• 한국전산유체공학회:학술대회논문집
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• 2004.03a
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• pp.17-22
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• 2004

A space launch vehicle departs the ground in a low speed, soon reaches a transonic and a supersonic speed, and then flies in a hypersonic speed into the space. Therefore, the design of a launch vehicle should include the prediction of aerodynamic characteristics for all speed regimes, ranging from subsonic to hypersonic speed. Generally, Empirical and analytical methods and wind tunnel tests are used for the prediction of aerodynamic characteristics. This research presents considerable factors for aerodynamic analysis of a launch vehicle using CFD. This investigation was conducted to determine effects of wake over the base section on the aerodynamic characteristics of a launch vehicle and also performed to determine effects of the sting which exist to support wind tunnel test model.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.1137-1142
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• 2008

In this paper, an effect on power conversion unit in high-speed railway vehicle by loss of contact between a catenary system and pantograph suppling electrical power to high-speed railway vehicle are investigated. One of the most important needs accompanied by increasing the speed of high-speed railway vehicle is reduced that arc phenomenon by loss of contact brings out EMI. in case of high-speed railway vehicle using electrical power, as comparison with diesel rolling stock, PLD(Power Line Disturbance) such as harmonic, transient voltage and current, EMI, dummy signal injection etc usually occur. To analysis the effect on loss of contact, it is necessary electrical modeling system between the contact line and the pantograph according to the loss of contact. Therefore analytical model of a contact line and a pantograph is constructed to simulate the behaviour of loss of contact. The reliability of the modeling system is verified by simulation implementation on kinds of loss of contact.

• Proceedings of the KSR Conference
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• 2006.11b
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• pp.245-250
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• 2006

From the research which it sees the safety regarding a high-speed railway vehicle collision and a derailment evaluation research it an example and executed. Japan, France, Germany and Spain, Italy and with our country together it compared a high-speed railway vehicle collision of the high-speed railroad operating nation and derailed relation safety standard and safety against the evaluation system trade name comparison it analyzed. The research which it sees it led and the accident instance against the hazard analysis against the collision and a derailment of the high-speed railway vehicle and a risk evaluation together and a high-speed vehicle collision and derailed it cannot prevention plan from hereafter domestic comparison it analyzed forecast it presented.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.1862-1867
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• 2011

Recently, a railway vehicle of the maximum speed of 350km/h or more high speed has been developed in the developed country. The next-generation railway vehicle(HEMU-400X) is being developed for aim to run over 430km/h in Republic of Korea, too. The safety of the railway vehicle should be conformed before manufacturing the railway vehicle. In this study, the next generation high-speed railway vehicle was modeled as a single-car system using commercial dynamic program ADAMS/Rail. Safety analysis was implemented through the international standard of the UIC 518 OR code. Also, appropriateness of the railway vehicle design variable were conformed by safety analysis results.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.393-398
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• 2004

From the research which it sees the noise of the high-speed railroad use nation it gave and the vehicle sound arresting tile masturbation which is a sound arresting unit standard it slept and in an environment noise standard side from it classified. The case foreign nation vehicle of the KTX vehicle where vehicle sound arresting from the side the high speed railroad use nations from the open ground with 64-68 dBA are used first of all from domestic and it compares and the efficiency almost is a possibility of knowing the beginning of history box from the interior sound arresting side. Also it will be developed from domestic and to case of the position KHST vehicle the speed 50 km/h is more speed up the KTX vehicle than in spite of the standard which is equal will pay with 350 km/h and it will be having and the possibility the strong point is knowing very from the interior sound arresting side it was. For railroad area along resident at the comfort improvement of the second the environment noise standard which it presents from the nation of most the patronage standard inland conforms in the law standard and the case high speed railroad of the place comparing domestic which is presented is not in spite of still prepared 2004 April commerce is operated standard easily not to be, it appeared with the fact that the speed governing one standard establishment by law is necessary.

• Journal of Auto-vehicle Safety Association
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• v.8 no.1
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• pp.13-18
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• 2016

More than 80 percent of traffic accidents related with lane departure believed to be the result of crossing the lane due to either negligence or drowsiness of the driver. Lane-departure related accident in the highway usually involve high fatality. Even though LDWS is believed to prevent accident 25% and reduce fatalities by 15% respectively, its effectiveness in performance is yet to be confirmed in many aspects. In this study, the vehicle lateral locations relative to warning zone envelop (earliest and latest warning zone) defined in ISO standard, ECE and NHTSA regulations are compared with respect to various factors including delays, vehicle speed and vehicle heading angle with respect to the lane. Since LDWS is designed to be activated at the speed over 60 km/h, vehicle speed range for the study is set to be from 60 to 100 km/h. The vehicle heading angle (yaw angle) is set to be up to 5 degree away from the lane (abrupt lane change) considering standard for lane change test using double lane-change test specification. The TLC is calculated using factors like vehicle speed, yaw angle and reaction time. In addition, the effect of vehicle type and reaction time have been considered to assess LDWS safety.

• Structural Engineering and Mechanics
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• v.77 no.5
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• pp.627-635
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• 2021

The speed of rail vehicles become higher and higher over two decades, and China has unveiled a prototype high-speed train in October 2020 that has been able to reach 400 km/h. At such high speeds, wheel-rail force items that had previously been ignored in common computational model should be reevaluated and reconsidered. Aiming at this problem, a new model for investigating the vehicle-bridge interaction at high moving speed is proposed. Comparing with the common model, the new model was more accurate and applicable, because it additionally considers the second-order pseudo-inertia forces effect and its modeling equilibrium position was based on the initial deformed curve of bridge, which could include the influences of temperature, pre-camber, shrinkage and creep deformation, and pier uneven settlement, etc. Taking 5 km/h as the speed interval, the dynamic responses of the classical vehicle-bridge system in the speed range of 5 km/h to 400 km/h are studied. The results show that ignoring the second-order pseudo-inertia force will underestimate the dynamic response of vehicle-bridge system and make the high-speed railway bridge structure design unsafe.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.04a
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• pp.248-253
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• 2013

The maximum speed is one of the most important performance in high speed railway vehicle. The higher the train speed is, the worse the ride comfort is, In order to solve this problem, a semi-active or active suspension can be applied to high speed railway vehicle. The variable damper with hydraulic solenoid valve is used in the semi-active suspension. But the variable damper with hydraulic solenoid valve requires tank for supplying fluid. The MR(Magneto Rheological) damper can be considered instead of hydraulic variable damper which needs additional device, i.e. reserver tank for fluid. In the case of active suspension, hydraulic actuator or electro-mechanical one is used to suppress the carbody vibration in railway vehicle. In this study the MR damper and electro-mechanical actuator was considered in secondary suspension system of high speed railway vehicle. The dynamic analysis was performed by using 10-DOF dynamic equations of railway vehicle. The performance of the semi-active suspension and active suspension system were reviewed by using MATLAB/Simulink S/W. The vibration suppression effect of semi-active and active suspension system were investigated experimentally by using 1/5-scaled railway vehicle model.

• Structural Engineering and Mechanics
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• v.80 no.5
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• pp.491-501
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• 2021

A difference in subgrade settlement between two rails of a track manifests as lateral differential subgrade settlement. This settlement causes unsteadiness in the motion of trains passing through the corresponding area. To illustrate the effect of lateral differential subgrade settlement on the dynamic response of a vehicle-track coupling system, a three-dimensional vehicle-track-subgrade coupling model was formulated by combining the vehicle-track dynamics theory and the finite element method. The wheel/rail force, car body acceleration, and derailment factor are chosen as evaluation indices of the system dynamic response. The effects of the amplitude and wavelength of lateral differential subgrade settlement as well as the driving speed of the vehicle are analyzed. The study reveals the following: The dynamic responses of the vehicle-track system generally increase linearly with the driving speed when the train passes through a lateral subgrade settlement area. The wheel/rail force acting on a rail with a large settlement exceeds that on a rail with a small settlement. The dynamic responses of the vehicle-track system increase with the amplitude of the lateral differential subgrade settlement. For a 250-km/h train speed, the proposed maximum amplitude for a lateral differential settlement with a wavelength of 20 m is 10 mm. The dynamic responses of the vehicle-track system decrease with an increase in the wavelength of the lateral differential subgrade settlement. To achieve a good operation quality of a train at a 250-km/h driving speed, the wavelength of a lateral differential subgrade settlement with an amplitude of 20 mm should not be less than 15 m. Monitoring lateral differential settlements should be given more emphasis in routine high-speed railway maintenance and repairs.

• Proceedings of the KSR Conference
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• 2009.05b
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• pp.217-222
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• 2009

High-speed EMU under development vibrates more than a articulated high-speed train since power units are attached on each vehicle and railway vehicle. In this study, anisotropic equivalent stiffness of a aluminum extrusion plate were calculated to know and predict vibration characteristic of High-speed EMU under development. Eigen frequencies and modal shape of high speed train vehicle were calculated. And vibration generated was predicted at each position of vehicle when vehicle was operating.