• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.05a
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• pp.1043-1047
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• 2007

Community Noise has been great concerned in public. Especially, the road traffic noise has affected too much damage on quiet living environment. In this paper, the noise barrier and reducer effect on the street has been analyzed by using the ray tracing method. The outcome of the analysis has been compared to the measurement at the street near the highway. It turns out that noise barrier and reducer decreases noise level by 7dB(A).

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.13 no.3
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• pp.17-24
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• 1999

This paper presents a method of ANC for transfonrer noise control utilizing a sproker and microphone pair. In this study, the main focus is on identifying the dynamic characteristics of speaker - amplifier microphone path. This study presents a theoretical method to identify the dynamic characteristics of speaker-microphone pairs. The transfer functions of microphone - speaker pair have been estimated utilizing sequential least square(SLS) algorithm. We identified the estimated transfer function has stable JXlles and zeros in z-plane. This paper also propose an architecture far the noise cancellation to which we applied the estimated transfer function.nction.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.8
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• pp.4776-4783
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• 2014

Many studies have examined the reduction of primary noise sources, but quality-related noise, such as BSR, is rarely studied. This study describes the quantitative BSR test method using a multi-axial simulator. The sine sweep test was conducted to detect the system resonance and its relation to BSR noise with high frequency. This method is applied to the seat frame with/without the vibration durability test. The results showed that the $1^{st}$ lateral resonance leads to higher BSR frequency noise. In addition, the reduction of the lateral mode system stiffness after the durability test results in a decrease in the BSR noise in sine sweep test mode.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.109-111
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• 2007

Community Noise has been great concerned in public. A road traffic noise has affected too much damage on quiet living environment. In this paper, the noise barrier effect on the street has been examned. As a tool of the path analyses, a cepstrum analyses of signal processing technique has been implemented.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.5
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• pp.1062-1068
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• 2007

We are using COS to block the excess current and to protect the transformer. But the fuse of COS is melt due to the overload resulting from the excess current flows and it destroys an air severing relations to clear as strong arc happens. Such phenomenon induces an impact ambient noise and it gives the circumstance area resident or pedestrian the fear. Thus, it is necessary that we urgently need to control the ambient noise from the actual circumstances. In this study, we investigate the characteristic of an impact ambient noise associate with the melting state of the COS fuse and suggest the method to reduce the noise.

• Journal of KSNVE
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• v.6 no.1
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• pp.35-44
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• 1996

This paper presents a new type of fuzzy-sliding mode controller for robust tip position control of a single-link flexible manipulator subjected to parameter variations. A sliding mode controller is formulated with an assumption that imposed parameter variations are bounded so that certain deterministic performance can be guaranted. In the design of the sliding mode controller, so called moving sliding surface is adopted to minimize the reaching phase and thus mitigate system sensitivity to the variations. The sliding mode controller is then incorporated with a fuzzy technique to reduce inherently ever-existing chattering which is impediment in position control of flexible manipulators. A set of fuzzy parameters and control rules are obtained from a relation between predetermined sliding surface and representative points in the state space. Computer simulations are undertaken in order to demonstrate superior control performance of the proposed methodology.

• The Journal of the Acoustical Society of Korea
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• v.22 no.5
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• pp.337-344
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• 2003

In DC/DC converter and VVVF inverter, which are the must dominant noise sources of Maglev train, noise is radiated from core and coil excited by MS(Magnetostriction). The main noise source of DC/DC converter is transformer whose spectrum shows strong peaks associated with harmonics of exciting frequency, On the other hand, LIM/VVVF noise is dominated by the harmonics of switching frequency, whereas harmonics of exciting frequency are not significant. As switching frequency is increased in VVVF inverter, it is shown that the harmonics are shifted to higher frequency range. If switching frequency is increased from 700㎐ to 2 ㎑, It is measured that noise can be reduced by 5 to 6 ㏈. Since complete mathematical description of MS phenomena is far beyond the present technology, vibration spectrum is investigated qualitatively in this paper, where effect of increasing switching frequency is confirmed.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.6 no.5
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• pp.667-675
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• 2002

In this Paper, we present a new nonlinear active noise control scheme using neural networks. Two neural network4 are used, one is for the active controller and another one is for the secondary path model. This scheme is suitable for the plant which has time-varing secondary path dynamics, because the secondary path modeling is performed via on-line fashion. Simulation results of active noise control with nonlinear primary/secondary path are presented. The results show that the new algorithm can reduce the noise level greatly.

• Journal of the Society of Naval Architects of Korea
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• v.29 no.1
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• pp.123-134
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• 1992

The reduction of the airborne noise level is essential to the comfortability for mien and passengers in ships. In this paper, the acoustic characteristics on the multilayered acoustic panel with the Helmholtz resonator was described analytically and experimentally. The design software based on the Transfer Matrix Analysis(TMA) method for the acoustic enclosing panel was developed. According to the change of the design parameters of the panel, verious transmission losses were obtained using the developed software. As a result, it was verified that the acoustic characteristics of the composite panel was excellent in comparison with the conventional acoustic partitioning structures. This panel can be applicable to the acoustic enclosure system.

• The Journal of the Acoustical Society of Korea
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• v.16 no.4
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• pp.11-20
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• 1997

The passive noise control techniques used until now cancel the noise in terms of the characteristics of materials, which increase the mass and the dimension and have a limit that is effective only to attenuate the high frequency components of the noise. But the active noise control techniques developed in recent years have merits that they decrease the mass and the dimension and are effective to attenuating the low frequency noises. In this paper, the real-time active noise control system attenuating the engine booming noise in a car using the digital signal processing(DSP) techniques in terms of the principle of active noise control. The multiple-error filtered-x LMS(Least-Mean Square) algorithm is used as the adaptive algorithm for active noise control and is implemented using the DSP processor Motorola DSP56001 as a controller. According to the result that the experiments are performed for the engine as the RPM changes in a car, the noise attenuating performances are achieved in an overall car interior and is verified to be 20 dB higher for pure-tone and globally, 15 dB.