• 한국음향학회지
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• 제41권2호
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• pp.192-198
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• 2022

DIrectional Frequency Analysis and Recording(DIFAR) 소노부이는 대잠전에 효과적인 무기체계로 하나의 무지향성 센서와 두 개의 지향성 센서로 구성된 3채널 빔형성을 통해 표적의 방향을 탐지한다. 하지만, 주변 소음의 영향으로 DIFAR소노부이의 특정방위(0°, 90°, 180°, 270°) 표적 탐지 성능이 저하되는 단점이 있다. 따라서, 본 논문에서는 주변 소음을 추정하고 제거를 통해 DIFAR 소노부이의 표적 탐지 성능을 향상시키는 방법을 제안하였다. 주변 소음 추정을 위해 소나신호처리에서 널리 쓰이는 Order Truncate Average(OTA)기법을, 추정된 소음을 제거하기 위해 음성신호처리에서 널리 쓰이는 위너필터링 기법을 사용하였다. 제안한 방법을 평가하기 위해 표적 방위추정 결과의 평균 제곱 오차를 비교한 결과 신호대잡음비 0 dB이하에서 제안한 방법이 효과적임을 확인할 수 있었다.

• 한국주거학회:학술대회논문집
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• 한국주거학회 2003년도 정기총회 및 추계학술대회
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• pp.89-93
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• 2003

The ambient noise in modem society is the factor to give people serious influence. Noise barriers installation is mostly used in the apartment estate to protect countermeasure about the road traffic ambient noise. The purpose of this study is to suggest reference data fur design of traffic noise reduction in apartment estate. It finds out how the traffic noise is measured about a noise barriers and physical characteristics. The 57dB was measured from the noise barriers in a 2m point. An ambient noise's of the part to belong noise attenuation is big at the sound arresting area of the noise barriers as the distance far.

• 한국공간구조학회논문집
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• 제17권1호
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• pp.93-100
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• 2017

With increasing number construction of high-rise building which has about 40 to 60 floors there have been many kinds of problem which related with usage from vibration. To predict response acceleration, it is important to assess correct natural frequency. However, due to the noise of MEMS sensor, it is difficult to measure dynamic characteristic such as natural frequency when measuring ambient vibration using MEMS sensor within cell phone. Therefore, a comparative analysis on vibration measuring applications was performed after measuring ambient vibration of 2 skyscrappers which have height between 133.5~244.3m that are located in Seoul and Observation tower using I-jishin APP with noise reduction function of MEMS sensor in order to verify the effectiveness of low noise type vibration measurement APP.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 ITC-CSCC -1
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• pp.260-263
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• 2000

A technique that uses linear prediction to achieve noise reduction in a voice signal which has been mixed with an ambient noise (Signal to Noise (S-N) ratio = about 0dB) is proposed. This noise reduction method which is based on the linear prediction estimates the voice spectrum while ignoring the spectrum of the noise. The performance of the noise reduction method is first examined using the transversal linear predictor filter. However, with this method there is deterioration in the tone quality of the predicted voice due to the low level of the S-N ratio. An additional processing circuit is then proposed so as to adjust the noise reduction circuit with an aim of improving the problem of tone deterioration. Next, we consider a practical application where the effects of round on errors arising from fixed-point computation has to be minimized. This minimization is achieved by using the lattice predictor filter which in comparison to the transversal type, is Down to be less sensitive to the round-off error associated with finite word length operations. Finally, we consider a practical application where noise reduction is necessary. In this noise reduction method, both the voice spectrum and the actual noise spectrum are estimated. Noise reduction is achieved by using the linear predictor filter which includes the control of the predictor filter coefficient’s update.

• 한국산학기술학회논문지
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• 제9권1호
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• pp.70-74
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• 2008

변압기 보호와 과전류를 막기 위한 목적으로 COS를 사용하고 있다. 그러나 COS 퓨즈는 과전류가 흐르면 과부하에 의하여 용단되면서 강한 아크를 발생하여 공기 절연파괴를 일으킨다. 이러한 현상은 소음을 발생하면서 주변 거주자나 행인들에게 두려움을 준다. 그래서 실제 환경하에서 발생되는 소음을 시급히 정립할 필요가 있다. 본 논문은 COS 퓨즈가 용단되면서 발생하는 충격성 소음의 특성을 파악하고 이러한 소음을 줄일 수 있는 방안을 제안한다.

• 한국음향학회지
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• 제28권5호
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• pp.454-460
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• 2009

본 논문에서는 핸즈프리 전화통신를 위한 선형예측기를 이용한 잔여반향 및 잡음제거구조를 제안하다. 제안하는 구조는 비동시통화구간의 잔여반향신호를 선형예측하여 백색화시킨다. 선형예측에 의해 백색화된 잔여반향신호에는 여전히 음성성분이 남아있다. 제안된 구조는 선형예측오차신호와 선형예측신호의 전력을 이용하여 백색화된 신호를 더욱 더 백색화시킨다. 이러한 백색화 과정을 거치면 동시통화구간에는 근단화자음성과 주변 잡음이 존재하고, 비동시통화구간에는 백색잡음이 존재하게 된다. 근단화자음성과 백색화된 신호를 결합하여 다시 선형예측기에 통과시켜 배경잡음을 추가로 제거한다. 컴퓨터 시뮬레이션을 통해 제안하는 방법이 AIC (acoustic interference cancellation) 측면에서 우수함을 보인다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.946-950
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• 2006

This paper proposed the ways for reduction of the prominent peak of the tone noise in air conditioning units. In order to find out the sources of the tone noise, the resonant frequencies and modes of the fans were investigated. Also, the effects of the ambient temperatures and material properties of the fans on the tone noise were studied. From the experiments, it was shown that the tone noise was greatly influenced by the torsional resonance of the fan and motor system and commutation frequency. In other words, the torsional resonance of the fan and motor system has not to be close to the commutation frequency (torque ripple frequency) which creates a rate of change in the angular acceleration in order to reduce the tone noise in air conditioning units.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문집
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• pp.687-692
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• 2002

In order to verify the effectiveness of adding visooelastic dampers to full-scale steel frame structure on the reduction of their seismic and wind response a experimental work was carried out. First, The test was conducted on the VE dampers subjected to sinusoidal excitations under a variety of ambient temperatures, frequency, and the damper strain. Results from these tests showed that the viscoelastic dampers have high energy dissipation capacity. Second, The vibration tests was conducted of the full-scale steel frame structure with md without added VE dampers at different temperatures. Viscoelastically damped full-scale structure test result on the effect of ambient temperature show that viscoelastic dampers are very effective in reducing excessive vibration of the structure due to sinusoidal excitation over a wide ringe of ambient temperature.

• 전기학회논문지
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• 제64권12호
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• pp.1756-1760
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• 2015

This paper focuses on a priori signal to noise ratio (SNR) estimation method for the speech enhancement. There are many researches for speech enhancement with several ambient noise cancellation methods. The method based on spectral subtraction (SS) which is widely used in noise reduction has a trade-off between the performance and the distortion of the signals. So the need of adaptive method like an estimated a priori SNR being able to making a high performance and low distortion is increasing. The decision directed (DD) approach is used to determine a priori SNR in noisy speech signals. A priori SNR is estimated by using only the magnitude components and consequently follows a posteriori SNR with one frame delay. We propose a modified a priori SNR estimator and the weighted rational transfer function for speech enhancement with wind noises. The experimental result shows the performance of our proposed estimator is better Perceptual Evaluation of Speech Quality scores (PESQ, ITU-T P.862) compare to the conventional DD approach-based systems and different noise reduction methods.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2013년도 춘계학술대회 논문집
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• pp.242-242
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• 2013

Recently, importance of working environment is increased in commercial vessel and offshore structure. Marine facility design and ambient environment condition are influenced to enhancing human performance and reducing human errors. Consequently, the quality of accommodation where offshore facility crews sleep, eat and relax will influence their job performance and overall sense of comport and well-being. Therefore, adequate acoustic isolation between adjacent spaces is normally required to achieve satisfactory internal noise levels, acoustic privacy and speech intelligibility. In this study, the reverberation time is investigated in the public areas where there are not provided the information of material's noise reduction coefficient (NRC). The experiment of reverberation time is rarely performed for the various type public areas in a marine structure. Therefore, the reverberation time in a vessel is investigate in order to evaluate the room's noise reduction coefficient (NRC) in a public area.