• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.1140-1143
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• 2007

The purpose of this study is the improvement of the prediction model of highway noise. It includes the measurement and analysis of predicted noise levels by various programs in types of road and environments. The results of the measurement are compared with the noise levels predicted by improved highway noise prediction model and domestic prediction models, (Improved highway noise prediction model was considered ASJ-2003, ISO-9613 part2 and noise power of road surface types at Korean highway road.)

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.30-33
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• 2006

The purpose of this study is the improvement of the prediction model of highway noise. It includes the measurement and analysis of the highway noise for various types of roads and environments. The results of the measurement are compared with the noise levels predicted by highway noise prediction models including domestic and foreign ones and any recommendation to improve the accuracy of the models should be provided.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.340-345
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• 2002

Passengers in automobile or train are exposed to a worse noise environment when they are in the tunnel than in the open field. This is due to a relatively higher space density of sound energy by multiple reflection phenomenon of noise generated by operation of transportation vehicles from tunnel wall compared to open field. In this study, noise characteristics of subway train running through a tunnel were investigated at straight/curved track and tunnel type(semi circular/box). Also the noise measured simultaneously at inner and outer sides of train running through a tunnel, so that the coherence of the various noise sources of subway train to inner noise was evaluated.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.1350-1354
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• 2000

철도 소음에 의한 환경문제가 증가하고 있으나 방음대책으로는 아직까지 방음벽을 철도 연변에 설치하는 것인데 이러한 방음벽은 주위 경관과의 부조화와 열차승객의 시아방해 등으로 높이에 제한을 받는다. 높이를 높이지 않고도 저감효과를 얻을 수 있는 방음벽과 상단형상의 개발이 중요한 연구과제로 대두되고 있다. 본 논문에서는 철도연변에 설치되는 방음벽의 종류별로 삽입손실을 ISO 10847에 근거하여 측정하였으며 그 결과를 상호 비교 분석 평가하였다.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.21 no.10
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• pp.916-923
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• 2011

The refrigerant after the expansion valve interchanges the heat at the evaporator. At this moment, the state of gas and liquid becomes two-phase flow and causes irregular noise. In order to avoid the noise, the two-phase flow pattern should be predicted. In this paper, the procedure to predict the two-phase flow patterns such as churn flow and annular flow was suggested using the CFD software. The experiments using refrigerant-supplying equipment was carried out and the noise levels according to the flow pattern were measured. The flow patterns predicted by this procedure showed good agreement with those by experiments. The churn flow is noisier than annular flow pattern.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.31 no.3 s.258
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• pp.217-224
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• 2007

A numerical analysis for a silencer with three baffles of 120mm tank gun has been performed. The Reynolds-Averaged Wavier-Stokes equations with Baldwin-Lomax turbulence model were employed to compute unsteady, compressible flow inside the tank gun and the silencer. An axisymmetric computational domain was constructed by using 12 multi block chimera grids. The resolution of flow field is observed by depicting calculated pressure and muzzle brake force. The peak blast pressure and noise through the silencer reduced approximately 99% and 41dB in comparison to the tank gun without the silencer at near filed.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.438-442
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• 2006

Reasonably accurate estimation of the exposed population to the distinct levels of noise is essential to the efficient management of urban environmental noise. This study proposes a method of calculating the number of exposed people to industrial noise by using GIS tool and noise mapping. The exposed population of noise based on estimation of the number of people that lived in each building in urban area is compared with the one based on density of population. This study suggests the six step method that consists of gathering the fundamental data, extracting the property from the digital map, noise mapping based on the three dimensional topography, estimating population that lives in each building, merging the various results with GIS tool, and estimating exposed population to industrial noise through analyzing the noise map with GIS tools

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.296-299
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• 2006

This study is about correlation between WECPNL and other units such as NNI, Leq and Ldn for aircraft noise that ere measured by automatic measuring system networks for grasping the effect of aircraft noise and investigated the aircraft noise level from 2004 to 2005 nearby 10 airports in Korea. It is very important to find the relationship among the various noise units, because exchange between the results of many other nation's study can improve the assessment and mitigation study of the aircraft noise. Correlation between WECPNL and M is better than one between WECPNL and Leq and between WECPNL and Ldn, because WECPNL and NNI are based on the PNL.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1996.10a
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• pp.71-76
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• 1996

스트레인 게이지 브리지와 한개의 진동변위 탐촉자를 이용하여 평판의 근접장에서 음향 인텐시티를 측정하는 방법에 대하여 설명하였다. 또한 구조감쇠의 모델링을 통하여 음향방사파워에 대한 내부손실파워의 비를 나타내는 계수를 정의하여 내부손실파워의 정도를 평가하는 척도로 사용할 수 있음을 설명하였다. 임의의 경계조건을 가지는 평판에서 2개의 마이크로폰과 1개의 가속계를 이용하여 근사적으로 측정된 음향 인텐시티와 본고에서 제시한 방법으로 측정한 음향 인텐시티가 거의 일치함을 보이므로써 제시된 측정방법의 타당성을 검증하였다. 실험에 사용된 계(system)는 일반적인 해석에서 유체부하를 무시할 수 있는 계로 평판내부의 에너지 흐름에 비하여 외부로 방사되는 소음의 에너지 흐름이 매우 작기 때문에 평판내부의 에너지 흐름으로부터 방사되는 소음의 에너지 흐름을 알아내는 것이 매우 어려울 것으로 예상되었으나 본고에 제시된 방법으로 좋은 결과를 얻을 수 있었다. 앞으로 본 방법의 측정 오차에 대한 면밀한 고찰이 있어야 할 것이다. 그리고 평판의 내부손실이 비교적 큰 경우에 본 방법의 실험적으로 검증이 필요할 것이다. 또한 실질적인 문제에 응용되어 얼마만큼 유용한 정보를 제공할 것인가를 살펴보아야 할 것이다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.131-134
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• 2005

This study examine the annoyance of transportation noise exposure and found the survey method about which noise induces more disturbance or annoyance when more than two kinds of noise exist. This study describes the noise annoyance survey performed in the vicinity of Sin-wol interchange. This residential area was exposed to aircraft noise and traffic noise simultaneously and aircraft noise exposure of this area is about 81 WECPNL, traffic noise exposure is about 81.2 dB(A) nearby road. Noise sources are grouped into three part, traffic noise, aircraft noise and community noise. The questionnaire includes how often, how loud each noise is heard. Also this deals with comparative annoyance reaction from specific noise sources such as aircraft or traffic and its disturbance of daily activities. Facade noise mapping are executed by using a commercial noise mapping software.