• 한국멀티미디어학회논문지
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• 제13권7호
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• pp.973-982
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• 2010

본 논문에서는 심음 향상을 위해 단일 채널 적응 잡음 제거기를 제안한다. 청진음은 일상적이거나 응급 상황 시 다양한 소리가 섞여 심음의 판독이 어려운 특징이 있다. 기존의 두 채널의 입력을 가지는 적응 잡음 제거기에서 단일 채널의 구현을 위해 단일 채널로 입력된 청진음은 심음의 특징을 기반을 둔 HS 분석기와 BS-Gate를 제안하여 기준 신호를 생성하였다. 제안한 단일 채널 적응 잡음 제거기는 BIOPAC Systems, Inc의 SS30L과 MP 36을 이용하여 획득한 청진음을 이용하여 실험하였으며, 그 결과 효과적으로 호흡음이 감쇄하여 심음이 향상되는 것을 확인할 수 있었다. 또한 단일 채널을 사용하는 적응 선 스펙트럼 강조기와의 비교 실험을 통해 심박의 변화에도 효과적으로 잡음을 제거하였음을 확인할 수 있었다.

• 한국음향학회지
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• 제19권3호
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• pp.3-10
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• 2000

본 논문에서는 등간격으로 직선배열된 마이크로폰 어레이군으로 각 측정지점마다 빔패턴을 형성하고 이를 기준신호로 이용하여 각 마이크로폰들간의 신호와 크로스스펙트럼 알고리즘에 의하여 음원의 절대위치를 추정할 수 있는 빔포밍 음향홀로그래픽 시스템을 제안한다. 실음장 측정을 통하여 기준 마이크로폰을 사용하는 음향홀로그래픽법과 본 연구에서 제안한 방법을 동일 알고리즘으로 비교·검토한 결과, 약 20% 이상의 분해능 향상을 가져왔으며 제작한 시스템의 음장측정에 대한 유용성을 확인하였다.

• 한국해양공학회지
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• 제26권2호
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• pp.14-19
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• 2012

There are insufficient data to consider the effect zone for the marine life of coastal fisheries, because no standard has been defined for the sound level of marine life. In this study, equations for distance attenuation were used to determine the effect zone for oceanic noises. A reference noise level was divided into 4 parts to consider the characteristics of the fishes, and the effect zone of each reference noise level was determined. To increase the reliability of the effect scope, approximately 100 repetitions of blasting work split into several parts by the boring depth, the sound level of the source caused by an increase in weight, and the effect zone were calculated using the prediction equation. According to the prediction, the maximum distance of the effect zone was 4.92 km.

• 한국항만학회지
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• 제14권3호
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• pp.341-351
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• 2000

This study is on the purpose that the influence caused by noise and shaking through construction works shall be ranged to the fishing species of fishing area of the surface of sea. This study have been performed through analysis of physical effect by the value of noise and shaking test. The resulted purpose of this study has been carried out regarding whether influence factor of the fishing species and others are related or not as per the noise and shaking. For the purpose of the survey of noise and shaking, observances have been performed regarding the direct water surface of fishing area are as well as undersea. As for this result, the influence area for the injury at the fishing area caused by the noise and shaking have been stretched out to the distance of 10km from the source of sound. In this conclusion, this study is regarded as the reference basis of the compensation of injury for the species of fish and others in fishing area.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.1280-1284
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• 2006

This paper describes the methodology for environmental assessments of traffic noise sources. An attempt is made to establish evaluation scale relationships between noise quality Parameters and subjective degrees annoyance. Subjective experimental was conducted to determine the subjective degrees annoyance that scaling score compare with reference and varieties noise source about modified traffic noises with $40{\sim}85dB$. Also a correlation analysis between noise rating index and satisfactory percentage of the noise dose response curves varied with response was conducted. As a result of study, subjective annoyance degree has not correlation of proportional linearity to the A weight noise level, but has correlation of proportional linearity to the index composed to loudness and tonality. It is suggested to be resonable level 4.9 (equivalence about 53dB) index on the out door noise limits for traffic noise and to be 6 step scale base on the linearity for evaluation traffic noise.

• The Journal of the Acoustical Society of Korea
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• 제29권1E호
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• pp.38-44
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• 2010

This paper is based on our comments and proposed amendments to the documents, Annex A, Phantom for determining Maximum Depth of Penetration, and Annex B, Local Dynamic Range Using Acoustical Test Objects 87/400/CDV. IEC 61391-2 Ed. 1.0 200X, prepared by IEC technical Committee 87; Ultrasonics. The documents are concerned with the influence of microstructure of reference target material on the ultrasonic backscattering. Previous works on the attenuation due to backreflection and backscattering of reference target materials are reviewed. The drawback to the use of ungraded stainless steel and metallic materials without microstructural data such as, crystal structure, basic acoustic data of sound velocity and attenuation, grain size, roughness and elastic constants has been discussed. The analysis suggested that the insightful conclusion can be made by differentiating the influence arising from target size and microstructure on the backscattering measurements. The microstructural parameters are associated with physical, geometrical, acoustical and mechanical origins of variation with frequency. Further clarification of such a diverse source mechanisms for ultrasonic backscattering would make the target material and its application for medical diagnosis and therapy simpler and more reliable.

• 한국생산제조학회지
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• 제8권3호
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• pp.66-75
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• 1999

This paper is concerned with a analysis of noise by inverse problem available for analyzing the two and three-dimensional acoustic field problems. The noise of analysis considered in this study can be reduced to an optimum problem to find the optimal set of parameters defining the vibrating state of noise source surfaces. The optimal set of parameters are searched by the standard optimization procedure minimizing the square sum of the residuals between the measured and computed quantities of sound pressure at some points in the acoustic field. Computation is carried out for typical examples in which the noise sources are located on the infinite plane. It is demonstrated that the noise of analysis can be effectively made by using the sensitive reference data.

• 한국음향학회:학술대회논문집
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• 한국음향학회 1994년도 FIFTH WESTERN PACIFIC REGIONAL ACOUSTICS CONFERENCE SEOUL KOREA
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• pp.764-769
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• 1994

The impedance of an electro-acoustic transducer can be controlled by motional feedback, and the noise in a duct can be reduced actively by adjusting the impedance using an additional sound. In this paper, two approaches for active noise control using motional feedback (MFB) loudspeaker are described. First configuration uses an external sensor to pickup of source directly. In this configuration, the adaptation of controller is necessary to compensate the change of transfer function from noise source to control poing. The second configuration uses a new adaptive algorithm specialized for peridic noise. Because this configuration does not require any reference input and the error sensor couples very tightly with control loudspeaker, this MFB system itself is independent of the duct condition. No microphone are required in both configurations, so that a more reliable and stable active control system can be realized under severe conditions such as high pressure, high temperature, dust, flow and so on.

• 한국음향학회지
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• 제20권3호
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• pp.76-82
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• 2001

대부분의 유체기계는 일정 조건하에서는 주기적인 소음 원들로 간주될 수 있으며, 소음원 및 관련 덕트의 음향계를 주파수영역으로 표현이 가능하게 되는데, 음원은 주파수의 함수인 음원강도와 음원 임피던스로 표현된다. 이들 변수를 알아내기 위하여는 다양한 이론적, 실험적 방법이 있으나, 고속, 고온, 고강도의 유체 기계와 같은 단일 연결구를 갖는 음원에 대하여는 다양한 길이의 많은 관들을 부하로 사용하는 다부하법만이 적용 가능하다. 문제는 이 다부하법을 적용했을 때, 음원 임피던스의 실수부가 부의 값을 갖는 경우가 많다는 점이다. 본 논문에서는 이 문제의 명확한 원인분석을 위한 일환으로서, 다양한 이론적 실험적 결과에 대한 분석을 바탕으로 하여 가능한 여러 가지 원인에 대한 물리적 조사 결과를 보이고, 분석 결과에 대한 새로운 해석을 통해 기본 가정의 위배와 함께 다부하법 자체의 문제점을 제시한다 유체 기계 덕트에서는 다른 무엇보다도 음원의 시변성이 부의 음원저항을 낳는데 가장 큰 영향을 미치게 되며, 부하 임피던스가 최종 결과에 지대한 영향을 미치게 된다.

• ETRI Journal
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• 제39권3호
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• pp.398-405
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• 2017

In this paper, an artificial stereo extension method that creates stereophonic sound from a mono sound source is proposed. The proposed method first trains deep neural networks (DNNs) that model the nonlinear relationship between the dominant and residual signals of the stereo channel. In the training stage, the band-wise log spectral magnitude and unwrapped phase of both the dominant and residual signals are utilized to model the nonlinearities of each sub-band through deep architecture. From that point, stereo extension is conducted by estimating the residual signal that corresponds to the input mono channel signal with the trained DNN model in a sub-band domain. The performance of the proposed method was evaluated using a log spectral distortion (LSD) measure and multiple stimuli with a hidden reference and anchor (MUSHRA) test. The results showed that the proposed method provided a lower LSD and higher MUSHRA score than conventional methods that use hidden Markov models and DNN with full-band processing.