• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.633-638
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• 2003

In this paper, we propose a humanoid active audition system which detects the direction of sound and performs speech recognition using just three microphones. Compared with previous researches, this system which has simpler algorithm, fewer microphones and better amplifier shows better performance. In order to verify our system's performance, we install the proposed active audition system to the home service robot, called Hombot II, which has been developed at the KIST (Korea Institute of Science and Technology), thus we confirm excellent performance by experimental results

• 한국해양공학회지
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• 제34권3호
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• pp.227-236
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• 2020

Underwater acoustics, which is the domain that addresses phenomena related to the generation, propagation, and reception of sound waves in water, has been applied mainly in the research on the use of sound navigation and ranging (SONAR) systems for underwater communication, target detection, investigation of marine resources and environment mapping, and measurement and analysis of sound sources in water. The main objective of remote sensing based on underwater acoustics is to indirectly acquire information on underwater targets of interest using acoustic data. Meanwhile, highly advanced data-driven machine-learning techniques are being used in various ways in the processes of acquiring information from acoustic data. The related theoretical background is introduced in the first part of this paper (Yang et al., 2020). This paper reviews machine-learning applications in passive SONAR signal-processing tasks including target detection/identification and localization.

• 설비공학논문집
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• 제26권2호
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• pp.91-96
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• 2014

An acoustical model for detecting the leak location in a buried gas pipeline has been developed. This model is divided into an experimental model for sound diagnosis, and a theoretical model for sound prediction, which is based on the transfer matrix method, representing the sound pressure and the volume velocity as state variables. The power spectrum is measured by attaching only one microphone to the closed end pipe. It has been shown that the response magnitude of acoustic pressure signals calculated by the acoustical model depends upon the thickness and diameter of a pinhole. The validity for the acoustical model has been verified through a comparison between the measured and calculated results.

• 한국음향학회지
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• 제14권4호
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• pp.12-20
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• 1995

본 논문은 충격 음향법에 의한 원통형 물체의 결함 검출 방법에 관한 원리와 실험 결과를 기술한다. 원통형 물체가 가지게 되는 공진 주파수는 물체의 직경, 길이 등의 물리적 크기에 따라 결정되며 이러한 원통형 물체를 자유 공진 시킬 경우 구조물 고유에 주파수 및 고조파 성분이 내포된 음향을 방생시킨다. 결함이 존재하는 물체에 충격ㄷ이 가해질 경우 발생하는 음향은 정상의 경우와 구별되며, 주파수 성분 분석을 통해 보다 명확한 식별이 가능하다. 본 연구에서 적용된 음향 충격법에 의한 결함 검출 기법은 연구 대상 물체의 경우 결함 유무를 완벽하게 판정할 수 있었으며, 차후 유사한 형태의 구조물에 대한 결함 검출에도 응용될 수 있다.

• 한국전자통신학회논문지
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• 제14권2호
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• pp.389-396
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• 2019

본 논문에서는 다양한 구조의 딥 뉴럴 네트워크를 소리 이벤트 검출을 위하여 적용하였으며 공통의 오디오 데이터베이스를 이용하여 그들 간의 성능을 비교하였다. FNN, CNN, RNN 그리고 CRNN이 주어진 오디오데이터베이스 및 딥 뉴럴 네트워크의 구조에 최적화된 하이퍼파라미터 값을 이용하여 구현되었다. 구현된 방식 중에서 CRNN이 모든 테스트 환경에서 가장 좋은 성능을 보였으며 그 다음으로 CNN의 성능이 우수함을 알 수 있었다. RNN은 오디오 신호에서의 시간 상관관계를 잘 추적하는 장점에도 불구하고 CNN 과 CRNN에 비해서 저조한 성능을 보임을 확인할 수 있었다.

• 한국음향학회지
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• 제2권1호
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• pp.11-19
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• 1983

An irregulary formed chamber was designed and constructed to recognize the direct sound radiated from the sound source and the reflected sound from the walls of the chamber. The sound signal used was tone burst in the frequency response characteristics with the signal detection after transient effect. The direct wave, transient phenomena and the primary reflected sound could be asiily distinguished each other by measurements of the arrival time of the time difference. And also noise could be easily distinguished by the same method. The result obtained can be used in industries for automatic measurement of the sound pressure reponse characteristics with respect to frequencies.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1999년도 춘계학술대회 논문집
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• pp.222-228
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• 1999

The two-microphone sound-intensity technique has been used for the detection of defects in radially loaded ball bearings. The difference in the sound-intensity levels measured for bearings with no defect and for those with intentionally introduced defects of different sizes in their elements under various operating conditions of loads and speeds is demonstrated. A change in the intensity frequency spectrum because of the defects is observed. The results show that the detectability of an outer-race defect is much better than that of on inner-race or ball defect. It is difficult to detect defects at lower speeds. Sound-pressure measurements were also performed fur comparison, and it is shown that the detectability of defects by sound-intensity measurements is better than that by sound-pressure measurements.

• 로봇학회논문지
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• 제17권3호
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• pp.273-281
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• 2022

In this paper, we propose a robot sound recognition system that detects various sound events. The proposed system is designed to detect various sound events in real-time by using a microphone on a robot. To get real-time performance, we use a VGG11 model which includes several convolutional neural networks with real-time normalization scheme. The VGG11 model is trained on augmented DB through 24 kinds of various environments (12 reverberation times and 2 signal to noise ratios). Additionally, based on random forest algorithm, a decision logic is also designed to generate event signals for robot applications. This logic can be used for specific classes of acoustic events with better performance than just using outputs of network model. With some experimental results, the performance of proposed sound recognition system is shown on real-time device for robots.

• 한국항공우주학회지
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• 제37권11호
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• pp.1089-1095
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• 2009

태핑 테스트 시 방사되는 음압을 Rayleigh 적분식을 이용하여 해석하였다. 구조물에 의해 방사되는 음은 구조물의 거동과 직접적으로 연관되므로 충격응답해석이 수행되어야 한다. 본 논문에서는 층간분리가 존재하는 적층판의 해석을 위하여 층간분리 모델을 사용하였으며, 해머 형상의 충격체를 모사할 수 있는 효과적인 스프링-질량모델을 제시하였다. 예측된 음압이력과 시험결과와 비교하였으며, 음압이력과 충격하중이력에 손상이 주는 영향을 검토하였다. 방사되는 음압과 충격하중이력은 적층판에 존재하는 손상에 영향을 주는 것을 보였다. 결과적으로 제안된 음을 이용한 태핑실험은 복합재에 존재하는 손상을 검출하는데 신뢰성 있는 방법임을 알 수 있었다.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2002년도 추계 학술대회논문집
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• pp.88-94
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• 2002

Curved intakes are commonly used from commercial aircraft to military missile. Sound radiation from the intake of air vehicle affects cabin noise, community noise and military detection. In this paper, Sound radiation from curved intake is computed using the high order, high resolution scheme. The generalized characteristic boundary conditions, adaptive nonlinear artificial dissipation model and conformal mapping for high order, high resolution scheme are used. The geometric change of curved intake and the frequency of acoustic source are considered. Two dimensional Euler equations are solved for theses analyses.