• 한국공간구조학회논문집
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• 제7권6호
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• pp.83-90
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• 2007

철근 콘크리트 구조물에서 발생하는 진동 가진원과 영향에 대하여 많은 연구가 진행 중에 있다. 이러한 진동 가진원은 주로 거주자가 보행할 때 발생하는 하중이며, 발생한 가진원은 철근 콘크리트 판을 통하여 다른 거주자에게 전달된다. 이러한 전달원은 탄성파의 형태로 전달되는데 판의 표면으로 전달되는 표면파(Ram Wave)와 판의 내부로 전달되는 체적파(Prima Wave, Secondary Wave)의 형태로 전달된다 현재 이러한 파를 분석하는 연구는 압전소자(PZT)센서를 주로 사용하고 있으나, 콘크리트 부재에서 3축 형데로 전달되는 탄성파를 분석하기에는 여러 가지 어려운 부분이 많다. 따라서 이를 해결하기 위해 마이크로 가속도센서(Micro Accelerometer)를 이용하여 이동하중으로 발생하는 가진원에 대하여 평가하였다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 추계학술대회논문집
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• pp.830-833
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• 2004

An indoor package air-conditioner (PAC) has complex noise sources such as motor noise and fluid noise caused by the fan motor, heat transfer and shroud. Sound intensity techniques and ODS(Operational deflection shape) techniques are applied to identify the noise characteristics of an indoor air-conditioner's cabinet. The sound intensity is used to visualize the noise source locations. and the ODS to visualize the vibration pattern and to obtain the dynamic characteristics of the noise source. Acoustic intensity and operational deflection distribution are obtained in space domains as well as frequency domains. Using the visual information of source locations and its dynamic characteristics, the damping patch is applied to reduce structure borne noise in the cabinet. As a result, the noise emitted by the cabinet is reduced by 5dB.

• Smart Structures and Systems
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• 제32권6호
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• pp.393-402
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• 2023

Recently, hybrid and electric vehicles have been actively developed to replace internal combustion engine (ICE) vehicles. However, their vibrations and noise with complex spectra cause discomfort to drivers. To reduce the vibrations transmitted through primary excitation sources such as powertrains, structural changes have been introduced. However, the interference among different parts is a limitation. Thus, active mounting systems based on smart materials have been actively investigated to overcome these limitations. This study focuses on diminishing the source movement when a structure with two active mounting systems is excited to a single sinusoidal and a multi-frequency signal, which were investigated for source movement reduction. The overall structure was modeled based on the lumped parameter method. Active vibration control was implemented based on the modeled structure, and a multi-normalization least mean square (NLMS) algorithm was used to obtain the control input for the active mounting system. Furthermore, the performance of the NLMS algorithm was compared with that of the quantification method to demonstrate the performance of active vibration control. The results demonstrate that the vibration attenuation performance of the source component was improved.

• 한국소음진동공학회논문집
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• 제15권8호
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• pp.918-923
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• 2005

The vibration level (dB(V)) and vibration velocity (cm/sec) on the ground and buildings due to the differences of the measuring sites from the blasting source was investigated. To compare with vibration level and vibration velocity theirs magnitude was not surely directly proportional and vibration velocity 0.1 cm/sec was $45\~50$ dB(V). The difference between the measured vibration level and the calculated vibration level by Ejima's equation using vibration velocity PVS(peak vector sum) showed $21.0\~30.9$ dB(V) on the ground, $15.3\~23.6$ dB(V) on the apartment, respectively. And the correlation of vibration velocity and nitration level at the measuring sites of lower altitude showed higher than that of higher altitude.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 춘계학술대회논문집
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• pp.766-771
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• 2005

To compare blasting vibration at blasting construction field in urban area, the vibration level (dB(V)) and vibration velocity (cm/sec) on the ground and the structure of buildings due to the differences of the measuring sites from the blasting source is investigated and the difference between the measured vertical vibration level and the calculated vibration level by using vibration velocity PVS and the correlation between vibration velocity and vibration level and is studied in the thesis.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 춘계학술대회논문집
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• pp.1540-1548
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• 2000

Sound intensity techniques and ODS(Operational Deflection Shape) techniques are applied to identify the acoustic noise source of a hard disk drive and its control system. The sound intensity is used to visualize the noise source locations, and the ODS information to visualize the vibration pattern and to obtain the dynamic characteristics of the noise sources. The measurement systems are customized to accurately measure the sound intensity and ODS distributions of HDD system in space domains as well as frequency domains. The measurement systems for the sound absorption and transmission loss of materials are also used to support the background data for the efficient noise control. Using the visual information of source locations and its dynamic characteristics, the partial noise barrier structure and optimum absorption are designed and its controlled sound power level is proved to be under 3.1 Bel(Idle)/3.3Bel (Seek) which is the lowest level in the disk drive industry.

• 한국소음진동공학회논문집
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• 제20권11호
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• pp.1089-1096
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• 2010

The relation between the vibration induced from machinery and the radiated sound is complicated. Acoustic intensity method is widely used to obtain the accuracy of noise measurement and noise identification. In this study, as groundwork, the complex acoustic intensity method is performed to identify noise source and transmission path on different free space point source fields. As an industrial application, the complex acoustic intensity method is applied to HVAC to identify sound radiation characteristics in the near field. Experimental complex acoustic intensity method was applied to HVAC, it is possible to identify noise sources in complicated sound field characteristics which noise sources are related with each other, and certificate the validity of complex acoustic intensity. Especially, it can be seen that complex acoustic intensity method using both of active and reactive intensity is vital in devising a strategy for identification of noise. Also, the vector flow of acoustic intensity was investigated to identify sound intensity distributions and energy flow in the near field of HVAC.

• 한국소음진동공학회논문집
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• 제19권8호
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• pp.802-808
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• 2009

In this paper, the experimental study on the identification of noise sources and noise transmission paths was carried out for the cabin noise control of construction equipment. In order to investigate noise and vibration characteristics of cabin structure, sound absorption, transmission, and radiation tests were performed using cabin assembly models. The noise/vibration source levels were obtained from the real cabins of wheel loader and excavator. Using transfer functions of cabins and real cabins' source data, cabin noise was decomposed into airborne and structureborne noise transmissions. Finally noise sources and major transmission paths were successfully identified for wheel loader and excavator's cabins.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 춘계학술대회논문집
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• pp.318-321
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• 2005

In vibro-acoustic analysis, the commercial CAE tools, such as SYSNOISE, is usually used to take into account of the coupled effects of fluid acoustics and structural vibration. The acoustic field can be solved by either FEM or BEM, while the vibration field is usually solved by FEM. The interior or exterior acoustic problems with the coupled effects of the structural boundary could be solved by the commercial tools. The commercial tools, however, could not solve the problems in case that both the interior and exterior acoustic field is coupled with the structural boundary. In this paper, a realistic method based on FEM/BEM coupling scheme is presented to analyze the acoustic radiation from the internal source in a chamber to external acoustic field through elastic structural boundary. Several numerical examples are implemented to validate the developed program.

• 시스템엔지니어링학술지
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• 제13권1호
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• pp.7-14
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• 2017

Korea Aerospace Research Institute takes part in the vibration control software development for an Active Vibration Control System (hereafter, AVCS) for helicopters with Korea Aerospace Industries Ltd. in the Light Civil Helicopter (LCH) Project. The vibration control software is being developed per RTCA/DO-178C certification regulation and use of configuration management tools for software outputs is required. Redmine, an open source software is for issue or bug tracking and management software. Git, another open source software is a distributed version control software and is developed for Linux OS development. This paper introduces the functionalities of Redmine and Git, the reason why they are selected for the configuration management tool for the software outputs, and how they are being used for AVCS software development.