• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.26 no.6
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• pp.481-490
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• 1997

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.919-924
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• 2004

A CFA(Cooling Fan Assembly) is composed of a fan, motor and shroud, which is at the back of the automotive radiator. By forcing the wind to pass, the CFA controls the cooling performance of the radiator. The noise and vibration of the CFA may be primarily due to the resonance between the CFA and engine. The Interference among the fan, shroud and radiator by deformation is considered when the CFA is designed. In this paper, in order to analyze the structural vibration of the CFA for automobiles, a finite element model of the CFA is established by using a commercial FEM code. After the finite element modeling, the natural frequencies and the mode shapes are obtained from the FE analysis. The natural frequencies are obtained from the vibration test as well. Then, the results of the vibration test are compared with those of the FE analysis. The natural frequencies obtained by experiment have a great similarity to the results from FE model. We have confirmed the validity of the FE model and verify the structural safety for the resonance. The stress and displacements are obtained from FE analysis. We have confirmed the safety for the interference and failure.

• The Journal of the Acoustical Society of Korea
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• v.34 no.1
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• pp.36-45
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• 2015

Recently, a lot of studies have been made about the methods used to generate turbulent velocity fields stochastically in order to effectively predict broadband flow noise. Among them, the FRPM (Fast Random Particle Mesh) method which generates turbulence with specific statistical properties using turbulence kinetic energy and dissipation obtained from the steady solution of the RANS (Reynolds Averaged Navier-Stokes) equations has been successfully applied. However, the FRPM method cannot be applied to the flow noise problems involving intrinsic unsteady characteristics such as centrifugal fan. In this paper, to effectively predict the broadband noise generated by centrifugal fan, U-FRPM (unsteady FRPM) method is developed by extending the FRPM method to be combined with the unsteady numerical solutions of the unsteady RANS equations to generate the turbulence considered as broadband noise sources. Firstly, an unsteady flow field is obtained from the unsteady RANS equations through CFD (Computational Fluid Dynamics). Then, noise sources are generated using the U-FRPM method combined with acoustic analogy. Finally, the linear propagation model which is realized through BEM (Boundary Element Method) is combined with the generated sources to predict broadband noise at the listeners' position. The proposed technique is validated to compare its prediction result with the measured data.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2008.04a
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• pp.273-275
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• 2008

Generally, automobile cooling fan is used to lower the temperature of radiator. The cooling fans are manufactured by plastic injection molding process. The center of gravity of cooling fan is often deviated from the center because of the use of deteriorated materials. As the unbalance of the cooing fan can generate noise, it is required to test the performance of the cooling fans. In this work, automatic fan balancer which can distinguish between the good and the bad, futhermore idenfify the position and magnitude of unbalance is develpoed.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.10a
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• pp.832-833
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• 2009

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.04a
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• pp.783-784
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• 2012

• The KSFM Journal of Fluid Machinery
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• v.2 no.3 s.4
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• pp.7-16
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• 1999

The flow angle at the inlet and exit of a rotor or stator is an important design parameter involved in the design a fan blade. Flow angles along the radial direction for 3-D stacking are calculated using two kinds of vortex methods, i.e. free vortex method and forced vortex method. The performance test shows that a fan designed by the free vortex method is more efficient than a fan designed by the forced vortex method. As a reference, an imported fan is tested. Even though the straightner of the imported fan is used for the comparison test, the difference of efficiency between the imported fan and the fan designed by the free vortex method is negligible. The noise of the fan designed by the free vortex method is less than that of the imported fan. A bellmouth installed at the fan inlet improved the fan efficiency more than $10\%$.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.942-945
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• 2003

Noise cause is dividing to fluid noise by exhaust flow of fan and vibration noise by rotational vibration of motor. Until now, measuring method has been used to measure vibration by the accelerometer, this method has been not measured for the vibration in some parts of brush and commutator because of motor construction. This research was purposed on the accurate analysis. using laser vibration analyzer, of noise cause against the difficult part in old times. By using this measured data, we would like to use for the design of silent motor.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.1416-1422
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• 2000

The cross-flow fans have been widely used to constitute the air moving systems in many air-ventilating and air-conditioning devices. The cross-flow fan system has many design parameters which have crucial influence on the performance and the noise characteristics of the devices. As a result, there are many difficulties in the design stage of the devices 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 the shape of the stabilizer, the profile of the scroll casing, and the diffusion angle of the flow exit. The results are expressed as the fan performance and the specific sound pressure level characteristic. These parts have been found to have crucial effects on the system performance/noise characteristics and should be considered with care in the design stage.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.772-777
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• 2002

A BEM is highly efficient method in the sense of economic computation. However, boundary integration is not easy for the complex and moving surface e.g. in a rotating blade. Thus, Kirchhoff surface is designed in an effort to overcome the difficulty resulting from complex boundary conditions. A Kirchhoff surface is a fictitious surface which envelopes acoustic sources of main concern. Acoustic sources may be distributed on each Kirchhoff surface element depending on its acoustic characteristics. In this study, an axial fan is assumed to have loading noise as a dominant source. Dipole sources can be computed based on the FW-H equation. Acoustic field is then computed by changing Kirchhoff surfaces on which near-field is implemented, to analyze the effect of Kirchhoff surface on it.