• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.04a
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• pp.658-664
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• 2012

This paper presents an investigation into driveline clonk noise of midi-bus. Test was performed for operational acceleration and pressure, torsional vibration of driveline and FRF to TPA. Wavelet analysis was used to study spectral-time characteristics to all measurement data and specially for torsional vibration, lash analysis was carried out. To investigate the path of the clonk in detail, time domain TPA was introduced. With time domain TPA, the contribution of each path for the clonk was estimated by both subjectively and objectively. As a result, Transmission mount part was came to light as the main contributor of issued clonk. This was verified by reinforcing the bracket of transmission side. And 1D torsional nvh performance simulation model was built with measured torsional vibration. The simulation tool was used for prediction of some clonk behavior in tip in-out transient condition.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.6 s.237
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• pp.809-814
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• 2005

The goal of this paper is to minimize the weight of the T-structure supporting steering system in reducing the vibration level on steering wheel which could be amplified by the resonance. Presently, requirements for reducing noise, vibration and harshness (NVH) in automotive area are more stringent than ever. One of them is the vibration of steering system which occurs sometimes at high speeds or when the engine is idling. Besides, the reduction of weight is also one of requirements for improvement of vehicle performance. This paper used the micro genetic algorithm as an optimization method to satisfy above two requirements. The whole T-structure assembly including steering column was used for frequency analysis.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.589-593
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• 2014

Recently, the market has been released a lot of excellent NVH performance cars such as hybrid, electric and luxury cars. Therefore, the consumer is a tendency of many sensitive of the noise inside the vehicle than in the past. In order to match the propensity of such consumers, the automotive industry defines the standard of product related to noise generation of a single product. However, it is difficult to reduce the noise of the product to automobile part suppliers to follow these standards. In this paper, we propose a method for evaluating several necessary in order to find a way to reduce the noise.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.342-352
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• 2003

Idle NVH characteristics are one of the most important aspects among the vehicle performances. Vehicle developers are devoted to improve vehicle interior noise and steering wheel and seat vibrations. In order to improve the idle quality, noise and vibration transfer path should be carefully evaluated. Also, effects of various components related to the idle performance should be confirmed. A general procedure for improving the idle qualify is described in detail. The relationship among cylinder pressure characteristics, crankshaft rotational speed variation, and vehicle vibrations is also investigated. Influences of drive shaft, torque converter, air conditioning system, vehicle structure including engine mount system, and idle control parameters on the vehicle idle quality are studied. Weak points of typical vehicles on the idle qualify are identified. Some of improvement measures are proposed and verified.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.14 no.2
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• pp.105-111
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• 2015

Car manufacturers and part manufacturers each have their own criteria with regard to strength, stiffness and NVH performance levels. Part manufacturers typically investigate such performances according to the part unit. To do this, the part manufacturer receives information from the relevant car maker. However, the information provided by the car maker is limited, making it difficult to develop a part which meets all of the design requirements specified by the car unit overall. To overcome this difficulty, the utilization of a VPG system is recommended for the designer. In this study, the durability performance of an optimized control arm as suggested in a previous study was investigated using the ETA-VPG, LS-dyna and FE/safe software packages. ETA-VPG provides several types of suspension and steering parts. In this study, a complete car is created using the library included in ETA-VPG, with the exception of the control arm. We also conducted a virtual proving ground analysis to predict the life cycle of the control arm.

• Journal of Mechanical Science and Technology
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• v.17 no.10
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• pp.1450-1457
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• 2003

Structural integrity of either a passenger car or a light truck is one of the basic requirements for a full vehicle engineering and development program. The results of the vehicle product performance are measured in terms of durability, noise/vibration/harshness (NVH), crashworthiness and passenger safety. The level of performance of a vehicle directly affects the marketability, profitability and, most importantly, the future of the automobile manufacturer. In this study, we used the Virtual Proving Ground (VPG) approach for obtaining the dynamic stress or strain history and distribution. The VPG uses a nonlinear, dynamic, finite element code (LS-DYNA) which expands the application boundary outside classic linear, static assumptions. The VPG approach also uses realistic boundary conditions of tire/road surface interactions. To verify the predicted dynamic stress and fatigue critical region, a single bump run test, road load simulation, and field test have been performed. The prediction results were compared with experimental results, and the feasibility of the integrated life prediction methodology was verified.

• Journal of the Korean Society of Safety
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• v.17 no.3
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• pp.36-42
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• 2002

Structural integrity of either a passenger car or a light truck is one of the basic requirements for a full vehicle engineering and development program. The results of the vehicle product performance are measured in terms of ride and handling, durability, noise/vibration/harshness(NVH), crashworthiness and occupant safety. The level of performance of a vehicle directly affects the marketability, profitability and, most importantly, the future of the automobile manufacturer. In this study, we used the virtual proving ground(VPG) approach for obtaining the dynamic characteristics. VPG approach uses a nonlinear, dynamic, finite element code(LS-DYNA3D) which expands the application boundary outside the classic linear, antic assumptions. VPG approach also uses realistic boundary conditions of tire/road surface interactions. To verify the predicted dynamic results, a single lane change test has been performed. The prediction results were compared with the experimental test results, and the feasibility of the integrated CAE analysis methodology was verified.

• Transactions of the Korean Society of Automotive Engineers
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• v.20 no.4
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• pp.52-59
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• 2012

The subframe has been generally manufactured by using stamped steel material. Recently, automotive designers are considering aluminum as lightweight material. This paper describes the development process of an aluminum subframe which is made by high level vacuum die casting process, which is beneficial for minimizing gas contents and material properties. The weight of manufactured subframe is reduced by 4kg with the comparison of steel subframe. The aluminum subframe is packaged for the current vehicle layout and the imposed requirement is to attain a better structural performance that is evaluated in terms of mounting stiffness, noise and vibration, and endurance performance. The NVH evaluation results show that sound level is decreased by 8dB with the help of high roll-rod mounting stiffness as well as high structural modes.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.04a
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• pp.367-368
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• 2012

In resent years, engineering thermoplastics represent a means for designers to integrate parts, facilitate assembly, reduce weight and lower the costs of their parts to improve the fuel efficiency and competitiveness of the cars. Thermoplastic turbo charger intake hose is one of most sophisticated application in thermoplastics under the hood. Used as part of weight & cost reduction and performance improvement program, thermoplastic turbo charger intake hose has been developed as rubber and metal replacement. For optimized product, NVH performance is a important criteria while keeping same durability required with current system. Though a number of studies have been conducted on the resonator hose and its analytical models, the most of studies were focused on transmission loss itself. This paper presents contribution of vehicle interior noise according to design parameters like profile, bellows type, bellows position, material characteristic. And we will review the design guidance for optimized product of thermoplastic turbo charger intake hose.

• Journal of Power System Engineering
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• v.14 no.3
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• pp.33-38
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• 2010

Technology of vehicle industry has been developing and it is required a better vehicle performance than before. Therefore, the consumers are asking not only an economic efficiency, functionality, polished design, ride comfort and silence but also a driving stability. The ride comfort, silence and driving stability are influenced by the size of vehicle and various facilities. But the principal factor is a room noise and vibration sensed by a driver and passenger. Thus, the NVH of vehicle has been raised and used as a principal factor for evaluation of vehicle performance. The primary objective of this study is an optimized design of powertrain mounting system. To optimized design was applied MSC.Nastran optimization modules. Results of dynamic analysis for powertrain mounting system was investigated. By theses results, design variables was applied 12 dynamic spring constant. And the weighting factor according to translational displacement and rotational displacement applied 3 cases. The objective function was applied to minimize displacement of powertrain. And the design variable constraint was imposed dynamic spring constant ratio. The constraint of design variable for objective function was imposed bounce displacement for powertrain.