• Journal of Mechanical Science and Technology
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• 제14권11호
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• pp.1267-1275
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• 2000

A series do wind tunnel tests were conducted for Korean high-speed train model with various shape components to assess the contributions to aerodynamic drag. In order to elucidate the ground effects, two different wind tunnels, one with a moving ground system and the other with a fixed ground, were used for the same model and the results of both were compared and analyzed in detail. The result show that a suitable ground simulation is necessary for the test of a train model with many cars and detailed underbody. But the relative difference of the drag coefficients for the modifications of shape components can be measured by a fixed ground test with high accuracy and low cost. The effects of the nose shape, the inter-cargap and the bogie-fairing on total drag were discussed and some ideas were prosed to decrease the aerodynamic resistance of high speed train.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 춘계학술대회 논문집
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• pp.2021-2026
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• 2008

Recently, a high speed rail consists of many train coaches and power cars. For keeping the reliable train communication system with train coaches and power cars, train uses the OSI model(Open Systems Interconnection Basic Reference Model) and KTX(Korea Train eXpress) only uses the Physical to Transport layer of OSI model. This paper describes the analysis of CLNP(Connectionless Network Protocol) and ES-IS(End System to Intermediate System) protocols used in KTX for the network layer. CLNP is used to send data to other system and ES-IS protocol is used to route and send information between end systems and intermediate systems. Also this paper presents the protocol parsing program and implementation of Network layer.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2003년도 가을 학술발표회 논문집
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• pp.444-451
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• 2003

In this study, a new three-dimensional finite element analysis model of high-speed railway bridges considering train-bridge interaction, in which various improved finite elements are used for modeling structural members, is proposed. The box-type bridge deck of a railway bridge is modeled by the NFS(Nonconforming Flat Shell) elements with 6 degrees of freedom. Track structures are idealized using the beam finite elements with the offset of beam nodes and those on Winkler foundation with two parameters. And, the vehicle model devised for a high-speed train is employed, which has an articulated bogie system. By Lagrange's equations of motion, the equations of motion of a bridge-train system can be formulated. Finally, by deriving the equations of the forces acting on a bridge considering bridge-train interaction the complete system matrices of total bridge-train system can be constructed. As numerical examples of this study, 2-span PC box-girder bridge is analyzed and results are compared with experimental results.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 B
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• pp.1352-1354
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• 2004

The accurate analysis on railway traction power system should be carried out a load forecast preferentially. Commonly, it has been performed through Train Performance Simulator (TPS). In the study focused on velocity or location of train, however, the electric power consumption have been computed by converting mechanical power according to given velocity. Therefore, this paper presents a development of a mathematical model for electric load. The proposed load model is expressed as polynomial to reflect the influence of variance of train speed, that is, the model expresses the power as a function of train speed. in this study, method of the least squares method is used to find each coefficient and field test is performed to acquire data, electric power and speed of train in commercial running line.

• 한국산학기술학회논문지
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• 제14권6호
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• pp.2985-2991
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• 2013

경부고속철도 2단계 구간에 도입된 열차무선시스템은 TETRA 기반으로 851MHz 대의 주파수를 사용하고 있다. 이와 같은 열차무선시스템에서 운행중인 차량과 지상과의 끊임없는 정보송수신을 위하여 전파 경로손실을 감안한 기지국 설계가 필수적이다. 본논문에서는 고속철도 선로에서의 측정데이터를 토대로, 열차무선의 전파 경로손실을 정량적으로 분석하였다. 열차무선 기지국 설계에서는 자유공간 전파 경로손실모델 및 Okumura-Hata모델이 사용되고 있는데, 이 모델들에 의한 예측치는 현장측정치보다 10dB 이상 작거나 20dB 이상 크게 나타남에 따라 고속철도 열차무선의 경로손실 예측에는 적합하지 않은 것으로 나타났다. 측정결과를 log-distance 경로손실모델에 적용하여 회귀분석을 수행한 결과 경로손실지수는 2.8~3.2의 범위로 나타났으며, 이 결과는 향후 고속철도 열차무선에서의 전파경로손실 예측에 적용할 수 있다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 춘계학술대회 논문집
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• pp.14-19
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• 2011

Wind tunnel tests are performed so as to investigate the aerodynamic drag characteristics of HEMU-400x, next generation Korean high speed train. The experiments of 1/20 scaled 5-car train model are done at 30, 40, 50, 60m/s with a normal bogie, a bogie cover, and a streamlined shape. The flat plate with knife edge are installed to minimize the effect of boundary layer of wind tunnel for the train model. The aerodynamic drag reduction was more by a streamlined shape than by a bogie cover from a normal bogie. Based on the experimental results, the aerodynamic drag of HEMU-400x test train(6-car) was predicted. It is prediceted that More bogie cover could reduce more aerodynamic drag of the test train in replacement of normal bogies.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 1995년도 창립기념학술대회
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• pp.30-36
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• 1995

An axisymmetric flow induced by a train moving into a tunnel is numerically simulated. The effect of train shape on wavefront of a compression wave created by a train is investigated parametrically using several model trains having the same nose shape but different blockage. The zonal method combined with the Fortified Solution Algorithm (FSA) is employed as a numerical algorithm to solve this moving body problem. The computational result is compared with the experimental data. Good agreement is obtained, which justifies the present computational approach. The compression waves created by the model trains are compared and the result shows that the pressure gradient of the wavefront of the compression wave becomes small in the case of small blockage even though the nose shape is same. The wavefront is not determined solely by the cross-sectional area distribution of the train nose.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2009년도 춘계학술대회 논문집 특별세미나,특별/일반세션
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• pp.447-453
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• 2009

The interior noise of the High Speed Train(HST) is analyzed by applying the statistical energy analysis (SEA) method. The interior of each vehicle is divided lengthwise into nine cavities. Since the rolling noise and aerodynamics noise are expected to be dominant noise sources, they are treated as the noise sources in the model. To further simplify the model, curtains and seats are excluded. The simulation runs involving one-car, three-car and five-car trains are conducted. The maximum predicted noise level is 98.4dB. The results also show that the predicted noise levels are within 0.23% of each other. The results imply that it is not necessary to estimate the interior noise of the train by constructing multiple-car train models. The noise estimate based on just one-car train can be optimal with respect to the computational effort and modeling time.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2005년도 춘계학술대회 논문집
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• pp.453-458
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• 2005

Weight minimization of double-deck train carbody is imperative to reduce cost and extend life-time of train. It is required to decide 36 thickness of aluminum extruded panels. However, the design variables are two many to tract. moreover, one execution of structural analysis of double-deck carbody is time-consuming. Therefore, we adopt approximation technique to save computational cost of optimization process. Response surface model is used to apporximate static response of double-deck carbody. To obtain plausible response surface model, orthogonal array is empolyed as design of experiment(DOE). Design improvement by approximate model-based optimization is described. Accuracy and efficiency of optimization by using response surface model are discussed.

• 한국철도학회논문집
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• 제8권6호
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• pp.602-609
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• 2005

In this paper, we consider the train-fleet assignment problem to determine fleet assignment and seat allocation synchronously. An integer programming model of the problem and a decomposition-based solution approach are developed to handle short-term period deterministic orgin-destination demands. The primary objective used in the developed model is to maximize the total number of passengers transported during peak load periods, such as Chuseok national holiday period. Thus, in developing the model we choose to profit-pursuing system. We also show how the proposed model can be readily modified to incorporate profit-maximization. Using the empirical data sets provided by a Korean railroad company, we have tested the proposed solution approach and carried out various comparison analyses by varying traffic demand patterns and train schedules. The computational experiments reveal that the proposed solutions approach produces high quality solutions in reasonable computation time.