• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 추계학술대회논문집
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• pp.189-195
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• 2003

This paper represents an identification procedure for leading mechanism of a car A/V system which is composed of a DC motor and a set of plastic gears. In addition, we studied dominant noise source of rattle noise generated by external forced vibration as a car drives. we made a dynamometer to produce stationary operation on loading mechanism of A/V system because noise generated by actual loading mechanism is non-stationary signal. operating the dynamometer setup at various motor speeds, sound pressure spectra are measured and the results are analyzed. its dominant noise source is also identified by using a sound Intensity technique. we made use of multi-dimensional spectral analysis to rind a dominant rattle noise. this method is so useful to eliminate coherence between vibration sources and helps us obtain coherent output spectrum of individual vibration source which make a rattle noise.

• 한국콘텐츠학회논문지
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• 제15권12호
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• pp.8-17
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• 2015

본 논문은 공감각의 한 부분인 색청(colored-hearing) 공감각을 이용한 사운드-컬러 신호 변환에 관한 연구로서, 인간이 인지 할 수 있는 오감 중 공감각적 변환이 가장 많이 일어나는 청각과 시각을 이용한 실시간 변환 시스템의 구축을 목표로 한다. 본 논문에서 제안하는 음-색 실시간 변환 방법으로서, 입력으로 사용하는 MIDI(Musical Instrument Digital Interface) 신호에서 음계(scale), 옥타브(octave) 및 음의 세기(velocity)를 추출한 후 HSI 컬러모델의 기본 요소인 색상(hue), 명도(intensity) 및 채도(saturation)에 각각 대응하여 변환하는 방법으로 단순하지만 직관적인 방법을 사용한다. 변환된 HSI 컬러 모델은 모니터 출력을 위해 RGB 컬러 모델로 최종 변환하여 출력한다. 실험에서, MIDI 입력신호 전송 H/W 시스템과 VC++ 기반 해당 사운드-컬러 변환 입 출력 S/W 모니터링 시스템을 구축하여 사운드에서 컬러로의 출력이 제안한 방식에 따라 값이 출력됨을 확인하였다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 춘계학술대회논문집
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• pp.1189-1194
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• 2002

Acoustic intensity is usually estimated by the cross-spectrum of acoustic pressure at two adjacent micrphones. The cross-spectrum calculated by digital Fourier transform technique will unavoidally have leakage error since the period of signal will not be usually coincident with record length. Therefore, the acoustic intensity estimated by the conventional r]n analyzer will show distorted value. In this paper the expression of the Fourier transformed data of a harmonic signal is formulated when there is leakage error. The method to elimate the effect of leakage error from the contaminated data is also proposed. Some numerical examples show the validation of the proposed method.

• 한국자동차공학회논문집
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• 제5권3호
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• pp.202-208
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• 1997

The knocking is one of major parameters to improve engine performance in a spark ignition engine. Many researches have been carried out to identify them using cylinder pressure, vibration signal and so on. In the present study, measurement and analysis was conducted to set up the criteria of knock occurrence by using microphone signal. Cylinder pressure was measured for the reference signal of knocking. It has been observed that resonance frequencies of pressure wave are nearly independent of engine operating conditions such as engine speed, air fuel ratio, load and octane number of fuel within to limited experimental conditions. SDBP(sum of different band-pass data) method using resonance frequency of knock was proposed for estimating knock intensity. SDBP method is superior to identify knock occurrence and its intensity in case of sound pressure measurement.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1996년도 춘계학술대회논문집; 부산수산대학교, 10 May 1996
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• pp.291-297
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• 1996

To visualize sound field or to identify noise sources, we can use many methods such as intensity method, acoustic holographic method, source identification method using line array, etc. Conventionally all these methods are performed with the assumption of stationary condition in space and time. But for moving source, spatial characteristics and frequency components are changing, so we need another processing algorithm. This paper shows some experimental results - sound field by moving noise sources. In the experiment cross type microphone line array is used for sensing pressure and cars and a motorcycle are used as moving sources that are assumed to have constant speed. The processing methods are acoustic holographic method, spherical beamforming and spectrogram.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2013년도 추계학술대회 논문집
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• pp.501-505
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• 2013

It is well known that monolithic glass has specific coincidence dip allowing transmittance of noise around the critical frequency. Laminated glass, made of a polyvinyle butyral(PVB) interlayer sandwiched by two panes of glass sheet, has long served for the advantage in noise attenuation properties as well as the safety purpose. More research on the improvement of sound insulation performance is needed, considering much of the noise is still transmitted through the glass. As a preliminary study, authors have made several test specimens, varied combinations of glass and interlayer film, to optimize the acoustic performance. Experimental investigation was carried out to study the sound transmission loss of test specimens in the reverberation chamber by using sound intensity method. Several new applications, instead of the existing PVB laminated glass, show better results in sound transmission loss and low temperature have a bad influence on the acoustic performance.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 추계 학술대회논문집(수송기계편)
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• pp.122-125
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• 2005

This study is an measurement and prediction of transmission loss through dash panel with multi-path in a vehicle. Measurement results of transmission loss are derided by sound power measured using the sound intensity method under locating a sound source in the anechoic room and reverberant room, respectively. Prediction one is decided by multi-path analysis of dash panel composed by a various part of materials and complicated shape. Finally, two results show a great agreement between measured and predicted transmission loss.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1997년도 춘계학술대회논문집; 경주코오롱호텔; 22-23 May 1997
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• pp.557-563
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• 1997

In order to satisfy the regulations concerned with the noise emission of fork-lift trucks and thereby increase export to the western countries, a noise reduction technique should be developed in the early design stage. In this paper, several noise sources are identified using the sound suppression method and sound intensity measurement, and their contributions to the sound levels at the operator's ears and at the distance of 7m from the vehicle are studied. For each of the major noise producting components, noise abatement alternative are suggested and their effects are analyzed.

• 한국음향학회지
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• 제20권3호
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• pp.98-103
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• 2001

인간의 청각기관은 소리의 방향과 거리인지에 있어서 여러 가지의 정보들을 복합적으로 이용한다. 이러한 양 귀에 들어오는 소리세기의 차이, 위상의 차이, 그리고 주파수 스펙트럼의 차이 등의 정보들을 종합적으로 포함하고 있는 것이 머리전달함수이다. 본 논문에서는 이 머리전달함수를 이용한 3차원 음상정위를 위해 사람의 청각기관에 알맞은 1/3-옥타브 대역통과필터를 이용한 알고리즘을 제안한다. 먼저 측정된 머리전달함수의 음색왜곡 및 음질저하를 최소화하기 위해 1/3-옥타브 대역통과필터를 이용해 간략화시켰으며, 간략화된 데이터베이스를 크기와 시간의 부분으로 나누어 모듈을 구성하였다. 이의 성능평가를 위해 객관평가와 주관평가를 실시하였으며, 실험결과 85.7％정도의 음상정위의 성능 개선을 가져왔다.

• 한국철도학회논문집
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• 제16권1호
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• pp.20-25
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• 2013

고속철도 차량의 프레임은 굽힘 강성이 높고 가벼운 알루미늄 압출재를 이용하고 있으나, 그 차음성능은 동일 면밀도의 평판에 비하여 취약하다. 본 연구에서는 유한요소해석을 통하여 알루미늄 압출재의 음향투과 손실 값을 예측하는 방법을 제시하였다. 압출재를 유한요소로 모델링하고 무반사 방사조건, 시편의 경계 조건, 재질의 감쇠손실계수 등을 사용하여 투과손실을 예측하였으며, 해석결과의 신뢰도를 검증하기 위하여 압출재 시편을 대상으로 ASTM E2249-02에 근거한 투과손실을 측정하였다. 제시된 해석방법은 철도차량용 알루미늄 압출재의 차음특성을 설계단계에서 파악하고 대책을 수립하는데 유용하게 활용될 것이다.