realistic feeling to their operators. Main purpose of dynamic analysis of model trains is to predict velocities in straight and circular tracks and estimate stopping distance after power shut off. Equations of motion for a model train are derived that relates velocity, traction, rolling resistance, and pulling force. Also, energy equations for calculating stopping distance after power shut off are derived. Experiments with model trains are preformed to measure velocity, rolling resistance, slip, and stopping distance. The results are compared with the prediction based on the equations of motion, and they showed good agreement. It can be concluded that the prediction is more accurate when the slip between wheel and rail is accounted for. The analysis procedures can be applied to determining various design factors in model trains.

• KDI Journal of Economic Policy
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• v.38 no.1
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• pp.23-52
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• 2016

This paper examines the impact of introducing high-speed trains on consumer welfare, taking the ensuing changes in train schedules into account. Based on the estimated demand model for travel which incorporates consumer's heterogeneous preferences for travel schedules into the standard discrete-choice model, I separately evaluate the impact from adding high-speed trains and that from changes in train schedules. The results indicate that consumers who travel between two cities connected by high-speed trains benefit from the introduction of high-speed trains, while some travelers whose choice set does not include high-speed trains face a reduced frequency of non-high-speed trains, resulting in significant losses.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.10a
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• pp.843-848
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• 2011

Planning and construction of railway for high speed trains up to 400 km/h are recently driven in Korea. High speed train is one of the environment-friendly fastest mass transportation means but its noise generated by rolling, traction and aerodynamic mechanism can cause public complaints of residents nearby railways. To cost-effectively prevent the troublesome noise in a railway planning stage, the rational railway noise prediction method considering the characteristics of trains as well as railway structures should be required but it is difficult to find authentic methods for Korean high speed trains such as KTX and KTX-II. In this study, we propose a framework of our own railway noise prediction model emitted by Korean high speed trains over 250 km/h based on the recent research results carried out in EU countries. The model considers railway sound power level using several point sources distributed in heights as well as tracks, whose detail speed- and frequency-dependent emission characteristics of Korean high speed trains should be determined in near future by measurement or numerical analysis. The attenuation during propagation outdoors is calculated by the well-known ISO 9613-2 and auxiliary methods to consider undulated terrain and wind effect.

• Wind and Structures
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• v.37 no.4
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• pp.275-287
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• 2023

Subgrade differential settlement of high-speed railways was a pivotal issue that could increase the risk of trains operation. The risk will be further increased when trains in the subsidence zone are affected by crosswinds. In this paper, the computational fluid dynamics (CFD) model and finite element (FE) model were established, and the data transmission interface of the two models was established by fluid-solid interaction (FSI) method to form a systematic crosswind-train-track-subgrade dynamic model. The risk of high-speed train encountering crosswind in settlement area was analyzed. The results showed that the aerodynamic force of the trains increased significantly with the increase in crosswind speed. The aerodynamic force of the trains could reach 125.14 kN, significantly increasing the risk of derailment and overturning. Considering the influence of crosswind, the risk of train operation could be greatly increased. The safety indices and the wheel-rail force both increased with the increase of the wind speed. For the high-speed train running at 350 km/h, the warning value of wind speed was 10.2 m /s under the condition of subgrade settlement with wavelength of 20 m and amplitude of 15 mm.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.2852-2859
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• 2011

Planning and construction of railway for high speed trains up to 400 km/h are recently driven in Korea. High speed train is one of the environment-friendly fastest mass transportation means but its noise generated by rolling, traction and aerodynamic mechanism can cause public complaints of residents nearby railways. To cost-effectively prevent the troublesome noise in a railway planning stage, the rational railway noise prediction method considering the characteristics of trains as well as railway structures should be required but it is difficult to find an authentic method for Korean high speed trains such as KTX and KTX-II. In this study, recent railway noise prediction methods developed by EU countries are introduced and discussed for consulting before setting the framework of our own railway noise prediction model emitted by Korean high speed trains over 250 km/h. Especially, the new Schall 03 model (2006) developed by Germany and IMAGINE model (2007) suggested by an EU framework research project are intensively reviewed. In addition, research items required for the development of our own model are suggested.

• Journal of the Korean Society for Railway
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• v.13 no.5
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• pp.535-540
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• 2010

We present an optimization model for how to assign the freight trains to transshipment tracks and allocate the containers to the freight trains in a rail container terminal. We formulate this problem as a multi-criteria integer programming to minimize the makespan of job schedule and simultaneously to maximize the loading throughput, i.e. the number of containers to be disposed per day. We also apply our model to the instance obtained from the real-world data of the Uiwang Inner Container Depot. From the experiments, we can see an improvement of approximately 6% in makespan, which means that our model can contribute to the improvement of the disposal capacity of containers without additional expansion of facilities.

• Journal of Industrial Technology
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• v.20 no.B
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• pp.95-103
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• 2000

A model trains must have similitude with its original model not only in shape but also in motion. Motion characteristics of a model train under considerations are maximum velocity in straight and circular tracks and stopping distance. Equations of motions are derived to obtain maximum speed and stopping distance based on the Newton's Second Law and the energy principal. To accurately predict traction and resistance force between wheel and rail. wheel slip, or creepage, is taken into consideration. To verify the equations of motion, various experiments have been carried out including measurement of gear efficiency, location of mass center, rolling resistance force, traction force, slip, maximum velocity and stopping distance. This paper addresses how the experiments are setup and carried out in detail. Also the results of experiments are compared with the analytical prediction, which showed good agreements with each other.

• Transactions of the Korean Society of Automotive Engineers
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• v.4 no.6
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• pp.97-108
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• 1996

A modeling technique is proposed for dynamic simulations of OHC valve trains with HLA(hydraulic lash adiuster). HLA is expressed by an air-oil mixture model considering HLA leak-down and aeraton effects. A compact nonlinear equation is derived which describe the short term dynamic behavior of the HLA. Valve spring is analyzed by a distributed parameter model including nonlinear characteristics in the spring surge phenomena. Global behavior of the remaining valve train is expressed by a lumped mass model. The experiental results prove that the simulation model developed here is accurate and useful for the dynamic simulations of OHC valve trains with HLA.

• Journal of Information Technology Services
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• v.19 no.3
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• pp.151-163
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• 2020

This paper describes a study on the FRACAS(Failure Reporting Analysis and Corrective Action System)-based dependability control platform for domestic urban railway trains. There are more demands for the verification of the dependability of trains as it becomes a regulation for train manufacturers to verify the dependability recently. Train manufacturers as well as railway operators need a effective FRACAS solution to perform the verification of the dependability. Yet current FRACAS solutions have limitations to support the verification processes effectively. This paper addresses the issues of current FRACAS solutions and suggests a FRACAS framework designed for the domestic urban railway trains. Service failure scenarios are standardized using the proposed availability model to implement a more user-friendly and reliable platform. A new FRACAS-based platform for the dependability control (SCARF^®) has been developed to implement the suggested framework. The detail interfaces and functions of the platform are explained. The SCARF^® platform is expected to engage the increasing demands for the dependability control successfully enhancing the reliability, maintainability, availability and safety of domestic urban railway trains eventually.

• Wind and Structures
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• v.37 no.5
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• pp.361-373
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• 2023

Suspended monorail trains (SMTs) are sensitive to crosswinds, and instantaneous aerodynamic characteristics of two SMTs passing each other under crosswinds are particularly complicated. In this study, a pressure measurement test is carried out on stationary train-bridge models arranged in several critical positions. In addition, a validated moving CFD model is developed with the dynamic and sliding mesh method to explore the realistic train movement effects. The time-varying aerodynamic forces and surface pressure distribution on, as well as the flow field around running trains and bridges during trains passing each other, are computed in detail to illustrate the shielding effect of the upstream train. The results reveal that when two trains begin to pass each other, the side force coefficient of the downstream train reduces significantly to negative values due to the wind shielding effect of the upstream train. The moving model successfully captures that airflow is separated on the middle line of the head car for the suspended monorail train, and the surrounding bluff double-beams can significantly affect the flow structures around the train. The wind shielding effect of the upstream train on the downstream train will weaken as the relative yaw angle decreases.