• 한국소음진동공학회논문집
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• 제26권7호
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• pp.774-780
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• 2016

In this paper noise source and transfer path of tactical vehicle are analyzed with partial coherence function and spectrum analysis. Engine, transmission, structure panel and aerodynamic are main source of cabin noise. To reduce cabin noise, identifying transfer path of sources and analyzing their contribution is important. With modeling of transfer path and partial coherence function, transfer path and principal noise source can be identified. Engine/transmission and structural resonance are principal source of low frequency noise and by adding stiffener and sound absorbing material, resonance of vibration and inflow air problem can be solved.

• 대한후두음성언어의학회지
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• 제15권1호
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• pp.31-36
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• 2004

Background and Objectives : It has been shown that the epilaryngeal tube in the human airway is responsible for vocal ring, or the singer's formant. In previous study, authors showed that in trained tenors, besides the conventional singer's formant in the region of ,5500Hz, another energy peak was observed in the region of 8,000Hz. This peak was interpreted as the second resonance of the epilarynx tube. Singers in other voice categories who produce vocal ring are assumed to have the same peak, but no measurements have as yet been made. Materials and Methods : Fifteen tenors, fourteen baritones, seven sopranos and five mezzo sopranos attending the music college, department of vocal music who could reliably produce the head and chest registers were chosen for this study. Each subject was asked to produce an/ah/sound for at least three seconds for the head register sound(tenors ; G4, barions ; E4 sopranos ; F5 and mezzosopranos ; C5) and for the chest register sound (tenors ; C3, baritones ; D3, sopranos ; D4 and Mezzosoprano ; A3). The sound data was analyzed using the Fast Fourier Transform (FFT)-based power spectrum, Long term average(LTA) power spectrum using the FFT algorithm of the Computerized Speech Lab (CSL, Kay elemetrics, Model 4300B, USA). Statistical analysis was performed using the Mann-Whitney test of the Statistical Package for Social sciences(SPSS). Results : For head register sounds, a significant increase was seen in the 2,200-3,400Hz region(p<0.05) and the Similar to the head register sounds, there was a significant increase in energy in the four trained singer group compared with the untrained group in the 2,200-3,100Hz region(p<0.05), the 7,800-8,400Hz region(p<0.05) for the chest register sounds. Conclusions : When good vocal production was made for the head and chest registers, an energy peak was observed near 2,500Hz, a frequency already known as the "singer's formant', in all subjects in the study group. Another region of increased energy was observed around 8,000Hz that had not been noticed previously. The authors believe this region to be the second singer's formant.

• 감성과학
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• 제20권3호
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• pp.61-70
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• 2017

감성을 인식하는데 있어 생리적 반응은 중요하다. 생리적 반응은 인체의 주요 기관들과 밀접한 관련이 있지만 감성을 인식하는데 연결성은 고려되지 않고 있다. 자율신경계는 감성과 밀접한 관련이 있는데, 심장과 폐와 같은 인체 내 주요 내장기관에 분포되어 기능적 상보작용을 통해 생리적 반응을 조절하기 때문이다. 따라서 본 연구는 심장과 호흡의 연결성을 분석하고 감성을 인식하는 중요한 연결 변수를 찾고자 하였다. 피험자 18명(남 10명, 평균 나이 $24.72{\pm}2.47$)은 소리 자극을 이용한 감성 유발 실험에 참여하였고 심전도와 호흡 데이터를 측정하였다. 수집된 심장과 호흡 데이터는 스펙트럼 분석을 이용하여 HRV와 BRV spectrum을 구하였고, 감성에 따른 HRV와 BRV spectrum의 동기화 차이를 일원배치분산분석을 통해 통계적 유의성을 확인하였다. Tukey 검증 결과, arousal-relaxation은 HF 대역에서 심전도와 호흡의 동기화 차이로 인식 가능하였고(p = 0.008, d = 1.4274), negative-positive는 LF 대역에서 인식이 가능하였다(p = 0.002, d = 1.7377). 본 연구 결과로 심장과 호흡의 연결성을 통해 차원적 감성을 정량적으로 평가할 수 있음을 확인하였고, 복합적인 원인으로 발현되는 감성을 인식하는데 생리적 반응들의 연결성 변수의 활용도가 높을 것으로 기대된다.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1994년도 춘계학술대회
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• pp.105-108
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• 1994

A comparative study was made of the valvular sounds produced by normal prosthetic valves with thrombosed prosthetic valves. Comparisons of the closing sound were made for the power frequency spectra associated with individual valves. We used periodogram approach to obtain the spectral characteristics of the valve. Spectral analysis system was tested in mock circulatory system by comparing normal valves with those produced by the same valves but having simulated thrombosis at the hinge of the valve. The heart sounds was recorded from two patients having normal mechanical valve and thrombosed mechanical valve. The estimated spectrum of the thrombosed mechanical valve displayed lower apparent peak frequency than that of the normal valve. The results showed that frequency spectra gave information pertinent to the valve malfunction. Sound spectral analysis is simple and alternative diagnostic tool for early detection of prosthetic valve mal function.

• 한국소음진동공학회논문집
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• 제21권9호
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• pp.834-841
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• 2011

Obtaining the real exciting force is important for the analysis of structural vibration or sound radiation to represent the actual condition. But in most cases, it is so difficult to get the actual force signals by direct measurement using sensors due to complex geometry. This paper suggests advanced source identification method which can be applied to the prediction of radiated noise considering correlations between measured signals. This method was implemented to the identification of the fan force in the refrigerator. The analysis of structural vibration and radiated noise caused by the fan force was also performed. The comparison between predicted SPL and measured SPL of the radiated noise by the refrigerator fan showed good agreement.

• Fibers and Polymers
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• 제7권4호
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• pp.450-456
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• 2006

The objectives of this study were to investigate physiological and psychological responses to the rustling sound of Korean traditional silk fabrics and to figure out objective measurements such as sound parameters and mechanical properties determining the human responses. Five different traditional silk fabrics were selected by cluster analysis and their sound characteristics were observed in terms of FFT spectra and some calculated sound parameters including level pressure of total sound (LPT), Zwicker's psychoacoustic parameters - loudness(Z), sharpness(Z), roughness(Z), and fluctuation strength(Z), and sound color factors such as ${\Delta}L\;and\;{\Delta}f$. As physiological signals, the ratio of low frequency to high frequency (LF/HF) from the power spectrum of heart rate variability, pulse volume (PV), heart rate (HR), and skin conductance level (SCL) evoked by the fabric sounds were measured from thirty participants. Also, seven aspects of psychological state including softness, loudness, sharpness, roughness, clearness, highness, and pleasantness were evaluated when each sound was presented. The traditional silk fabric sounds were likely to be felt as soft and pleasant rather than clear and high, which seemed to evoke less change of both LF/HF and SCL indicating a negative sensation than other fabrics previously reported. As fluctuation strength(Z) were higher and bending rigidity (B) values lower, the fabrics tended to be perceived as sounding softer, which resulted in increase of PV changes. The higher LPT was concerned with higher rating for subjective loudness so that HR was more increased. Also, compression linearity (LC) affected subjective pleasantness positively, which caused less changes of HR. Therefore, we concluded that such objective measurements as LPT, fluctuation strength(Z), bending rigidity (B), and compression linearity (LC) were significant factors affecting physiological and psychological responses to the sounds of Korean traditional silk fabrics.

• 한국해양학회지:바다
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• 제12권3호
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• pp.142-146
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• 2007

2001년 5월에 황해 연안의 수심 약 20 m의 해역에서 10시부터 13시까지 3시간 동안 수중소음을 관측하였다. 측정기간 내내 생물음으로 추정되는 강한 수중음이 지속적으로 관찰되었다. $1{\sim}20kHz$의 주파수 대역에서 측정된 수중음의 레벨은 수중 배경소음 레벨과 비교하여 매우 높게 측정 되었다. 이러한 수중음은 연안 수중소음 레벨에 지속적으로 영향을 줄 수 있으므로 수중음의 발생 원인을 규명하고자 하였다. 본 연구에서는 기존에 발표된 논문들을 근거로 하여 수중음의 가장 유력한 음원으로 해저바닥에 서식하는 딱총새우의 음을 제시하였으며, 동일해역에서 채집한 살아있는 딱총새우로부터 방출되는 음향신호를 실험실에서 측정함으로서 이 수중음이 딱총새우에 의하여 발생된 것임을 재확인할 수 있었다.

• 수산해양기술연구
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• 제22권3호
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• pp.36-41
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• 1986

Uederwater ambient noise was measured at the set net in the Neung-Po Eay. The environment characteristics depend upon oceanographic conditions of sound propagation and its implication on the source of ambient noise. The results of measurement and analysis were as follows: 1. The frequency of the maximum noise level of two passenger. vessels was around 300 Hz. The spectrum level of the fast vessel (the Air-Ferry) was lower than the little slow vessel (the Olympic) between 50-150 Hz in frequences. 2. The spectrum level of the surface in the playground of the set net was lower than the deeper water till 500 Hz, but over that frequency the level was getting lower as the depth was deep. 3. The spectrum level outside the bag of the set net was greater than the inside between 50 and 700 Hz, but over 1,500 Hz the level inside the bag was higher than the outside. 4. The spectrum level of the outside of the breeding tank was higher than the inside in the daytime. However at night opposite phenomenon occurs.

• 한국음향학회지
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• 제16권4호
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• pp.94-100
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• 1997

성덕대왕 신종의 방사 음장 특성을 분석하기 위하여 30개의 마이크로폰으로 구성된 어레이를 이용하여 360개의 위치에서 음압을 측정한 후 원통형 음향 홀로그라피 방법을 적용하여 시간, 주파수별로 음장 해석을 행하였다. 타종 직후, 신종에서 방사되는 음장은 넓은 주파수 영역(800Hz까지 해석)에 걸쳐 고른 분포를 가지나 시간이 지남에 따라 고주파 성분은 급격히 감쇠하여 약 10초 이후에는 저주파 성분만이 존재한다. 마찬가지로 시간에 따른 음압 신호를 살펴보면 초기에 여러 성분의 모우드들이 중첩되어 복잡한 모양을 하고 있으나 10초 이후에는 한쌍의 저주파 성분(64.06Hz, 64.38Hz)에 의한 맥놀이 현상이 나타남을 확인할 수 있다. 이 맥놀이에 의한 여음이 초기의 화려하면서 장엄한 소리와 어우러져 신종만의 독특한 소리를 나타낸다. 맥놀이 현상은 종의 축에 대한 비대칭 현상에 의해 근접한 고유진동수를 가지기 때문에 발생하며 다른 고주파 성분에서도 쌍으로 존재하는 고유진동수를 관찰할 수 있다. 저주파 모우드의 경우 쌍으로 존재하는 방사 음장 형태는 길이 방향 절선 간격의 반에 해당되는 각도만큼 회전되어 나타난 것을 제외하고는 동일함을 알 수 있으며 고주파 모우드의 경우는 이보다 복잡한 모양을 이루고 있다.

• 한국소음진동공학회논문집
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• 제22권7호
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• pp.676-684
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• 2012

Numerical analysis was performed to investigate the heavy-weight impact noise of apartment houses. The FEM is practical method for prediction of low-frequency indoor noise. The results of numerical analysis, the shape of the acoustic modes in room-2 are similar to that of acoustic pressure field at the fundamental frequency of acoustic modes. And the acoustic pressure was amplified at the natural frequency of the acoustic modes and structural modes. The numerical analysis result of sound pressure level at 63 Hz and 125 Hz octave-band center frequency are similar to the test results, but at 250 Hz and 500 Hz have some errors. Considering most of bang-machine force spectrum exists below 100 Hz, the noise at 250 Hz and 500 Hz are not important for heavy-weight impact noise. Thus, the FEM numerical analysis method for heavy-weight impact noise can apply to estimate heavy-weight impact noise for various building systems.