• 말소리와 음성과학
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• 제1권2호
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• pp.105-110
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• 2009

This paper introduces the technique of semi-automatically identifying different types of noise in the frequency domain. Given the lower cutoff frequency of the frication noise, and a user-specified constant, the technique identifies the boundary between the frication and aspiration noise in a Korean lax fricative followed by the vowel /a/ by comparing the upper and lower sums of energy with respect to the cutoff frequency. The user-specified constant can be adjusted for different speakers. When the technique was applied to distinguish the two types of noise of Korean lax fricatives from the same speaker, the average and standard deviation of the difference between the manually inserted boundaries and the automatically inserted boundaries were 2.67ms and 1.80ms respectively.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 춘계학술대회논문집
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• pp.603-606
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• 2005

This study is to make good acoustic environment around Gwang-ju riverside and performed survey and measurement of soundscape. The survey was focused on the types of sound producing. The results of measurement and analysis are as follows: 1) The types of sound at reverside were twenty and the Leq(equivalent noise level) was ranging from 50 dB(A) to 76 dB(A). The dominant sound was road traffic noise. 2) In the upperstream and the downstream, the sound of wind, bird and water was observed. 3) In the inner city, the water sound was produced by the difference of the height of the weir to mask the road traffic noise.

• 한국철도학회논문집
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• 제2권1호
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• pp.28-37
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• 1999

Many residential areas are situated near to railroad tracks so that a railroad noise has been one of the major environmental issues. In this paper two important aspects have been investigated in order to properly evaluate the railroad vehicle noise : sound power levels for different types and sound propagation characteristics of the railroad vehicles. For noise source characteristics of railroad vehicles, sound power values for various types of trains that are in active service have been measured. In this paper, domestic railroad vehicles are measured and compared with high speed train(TGV). Based on sound power information of railway vehicles, prediction on the sound pressure level and equivalent noise level near to railway areas have been evaluated.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2010년도 춘계학술대회 논문집
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• pp.1991-1996
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• 2010

The concrete track system on domestic urban transit has being constructed since 1974. Because a maintenance and repair of concrete track system is convenient, a construction is increased. The concrete track system on domestic urban transit is constructed 71.8% of total track system length and constructed variously, for example STEDEF, LVT, ALT and so on. Recently, railway noise is issued as environment problem. The method for mitigation of urban transit noise is required. In this study to study noise characteristics on concrete tracks we measured noise by concrete track types and analysis the result.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1997년도 춘계학술대회논문집; 경주코오롱호텔; 22-23 May 1997
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• pp.594-601
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• 1997

Propeller fans are commonly equipped in outdoor units of air-conditioners to provide effective cooling in a dried heat exchanger. A new design technique was developed to satisfy requirements of aerodynamic and aeroacoustic performance, which employs the intersection method of two cylinders for mean camber line. Three proto-types of propeller fan including Palm-Shaped, Highly-Swept(PSHS) fan (proto 3)were not only to provide low lift forces for dipole sound, but also to reduce the organized tip vortices interacting with the fan guide causing narrow-banded rotating instabilities. Cross-correlation technique was applied to study flow noise source characteristics for three proto-type fans designed. The cross-correlations between a microphone at far field and a hot-wire sensor at near field show that flows near hub region of proto 3 fan are less organized and the flow structures especially at high flow rate coefficients for proto 3 fan are less correlated with noise generated than other proto-types fans.

• 환경영향평가
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• 제28권4호
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• pp.387-399
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• 2019

본 연구에서는 고속도로 방음벽을 대상으로 방음벽의 손상유형 분류 및 손상등급 체계를 마련하고 이를 반영한 방음벽 노후도 평가기법 개발을 목표로 하였다. 방음벽이 방음판, 기초, 지주로 구성되어 있고 10종의 다양한 재질이 활용되고 있는 방음판은 단일 또는 혼합형으로 사용되고 있으며, 방음판의 손상은 단일 또는 복합적인 손상을 나타내는 특징을 나타내고 있어 이러한 방음벽의 특징을 반영할 수 있는 방음벽 노후도 평가모델을 개발하고자 하였다. 방음벽에 주로 사용되고 있는 재질을 금속재, 플라스틱재, 목재, 투명재, 콘크리트재의 재질유형으로 나누고 또한, 각 재질별 손상유형을 부식, 변색, 변형, 깨짐, 탈리로 분류하여 방음벽의 손상유형을 방음벽 구성부재와 재질에 따라 세분화하였다. 방음벽 주요부위별로 각 손상유형별 손상등급을 양호, 경미, 보통, 심함으로 구분하여 방음판, 지주, 기초의 손상등급을 평가, 이를 바탕으로 부위별 노후도를 평가하여 가중평균을 통한 방음벽 전체의 노후도를 평가하는 방식을 통해서 종합적인 방음벽 노후화 정도를 평가하였다. 단일형 또는 혼합형 방음판을 사용하는 방음벽의 노후도 평가는 물론, 손상유형이 단일형 뿐만 아니라 복합형으로 나타나는 방음벽에 대해서도 체계적인 평가가 가능한 노후도 평가 기법을 개발하였으며, 이러한 평가시스템을 통하여, 현재 설치되어 있는 방음시설의 노후화 현황을 체계적으로 파악함은 물론, 이를 토대로 방음벽의 보수 및 개량을 위한 효율적인 유지관리 계획 및 시행에 활용이 가능할 것으로 판단된다.

• 한국산업보건학회지
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• 제24권1호
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• pp.74-78
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• 2014

Objectives: Purpose of this study was to evaluate the noise level exposures at the different cannonball type and locations in the tank gun drill ranges. Methods: We visited the tank gun drill ranges and measured with a sound level meter(3M Quest SoundPro$^{TM}$) with the value of Peak(dB(A)). Results: The highest peak value of impulse noise level averaged 166.3 dB(A) at the site of loading solider. The highest peak value of impulse noise level by size of cannonball averaged 165.9 dB(A) at the 120 mm size cannonball of the tank. This result was significantly different from the other size of cannonballs such as 7.62 mm, 90 mm, and 105 mm(p < 0.001). Among the four types of soldier site on the tank, average noise levels of loading soldier, 156.6 dB(A), were higher than the other three types of soldier site (p > 0.05). Conclusions: This study confirmed that there were needed for a proper control to reduce the amount of impulse noise exposure at the tank gun drill ranges.

• 한국산업보건학회지
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• 제28권4호
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• pp.393-405
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• 2018

Objective: This study examines the types of hazardous factors in the working environment and the time-trend for their exposure levels over 10 years (2007 to 2016). Study Design and Method: The types of hazardous factors and exposure levels were drawn from the 19 measurement reports on the working environment over 10 years at a shock absorber manufacturing facility. Risk assessment of the types of factors and time-trend of exposure levels were evaluated using the factors and exposure levels. Results: A total of 34 hazardous factors were evaluated. The types were noise, 15 organic compounds, seven kinds of acid sand alkalis, eight kinds of heavy metals, and three other compounds. Special management materials used were nickel, hexavalent chrome, and sulfuric acid. Human carcinogens (1A) used were trichloroethylene, nickel, and sulfuric acid. There were six types of substances belonging to the IARC's 2B (body carcinogens) classification or higher, including, methyl isobutyl ketone, ethyl benzene, and trichloroethylene. No detection was found for 627 out of the 2065 total measurements in 19 exposure survey reports, representing 30.4%. Organic solvents, acid and alkali products, and heavy metals showed continuous low exposure concentrations. Noise, welding fumes, and the evaluation of mixed solvents show a gradual decrease in geometric mean and maximum over the time-trend of 10 years. Conclusions: In the case of a shock absorber manufacturing facility, the hazardous factors of noise and the evaluation of mixed solvents still indicate high concentrations exceeding the exposure limits and necessitate reduction studies. These two factors and welding fumes showed a continuous decrease in their ten-year tendency. Organic compounds, acids/alkalis, and heavy metals were managed smoothly in a work environment of continuous low concentrations.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 추계학술대회논문집
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• pp.1129-1133
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• 2007

Assessment of noise exposed population is a method for checking the degree of environmental noise and social influence in order to reduce the risks such as annoyance and disturbance that are generated by environmental noise. Also, this method suggests the preferential noise reduction policy and action plan by accurately assessing the area that noise causes harm to human health. Recently, a noise map, which can predict noise in comprehensive areas, is used for the assessment of noise exposed population, breaking from the methods using existing measures. In particular, countermeasure for the noise can be considered more effectively by using assessment methods of noise exposed population for specific noise levels, areas, and building types which are the main input factors in noise maps. In this study, Assessment methods of noise exposed population by using 2D noise map are compared with those by 3D noise map.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1998년도 춘계학술대회논문집; 용평리조트 타워콘도, 21-22 May 1998
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• pp.747-752
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• 1998

SONICS is the software developed by authors. The program provides the noise level in outdoors due to various noise source types : construction machines including blast sources, railroad vehicles and automobiles. h operates in the Windows system. Since the software is compiled by using Visual C++ 4.0, users can run the program interactively. Also SONICS uses Windows' dialog-box and choice-button so that a novice user can easily implement the program for the environmental noise planning.