• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.1149-1152
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• 2007

Many kind of damping materials are generally used on concrete slab in apartment building to reduce floor impact noise level. Lately, multi-layered damping material that is consist of several materials are used to improve the effect of floor impact noise insulation. In this study, dynamic stiffness of multi-layered damping material that is consist of common materials such as expanded polystyrene(EPS), expended polyethylene(EPE), ethylene vinyl acetate(EVA) and polyester was investigated. It was found that dynamic stiffness of multi-layered damping material could be estimated if know value of each layer that compose whole structure. And it was found that dynamic stiffness of whole structure did not change even if change order that build layer.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.791-794
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• 2002

On this study, the dynamic response of vibration absorber was operated by finite element analysis and this paper proposed the optimum value of spring constant and damping coefficient for three types of impact absorber. Also the reaction farce of piston which is the objective function was proposed by the optimum design and the model which has the optimum value among the reaction forces was shown.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.690-693
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• 2006

As the silence of vehicle is more important, noise reduction of tire is more required. Noise of tire is divided into structure home noise and air borne noise. Tire tread has the property such as Hardness. Pattern Noise is caused by changing of tread hardness. This property has influence on the mechanisms which are Block Impact & Stick-slip sound. In the study, we found that the effect of Hardness is related to more Stick-Slip than Impact.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.193-195
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• 2006

In order to minimize the influence of aircraft noise in the vicinity of domestic airports, the establishment of proper land-use plan according to the influence scope of aircraft noise in the opening part of preparing a housing site around domestic airports is needed. For the purpose of doing it, the environmental impact assessment accompanied by the accurate prediction of aircraft noise distribution is preceded, and this paper describes the improvement plan for performing the trustworthy environmental impact assessment of aircraft noise in the neighborhood of domestic airports.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.474-479
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• 2002

In this research, the relationship between physical measurements and subjective evaluations of floor impact noise in apartment building was quantified by applying the neural network analysis due to its complex and nonlinear characteristics. The neural network analysis was undertaken by setting up L-value, inverse A index, Zwicker parameters and ACF/IACF factors, as input data, which came from the measurements at real suites of apartment building having various sound insulations. The subjective responses from the psychoacoustic experiments were extracted as output data. Then, the reliability of the quantitative prediction for the subjective loudness was evaluated.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1998.04a
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• pp.407-412
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• 1998

In this work, a new time integration method is proposed using the generalized derivative concept to simulate the dynamic phenomena having sudden constraint occurring in dynamic contact/impact problems. By the adoption of the generalized derivative concept and jump assumption, discontinuity can be incorporated in time integration and as a result, the algorithm does not need any other special consideration of jumps in dynamic field variables due to sudden constraint like dynamic contact-release conditions. To observe the characteristics of the proposed time integration method, the stability and convergence analyses are carried out. In numerical tests, several dynamic contact/impact problems are analyzed by straightforward application of the proposed time integration method with the exterior penalty method.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.6
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• pp.515-520
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• 2010

The noise map has been applied to predicting the effect of noise and establishing the noise abatement measure for several years overseas. However the introduction of the noise map in Korea is at the initial stage. Thus, we surveyed the several prediction models for road traffic noise used in EU, and the method of applying the noise map in noise impact assessment. In order to improve the noise impact assessment we have to apply the noise map, and propose the guideline of predicting the road traffic noise. We intend to obtain coherency and accuracy of prediction results. As a result of this study, we know that the prediction guideline is an essential prerequisite in order to predict the unified and accurate road traffic noise.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.05a
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• pp.952-955
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• 2007

경량충격음레벨을 평가하기 위해서는 수음실의 잔향시간을 측정하여 규준화 바닥충격음레벨을 구하여야 한다. 본 논문에서는 규준화 바닥충격음레벨과 표준화 바닥충격음레벨을 구할 때 고려하는 보정레벨을 중심으로 등가 흡음력을 결정하는 잔향시간과 수음실의 체적을 변수요인으로 분석하였다. 그 결과 측정된 잔향 시간은 공간에 관계없이 기준보다 2배 이상 길게 나타났고, 등가 흡음력은 기준보다 침실의 경우 1/2 정도 작지만 거실의 경우 기준과 거의 유사하게 나타나 침실의 경우 두 보정레벨이 유사하지만 거실의 경우 전자가 후자보다 낮게 보정되는 것으로 나타났다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.05a
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• pp.843-847
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• 2007

The unbalanced mass of a high precision rotor deteriorates mechanical performance of the rotor. The geometrical center of a rotor generally corresponds to the rotational axis of the rotor. However, this alignment carried out with a stationary rotor does not guarantee the dynamic rotor balance. There have been a number of schemes for the correction of the imbalance published for decades especially in the hard drive industry where the issues are directly affecting manufacturing costs and product performances. Realizing the significance of the problem, the present work tries to refine one of the methods that works by applying external impact during a rotor spins. A systematic way to apply the external impact to a rotating rotor has been introduced to minimize imbalance correction process time.

• Structural Engineering and Mechanics
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• v.2 no.1
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• pp.95-112
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• 1994

This paper describes the formulation and application of a dynamic model for a conventional rail track subjected to arbitary loading functions that simulate wheel/rail impact forces. The rail track is idealized as a periodic elastically coupled beam system resting on a Winkler foundation. Modal parameters of the track structure are first obtained from the natural vibration characteristics of the beam system, which is discretized into a periodic assembly of a specially-constructed track element and a single beam element characterized by their exact dynamic stiffness matrices. An equivalent frequency-dependent spring coefficient representing the resilient, flexural and inertial characteristics of the rail support components is introduced to reduce the degrees of freedom of the track element. The forced vibration equations of motion of the track subjected to a series of loading functions are then formulated by using beam bending theories and are reduced to second order ordinary differential equations through the use of mode summation with non-proportional modal damping. Numerical examples for the dynamic responses of a typical track are presented, and the solutions resulting from different rail/tie beam theories are compared.