• 한국유체기계학회 논문집
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• 제13권2호
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• pp.48-53
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• 2010

A computerized design system of axial fan is developed for constructing 3-D blade geometry and predicting both aerodynamic performance and noise. The aerodynamic blading design of fan is conducted by blade angle distribution, camber line determination, airfoil thickness distribution and blade element stacking along spanwise distance. The internal flow and the aerodynamic performance of designed fan are predicted by the through-flow modeling technique with flow deviation and pressure loss correlations. Based on the predicted internal flow field and performance data, fan noise is predicted by two models for discrete frequency and broadband noise sources. The present predictions of the flow distribution, the performance and the noise level of actual fans are well agreed with measurement results.

• 조명전기설비학회논문지
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• 제22권10호
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• pp.104-110
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• 2008

최근 생활수준의 향상으로 쾌적한 주거환경에 대한 요구가 증대되어, 변압기 소음으로 인한 민원이 끊임없이 발생하고 있다. 소음민원을 해결하기 위하여 옥내변전소에서는 공명형 소음기, 방음보조셔터 등의 대책을 시행하고 있으나, 주변환경 변화에 따라 소음대책을 재수립하는 경우가 발생한다. 따라서 소음문제를 근본적으로 해결하기 위해서는 변압기의 소음전파를 예측하여, 변전소 경계지역에서 소음규제기준을 만족시키는 변압기 소음레벨을 제시할 필요가 있다. 본 논문에서는 옥내변전소에서 변압기 증설, 주변압기실 셔터의 개방 등의 운전상황에 따른 소음레벨 변화를 예측하고, 옥내변전소 경계지역에서 소음규제기준을 만족시키는 변압기 소음레벨을 제시하였다.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2000년도 유체기계 연구개발 발표회 논문집
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• pp.91-98
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• 2000

Developed is a computer program for the prediction of the aero-acoustic performance characteristics such as discharge pressure, efficiency, power and noise level in the basic design step of axial flow fan. The flow field and the aerodynamic performance of fan are analyzed by using the streamline curvature computing scheme with total pressure loss and flow deviation models. Fan noise is assumed to be generated due to the pressure fluctuations induced by wake vortices of fan blades and to radiate via dipole distribution. The vortex-induced fluctuating pressure on blade surface is calculated by combining thin airfoil theory and the predicted flow field data. The predicted aerodynamic performances, sound pressure level and noise directivity patterns of fan by the present computer program are favorably compared with the test data of actual fan. Furthermore, the present computer program is shown to be very useful in optimizing design variables of fan with high efficiency and low noise level and in analyzing their design sensitivities.

• Journal of Electrical Engineering and Technology
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• 제7권2호
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• pp.255-263
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• 2012

This paper presents the smart interacting multiple model (SIMM) using the concept of predicted point and maximum noise level. Maximum noise level means the largest value of the mere noises. We utilize the positional difference between measured point and predicted point as acceleration. Comparing this acceleration with the maximum noise level, we extract the acceleration to recognize the characteristics of the target. To estimate the acceleration, we propose an optional algorithm utilizing the proposed method and the Kalman filter (KF) selectively. Also, for increasing the effect of estimation, the weight given at each sub-filter of the interacting multiple model (IMM) structure is varying according to the rate of noise scale. All the procedures of the proposed algorithm can be implemented by an on-line system. Finally, an example is provided to show the effectiveness of the proposed algorithm.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 추계학술대회논문집
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• pp.390-393
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• 2005

In this study, examined heavy-weight floor impact sound to rahmen structure(steel reinforced concrete structure) and bearing-wall structure(box frame type structure) that have slab thickness of 4 form at a standard laboratory through noise and vibration measured. The results of ANSYS modeling of structures was predicted that the nature natural frequency increased according to change of thickness of each slab by finite element analysis, and acceleration value decreased. Rahmen structures compares with bearing-wall structure, nature frequency was predicted low. Measurement results of natural frequency and acceleration level for structures at a standard laboratory, tendency department such as ANSYS modeling appeared. Rahmen structures appeared that reduction effect is less in Acceleration level and heavy impact sound transmission level comparing with bearing-wall structure.

• 한국유체기계학회 논문집
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• 제13권2호
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• pp.59-64
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• 2010

A design method of Sirocco fan is developed for constructing 3-D impeller and scroll geometries, and for predicting both the aerodynamic performance and the noise characteristics of the designed fan. The aerodynamic blading design of fan is conducted by blade angle, camber line determinations and airfoil thickness distribution, and then the scroll geometry of fan is designed by using logarithmic spiral. The aerodynamic performance of designed fan is predicted by the meanline analysis with flow blockage, slip and pressure loss correlations. Based on the predicted performance data, fan noise is predicted by two models for cutoff frequency and broadband noise sources. The present predictions for the performance and the noise level of actual fans are well agreed with measurement results.

• 한국소음진동공학회논문집
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• 제22권5호
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• pp.437-443
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• 2012

In this paper, the hybrid method to identify the exciting forces and radiated noise generated from the reciprocating compressor was presented. In order to identify the exciting force, both the acceleration data measured at the compressor shell and numerical finite element model for the full set of compressor were used simultaneously. Applying the identified exciting forces to the numerical model, the velocity responses of all nodes at the shell were predicted. Finally the radiated noises from the vibrating shell were predicted by using the direct boundary element acoustic analysis. For precise numerical modeling, the stiffness of rubber mounts and body springs were identified experimentally from the natural frequencies measured by impact testing. The error of over-all sound pressure level between predicted noise and measured noise was about 2.9 dB.

• 한국소음진동공학회논문집
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• 제17권11호
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• pp.1021-1027
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• 2007

A construction noise is the main reason for people's petition among the pollution. The purpose of this study is to develop the noise prediction program to see the level of the noise on the construction site more accurately. For this purpose, the database of the power level on the various equipments was made. The noise reduction by distance and the noise reduction by diffraction of barrier were mainly considered and calculated. The simple noise prediction program will provide the information about proper height and length of the potable barrier which satisfies noise criteria of the construction sites from a construction planning stage. To investigate the reliability of this program, the predicted data was compared with the measured data. An average of difference between measured data and predicted data is $0.1{\sim}2.8\;dB(A)$ and a coefficient of correlation is about $0.85{\sim}0.95$.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2000년도 추계학술대회 논문집
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• pp.142-149
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• 2000

It is required that the indoor-noise level of KHST (Korean high speed train) should be lower than 66 ㏈(A) at 350 km/h. In this study, the indoor-noise level of KHST has been predicted to determine the maximum allowable sound power levels of major noise sources. It is found that the indoor-noise requirement for KHST can be met by increasing the transmission losses of the floor and side-wall structures as well as by lowering the sound power levels of two major noise sources including the motor fans.

• KIEAE Journal
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• 제9권1호
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• pp.61-68
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• 2009

In this study, computer simulation program was using to identify the effects of road traffic noise propagation depending on the road types which are very variable in dense city. To achieve this goal, the roads should adjacent to housing complex were categorized into 7 types and propagation noise level should predicted then after simulation of noise exposure population calculation are carried out. Followings the results. First, the road types producing the higher noise level are R1, R2, R3 and R7. The lowest one is R6. And R4, R5 showed that some amount of noise level reduction. Second. the R6 road type which is tunnel shaped showed the highest noise level reduction in vertical distance gap. Last, the order of noise exposure population ratio is R1>R2>R7 and R6 showed the lowest.