• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 추계학술대회 논문집
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• pp.121-124
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• 2014

Many of research on noise reduction techniques have been progressed for the improvement of noise environment in subway train. There are many way to noise reduction techniques in the tunnel, but it has been reported as an alternative to attach sound absorption material on tunnel wall. For this reason sound absorption material has been studied for application of tunnel. The objective of this study is to investigate design parameters on a Helmholtz resonator with built-in sound absorption panel for the reduction of the tunnel noise in the subway. Sound absorption panel composed of the perforated panel with sub-millimeter holes and the airspace backed a rigid wall or between panels. The experiment is performed through the change of number of perforated panel, cross sectional area and the depth of airspace of the sound absorption panel under the normal incidence sound.

• 화약ㆍ발파
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• 제25권1호
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• pp.1-14
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• 2007

발파작업에 따라 필연적으로 발생되는 발파소음은 충격성소음으로 인체에 영향을 미친다. 이로 인한 민원 발생은 공사 중지, 발파규모의 축소 등을 유발시킨다. 발파소음저감을 위한 방음시설은 대부분 민원의 정토에 따리 설치시기나 설치방법 등이 각 현장마다 자체적으로 이루어지고 있으나 소음 저감도는 매우 낮은 실정이다. 본 연구의 최종적인 목표는 방음시설의 방법과 재질에 따른 소음저감 기술연구이다. 1단계 기포자료 확보를 위한 연구단계로서 철도, 도로, 전력구 등의 약 20여개의 터널 현장을 대강으로 방음시설의 설치시기와 설치방법, 재질에 대한 조사를 수행하였다.

• 대한기계학회논문집B
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• 제20권12호
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• pp.4036-4043
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• 1996

When a high-speed railway train enters a tunnel, a compression wave is generated ahead of the train and propagates along the tunnel, compressing and accelerating the rest air in front of the wave. At the exit of the tunnel, an impulsive wave is emitted outward toward the surrounding, which causes a positive impulsive noise like a kind of sonic boom produced by a supersonic aircraft. With the advent of high-speed train, such an impulsive noise can be large enough to cause the noise problem, unless some attempts are made to alleviate its pressure levels. In the purpose of the impulsive noise reduction, the present study tested the effect of porous walls on the compression wave propagating into a model tunnel. Experimental results were obtained using a shock tube with an open end. The results showed that the cavity/porous wall is very effective for the compression wave with a large nonlinear effect. The porosity of 30% is most effective for attenuation and pressure gradient reduction of the compression wave front. Also the impulsive noise reduction increases with increasing the length and height of the cavity, compared with the tunnel equivalent diameter.

• 한국공작기계학회논문집
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• 제17권3호
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• pp.122-127
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• 2008

The source of wayside noise for the train are the aerodynamic noise, wheel/rail noise, and power unit noise. The major source of railway noise is the wheel/rail noise caused by the interaction between the wheels and rails. The Structure borne noise is mainly a low frequency problem. The train noise and vibration nearby the elevated railway make one specific issue. The microphone array method is used to search sound radiation characteristics of elevated structure to predict the noise propagation from an elevated railway. In this paper, the train noise and structure borne noise by train are measured. From the results, we investigated the effect on the sound absorption tunnel for elevated railway.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 추계학술대회 논문집
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• pp.125-130
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• 2014

High speed railroad car and high-rise apartment with development of railway technology cause different problems of noise contrary to the previous generation. It is the most efficient noise reduction countermeasure but we studied that is the way on noise propagation with sound proof wall or sound proof tunnel around railroad. But if it were railroad on bridge, additional cost which is more expensive than installing one on the ground is needed. So sound insulation material considering reducing weight of recent soundproof facilities must be selected. It is in this study that predicted and analyzed acoustical and structural effect for noise reduction by installing soundproof tunnel. If it were departmentalized into additional study, could be able to expect noise reduction effect of sound proof tunnel establishment on the bridge.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 춘계학술대회논문집
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• pp.34-40
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• 2001

Aeroacoustic technology to improve the acoustic comfort in high-speed became a major topic in vehicle development process. Although most of wind noise reduction and sound quality improvements are possible with full vehicle, the countermeasures should be applied at the early design stage. Acoustic holography technology was used to identify the external wind noise sources of a vehicle in Hyundai Aeroacoustic Wind Tunnel. Microphone self-noise reduction techniques and several reference microphone positions are investigated in order to obtain proper results.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 추계학술대회논문집
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• pp.49-52
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• 2004

High-speed trains with the maximum speed of 300 km/h have started revenue services since April 2004. A large portion of the 'Kyung-Bu' line is comprised of tunnels or bridges, which may cause excessive noise in a vehicle. The vibration generated by the trains propagates into the structure of the tunnel and the vehicle and it can be radiated as noise inside the vehicle interior. This noise can usually be heard as low frequency structure-borne noise. Measurement of the noise and vibration inside the KTX vehicle confirmed that the noise comprises of frequencies below 250 Hz with a couple of broad peaks.

• 화약ㆍ발파
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• 제20권3호
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• pp.59-71
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• 2002

The points of this design case are the planning and excavation method of a new double-tracked railroad tunnel which is approx. 11∼22 meters apart from existing single-tracked railroad tunnel. For the optimum excavation method some needs are required in design stage, such as the reduction of noise and vibration, public resentment, damage of buildings and construction costs. Hence the estimation and application of allowable noise and vibration criterion is important. The ground coefficient (K, n) of this site is determined by field trial blasting. The excavation method is chosen to satisfy the allowable noise and vibration criterion. In addition, in order to ensure the stability of existing single-tracked railroad tunnel, the instrumentation of maintenance level is accompanied during the construction stage. As a result of this design condition, central diaphragm excavation with line drilling and pre-large hole boring blasting is applied to the area within 15 meters apart from existing tunnel. And above 15 meters apart, pre-large hole boring blasting is designed.

• 항공우주시스템공학회지
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• 제14권spc호
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• pp.39-48
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• 2020

본 논문에서는 풍동 실험을 통해 측정한 소음 결과를 활용하여 실제 비행하는 기체에서 발생되는 소음수준을 예측하고 비행시험을 통해 검증하는 과정을 다루었다. 항공기의 환경소음 평가를 위해서는 일반적으로 국제민간항공기구(이하 ICAO)에서 규정한 절차에 따라 소음시험 및 평가를 수행하게 된다. 본 논문에서는 고정익 및 회전익(멀티콥터)의 특징을 모두 가지고 있는 복합형 기체에 적용이 가능한 환경 소음평가 방안과 실험을 통해 검증한 결과를 제시하였다. 고정익과 회전익 소형 무인기를 활용하여 풍동실험에서 측정한 소음시험 결과를 실제 비행 시험결과로 시뮬레이션 하는 과정을 제시하였다. 또한, ICAO에서 제시하는 비행 운용조건 및 소음 측정 방법을 고려하여 풍동실험을 통한 결과와 실 기체 비행시험을 모두 수행하여 항공기 소음인증을 위한 실효감각소음레벨(EPNL)을 예측 및 고찰하였다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 춘계학술대회논문집
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• pp.750-750
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• 2001

Todays, according to development of traffics, there are so many tunnels around us. Tunnels are used for trains, subway trains, cars, etc. Especially for subway, all of its routes are tunnels. So the noise of the subway train cannot radiated out of the station and the noise level in the station and train cabin is so high. There are some methods to reduce this noise and one of them is using absorbing materials. But the area of the tunnel and station is very large, so it is important to determine the effective position and amount of absorbing materials before attaching them. In this study, we studied the effect of sound absorbing materials in the tunnel using boundary element method. We applied BEM for general boundary conditions. With BEM calculations, we found the effect of absorbing materials and effective positions for the subway tunnel and station.