• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2012년도 추계학술대회 논문집
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• pp.202-203
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• 2012

• 한국정밀공학회지
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• 제27권7호
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• pp.13-20
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• 2010

Due to the recent quantum leaps forward in bio-, nano-, and information-technologies, the precisionization and miniaturization of mechanical and electrical components are in high demand. The allowable margin for vibration limits for such equipments is becoming stricter. In order to meet this demand, understandings on the characteristics of vibration isolation systems are highly required. Among the components comprising the vibration isolation system, air spring has become a focal point. In order to develop a complex defect tester for COG bonding of display panels, a vibration isolation system composed of air springs for mounting is considered in this study. The dynamic characteristics of the air spring are investigated, which is the most essential ingredient for reducing the vibration problem of the tester to the lowest level. Uncoupled dynamic parameters of the air spring are identified through MTS experiments, followed by suggestion of a model-based approach to obtain the remaining coupled dynamic parameters. Finally, the dynamic behaviors of the air spring are estimated and discussed.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 춘계학술대회논문집
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• pp.1050-1055
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• 2001

A software for prediction of apartment noise level ihas been improved. The program is based on the ray tracing technique which has been widely used in the environmental noise analysis and prediction. Especially for prediction of environmental noise in apartment complex, this program is advanced in the graphics routine by bilinear interpolation. In this paper, we analyze the railway noise distribution in apartment environment and develop a 3D graphics routine for illustrating the noise level.

• 소음진동
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• 제8권5호
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• pp.957-963
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• 1998

A new signal processing technique, the directional harmonic wavelet map(dHWM), is presented to characterize the instantaneous planar motion of a measurement point in a structure from its transient complex-valued vibration signal. It is proven that the directional auto-HWM essentially tracks the shape and directively of the instantaneous planar motion, whereas the phase of the directional cross-HWM indicates its inclination angle. Finally, the technique is suessfully applied to an automobile engine for characterization of its transient motion during crank-on/idling/engine-off.

• 한국소음진동공학회논문집
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• 제25권4호
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• pp.275-283
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• 2015

The aim of this study is to estimate the noise exposure of roadside apartment complex according to the characteristics of apartment complex. The facade noise level of residential buildings and the ground noise level inside apartment complexes were predicted and analyzed using noise mapping based on a computerized noise model. In addition, the correlation analysis between these noise levels and the characteristics of apartment complex such as traffic volume, building coverage, the number of adjacent roads, etc. was done in a total of 21 apartment complexes. The results showed that building facade noise level and ground noise level were positively correlated with traffic volume (correlation coefficient, r=0.616~0.623) and the number of adjacent roads (r=0.340~0.496). On the other hand, they were negatively correlated with building coverage (r=-0.413~-0.477) and complex area per the number of roads (r=-0.478~-0.615).

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 추계학술대회논문집
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• pp.502-505
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• 2006

Acoustic holography allows us to predict spatial pressure distribution on any surface of interest from measured hologram. It is noteworthy that the data size is so huge that it takes long time to calculate pressure field. Moreover the reconstructed pressure field is frequently too complicated to get what we want to know. One possible candidate is complex envelope. Complex envelope in time domain is well known and widely used in various engineering field. We have attempted to extend this method to space domain, so that we can have rather simple spatial pressure picture that provides information we need, for example, where sound sources are. First we start with the simplest case. We examine the complex envelope of a plane wave on both space and wave number domain. Then we extend to monopole case. Holographic reconstructed sound field on the monopole is processed according to what we propose. We demonstrate how this method provides better picture for analyzing the sound field.

• 한국지진공학회논문집
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• 제11권3호
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• pp.53-62
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• 2007

이 연구에서는 작용하는 하중특성에 따라 적절한 감쇠력을 발휘할 수 있는 복합감쇠기(complex damper)를 제안하고 그 유용성을 장대교량의 지진응답해석을 통하여 검토하였다. 제안한 복합감쇠기는 두개 이상의 탄소성감쇠기(elasto-plastic damper)와 오일 감쇠기(oil damper)의 조합에 의하여 구성되며, 탄소성감쇠기의 변위의존적인 특성과 오일감쇠기의 속도의존적인 특성을 적절히 결합함으로서 효율적인 감쇠시스템의 구성이 가능하게 하였다. 중소형의 지진이나 작은 진폭의 진동에서는 오일감쇠기가 주로 진동을 흡수하며, 발생 빈도가 낮으나 규모가 큰 지진 등에 대해서는 탄소성 감쇠기가 진동에너지를 흡수한다. 이와 같이 복합감쇠기는 두 가지 종류의 감쇠기 역할을 잘 구분시켜 경제적이고 제진효율성이 뛰어난 설계를 가능하게 한다. 복합감쇠장치의 수학적 모델을 정립하였고, 수치모사를 통하여 응답특성과 효율성을 평가하였다. 수치모사 결과, 복합감쇠기는 단일의 수동형감쇠기를 이용하는 경우보다 뛰어난 감쇠효과를 더욱 경제적으로 구현할 수 있으며 내진성능을 크게 향상시킬 수 있는 것으로 나타났다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 춘계학술대회논문집
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• pp.1333-1337
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• 2000

The flexural vibration of laminated composite beams with active and passive constrained-layer damping has been investigated to design structure with maximum possible damping capacity. The equations of motion are derived for flexural vibrations of symmetrical, multi-layer laminated beams. The damping ratio and modal damping of the first bending mode are calculated by means of iterative complex eigensolution method. This paper addresses a design strategy of laminated composite under flexural vibrations with active control.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 1998년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Spring 1998
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• pp.157-162
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• 1998

Dynamic loads may arise from rotating parte of pump if they are insufficiently balanced. The magnitude of pump induced vibrations varies according to the weight, eccentricity, and unbalanced mass of pump. This is a study to estimate the pump induced vibration in time and frequency domain by transfer function. The transfer function has real and imaginary information of signals, and response function has also real and imaginary information. So the vibration force can be obtained from the response and transfer function by complex calculation. The amplitudes and components of 50Hp pump vibration force are suggested.

• 소음진동
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• 제10권1호
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• pp.138-143
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• 2000

Longitudinal vibration of an axially moving material is investigated by using the assumed modes method. To circumvent a difficulty in choosing the comparison functions which satisfy the boundary conditions, the assumed modes method is adopted by which equations of motion are discretized. Based on the discretized equations, the complex eigenvalue problem is solved and then the effects of the translating velocity on the natural frequencies and modes are analyzed.