• Journal of the Korean Society for Precision Engineering
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• v.27 no.2
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• pp.117-122
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• 2010

The shock performance of hard disk drives has been a serious issue for Car PC. Since the vibration and disturbances from a car gives an adverse effect on a HDD of Car PC, it is necessary to protect a HDD from them. In this study, passive vibration attenuation system for a vehicle HDD was developed. Acceleration from the ground through the tire and suspension system was measured to figure out the frequency translated to Car PC. Critical frequency to Car PC was determined by exciting it with a shaker and measuring a data transmitting speed from HDD. A newly designed vibration attenuation system was fabricated to protect HDD from the acceleration. It was shown that the developed system had an excellent vibration attenuation ability.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.12 no.3
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• pp.204-212
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• 2002

The ride comfort is one of the important dynamic performances of railway vehicle and is affected by the various factors, such as vibration, sound, temperature, humidity, etc. In general, vibration is known to be a major effect of rode comfort. There are many studies on the evaluation methods of ride comfort in the railway vehicle vibration. Each of the evaluation methods suggested by Spelling and in the standards recommends a different evaluation method and guidance. So users must review whether they can apply it to their railway system or not. In this study, we have suggested the relationship between several evaluation methods using the statistical vibration model based on the experimental data.

• Journal of the Korean Society for Railway
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• v.6 no.4
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• pp.286-293
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• 2003

The prototype of Korean high speed train (HSR350), composed of two power cars, two motorized cars and three trailer cars, has been designed, fabricated and tested. In this paper, the body vibration has been reviewed from the viewpoint of the vehicle's safety and the vibration limits for components and sub-assemblies mounted on the car-body using by the experimental method. And, the dynamic characteristics, such as jerk, natural mode and kinematic mode, have been reviewed. The KHST has been run to 300 km/h in the KTX line and the results of on-line test show that it has no problems in the vehicle's safety and the vibration limits. And the characteristics of body vibrations has been predicted at 350 km/h by fitting curve about the measured acceleration signals.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.3
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• pp.235-241
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• 2010

Engine Mount plays an important role which supports engine, isolates vibration from engine and blocks the vibration from road. Development of engine mount for NVH costs great a deal. So, the cost of development being reduced, the way developed effectively engine mount using DFSS technique is proposed in this paper. CTQ(critical to quality) is vibration and parameter is dynamic stiffness of mounts. The core parameters are selected with TPA(transfer path analysis) technique. It uses design of experiments(DOE) or Taguchi Methods to optimize parameter values and reduce variation. And then, this paper shows the result of improvement for vibration in the developing vehicle.

• Journal of the Korea Institute of Military Science and Technology
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• v.25 no.6
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• pp.596-605
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• 2022

In this study, analysis of dynamic characteristics and flight vibration was performed to unmanned aerial vehicles. The analysis model was supplemented by performing a dynamic characteristic test and a random vibration test using manufactured dummy aerial vehicle. For the dynamic characteristic test, a bungee cable was used to implement the free end boundary condition. Prior to the flight vibration test using a multiple electric shaker, a random vibration test was performed to predict the excitation force during the actual flight vibration test. It was judged that the actual test could be predicted more accurately by supplementing the analysis model from the test results. In addition, it was possible to determine the feasibility of the test by predicting the excitation force of the flight vibration test.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.8 s.101
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• pp.945-953
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• 2005

The purpose of this paper is to develop a linear regression model for the sound quality index of vehicle Interior noise. For this, objective measurement data of the vehicles driving in acceleration was measured. On the basis of analysis, psychoacoustic parameters were extracted and subjective evaluation was performed by noise and vibration expert evaluators. For the subjective evaluation, the paired comparisons and the semantic differential methods were used to evaluate sound quality of vehicle interior noise. By the paired comparison which evaluate two pairs of vehicle interior noise, the preference was estimated. With the semantic differential and the factor analysis, it was evaluated words of two pairs which expressed appropriately the sense of evaluator about noise source. Therefore the characteristics of the sound qualify for the vehicle were differentiated. From the results of both the correlation analysis and the multiple factor regression analysis, the sound quality evaluation model for the sense of human hearing was derived and indexed.

• Journal of the Korea Institute of Military Science and Technology
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• v.4 no.1
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• pp.13-19
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• 2001

It is known that displacements, velocities and accelerations of the tractor- trailer type vehicle system in shock & vibration analysis by the flexible-multi-body dynamics including the flexibility of structure are bigger and more repetitive than them by the rigid-multi-body dynamics, and it is necessary to prove above results by the experimental field test. Therefore, in this paper, theoretical analysis by the flexible-multi-body dynamics and experimental field test for a tractor-trailer type vehicle system are conducted and their results are compared with each other. Because of unexpected metal contact and impact in the air coupler part in the field test, some accelerations measured from the experimental field test are bigger than them analyzed from the theoretical analysis, but most accelerations are well coincide with each other in the amplitudes and trends. Thus more refined dynamic analytical models for some special type vehicle systems will be possible in the future.

• Computational Structural Engineering
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• v.7 no.1
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• pp.91-98
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• 1994

Design sensitivity analysis method for the vibration of vehicle structure is developed using adjoint variable method. A variational approach with complex response method is used to derive sensitivity expression. To evaluate sensitivity, FEM analysis of ship deck and vehicle structure are performed using MSC/NASTRAN installed in the super computer CRAY2S, and sensitivity computation is performed by PC. The accuracy of sensitivity is verified by the results of finite difference method. When compared to structural analysis time on CRAY2S, sensitivity computation is remarkably economical. The sensitivity of vehicle frame can be used to reduce the vibration responses such as displacement and acceleration of vehicle.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.11
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• pp.995-1000
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• 2010

With the development of the auto industry, the automobile manufacturers demand to shorten development period and reduce the cost. Compared with the traditional method, applying the virtual prototype is more economical. This paper presents a method for parameters sensitivity analysis and optimizing the performance of vehicle noise and vibration. The existing design processes were repeatedly analyzed with a focus on vehicle performance to decide the design parameters of dimension, thickness, mounting type of body and chassis systems in the vehicle development period. This paper describes the prediction technique of vehicle performance using L18 orthogonal array layout, quality deviation analysis and parameter sensitivity analysis for robust design. This paper analyzed the performance correlation equation through the frequency and sensitivity database according to a design factor change. The new concept is that the performance prediction is possible without repeated activities of test and analysis. This paper described the parameter analysis applications such as bush dynamic stiffness and bush void direction of rear suspension. Design engineer could efficiently decide the design variable using parameter analysis database in early design stage. These improvements can reduce man hour and test development period as well as to achieve stable NVH performance.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.18 no.2
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• pp.169-176
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• 2008

This paper presents optimal design of controllable magnetorheological(MR) shock absorbers for passenger vehicle. In order to achieve this goal, two MR shock absorbers (one for front suspension; one for rear suspension) are designed using an optimization methodology based on design specifications for a commercial passenger vehicle. The optimization problem is to find optimal geometric dimensions of the magnetic circuits for the front and rear MR shock absorbers in order to improve the performance such as damping force as an objective function. The first order optimization method using commercial finite element method(FEM) software is adopted for the constrained optimization algorithm. After manufacturing the MR shock absorbers with optimally obtained design parameters, their field-dependent damping forces are experimentally evaluated and compared with those of conventional shock absorbers. In addition, vibration control performances of the full-vehicle installed with the proposed MR shock absorbers are evaluated under bump road condition and obstacle avoidance test.