• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.933-938
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• 2014

The combined method utilizing airborne LiDAR and GIS data is suggested to extract 3-dimensional hybrid city model including roads and buildings. Combining the two types of data is more efficient to estimate the elevations of various types of roads and buildings than using either LiDAR or GIS data only. This method is particularly useful to model the overlapped roads around the so called spaghetti junction. The preliminary model is constructed from the LiDAR data, which can give wrong information around the overlapped parts. And then, the erratic vertex points are detected by imposing maximum vertical grade allowable on the elevated roads. For the purpose of efficiency, the erratic vertex points are corrected through linear interpolation method. To avoid the erratic treatment of the LiDAR data on the facades of buildings 2 meter inner-buffer zone is proposed to efficiently estimate the height of a building. It is validated by the mean value (=5.1%) of differences between estimated elevations on 2 m inner buffer zone and randomly observed building elevations.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.30 no.2
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• pp.174-184
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• 2020

Objectives: The purpose of this study was to improve the working environment by identifying the work satisfaction of the cleaning workers of the aircraft and measuring and assessing the harmful factors of the cleaning process. Methods: We asked 23 cleaning companies for questionnaires and got 100 answers from 5 companies. The A-E Airline health manager has been contacted to establish a site survey schedule. The in-flight and lounge were measured using direct reading equipment. The harmful factor to be measured are noise, dust, temperature, volatile organic compound, total airborne bacteria, and total airborne bacteria. Results: Uncomfortable positions when replacing blanket, cleaning the table, and cleaning the floor have been identified as factor that reduce work satisfaction. Noise when replacing newspapers and cleaning toilets has been identified as a factor that lowers work satisfaction. Temperature and humidity were found to reduce work satisfaction during in-flight disinfection. Measurements of aircraft cabin and lounge with direct read equipment have shown that none of the items exceed the exposure criteria. Conclusions: As a result of measuring direct-reading equipment, no items exceeded the exposure criteria for each harmful factor. A clear survey of the working environment is required based on the results, and additional research is needed using personal sample measurement.

• 연구논문집
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• s.29
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• pp.83-90
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• 1999

In naval ships, pump machineries are the major sources of airborne and structure-borne noise. Noise is critical issue in ships not only it causes annoyance to crews, but also it can increase the underwater radiated noise, which is crucial in anti-submarine warfare. In present study, it is discussed the reduction of structure-borne noise of pump machineries by showing several examples. The most typical and effective solution is to use double resilient mount system. However, in cases where double resilient system cannot be applied due to space and weight increase, rubber pad can be used to reduce the structure-borne noise. In principle, the concept of structure-borne noise reduction is the same as that of vibration isolation.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.2 s.119
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• pp.143-148
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• 2007

This study examines the influence factor of flanking noise in the wall. Generally, there is the difference of airborne sound isolation between laboratory and field test. The purpose of this study is examing the cause of droping sound insulation performance in the field and searching the method of improving sound insulation performance. First, we measured the sound isolation in the wall at the lab. Then, we measured it in the field and compared them. At the base of these datum, we measured the flanking noise and solid transmission. For the flanking noise in the wall, we used intensive method. So, we found the influence of solid transmission.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.25 no.3
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• pp.199-205
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• 2007

In this study, we have intended to precisely analyze the aspect of propagation and the extent of damage due to the traffic noise as hon as a main source of noise in urban area. The propagation of traffic noise has a strong relationship between distance and shape of surface. Thus, it is necessary to consider the distribution of buildings for estimating effects of noise in urban area because noise propagations will be affected by buildings. For this, we developed the DEM and DBM using the airborne LiDAR data in the study area and compared with results from the noise simulations using the each model. The extent of damage occurred by the traffic noise above 60 dB(A) from the case of DEM were shown at the 60% of a whole study area, whereas the extent from other case of DBM were shown at the 30% of a whole study area. Also, the extent of the noise levels between 45 dB(A) and 50 dB(A) will be generally recognized as calm environment was increased(the 0% to the 43%) in the case which simulated with building informations. These results indicated that the shape informations of buildings like a DBM is a essential source to simulate the propagation of traffic noise in urban area especially. With results in this study, the effect of traffic noise at a specific area will be easily and precisely estimated if we have the LiDAR data and a traffic census for Korea. Furthermore specific area's traffic noise simulation could be possible using only road traffic information once we have DBM data from LiDAR surveying. This also could be applied as a base data for noise pollution petitioning, traffic planning, construction, etc. in huge city planning projects like a U-City.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11a
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• pp.387-391
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• 2001

In evaluating sound performance of building, it is important to carry on tests and evaluations based upon residential sound performances. Korean Standards include test methods on sound performance, but don't include any code on evaluation methods. Therefore, evaluation methods from Japan or ISO have been used for evaluating sound performance in domestic so far. In this study, a draft of Korean Standards on a sound performance evaluation method in buildings is proposed.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.363-366
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• 2005

Social survey and auditory experiment on residential noises such as floor impact, air-bome, bathroom, drainage and traffic noises were conducted to investigate the effects of sensitivity and background noise levels on subjective response to residential noises. Results of survey showed that multiple questions for sensitivity to noise have a more power for discrimination against subjective response to noise than single question. It was also found that the correlation between sensitivity and annoyance was relatively low, but the differences in annoyance between sensitivity groups were significant. Result of auditory experiment showed that effects of sensitivity on annoyance were different according to noise type and noise level. It was also shown that the difference in annoyance between the lowest sensitive stoup and the highest sensitive group was significant in low noise level. The effects of background noise on subjective responses to noise was also different according to noise source and noise level, and were significant in low noise level of airborne and drainage noise.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.18 no.9
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• pp.943-951
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• 2008

In this paper, the mathematical model on crosstalk effect between acoustic noise sources is presented. Based on this model, a theoretical value to quantitate crosstalk effect of sources can be defined on the authority of reverberation property of surrounding which sources are located, relative magnitudes of sources and phase deference between acoustic wave transferred from all of sources. In order to verify crosstalk effect factor, experiments are made for two cases, weak and strong crosstalk effect condition, by using toro representative transfer path analysis(TPA) methods.

• KIEAE Journal
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• v.10 no.4
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• pp.39-44
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• 2010

Reading room in the university is one of necessary facilities that university student must use. It is, therefore, very important to make reading room comfortable acoustically not only to minimize the annoyance to the users but also to provide efficiency in studying. Present study aims to investigate the current situation of reading room in terms of acoustics and moreover to find out the relationship between the indoor noise and users' satisfaction through questionnaire survey. As a result, the indoor noise level is quite higher than the 1st grade, 35 dB(A), that the Ministry of land, transport and maritime affairs suggests as certificate regulation for environment friendly building and there were lots of noise sources that can provoke users in studying or concentrating. Questionnaire survey illustrates that the sound when opening and closing door, and airborne sound from outdoor transmitted through window are most annoying, which affected users' dissatisfaction.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.8
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• pp.155-161
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• 1999

아이들 상태에서 차실 내에 불쾌감을 주는 매우 높은 크기의 소음이 발생하였다. 본 논문에서는 아이들 시 문제소음의 원인을 분석하고 저감하는데 필요한 관련이론의 적용과 이에 수반되는 데이터측정, 데이터처리 및 데이터 해석과정을 자세하게 기술하였다. 소음진동 측정 및 분석 결과 문제의 소음은 엔진의 회전 2.5차 성분을 가지고 구조기인소음이었다. 아이들 시 문제의 실내소음에 영향을 미치는 구조전달경로들의 기여도를 분석하기 위해 소음경로해석시험 및 모드시험을 실시하였다. 시험분석 결과에 따라 기여도가 놓은 배 기계 및 트랜스미션계의 진동 전달특성을 개선하므로써 만족할 수준의 소음 저감효과를 얻었다.