• Journal of Korean Institute of Industrial Engineers
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• v.39 no.5
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• pp.351-360
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• 2013

Taguchi's robust design is a method for quality improvement by making a system insensitive to uncontrollable variations incurred by noise factors and it has received much attention in a wide range of engineering fields. Robust design can be broadly classified into static and dynamic ones. This paper is concerned with dynamic robust design. Taguchi suggested to use a signal-to-noise ratio as a robustness measure, but there has been much debate and criticism on its blind use. In order to cope with this drawback, many alternatives have been proposed. They are divided into performance measure modeling (PMM) and response function modeling (RFM) approaches. In this paper, both PMM and RFM approaches for dynamic robust design are reviewed. An example for illustration is provided as well.

• The Journal of the Acoustical Society of Korea
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• v.11 no.1E
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• pp.56-63
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• 1992

The poblem of active oise control has been analysed using a adaptive signal processing technique. In this methods, the adaptive signal processor or model predicts the primary sound wave travelling along the acoustic plant and generates the secondary source 180° out of phase which attempts to attempts to attenuate the undesired noise by destructive interference. In the solutions presented here, acoustic propagation delay is considered as a part of the model which used the FIR filter. The effects of error path and auxiliary path transfer functioin are anayzed and a new on=-line technique for error path modeling, adaptive delayed inverse modeling is presented. In this study, using these new concepts, our system can more reduce the noise level in duct to 5dB-15dB than only using LMS algorithm system.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.1704-1709
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• 2000

This paper proposes a spherical probe allowing acoustic intensity measurements in three dimensions to be made, which creates a diffracted field that is well-defined, thanks to analytic solution of diffraction phenomena. Six microphones are distributed on the surface of the sphere along three rectangular axes. Its measurement technique is not based on finite difference approximation, as is the case for the ID probe but on the analytic solution of diffraction phenomena. In fact, the success of sound source identification depends on the inverse models used to estimate inverse diffraction phenomena, which has non-linear properties. In this paper, we introduce the concept of nonlinear inverse diffraction modeling using a neural network and the idea of 3 dimensional sound source identification with several tests.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.1318-1320
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• 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.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.26 no.7
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• pp.774-780
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• 2016

In this paper noise source and transfer path of tactical vehicle are analyzed with partial coherence function and spectrum analysis. Engine, transmission, structure panel and aerodynamic are main source of cabin noise. To reduce cabin noise, identifying transfer path of sources and analyzing their contribution is important. With modeling of transfer path and partial coherence function, transfer path and principal noise source can be identified. Engine/transmission and structural resonance are principal source of low frequency noise and by adding stiffener and sound absorbing material, resonance of vibration and inflow air problem can be solved.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.10a
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• pp.605-610
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• 2013

This study proposes an analysis model to simulate a noise map and estimate noise distribution for a location and its surroundings of a power plant. The noise map analysis was executed by using ENPro that is a commercial program for environmental noise prediction. Experimental evaluation for the proposed analysis model was carried out by comparing the results from noise analysis and measurement at several major points of the power plant and residential areas.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.554-558
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• 2004

In this paper, we introduce noise prediction program of HVAC system to assist low-noisy design of ship's cabin. The developed program calculates sound power levels at HVAC components considering primary and secondary noise generated by fan and duct element, duct element noise attenuation, and duct break-in noise based on the authentic empirical method suggested by NEBB and acoustic power balancing method. Sound pressure level at cabin with or without ceiling system is evaluated by the diffuse-field theory considering diffuser and duct break-out sound powers. Moreover, the program provides intuitive pre- and post-processors using modem GUI functions to help efficient modeling and evaluation of cabin and HVAC component noise. To validate the accuracy and convenience of the program, noise prediction for a HVAC system is demonstrated.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.1441-1447
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• 2008

This research studies the effects of community noise around railway, noise from the inside/outside noise of the High-Speed EMU. First study part of this year is research of the noise source. The modeling methodology for prediction of noise level including the frequency property, velocity dependence, sound pressure of noise source is investigate. Second part is research on the sound transmission loss. An exclusive program which could analyze the sound transmission loss of the floor, the sides(mirror), insulator in High-Speed EMU has to be developed. Third part is research on the train inside/outside and Prediction for community Noise. In order to predict the noise when the High-Speed EMU is traveling at the outside and along tunnels, the result of the research can be derived by evaluating the effect of the noise on the upper/middle parts of the carriage and on the railroad way round about with using the program.

• Journal of Environmental Impact Assessment
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• v.18 no.3
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• pp.143-150
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• 2009

The present study investigates the effects of the flight paths of military aircraft on noise map and its WECPNL(Weighted Equivalent Continuous Perceived Noise Level) distribution. Aircraft noise modeling and simulation have been performed on a Korean military air base by means of INM(Integrated Noise Model) with the input data of airfield location, aircraft specifications, flight paths and aircraft's operation schedules. The result of noise modelling has been verified in comparison with the result of measured noise level. The flight path of military aircraft, as the key parameter of the present study, was modeled by combining takeoff, overfly, approach and touch-and-go modes. The present INM simulations have been conducted for various flight path cases with different takeoff, approach modes and overfly modes. The simulation results showed that the change of flight path can remarkably affect the noise influence region and the WECPNL distribution around the airfield.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.11
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• pp.1071-1077
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• 2010

The reduction of the vehicle interior noise has been the main interest of noise and vibration harshness(NVH) engineers. A passenger vehicle has various and complicated transmission paths of sound and vibration. In order to identify the mechanism of transfer path, estimation of excitation force and exact modeling of transfer path are required. This paper presents method for estimating the noise source contribution on the road noise of the vehicle in a multiple input system where the input sources may be coherent with each other. And vector synthesis technique is employed to identify the characteristics of road noise and its transmission to vehicle compartment through noise and vibration analysis. Vibration reduction efficiency of each transfer path is evaluated by comparing individual vector components obtained virtual simulation.