• 한국화재소방학회논문지
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• 제34권4호
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• pp.29-35
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• 2020

본 연구는 단독주택에 설치된 단독경보형감지기의 성능을 조사하기 위해 수행되었다. 1층 주택 2개 및 2층 주택이 포함된 세 가지 유형의 주택을 대상으로 실험을 실시하였다. 주거 공간에서 경보음 발생에 따른 음압 레벨을 예측하기 위해 컴퓨터 시뮬레이션 프로그램을 사용하였다. 시뮬레이션에 적용된 음원의 특성을 직접 측정하여 입력 데이터로 사용했다. 시뮬레이션 결과, 부엌과 거실에서의 음압레벨이 탐지기의 경보음이 발생했을 때 기준을 충족시키는 것으로 나타났다. 그러나 침실에서의 음압레벨은 미국화재방지협회 기준인 75 dB(A)보다 최소 20 dB(A) 낮을 것으로 예상되었다. 따라서 주택 내부의 침실 공간에서 충분한 음압레벨을 유지하기 위한 계획을 수립해야 하며, 관련 표준을 제정하여 화재시 안전한 대피를 보장하기 위한 노력이 필요하다.

• International journal of advanced smart convergence
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• 제2권2호
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• pp.16-18
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• 2013

In this paper, we develop a method to design a flexible thin film audio systems utilizing Polyvinylidene fluoride. The system we designed showed the properties of increased transparency and sound pressure levels. As an input terminal transparent oxide thin film is adopted. In order to provide dielectric insulation, a transparent insulating oxide thin film is coated to obtain double -layered structure. In the range of visible light, the output from the output of the system showed an increased and improved sound pressure level. The piezoelectric polymer film of polyvinylidene fluoride (PVDF) is used to produce mechanical vibration due to the applied electrical voltage signal. An analog electric voltage signal is transformed into sound waves in the audio system.

• International Journal of Internet, Broadcasting and Communication
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• 제6권1호
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• pp.13-15
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• 2014

We develop a method to fabricate a flexible thin film audio systems using polyvinylidene fluoride(PVDF). The system we designed showed the properties of increased flexibility, transparency, and sound pressure levels. As an input port of two terminals, transparent oxide thin film with a low resistivity is adopted. In order to provide dielectric insulation, a transparent insulating oxide thin film is coated to obtain double-layered structure. In the range of visible light, the output from the output of the system showed a increased and improved sound pressure level. The piezoelectric polymer film of PVDF is used to produce mechanical vibration due to the applied electrical voltage signal. An analog electric voltage signal is transformed into sound waves in the audio system.

• 한국소음진동공학회논문집
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• 제22권3호
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• pp.203-207
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• 2012

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.

• 소음진동
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• 제10권2호
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• pp.345-352
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• 2000

최근 여객선이 고속화, 고금화되고 있는 추세에 따라 선실내 소음 저감이 중요한 설계 요소로 간주되고 있다. 일반적으로 선박 소으믄 음암레벨로 평가되나 여객선의 경우 승객에게 더욱 쾌적한 환경을 제공하기 위하여 음질을 개선할 필요가 있다. 본 연구에서는 연근해를 운항 중인 기존 고속 여객선의 소음을 계측하고, 정신음향학 분야에서 제시된 Zwicker Loudness 계산식에 의거하여 음의 크기, 거칙기, 변동세기 및 날카로움으로 음질을 평가하였다. 또한, 각각의 음질 평가요소와 음압간의 상관관계를 분석하였다. 상기 결과로부터 고속여객선의 음의 크기는 음압과 비례하는 반면에 음의 거질치 (roughness),변동세기(fluctuation strength)및 날카로움(sharpness)은 선박의 운동과 추락변동 등으로 인하여 음압과 비선형적인 상관관계를 나타냄을 확인하였다.

• 한국소음진동공학회논문집
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• 제26권3호
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• pp.340-349
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• 2016

A coupled room system consists of adjacent rooms and apertures where the sound energy is exchanged between the two rooms. Acoustically, a coupled room system shows a non-exponential decay profile. Most of the related researches have been to analyze the acoustic properties of two-room coupled system so far whereas three-room coupled system were seldom studied. In this regard, this paper aims to analyse the distribution of sound pressure level, sound decay curve of three-room coupled system and sound energy flow between them by using the acoustic diffusion model and to further verify them through experiments. Firstly, the sound pressure level distribution and mean sound pressure level in the steady-state condition are analyzed at various frequencies and source locations. Good agreements are observed in both experiments and analysis results. Secondly, two double slope effect quantifiers of sound attenuation, LDT/EDT and LDT/T10 are compared at various frequencies and for different source locations. The result indicates that LDT/T10, less affected by the early reflection patterns than LDT/EDT, is more suitable to the analysis and experiments of a multi-slope sound decay curve. Lastly, the sound energy flow in each room is analyzed based on the acoustic diffusion model. After the early decay stage, the sound energy is observed to flow from the room with a long reverberation time to the room with a short one.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 춘계학술대회논문집
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• pp.952-955
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• 2007

경량충격음레벨을 평가하기 위해서는 수음실의 잔향시간을 측정하여 규준화 바닥충격음레벨을 구하여야 한다. 본 논문에서는 규준화 바닥충격음레벨과 표준화 바닥충격음레벨을 구할 때 고려하는 보정레벨을 중심으로 등가 흡음력을 결정하는 잔향시간과 수음실의 체적을 변수요인으로 분석하였다. 그 결과 측정된 잔향 시간은 공간에 관계없이 기준보다 2배 이상 길게 나타났고, 등가 흡음력은 기준보다 침실의 경우 1/2 정도 작지만 거실의 경우 기준과 거의 유사하게 나타나 침실의 경우 두 보정레벨이 유사하지만 거실의 경우 전자가 후자보다 낮게 보정되는 것으로 나타났다.

• 한국소음진동공학회논문집
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• 제27권2호
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• pp.129-138
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• 2017

The subjective experiments on professional musicians using the four channel real-time convolution system were conducted to investigate the effect of reverberant sound pressure level ($L_{rev}$) for stage acoustics. The strength of $L_{rev}$ was changed to 2 dB steps to investigate the optimal strength for ease of performance and the subjective questionnaire survey was conducted to investigate the effect of subjective factor by $L_{rev}$. From the experimental results, a specific strength of $L_{rev}$ is related to ease of music performance. Loudness and directivity are highly correlated.

• 한국철도학회논문집
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• 제2권1호
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• pp.28-37
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• 1999

Many residential areas are situated near to railroad tracks so that a railroad noise has been one of the major environmental issues. In this paper two important aspects have been investigated in order to properly evaluate the railroad vehicle noise : sound power levels for different types and sound propagation characteristics of the railroad vehicles. For noise source characteristics of railroad vehicles, sound power values for various types of trains that are in active service have been measured. In this paper, domestic railroad vehicles are measured and compared with high speed train(TGV). Based on sound power information of railway vehicles, prediction on the sound pressure level and equivalent noise level near to railway areas have been evaluated.

• 한국소음진동공학회논문집
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• 제24권7호
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• pp.569-574
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• 2014

In order to investigate low frequency swishing noise of wind turbines, acoustic source model using a singularity in circular motion is introduced to derive analytic solution of Lowson acoustic analogy in time domain. Results in time and frequency domains computed by the solution show apparent modulation of amplitude and frequency. The solution indicates that time histories of acoustic pressure at receiver points varied significantly according to receiver's directional location, even when the retarded time distributions are similar. However, the corresponding time-averaged spectra of sound pressure at the receiver locations where the retarded time distributions are almost same are not significantly different. It can be inferred from these results that the time-averaged sound pressure spectra which cannot take into account the detailed difference in the time-variation of wind turbine noise may not represent the sound quality of wind turbines due to its swishing. Finally, as an introduction of procedure to quantify low frequency swishing noise level, relative variation of overall sound pressure level is obtained using tonal low frequency noise model.