• Proceedings of the KSR Conference
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• 2005.05a
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• pp.308-313
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• 2005

An urban railway vehicle has a characteristics such as that a lot of passenger use it and the major of passenger is standee. The ride comfort of standee is greatly influenced by the lateral dynamic characteristics of vehicle. So the lateral vibration is important factor for the improvement of ride comfort. In this study, vibration test of railway vehicle is carried out under the same condition of field driving to find out the major factor of vibration. By considering the test results under the various driving condition, the vibrational characteristics of vehicle is verified.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.1389-1396
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• 2008

There are many studies on the ride comfort for the train from the viewpoint of passenger. But there are only a few studies on the ride comfort for engineers in the locomotive. The railway has the track conditions, such as irregularities, rail joints, turnout, level crossing, transition curves and super-elevation ramps, which cause vibrations. Generally, the ride comfort for the train is evaluated by using the vibrations. In this study, vibration accelerations have been measured in the cabin rooms of locomotives, such as DL(Diesel-electric Locomotive), DHC(Diesel Hyduralic Car) and NEL(New-Electric Locomotive) when running on the Kyoungbu conventional line. And then, their ride comforts has been analyzed and evaluated by statistical method according to UIC 513R.

• Proceedings of the KSR Conference
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• 2003.05a
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• pp.747-754
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• 2003

In this paper, a new evaluation system was developed for ride comfort test and vibration level test on railway vehicles. Combining two tests carried out by different test equipment seperately before, the developed system is capable of ride comfort test and vibration test by one system. Also, the assessment algorithm of ride comfort and vibration was compared and verified by simulation results with VAMPIRE software. With the developed system, the comfort in a passenger coach and the vibration in a freight car were evaluated through field test.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.6 s.111
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• pp.619-626
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• 2006

Body-on-frame type vehicle has a set of frame bushes between body and frame for vibration isolation. Such frame bushes are important vibration transmission paths to passenger space for excitations during driving. In order to reduce the vibration level of passenger space, therefore, change of complex stiffness of the frame bushes is more efficient than modification of other parts of the vehicle such as body, frame and suspension. The purpose of this study is to reduce the vibration level for ride comfort by optimization of complex stiffness of frame bushes. In order to do this, a simple finite element vehicle model was constructed and complex stiffness of the frame bushes was set to be design variables. The objective function was defined to reflect frequency dependence of passenger ride comfort. Genetic algorithm and sub-structure synthesis were applied for minimization of the objective function. After optimization level at a position of interest on the car body was reduced by about 43.7 % in RMS value. Causes for optimization results are discussed.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.10a
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• pp.343-348
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• 2011

This paper presents ride comfort characteristics of a quarter-vehicle magneto-rheological (MR) suspension system with respect to different tire pressure. As a first step, controllable MR damper is designed and modeled based on both the optimized damping force levels and mechanical dimensions required for a commercial full-size passenger vehicle. Then, a quarter-vehicle suspension system consisting of sprung mass, spring, tire and the MR damper is constructed. After deriving the equations of the motion for the proposed quarter-vehicle MR suspension system, vertical tire stiffness with respect to different tire pressure is experimentally identified. The skyhook controller is then implemented for the realization of the quarter-vehicle MR suspension system. Finally, the ride comfort analysis with respect to different tire pressure is undertaken in time domain. In addition, a comparative result between controlled and uncontrolled is provided by presenting vertical RMS displacement.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.7
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• pp.631-639
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• 2013

Virtual seat method(VSM) which is an evaluation method combined objective and subjective process is used in this study in order to determine seat comfort index of idle vibration of passenger vehicle. The VSM is implemented by two steps which are for objective index in the first step and for subjective estimation in the second step. In the study, two seats mounted on passenger vehicle was compared in terms of dynamic seat comfort by six subjects employed for the VSM method as well as SEAT value which is a conventional objective method. It is concluded that the dynamic comfort index by the VSM is more reliable than the SEAT value thanks to adding subjective evaluation on top of the objective result.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.282-285
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• 2003

Two criteria of good vehicle suspension performance are typically their ability to provide good road handling and increased passenger comfort. So far, The existing active vehicle suspension uses pneumatic and hydraulic actuators that enhance road handling and passenger comfort. But these kinds of actuators have nonlinear characteristic less than an electromagnetic motor. In this research, we are trying to examine the feasibility and the experiment of an active vehicle suspension using electromagnetic motor in order to enhance the ride quality because existing active vehicle suspension using active power sources such as compressors, hydraulic pumps has nonlinear characteristic. Active vehicle suspension using electromagnetic motor will have the ability to behave differently on smooth and rough roads. The desired response should be soft in order to enhance ride comfort, but when the road surface is too rough the suspension should stiffen up to avoid hitting its limits.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11b
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• pp.194-199
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• 2005

Body-on-frame type vehicle has a set of frame bushes which are installed between body and frame fur vibration Isolation. Such frame bushes are important vibration transmission paths to passenger space. In order to reduce the vibration level of passenger space, therefore, the change of complex stiffness of the frame bushes is more efficient than modification of other parts of the vehicle such as body, frame and suspension. The purpose of this study is to reduce the vibration level for ride comfort by optimization of complex stiffness of frame bushes. In order to do this end, simple finite element vehicle model was constructed and the complex stiffness of frame bushes was set to be design variable. Objective function was defined to reflect passenger ride comfort and genetic algorithm and sub-structure synthesis were applied for minimization of the objective function.

• Journal of the Korean Society for Railway
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• v.14 no.6
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• pp.495-500
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• 2011

In evaluating the ride comfort of railway vehicles, relationship between passenger's feeling and vibration characteristics is very important because human feeling is dependent on frequency spectrum of vibration. Therefore, the weighing curves in frequency domain are used to evaluate the ride comfort of railway vehicles. These curves have been defined in the Laplace transfer functions. It is necessary to convert the Laplace weighing function to the z weighing function in order to obtain the rms value in the time domain. In the present paper, we have applied Tustin's approximation to transform the Laplace weighing function to the z weighing and validated this method by reviewing the various cases.

• Journal of the Korean Society for Railway
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• v.13 no.6
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• pp.552-558
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• 2010

Ride comfort of railway vehicles is affected by many factors, such as vibration, noise, smell, temperature, visual stimuli, humidity and a seat design. In general, vibration, which originates from vehicle motion, is considered as the primary concern. In evaluating the ride comfort, relationship between passenger's feeling and vibration characteristics is very important because human feeling is dependent on frequency spectrum of vibration. Therefore, the weighing functions in frequency domain are used to evaluate the ride comfort of railway vehicles. In the present paper, we have analyzed the characteristics of the frequency weighting curves defined in many standards and reviewed the effect resulting from their difference on the ride comfort.