도심지나 문화재가 인접한 지역 등의 소음, 진동 등 기존 발파해체 공법이 제한적인 조건에서 사용할 수 있는 구조물 해체 공법으로 무소음화학팽창제(soundless chemical demolition agent, SCDA)를 이용한 공법이 있다. 그러나 SCDA의 사용에 대한 기준이나 가이드라인에 참고될 만한 연구는 미미한 실정이다. 이 연구에서는 실내실험을 수행하여 강관의 길이, 외부수분차단, 수화열 발산 등의 다양한 조건에 따른 SCDA의 팽창압 발현 특성을 확인하였다. 또한 SCDA의 최소요구팽창압 예측을 위한 해석모델(자유단 1면, 고정단 3면의 직사각형 모델)을 개발하고 주요변수해석(홀 간 거리, 콘크리트 압축강도)을 수행하였다. 이 연구의 해석결과를 활용하여 자유단으로부터 콘크리트 구조물의 박락을 효과적으로 유도할 수 있을 것으로 판단된다.

선박의 고속, 대형화 및 규제강화의 추세에 따라 유동소음의 중요성이 강조되고 있다. 그러나 항공, 철도 등의 공력소음 분야에서 유동소음을 설계에 반영하고 있는 것에 반해 조선해양분야에서는 고려되지 않고 있다. 본 연구에서는, 선체유기 유동소음의 해석절차를 정립하고 쇄파의 영향이 작고 선체선형에 의한 유기소음의 특성이 뚜렷한 파랑관통형 선형에 대해 소음특성을 분석하였다. 선체유기 유동소음의 주요 메커니즘인 난류경계층 내부의 복잡한 난류유동과 구조물의 유체-구조 연성적 소음원은 벽면변동압력을 이용하여 가진력을 모델링하고 파워흐름해석법을 이용하여 진동음향 응답해석을 수행하였다. 주파수 영역 및 선체부위에 따라 상의한 소음특성을 가지며 저주파수 영역에서 선형의 영향이 상대적으로 크고 유속에 비례하는 경향을 확인할 수 있었다.

High power trends in the diesel engines due to engine downsizing do not provide noise attenuation that can be satisfied with the performance of the existing silencer on account of high frequency increases in the exhaust noise. This study improves the attenuation performance of the exhaust silencer of the diesel engine and suggests silencer structure that performs best attenuation performance, especially at the high frequency range in the exhaust noise. It proposes dual silencer structure with an average attenuation performance of 6.4 dB and a maximum of 10.7 dB in the high frequency range (over 500 Hz), and analyzes its characteristics compared with the existing silencer. The performance analysis is performed according to 'Measurements on silencers in situation–ISO 11820:1996 Acoustics' and describes the results of comparative analysis with the existing silencer.

The study on the database for the noise of the large machine and high power machine. The object of this project is to prepare the countermeasure of the health care according to investigate and database the basic information of the large machine and high power machine. To accomplish the object ; The dimension and noise of the large machine, which is mounted in the factory, was investigated. And the prediction and measurement method of the noise for the machine by manufacturers were investigated. The database of the noise by the machine type and power was built. The measurement and management methods for the machine noise were considered. The database of the noise was built from the measurement data. The major sound sources and frequency range for the large machine and the high power machine were investigated. The noise effect by the large machine and the high power machine was investigated. The application fields are; The setting of the management plan of the noise which generates from the large machine and the high power machine. The effective noise reduction for the major sound source with low cost. The application as the frequency transition considering the psycho-acoustics characteristics.

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 and prediction. From the results, we investigated the effect for elevated railway noise.

PURPOSES : We propose a parameter-setting-free harmony-search (PSF-HS) algorithm to determine the individual sound power levels of noise sources in the cases of industrial or road noise environment. METHODS: In terms of using methods, we use PSF-HS algorithm because the optimization parameters cannot be fixed through finding the global minimum. RESULTS: We found that the main advantage of the PSF-HS heuristic algorithm is its ability to find the best global solution of individual sound power levels through a nonlinear complex function, even though the parameters of the original harmony-search (HS) algorithm are not fixed. In an industrial and road environment, high noise exposure is harmful, and can cause nonauditory effects that endanger worker and passenger safety. This study proposes the PSF-HS algorithm for determining the PWL of an individual machine (or vehicle), which is a useful technique for industrial (or road) engineers to identify the dominant noise source in the workplace (or road field testing case). CONCLUSIONS : This study focuses on providing an efficient method to determine sound power levels (PWLs) and the dominant noise source while multiple machines (or vehicles) are operating, for comparison with the results of previous research. This paper can extend the state-of-the-art in a heuristic search algorithm to determine the individual PWLs of machines as well as loud machines (or vehicles), based on the parameter-setting-free harmony-search (PSF-HS) algorithm. This algorithm can be applied into determining the dominant noise sources of several vehicles in the cases of road cross sections and congested housing complex.

PURPOSES : The purpose of this study is to compare noise reduction quantities between before/after two-layer low noise pavement implementation using equivalent noise level analysis and to analyze the noise reduction effects of the two layer low noise pavement with a statistical method such as the Anderson-Darling Test.METHODS: In order to compare and to analyze noise reduction effects between before/after two-layer low noise pavement implementation, data acquisition as noise levels on a roadside and an apartment rooftop was conducted in the study area. The equivalent noise level was estimated in order to compare noise reduction quantities and the Anderson-Darling Test was carried out for estimating noise reduction effects of the two-layer low noise pavement.RESULTS: The equivalent noise levels of before/after two-layer low noise pavement implementation for the roadside during the daytime are 65.355 dB and 63.520 dB and during the nighttime are 62.463 dB and 59.088 dB. The equivalent noise levels for the apartment rooftop during daytime are 57.301 dB and 59.088 dB and during the nighttime are 54.616 dB and 52.464 dB. Also two-layer low noise pavement decreased the noise reduction effects estimated with the statistical method as the Anderson-Darling test for the roadside during the daytime by around 66.68% and decreased noise reduction effects on the roadside during the nighttime by 0.70%. Moreover it reduced noise reduction effects in the apartment rooftop during the daytime and nighttime by 0% and 96.32%, respectively.CONCLUSIONS : Based on the result of this study, two-layer low noise pavement can positively affect noise reduction during both the daytime and nighttime according to the results of estimating the equivalent noise levels and the Anderson-Darling test.

In commercial vehicles. the pulsation noise when the power steering operating is the major item to make the complain for users. If this noise have related to vibration characteristics in steering system's parts or assembly, it makes the problem in vehicle quality. Recently, the users demand the high quality in commercial vehicles, and we must identified the relevance between the pulsation noise and the vibration characteristics. After the identification, we can design the power steering system for satisfaction the user’s needs. Finally, the identification of relevance in pulsation noise for analysing the vibration characteristics will be suggested advanced power steering system.

Assessment of noise exposed population is to check the environment noise level 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 abatement policy and action plan by accurately finding the area that the noise causes harmful effect to human health. Recently, a noise map, which can predict noise in comprehensive area, is used for the assessment of noise exposed population, breaking from the methods using existing measures. In particular, countermeasure for noise can be considered more effectively by using assessment methods of noise exposed population for specific noise level, area, and building types which are the main input factors in noise maps. In this study, we propose noise reduction ranking decision at ship construction and repair process due to noise map.