• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 추계학술대회논문집
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• pp.1044-1047
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• 2004

This aim of this study is is an experimental study to introduce the Reduction method of Floor Impact Sound in Apartment Houses by using Model Test, We are measured the floor impact sound in Rahamen and Apartment with Shear Wall and Post-tensioning. There is comparison between Rahmen Structure and Apartment with Shear Wall. The main results from this study are effective in reduction of heavt-weight The slab was constructed by rahamen structure. Heavy-weight can reduced by upgrading naturial frequency of floor impact sound in rahmen structure.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 추계학술대회논문집
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• pp.1036-1039
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• 2004

This paper is to experimentally study on the sound absorption of a membrane resonance type system. Membrane resonance type system improves the weak point of a perforated plate system. The experimental results for a membrane resonance type system are explained in comparison with those of a perforated plate system. From the experimental results, it is found that there is an influence of the membrane on the absorption performance. The sound absorbing performances of a membrane resonance system are similar to those of a perforated plate system.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 추계 학술대회논문집(수송기계편)
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• pp.129-133
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• 2005

Vibration transmitted through rolling tire is a major source of road noise in vehicle interior noise on the range of low frequency.($0{\sim}500Hz$) Among various road noises, tire cavity noise has very peak on $200{\sim}250Hz$. And generally it is generated by cavity resonance of tire. In this paper, tire cut-sample is used to calculate the tire cavity frequency. Cavity resonance frequency of tire is measured through vertical/tangential forces at load cell of axle using drum cleat impact. This method is useful to find cavity peak because measured forces do not have complex peaks. And changing the test conditions (air inflation, loads), tire cavity resonance characteristics are identified. Finally, vehicle interior noise is measured as tire/vehicle are changing. As difference of tire vertical force is bigger, interior noise level is higher at cavity frequency. Also we can assume that vehicle sensitivity is important factor at tire cavity noise.

• KIEAE Journal
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• 제7권1호
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• pp.57-64
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• 2007

This study aims to propose appropriate evaluating method of noise emission from water supply and drain installations in apartment bathroom. The measurement procedure of water installations noise in apartment bathroom were established, so it is necessary to provide the evaluating method and criteria to improve the sound insulation performance of the apartment and to reduce the apartment dweller's unsatisfaction with the noise. Thus, this study reviewed the standards and evaluating methods about the water supply and drain installations noise of many other country. After measuring the noise emission from the installations in many apartment bathroom, The noise were evaluated dB(A), N, NC index, To induce the appropriate method, the coefficient of the correlation among the evaluated numbers were analyzed. As a result, the dB(A) method is most easy to evaluating and very high correlated with N and N index, So the dB(A) method is suitable to be adopted KS evaluating procedure of noise emission from water installations in apartment bathroom.

• 한국음향학회지
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• 제37권5호
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• pp.369-377
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• 2018

본 논문은 주거공간에서 고령자 청력손실을 고려한 소음 및 잔향에 따른 음성 전송 성능을 청취실험을 통해 평가하였다. 주거환경 소음으로 바닥충격음, 교통소음, 공기전달음과 배수소음을 대상으로 하였으며, 공동주택의 잔향환경을 모사하기 위해 실내음향 컴퓨터시뮬레이션을 실시하여 충격응답를 추출하였다. 청취실험 음원은 고령자 청력손실(65세 남성)을 반영하기 위해 소음 및 단어 음원의 고주파대역의 음압레벨을 저감시킨 음원(고령자 음원)과 정상청력을 반영한 원음(청년 음원)을 대상으로 하였다. 청취실험은 각각 3개의 소음레벨($L_{Aeq}$ 30, 40, 50 dB)과 잔향시간(0.5, 1.0, 1.5 s)을 갖는 음환경 조건에서 제시된 단어($L_{Aeq}$ 55 dB)의 음성요해도(speech intelligibility)와 듣기 어려운 정도(listening difficulty)를 평가하는 것으로 하였다. 청취실험 결과, 음성레벨이 55 dB($L_{Aeq}$)일 때 잔향시간 1.0 s 이하 조건에서 충격소음(점핑음) 50 dB($L_{i,Fmax,AW}$)와 정상소음(도로, 음악, 배수 소음) 40 dB($L_{Aeq}$) 이하의 소음레벨에서는 고령자 및 청년 음원 모두 90 % 이상의 음성요해도와 30 % 이하의 듣기 어려운 정도를 확보할 수 있을 것으로 판단된다. 고령자 청력손실을 반영한 고령자 음원의 경우 청년 음원 보다 음성요해도는 0 % ~ 5 % 낮았고 듣기 어려운 정도는 2 % ~ 10 % 높은 것으로 나타났다.

• 한국음향학회:학술대회논문집
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• 한국음향학회 1993년도 학술논문발표회 논문집 제12권 1호
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• pp.17-20
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• 1993

The acoustic mode of a perforated tube muffler was investigated both theoretically and experimentally to explain the cavity-tones induced by through-flow. The cutoff frequencies for the axisymmetric modes were obtained and confirmed experimentally. It was found that the cutoff frequencies are decreased significantly by the perforated tube. The onset frequencies of the cavity-tones were compared with the cutoff frequencies of the acoustic mode and it was found that the cavity-tones are induced by the radial acoustic modes and their frequency stages are coincident with the discrete cutoff frequencies.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 춘계학술대회 논문집
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• pp.218-223
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• 1997

The technique used is the active structural acoutrol (ASAC)approach which involves controlling the acoustic response of a panel-cavity covpled system by applying oscillating force inputs in the form of prezoelectric actuators directly to the flexible panel. The linear quadratic Gaussian control scheme is used for attenuating nosie inside the rectangular enclosure causing by flexible wall vibration. Results indicated the application of control inputs to the radiating wall resukted in considerable noise reductions inside the cavity. Auso,the possibility of application to the more complicated fluid-structure coupled system is verified.

• 한국소음진동공학회논문집
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• 제23권12호
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• pp.1096-1102
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• 2013

The useful practical land shall be reserved when an artificial land covers the railway and road. However, the problem is that since the artificial land places directly on the top of noise sources likely on the railway and road there will arise the weak points, noise and vibration. On this study based on creating the artificial land on the top of a railway vehicle base and placing a tenement on that land, it was comprehended the noise influence from the railway car through the simulation. In order to secure the input value for the simulation, at first measured the noise condition of the railway station building and the railway vehicle base. The output value for the railway station building (place A) was around (53.6~57.6) dB(A), the equivalent continuous sound level for an hour, and for the railway station building (place B) it was around (63.7~68.9) dB. The maximum outdoor noise of the tenement on the artificial land was measured as 64.1 dB(A) under the fixed condition on the simulation modeling. The built purpose of placing the artificial land to prevent the noise influence from the railway met the expectation to be less influenced on the tenement. Rather, because of placing the artificial land the noise level on the lower space could be increased so there requires having a noise control.

• 한국항공우주학회지
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• 제30권1호
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• pp.28-35
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• 2002

공동흐름에서 직각 계단은 커다란 소음의 원인이 되어 많은 사람들의 와류와 직각계단의 상호 작용 시에 발생되는 소음의 저감 방안을 연구하여 왔다. 본 연구에서는 2차원 저아음속 와류 흐름이 전향계단을 지날 때 발생되는 유동 소음을 전향계단의 형상 변화를 통한, 즉, 계단의 모따기 양과 각도를 바꾸어 가면서 수치적으로 계산하였다. 내부 유동장을 구하기 위해서 비압축성 비점성 이산와류 모델을 가정하였으며, 유동정보로부터 원거리로의 음향장 계산은 MAE 이론을 적용하여 구하였다. 음원에서의 음압과 음압강도를 모따기 높이 및 모따기 각도와 최기 와류의 높이를 변화시켜가면서 다양하게 수치적인 결과를 얻어내었다. 본 연구를 통해서 계단에 접근하는 와류에 의한 원거리 음압은 모따기 양이 계단 높이의 30%에서 모따기 각도가 $15^{\circ}C$에서 $30^{\circ}C$°사이일 때 가장 소음이 적게 발생되는 결과를 얻어내었다.

• 대한기계학회논문집B
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• 제39권6호
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• pp.477-483
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• 2015

공동유동에 관한 연구는 공동시스템에서 발생하는 소음/진동 문제로 인하여 많은 연구가 이루어졌으며, 현제 항공우주 산업의 급속한 발전과 더불어 다양한 공학적 장치에 적용되고 있다. 하지만, 실제 공학적 응용에서 많이 적용되는 곡면 벽상에 설치한 공동유동에 관한 연구에 대해서는 거의 수행되지 않았다. 본 연구에서는 곡면벽상에 설치한 공동유동의 특성을 조사하기 위해 수치계산을 수행하였으며, 곡면의 곡률 반경의 비(L/R) 및 입구 유동의 마하수를 변화시켜, 천음속/초음속 공동유동에서 발생하는 압력진동을 조사하였다. 그 결과 곡면에 부착된 공동유동의 경우 와류의 상호작용으로 인한 압력 교란을 완화시켰으나, 압력 진동의 진폭을 증가시켰으며, 또한 마하수가 증가함에 따라 압력 진동의 진폭이 증가하였다. 주파수 분석 결과, 곡관의 무차원 진동수는 직관에 비해 낮은 값이 측정되었으며, 또한 Rossiter의 실험값에 비해 낮은 값을 가졌다.