• 한국도로학회논문집
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• 제19권6호
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• pp.1-11
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• 2017

PURPOSES : The purpose of this study is to compare noise reduction quantities between before/after two-layer low noise pavement implementation using equivalent noise level analysis and to analyze the noise reduction effects of the two layer low noise pavement with a statistical method such as the Anderson-Darling Test. METHODS : In order to compare and to analyze noise reduction effects between before/after two-layer low noise pavement implementation, data acquisition as noise levels on a roadside and an apartment rooftop was conducted in the study area. The equivalent noise level was estimated in order to compare noise reduction quantities and the Anderson-Darling Test was carried out for estimating noise reduction effects of the two-layer low noise pavement. RESULTS : The equivalent noise levels of before/after two-layer low noise pavement implementation for the roadside during the daytime are 65.355 dB and 63.520 dB and during the nighttime are 62.463 dB and 59.088 dB. The equivalent noise levels for the apartment rooftop during daytime are 57.301 dB and 59.088 dB and during the nighttime are 54.616 dB and 52.464 dB. Also two-layer low noise pavement decreased the noise reduction effects estimated with the statistical method as the Anderson-Darling test for the roadside during the daytime by around 66.68% and decreased noise reduction effects on the roadside during the nighttime by 0.70%. Moreover it reduced noise reduction effects in the apartment rooftop during the daytime and nighttime by 0% and 96.32%, respectively. CONCLUSIONS : Based on the result of this study, two-layer low noise pavement can positively affect noise reduction during both the daytime and nighttime according to the results of estimating the equivalent noise levels and the Anderson-Darling test.

• 소음진동
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• 제5권2호
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• pp.197-206
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• 1995

Microphone array is designed to measure the equivalent source height of vehicle noise. The equivalent source position is defined for an arbirary distribution of acoustic sources above a perfectly reflecting plane and a microphone array for its measurement is developed. The normalized errors of the measured equivalent source heights are defined including the effects of background noise, the geometric near field, and source size. Normalized errors of the measured source heights obtained by a nemerical simulation for each parameter lead to optimization of the microphone spacing and to the design of an array which gives the equivalent source height as a function of frequency. The performance of the designed array is verified using the stationary loudspeaker experiments.

• KEPCO Journal on Electric Power and Energy
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• 제6권4호
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• pp.473-480
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• 2020

In this paper, we proposed a high frequency equivalent circuit considering parasitic impedance components for differential noise analysis on the input stage during DC-DC buck converter switching operation. Based on the proposed equivalent circuit model, we presented a method to measure parasitic impedance parameters included in DC bus plate, IGBT, and PCB track using the gain phase method of a network analyzer. In order to verify the validity of this model, a DC-DC prototype consisting of a buck converter, a signal analyzer, and a LISN device, and then resonance frequency was measured in the frequency range between 150 kHz and 30 MHz. The validity of the parasitic impedance measurement method and the proposed equivalent model is verified by deriving that the measured resonance frequency and the resonance frequency of the proposed high frequency equivalent model are the same.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 춘계학술대회논문집
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• pp.1040-1044
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• 2001

This study is to propose an analyzing method of road traffic noise in apartment sites using computer simulation program. The evaluation method used in this study is to calculate "Site Equivalent Noise Level". It will be possible to set up effective sound proof system with calculation of "The Number of Houses Exceeding Standard Noise Level".

• International Journal of Automotive Technology
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• 제5권3호
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• pp.189-194
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• 2004

The viscoelastic layer material is widely used to control the noise and vibration characteristics of the panel structure. This paper describes the design technology of the effective vibration damping treatment using the concept of the equivalent parameter of viscoelastic layer materials. Applying the equivalent parameter concepts based on theories of shell, it is possible to simulate the finite element analysis of damping layer panel treatments on the vibration characteristics of the structure. And it is achieved the reduced computational cost and the optimal design of topological distribution for the reduction of vibration effect.

• 센서학회지
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• 제4권4호
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• pp.29-40
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• 1995

본논문(本論文)에서는 정전유도(靜電誘導) 트랜지스터의 잡음원인분석(雜音原因分析)을 위하여 직류(直流) 및 잡음특성(雜音特性), 잔존성분(殘存成分), 입력용량등(入力容量等)의 정무화(定武化)에 필요(必要)한 잡음(雜音) 등가회로(等價回路)를 제안(提案)하였다. 가장 단순(單純)한 잡음(雜音) 등가회로(等價回路)는 정전유도(靜電誘導) 트랜지스터의 동작원리(動作原理)에 의한 모델이며, 이 모델에 의한 실측치(實測値)가 산탄(shot) 잡음(雜音)보다 작게 나타났다. 소스 저항(抵抗)이 삽입(揷入)된 등가회로(等價回路)에서는 소스 저항(抵抗)의 부귀환효과(負歸還效果)에 의하여 산탄 잡음(雜音)이 저감(低減)됨을 확인(確認)하였다. 정확(正確)한 잡음저감원인(雜音低減原因)을 분석(分析)하기 위하여 소스 저항(抵抗)과 드레인 저항(低抗)의 계산식(計算式)을 유도(誘導)하기 위한 등가회로(等價回路)를 제안(提案)하였다. 등가회로(等價回路) 확인(確認) 실험(實驗)에서는 잔존성분(殘存成分)에 대한 신호원저항(信號源抵抗)과 출력부하저항(出力負荷抵抗)의 영향(影響)은 작으며, 잔존성분(殘存成分)은 입력환산등가잡음저항(入力換算等價雜音抵抗)으로 나타낼 수 있다. 또한, 입력용량(入力容量)은 부하저항(負荷抵抗)이 $0{\Omega}$일 때 13.6pF이며, 게이트 배선등(配線等) 정전유도(靜電誘導) 트랜지스터 동작(動作)에 직접(直接) 관여(關與)하지 않는 용량(容量)은 10pF정도(程度)이다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 추계학술대회논문집
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• pp.1218-1223
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• 2007

In this study, we experimentally investigate the equivalent ring theory for a slightly asymmetric ring. The slightly asymmetric ring has mode pair and frequency pair due to the small asymmetry and this mode pair generates beat in vibration and sound. In this paper, a slightly asymmetric ring is modeled as the equivalent ring, i.e., the assemblage of a symmetric ring and imperfect point masses. The equivalent ring has the same mode pair condition as that of the original asymmetric ring. Effect of the additional mass attachment is investigated by the equivalent ring theory and the result is compared with those of the measurement and the finite element analysis. It is confirmed that the original ring and the equivalent ring show the same change in frequency and mode under the various additional imperfection mass conditions. The equivalent ring theory explains how the asymmetric elements influence the mode characteristics and provides useful information to tune the beat property.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 춘계학술대회논문집
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• pp.712-717
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• 2004

Recently, the concern for the environmental noise has increased due to the growing of the living standard. The environmental noise regulations based on the equivalent noise level are widely used. However, the noise level, which Is based mainly on the magnitude with A-weighting, the important characteristics of noises in frequency and time domains and the impulsive nature cannot be assessed properly. These can have substantial effects on how human respond to noise. Therefore, the noise evaluation methodology based on the sound quality rather than the equivalent noise level can be more suitable to represent human response to the environmental noise. This paper describes the study on environmental noise quality analysis for various noises. A cluster analysis was carried out and the noises were classified into several clusters using the values of sound quality metrics. The classification was confirmed by comparing time and frequency characteristics of the noises. And then the result of Jury testing was analysis.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2012년도 추계학술대회 논문집
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• pp.516-519
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• 2012

This study proposes a method of an equivalent bell model in order to tune the beat period of a Korean bell. In a Korean bell having a slight asymmetry, each circumferential mode splits into a mode pair which has a slight difference in frequency, and the interaction of the mode pair makes a beat in vibration and sound. An equivalent bell model which consists of an axi-symmetric bell and an equivalent point mass, has the same mode property as in a real bell. The equivalent bell model is constructed by the finite element analysis based upon the theory of a revolutionary shell Using the equivalent bell model, the beat period is predicted when the bell thickness is locally decreased to improve the beat property. The predicted result is verified by experiment on a test bell. The proposed method is useful to save the time required for tuning the beat period of a large bell.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 추계학술대회논문집
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• pp.1101-1106
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• 2004

This study presents the reconstruction of sound field radiated from an automotive engine using equivalent sources. Basic concept of the method presented is to replace the engine noise source with elementary sources of multipoles, e.g., monopoles and dipoles. The so-called Helmholtz equation least-squares (HELS) method can reconstruct the sound radiation fields from spherical geometries in a series expansion of spherical Hankel functions and spherical harmonics. In this paper, multi-Point, multipole equivalent sources are employed to reconstruct the sound field radiated from an automotive engine with a fixed rotation speed. To ensure and improve the accuracy of reconstruction, the spatial filters of multipole coefficients and wave-vectors are adopted for suppressing the adverse effect of high-order multipoles. Optimal filter shapes are designed with regularization parameters minimizing the generalized cross validation (GCV) function between actual and reproduced model. After regeneration of field pressures using the proposed method as many as necessary, the vibro-acoustic field of an engine could be reconstructed by using the BEM-based near-field acoustic holography (NAH) technique in a cost-effective manner.