• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2011년도 춘계학술대회 논문집
• /
• pp.638-643
• /
• 2011

The aluminum soundproofing panel used to the traffic noise reduction will judge with the material to improve because the CO2 emission is greater than other soundproofing panel such as plastic soundproofing panel. Also, if the air-passing soundproofing panel which can endure the fast wind velocity will be developed, it judged that it can reached to the target of low CO2 traffic technology development using the reduction of material cost and the lower consumption of steel. The objective of this study is to improve the soundproofing panel and to develop the air-passing soundproofing panel for the replacement of aluminum sound proofing panel which is more emit CO2 than other soundproofing panel. And, we tried to develop the reduction technology of CO2 emission through the development of air-passing soundproofing panel. At first, the flow and noise simulation were conducted for the purpose of the calculation of wind pressure on soundproofing wall and noise exposure level on receiver points according to the open ratio of air-passing soundproofing panel. And the 1st and 2nd mockup of air-passing soundproofing panel were made, and the design load test were conducted for these mockup.

• 한국자동차공학회논문집
• /
• 제2권6호
• /
• pp.29-37
• /
• 1994

Active noise control of random noise which propatate in the vehicle cabin as a form of spherical wave is the target of this study. In the previous study, the adaptive algorithm for adaptive controller is presented for the application in active noise control system. And for the preliminary study of adaptive active noise control in vehicle cabin as a real system, a computer simulation is performed on the effectiveness of the adaptive algorithm in the amplitude of the pressure fluctuation. This work studies the implementation of multi-channel feedforward adaptive algorithm for the reduction of the noise inside a vehicle cabin using a number of secondary sources derived by adaptive filtering of reference noise source. Multi-channel adaptive feedforward algorithm are verified in numerical simulation and semi-experimental justification of developed system is made on a domestic passenger car. In the results of semi-experimental study, the noise of specific region in the interior of automobile are reduced for the appreciabe sound pressure level in the operating engine rpm and finally this study suggests the capabilities of the real time active noise control in 3 dimensional acoustic fields.

• 한국군사과학기술학회지
• /
• 제20권4호
• /
• pp.505-513
• /
• 2017

Cavitation is a phenomenon caused by vapour cavities that is produced in rapid pressure changes. When the cavitation happened, the sound pressure level of a underwater radiated noise is increased rapidly. As a result, it can increase the probability of the identification or classification of a our warship's acoustic signature by an enemy ship. However, there is a problem that it is hard to precisely detect the occurrence of a cavitation noise. Therefore, this paper presents recent improvements in terms of the cavitation noise measurement by using continuous wavelet transform and DEMON(Detection of Envelope Modulation on Noise) signal processing. Then, we present that the suggested scheme is more suitable for detecting the cavitation than existing algorithms.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2001년도 추계학술대회논문집 II
• /
• pp.676-681
• /
• 2001

We usually divide the noise of exhaust system into pulsation noise and flow noise. Pulsation noise is the shock wave to occur when the burning gas of low pressure emits and include harmonic having basic frequency as the exhaust cycle of engine. Flow noise is the noise that is produced when gas flow emits into the atmosphere through the pipe and has the character of frequency like pink noise which has the high level of high frequency component. A muffler is divided into reflective type and absorptive type. We usually use the muffler compounding the property of them. In this study, it is the case of transfer matrix method that a muffler is compounded to analyze the elements of each section according to sound wave's proceed direction. But we use simple model. So, we use finite element method that takes short time to analyze. Acoustic analysis gives us transfer matrix to use FEA of SYSNOISE and we use STAR-CD for fluid analysis. We made database that is based on analytical results about the muffler of expansion type, extended type, offset type, reverse type, and perforated type and developed the muffler design system to perform work efficiently.

• Journal of Mechanical Science and Technology
• /
• 제17권4호
• /
• pp.590-598
• /
• 2003

A computational aero-acoustic (CAA) method is used to predict the tonal noise generated from a cavity of automobile door seals or gaps at low flow Mach numbers (A$\_$$\infty$/=0.077 and 0.147) In the present method, the acoustically perturbed Euler equations are solved with the acoustic source term obtained from the unsteady incompressible Navier-Stokes calculations of the cavity flow in self-sustained oscillations. The aerodynamic and acoustic fields are computed for the Reynolds numbers based on the displacement thickness, Re$\_$$\delta$*/=850 and 1620 and their fundamental mode characteristics are investigated. The present method is also verified with the experimentally measured sound pressure level (SPL) spectra.

• 한국소음진동공학회논문집
• /
• 제13권11호
• /
• pp.838-844
• /
• 2003

The noise and vibration reduction schemes of an industrial robot are studied. Experimental procedures are employed to examine the sources of robot noise. A parametric study is undertaken to observe the effects of each part such as gear, shaft and housing on the sound pressure level. After the part which mainly effects on the noise is proved, we propose countermeasures for reducing the noise and vibration of the robot system.

• 소음진동
• /
• 제10권3호
• /
• pp.430-436
• /
• 2000

The cross-flow fans have been widely used to constitute the air moving systems in many air-ventilating and air-conditioning units. The cross-flow fan system has many design parameters which have crucial influence on the performance and the noise characteristics of the units. As a result there are many difficulties in the design stage of the system and the general design guide has not been sufficiently established yet. This study presents the experimental results of the parametric investigation of some chosen design parameters which are directly related to the shape of the stabilizer the profile of the scroll casing and the diffusion angle of the flow exit. The results are expressed in terms of the fan performance and the specific sound pressure level characteristics. Some parameters have been found to have crucial effects on the system performance/noise characteristics and should be considered with care in the design stage.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2007년도 추계학술대회논문집
• /
• pp.1318-1320
• /
• 2007

Fan noise prediction method is presented for air conditioning and/or cooling system applications where fan acts as an internal equipment having very complicated flow interaction with other various system components. The internal flow paths and distribution in the fan-applied systems such as computer or air conditioner are analyzed by using the FNM(Flow Network Modeling) with the flow resistances for flow elements of the system. Based on the fan operation point predicted from the FNM analysis results, the present fan noise model predicts overall sound power, pressure levels and spectrum. The predictions of the flow distribution, the fan operation and the noise level in electronic system by the present method are well agreed with 3-D CFD and actual noise test results.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2007년도 추계학술대회논문집
• /
• pp.1450-1454
• /
• 2007

주상복합형 주거공간에 각 실간 Cross Talking에 의한 소음을 저감시키고 실내기의 공기조화로 발생하는 팬의 소음을 저감 시키기 위하여 소음 환기 장치를 개발 하였다. 공명형과 팽창형의 특성을 적용한 복합적 소음기로 저감주파수 대역에 따른 설계가 가능하며 이 소음기 성능시험 결과 특정 주파수 대역에서 20dB이상의 삽입손실치가 발생하고, 삽입에 의한 압력손실 2mmAq 이하가 됨을 확인하였다. 본 개발품의 특성은 구조가 간단하고 분해조립이 가능하여 설치 및 유지보수가 용이한 제품이다.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2007년도 추계학술대회논문집
• /
• pp.943-946
• /
• 2007

The vibration and noise characteristic of the Axial-gap motor for an air conditioner were analyzed. Experimental Modal Analysis was performed to understand the vibration characteristic of the motor. The noise of motor was measured in a dead room. Finite Element Method was performed to find the vibration characteristic of the motor by using ABAQUS program.