기준음원의 교정 절차 개발 및 불확도 평가 사례

서재갑,조완호 한국음향학회 2024 韓國音響學會誌 Vol.43 No.3

기준음원은 음향파워 측정에 활용되는 중요한 기준기로, 국제 표준으로 그 사양이 규정되어 있으며, 측정표준 분야에서 주요 교정 품목으로 분류되고 있다. 이러한 기준음원은 공급 전압에 의하여 그 출력이 영향을 받기 때문에 각국에서 자체적으로 교정 서비스 체계를 확보할 필요가 있다. 본 연구에서는 잔향실 조건에서 기준음원을 교정하는 절차를 수립하고 불확도를 평가하였다. 교정 절차는 기본적으로 음향 파워의 정밀급 측정과정을 적용할 수 있으며, 여기서는 ISO 3741의 잔향실을 활용한 측정 방법을 검토하였다. 이를 위한 측정 시스템을 구성하고 실제 2종의 기준음원에 대하여 측정을 수행하고 측정 불확도를 산출하였다. 측정 예를 통하여 잔향실 내 음압 분포의 불균일성과 체적측정 불확도가 전체 불확도에 기여가 큰 것을 확인하였다. 추가적으로 입력 전압에 대한 영향을 실험적으로 검토하여음향 파워 측정에서 반영할 수 있는 불확도 기여량을 검토하였다. A Reference Sound Source (RSS) is an important standard device employed in measuring sound power. The specifications of RSS is specified in international standards, and it is classified as a major calibration item in the field of acoustic metrology. Since the output power of RSS is affected by the supply voltage, each country needs to secure its own calibration service system. In this study, a procedure for calibrating a RSS is established based on the reverberant room conditions and uncertainty evaluation is conducted. Basically, the calibration procedure can apply a precision measurement process of acoustic power, and here, the measurement method using the reverberation chamber of ISO 3741 is applied. For this purpose, a measurement system is constructed, measurements are conducted with two types of RSS, and measurement uncertainty is evaluated. Through measurement examples, it is confirmed that the non-uniformity of the sound pressure distribution in the reverberation room and the volume measurement uncertainty contributed significantly to the overall uncertainty. Additionally, the influence of input voltage is experimentally examined to examine the uncertainty contribution that can be reflected in acoustic power measurements.

청각장애인을 위한 동력수상레저기구 운영 개선방안에 관한 연구

최원삼,정봉규,박철홍,이남우 해양환경안전학회 2023 해양환경안전학회지 Vol.29 No.7

「장애인복지법」에 따라 국가 자격시험은 장애인과 비장애인이 동일한 시험에 응시할 수 있도록 하고 있으며, 청각장애는 동력수상레저기구 면허취득 결격사유에 해당하지 않아 청각장애인도 면허취득을 할 수 있다. 선박이나 동력수상레저기구에서는 해상에서 충돌위험이 있을 때 조종신호, 경고신호 등의 위험신호를 음향신호를 통해 상대에게 알려 주위의 위험 상황을 발견하지 못하여 발생할 수 있는 사고를 예방하도록 하고 있다. 하지만, 청각장애인의 레저활동 중 주위 선박이나 동력수상레저기구의 소리를 통한 위험신호를 청각장애로 인해 위험신호를 확인하지 못해 발생할 수 있는 해양사고를 방지할 수 있는 방안이 필요하다. 음향수신장치(Sound Reception System)는 선교가 완전히 폐위된 선박에 설치하여 외부 소리의 증폭과 소리의 수신 방향을 화면상에 표시하는 장치로서, 청각장애인의 동력수상레저기구에 선박 음향수신장치를 활용하여 청각장애로 인해 청취할 수 없는 위험신호와 같은 음향신호의 유무 및 방향을 동력수상레저기구의 화면상에 시각적 표시를 통해, 청각장애인의 레저활동 중 음향신호를 확인하지 못하여 발생할 수 있는 해양사고를 예방하기 위한 개선방안을 제시하였다. Under the Welfare of Disabled Persons Act, the national qualification test allows disabled and non-disabled people to appear for the same test, and the deaf do not fall under the reason for disqualification from obtaining a license for power-driven water leisure crafts; therefore, even the deaf can obtain a license. During a risk of collision at sea, ships and power-driven water leisure crafts notify the other party of dangerous signals such as maneuvering and warning signals through sound signals to prevent accidents that may occur because surrounding ships are not visible. However, a method is required to prevent marine accidents that may occur when the deaf cannot hear danger signals through sounds from nearby ships or power-driven water leisure crafts during leisure activities owing to hearing impairment. A sound reception system is a device installed on a ship where missionary work is completely deposed to display the amplification of external sounds and the direction of sound reception on the screen. Through visual display of sound signals such as dangerous signals that cannot be heard owing to hearing impairment, improvement measures were proposed to prevent marine accidents that can occur owing to the inability of the deaf to check sound signals during leisure activities.

CPX 및 Pass-by 계측을 이용한 단독 주행 차량의 음향파워 평가 방법에 관한 연구

최태묵(Choi, T.M.),문성호(Moon, S.H.),서영국(Seo, Y.G.),김진형(Kim, J.H.),김병희(Kim, B.H.),배효준(Bae, H.J.),지우진(Ji, W.J.),조대승(Cho, D.S.) 한국소음진동공학회 2006 한국소음진동공학회 논문집 Vol.16 No.11

This paper presents a novel method to determine sound power level(PWL) emitted by a travelling vehicle for road traffic noise simulation. The PWL is evaluated by the equivalent sound pressure level (SPL) measured by close proximity method and the sound power correction factor derived from the maximum SPL measured by pass-by method and the propagation attenuation of vehicle noise during the pass-by measurement. Using the method, we derive the empirical formula for PWL estimation in 1/1-octave and overall frequency bands for 8 vehicles (automobile, SUV, small truck, large bus, trailer, 3 dump trucks) tested at two road surfaces (dense graded asphalt, 30mm transverse tinning concrete) of Korean highway test road. The suggested approach, if securing sufficient data to represent the acoustic characteristics of all vehicle types, has il strong merit to be able to evaluate sound power levels for any combination of vehicle categories and traffic volumes.

화력발전소의 소음분포 해석 및 방음벽 대책

윤준호,김원진 한국음향학회 2020 韓國音響學會誌 Vol.39 No.2

An analysis model of noise map is proposed to evaluate and reduce the acoustical noise of power plant and its surroundings. The sound powers of many noise sources are estimated by measuring the sound levels of major equipments in the power plant. The analysis of noise has been made by using ENPro that is a commercial program for environmental noise prediction. The proposed model is verified by comparing the results from noise analysis and measurement at several points of the power plant units 1 through 4, and residential areas. It is shown that noise map simulation using the proposed model has a reliability, since the overall noise level approximates within the error of ±2 dB. Furthermore, through noise analysis, the increasing effect of noise due to newly established units 5 and 6 on residential areas is also analyzed. Consequently, the noise barrier is designed to meet an environmental noise standard and satisfy low cost and safety conditions. 발전소 소음을 저감하기 위해서는 여러 가지 설비요소의 소음원에 대해 설계단계에서부터 정확한 소음예측 을 수행하고, 과도한 소음에 대해서는 효과적이고 경제적인 방음대책의 수립이 필요하다. 이에 본 논문에서는 발전소 지역 및 주변 주택지역을 포함한 소음분포 해석 가능 모델을 제안하고, 주택지역의 소음저감 방법을 수립하였다. 발전 소의 주요 소음원에 대한 소음레벨의 측정을 통하여 음향파워레벨을 평가하고, 설계도면 및 지형정보를 이용하여 소 음전달에 영향을 주는 지형 및 지물 등을 최대한 상세히 모델에 포함함으로써 발전소 및 주택 지역의 소음분포를 효과 적으로 해석할 수 있는 모델을 수립하였다. 수립된 소음 해석 모델의 신뢰성은 주요 위치에서의 소음레벨 해석 결과와 측정 결과를 비교하여 검증하였으며, 이를 바탕으로 신규호기의 증설에 의한 인근 주택지역에서의 소음 영향도를 평 가하고, 발전소의 가동 시에 소음환경기준을 만족시키는 방음벽을 제안하였다.

균열을 갖는 직사각형 진동평판의 음향 방사특성

김태진,박종환,이우식 한국철도학회 2003 한국철도학회논문집 Vol.6 No.3

This paper considers the sound radiation characteristics of a cracked rectangular vibrating plate, varying the orientation angle of a line crack. The vibration response of the cracked vibrating plate is obtained by using ANSYS, the acoustic theory based on the lumped parameter model is used to calculate radiated sound power. The radiated sound powers are computed with varying the orientation angle of the crack: i.e, 0°, 45°, and 90°. It is found that characteristics of the radiated sound power are very closely related to the crack orientation, vibration mode and crack location.

균열을 갖는 직사각형 진동평판의 음향 방사특성

김태진(Taejin Kim),박종환(Jonghwan Park),이우식(Usik Lee) 한국철도학회 2003 철도저널 Vol.6 No.3

This paper considers the sound radiation characteristics of a cracked rectangular vibrating plate, varying the orientation angle of a line crack. The vibration response of the cracked vibrating plate is obtained by using ANSYS, the acoustic theory based on the lumped parameter model is used to calculate radiated sound power. The radiated sound powers are computed with varying the orientation angle of the crack: i.e, 0˚, 45˚, and 90˚ It is found that characteristics of the radiated sound power are very closely related to the crack orientation, vibration mode and crack location.

分布 移動 荷重을 받는 無限보에서의 音響放射

전형주,김병삼,방두열 순천대학교 공업기술연구소 1998 工業技術硏究所論文集 Vol.12 No.-

The problem of sound radiation from infinite elastic beams under the action of harmonic moving line forces is studied. The reaction due to fluid loading on the vibratory response of the beam is taken into account. The beam is assumed to occupy the plane z=0 and to be axially infinite. The beam material and elastic foundation are assumed to be lossless and to follow Bernoulli-Euler beam theory including a tension force (T), damping coefficient (C) and stiffness of foundation (K_S). The non-dimensional sound power is derived through integration of the surface intensity distribution over the entire beam. The expression for sound power is integrated numerically and the results are examined as a function of Mach number(M), wavenumber ratio(r) and stiffness factor(T). Here, the purpose is to explain the response of sound power over a number of non-dimensional parameters describing tension, stiffness, damping and foundation stiffness.

열음향파 발생장치의 최적 작동 조건에 대한 실험적 연구

신상웅(Sang Woong Shin),오승진(Seung Jin Oh),이윤준(Yoon Joon Lee),김남진(Nam Jin Kim),천원기(Wongee Chun) 대한기계학회 2013 大韓機械學會論文集B Vol.37 No.2

본 연구에서는 열음향 시스템의 음향파 출력에 대한 주요한 기하학적 변수에 대해 다루고 있다. 음향파의 출력은 스택의 위치와 스택의 길이, 입력 파워와 공진기의 길이에 의존한다. 본 실험을 통하여 최고의 실험 조건을 얻을 수 있었다. 실험결과에 의하면 최고 음압레벨은 폐쇄된 부분에서 공진기길이의 1/4 -1/2지점 사이에 스택을 위치시켰을 때, 공진기와 스택의 길이가 길 때, 그리고 입력전압이 증가할 때 나타난다. 또한 주파수의 경우 공진기의 길이가 200mm일 때 437Hz, 100mm일 때 885Hz를 기록하였다. 연구 결과 공진기의 길이가 짧을수록 더 높은 주파수를 얻을 수 있는 것을 알 수 있다. This study deals with the effects of major geometric parameters on the sound wave output of a thermal acoustic system. The output power of the acoustic wave was dependent on the stack position, stack length, resonator tube length, and input power. In experiments, the maximum SPL was generated when the stack was placed between one-fourth to half, resonator and stack length were longer, and input power was increased. The frequency was recorded to be 437 and 885 Hz when the resonator tube length was 200 and 100 mm, respectively. Therefore, when the resonator tube length was shorter, a higher frequency was recorded.

굴착기의 음향파워레벨 회귀분석

구진회(Gu, Jin-Hoi),이재원(Lee, Jae-Won),서충열(Seo, Chung-Youl),장성기(Jang, Seong-Ki),최경희(Choi, Kyung-Hee),한진석(Han, Jin-Seok) 한국소음진동공학회 2012 한국소음진동공학회 논문집 Vol.22 No.3

The noise emitted from an excavator has long been a cause of environmental disputes, while causing displeasure to the nearby residents. So, the ministry of environment adopted the construction machinery noise labeling system to encourage the construction machinery manufacturing companies to develop the low noise construction machinery voluntarily. But, as the quality of life improves, a growing number of people desire the comfortable and quite environment to live in. Under the situation, noise from the construction machinery has been a major cause for stress and complaints. When the noise dispute happened in the construction site, the sound pressure level of the construction machinery like a excavator was measured at the lot boundary of the noise victim's residence to judge how much noise damage occur. But the sound pressure level of the construction machinery is measured differently according to the acoustic environment of construction site and the measuring position, respectively, which makes it difficulty to judge whether the noise damage occur or not. As the sound power level of noise source is not affected by the acoustic environment of construction site and the measuring position, if we use the information of the sound power level, it will be easy to judge whether the noise damage occur and to establish the soundproofing measures. Therefore, we derive the sound power level regression model of the excavator to judge whether the noise emitted from the excavator damages to residents near the construction site. Also, the sound power level regression model of the excavator drawn in this paper will help construction companies to plan the noise reduction program in the construction sites.

측정방법별 가전제품의 음향파워레벨

강대준(Kang, Dae-Joon),구진회(Gu, Jin-Hoi),이재원(Lee, Jae-Won) 한국소음진동공학회 2009 한국소음진동공학회 논문집 Vol.19 No.4

As the economy has grown and the main industry in Korea has been changed from secondary industry to tertiary industry, the importance of indoor environment has been a matter of common concern, in which one of the main concerns is to improve the indoor acoustic conditions. However, even though this is required more than before, there are no measures to protect the human being from the noise of electric home appliances. This is owing to the absence of the data about sound power level of electric home appliances. So, we investigate the sound power level of them and analyze the acoustical characteristics of each one. First, we tried to investigate the sound power measurement method of each electric home appliance. After it we test the sound power level of them. From the survey, we can know that the vacuum cleaner is the most noisy electric home appliance, and the refrigerator is the least noisy one. This results will help us predict the indoor noise level using the basic data of sound power level.