• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 춘계학술대회논문집
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• pp.1157-1161
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• 2007

A construction noise is the main reason for people's petition among the pollution. The purpose of this study is to develop the noise prediction program to see the level of the noise on the construction site more accurately. For this purpose, the database of the power level on the various equipments was made. The noise reduction by distance and the noise reduction by diffraction of barrier were mainly considered and calculated. The simple noise prediction program will provide the information about proper height and length of the potable barrier which satisfies noise criteria of the construction sites from a construction planning stage. To investigate the reliability of this program, the predicted data was compared with the measured data. An average of difference between measured data and predicted data is 1.3 dB(A) and a coefficient of correlation is about 0.95.

• 한국소음진동공학회논문집
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• 제16권7호
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• pp.697-703
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• 2006

This article proposes a new technique for the reduction of vibration and noise in the geared system by adjusting the distance between gear shafts. The vibration and noise may be produced by the abnormal force applied to the tooth face. And the force may be the cause of ununiform velocity in the driven shaft. If the velocity is obtained to be uniform by adjusting the distance between shafts. the vibration and noise may be reduced to some extent. In order to review, a dynamic analysis model for the gear train used in a mill turret and a test rig are developed. The velocities in the driven shaft are calculated by dynamic simulations for the model and noises in the test rig are measured with varying of the distance between shafts. The comparison of simulation and test data shows that the distance between shafts at the most uniform velocity has the lowest level of noise.

• 한국소음진동공학회논문집
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• 제17권11호
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• pp.1021-1027
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• 2007

A construction noise is the main reason for people's petition among the pollution. The purpose of this study is to develop the noise prediction program to see the level of the noise on the construction site more accurately. For this purpose, the database of the power level on the various equipments was made. The noise reduction by distance and the noise reduction by diffraction of barrier were mainly considered and calculated. The simple noise prediction program will provide the information about proper height and length of the potable barrier which satisfies noise criteria of the construction sites from a construction planning stage. To investigate the reliability of this program, the predicted data was compared with the measured data. An average of difference between measured data and predicted data is $0.1{\sim}2.8\;dB(A)$ and a coefficient of correlation is about $0.85{\sim}0.95$.

• 한국환경보건학회지
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• 제34권4호
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• pp.311-315
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• 2008

This study was performed to investigate propagation characteristics and effects of road traffic noise generated from vehicles. Noise levels of expressway and general road were measured at four points in a straight line based on distance from the road, and analyzed. The average noise level of expressway was 78.9 dBA at 5 m, 76.4 dBA at 10 m, 72.0 dBA at 20 m, 69.0 dBA at 30 m. That of general road was lower about $3.1{\sim}3.5\;dBA$ than that of expressway. There was no significant difference in distance attenuation between expressway noise and general road noise. The farer the distance from source is, the more the attenuation is. The influence range of noise is assessed by noise environmental standards or road noise limits. Noise levels of the time zone were measured at a boundary line of apartment to grasp noise variation by time. The time zone of lowest noises was $3{\sim}4$ a.m. and that of highest noise was $8{\sim}10$ a.m. Data recorded on tapes were analyzed to understand the characteristics of frequency because these characteristics are important factors to plan the noise reduction measures, namely path measures.

• 한국도로학회논문집
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• 제18권5호
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• pp.49-56
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• 2016

PURPOSES : In this study, noise reduction effect of a two-layer porous asphalt pavement was investigated through site measurement and computer simulation. METHODS : To examine noise reduction effect, a 3 km long quiet pavement was installed by removing previous normal pavement, which had a rather low porosity. The studied site was a high-rise apartment building surrounded by the quiet pavement and Seoul ring road with heavy traffic volume, indicating relatively high background noise. RESULTS : The measurement result before and after installing the quiet pavement showed a noise reduction effect of 4.3 dB(A) at a distance of 7.5 m from the road. After validating the accuracy of simulation using SoundPLAN, the reduction in SPL(sound pressure level) at the facades by the quiet pavement was predicted by considering five different road conditions generating traffic noise from each road or in the combination of the quiet pavement and Seoul ring road. In the case of no noise from Seoul ring road, noise reduction at the facades was 4.2 dB(A) on average for 702 housing units. With background noise from Seoul ring road, however, the average SPL decreased to 2.0 dB(A). Regarding subjective response of noise, the number of housing units with a noise reduction of over 3 dB(A) was 229 out of 706 units (approximately 32%). For 77 housing units, the noise reduction was between 1~3 dB(A), while it was less than 1 dB(A) for 400 housing units. CONCLUSIONS : The overall result indicates that the quiet pavement is useful to reduce noise evenly at low and high floors compared to noise barriers, especially in the urban situation where background noise is low.

• Journal of Electrical Engineering and Technology
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• 제12권4호
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• pp.1627-1633
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• 2017

This paper proposes a voice enhancing ear-protection system which is based on feedback active noise control(FBANC). The proposed system selectively suppresses the background noise and preserves the talking voice by controlling the adaptive algorithm with the voice activity period detection module. The noise reduction performance of the proposed noise canceling algorithm is analytically derived for the two key performance affecting parameters, i.e., electro-acoustic coupling distance and noise bandwidth. The proposed system is also implemented with a floating-point DSP system and its performance is experimentally tested to compare with the analytically derived results. The achieved levels of noise reduction for the three different noise bandwidths cases, i.e., 10Hz, 50Hz, and 90Hz, are high to show 17.05dB, 10.54dB and 8.99dB, respectively. The feasibility of the proposed system is also shown by the peak noise reduction achieved more than 25dB while preserving the voice component in the frequency range between 200-800Hz.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 추계학술대회논문집
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• pp.311-317
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• 2007

The reduction of the Vehicle interior noise has been the main interest of NVH engineers. The driver's perception on the vehicle noise is affected largely by psychoacoustic characteristic of the noise as well as the SPL. The previous methods to evaluation of the SQ about vehicle interior noise are linear regression analysis of subjective SQ metrics by statistics and the estimation of the subjective SQ values by neural network. But these are so depended on jury test very much that they result in many difficulties. So, to reduce jury test weight, we suggested a new method using Mahalanobis distance for SQ evaluation. And, optimal characteristic values influenced on the result of the SQ evaluation were derived by signal to noise ratio(SN ratio) of the Taguchi method. Finally, the new method to evaluate SQ is constructed using Mahalanobis-Taguchi system(MTS). Furthermore, the MTS method for SQ evaluation was compared by the result of SQ grade table at the previous study and their virtues and faults introduced.

• 지역연구
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• 제6권1호
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• pp.57-68
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• 1990

The purpose of this study is to develop the models to predict the noise PCE (Passenger Car Equivalence) of large running vehicles through noise prediction models. The noises were measured at the distance of 7.5M, 11.0M, and 14.5M from the noise source with test vehicles running at the speed of 40 Km/h, 60 Km/h, and 80 Km/h while normal traffic were detoured. Total noise levels were measured while vehicles were running at given speeds, Engine noise level was considered as the noise of its idle running at the three vehicle speeds shown above friction noise level was ascertained by moving the vehicle at given speeds without the engin operating. The noise prediction models for each noise source were developed by factors which affect to the each noise level. As a result of this paper, the reduction of total vehicle noise by increasing the distance to the noise source from 10 M to 15 M is as much as that by dropping its speed from 60 Km/h to 40 Km/h. Also, the reduction of PCE of total noise of large vehicle by making the noise source to that by reducing its speed from 80 Km/h to 60 Km/h. Enging noise PCE, which is in range between 65 and 160, is larger than friction noise PCE which is in range 3.5 and 5.5. Engin noise is the main noise of the large vehicles while friction noise is that of the small vehicles. Machine noise for large vehicles, and engin noise for small vehicles should be tightly controlled to reduce the vehicle noise. A low noise engine and tire, and the shape of vehicle body are needed to be developed to reduce noise further.

• 한국음향학회지
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• 제38권3호
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• pp.352-362
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• 2019

가로변 이면지역에 위치한 노후된 공동주택은 주도로의 교통소음의 피해를 받는다. 이면지역의 소음은 가로면 건물의 높이와 주도로와의 이격거리, 그리고 도로변 건물간의 이격거리 및 도로변 건물간의 높이차이에 의하여 영향을 받는다. 본 연구는 한 도시 내의 15개의 블록을 선정하여 가로변 건물배치형태를 1)블록에 단일건물이 배치된형태, 2)블록에 다수의 건물이 하나의 축으로 연속하여 배치된 형태로 분류하였으며, 가로변과 이면지역에서 도로교통소음을 동시에 측정하여 가로변의 건물 배치형식에 따른 이면지역소음의 상관성을 분석하였다. 분석결과, 이면지역으로 전달된 도로교통소음은 가로변에 배치된 건물의 높이, 건물과 건물간의 이격된 거리, 인접한 건물의 높이차에 영향을 받으며 건물의 너비에 의한 소음도의 감소는 나타나지 않았다. 가로변에 위치한 건물의 높이가 4 m(단층)인 경우 이면지역의 소음도는 12 dB(A)감소하였으며 높이가 4 m 증가할 때마다 2 dB(A)씩 감소하는 것으로 나타났다. 또한 인접한 두 건물의 높이차가 4 m 증가할 때마다 이면지역의 소음도는 1 dB(A)씩 증가하였으며, 인접한 두 건물의 이격된 거리가 0.5 m 증가할 때마다 이면지역의 소음도는 1 dB(A)씩 증가하는 것으로 나타났다.

• 한국소음진동공학회논문집
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• 제19권4호
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• pp.425-432
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• 2009

Recently, reduction of road traffic noise in residential buildings has become one of the most important subjects. To reduce the road traffic noise, noise impact assessment by the road traffic prediction model is required before building construction. For reasonable road traffic noise prediction, it is required to analysis of various factors in road traffic prediction models. This paper was studied the road traffic noise propagation factors such as distance from road to building, receiver height, alignment angle of building and reflection coefficient of the building facade by two calculation models, RLS-90 and CRTN. The result showed that noise reduction was generally higher at bottom stories by ground absorption effect. The reflection coefficient of the building facade was affect of additional sound pressure level by facade reflecting. And alignment angle of building at $90^{\circ}$ was performed effective noise reduction better than $0^{\circ}$.