• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 봄 학술발표회 논문집(I)
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• pp.29-32
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• 1998

In this paper, the properties of the agitation noise of agitator truck when flowing concrete practice is applied in construction field of our country are investigated. According to the experimental results, the solution on the noise during the agitation in flowing concrete should be considered in order to apply flowing concrete into construction field without the problems such as a civil appeal.

• 한국음향학회지
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• 제14권3호
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• pp.71-81
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• 1995

본 논문에서는 수중에서 발생되는 전이 신호의 자동 식별을 위하여 특징벡타를 추출하는 기법과 식별 알고리즘에 대하여 논한다. 특징벡타 추출기법으로 적은 계수로도 우수한 성능을 보이는 wavelet 변환을 사용한 방법을 제안하고 기종의 고전적인 방법들과 비교한다. 자동식별을 위해서는 MLP (Multilayer Perceptron), RBF (radial Basis Function), MLP-클래스 등 세 종류의 신경회로망을 사용하고, 성능 및 신뢰성을 높이기 위해서 두가지 특징벡타 및 세 식별기를 결합하는 방법을 사용한다. Traco의 표준 천이 데이터 집합 (standard transient data set) I과 모의 실험 데이터를 사용하여, 주어진 천이신호가 배경잡음에 비하여 충분히 에너지가 크고, 유한개의 소음원이 존재하며, 동시에 둘 이상의 소음원이 존재하지 않는다는 가정하에서 제안된 특징벡타 추출기법과 식별 알고리즘의 우수성을 확인한다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2011년도 전력전자학술대회
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• pp.402-403
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• 2011

EMI 필터 설계 시 주로 사용되는 공통모드 초크의 경우 자화 인덕턴스로부터 공통모드 노이즈 감쇠를, 누설 인덕턴스로부터 차동모드 노이즈 감쇠를 기대할 수 있다. 이때, 누설인덕턴스가 너무 클 경우 차동모드 노이즈 감쇠에는 우수하지만, 전기/전자제품이 슬림화됨에 따라 공통모드 초크의 누설 자속과 전원공급기를 덮고 있는 금속덮개 사이에 자계 간섭에 의한 진동/소음문제가 발생될 수 있다. 본 논문에서는 누설자속을 조절할 수 있는 공통모드 초크의 코어형상 및 권선기법을 제안한다. 제안된 방법은 진동 및 소음을 제어할 수 있는 장점을 지니고 있다.

• 한국소음진동공학회논문집
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• 제17권12호
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• pp.1201-1207
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• 2007

The Timoshenko beam theories are used to model the rotating shaft. The nondimensional equations of motion for the rotating shaft subjected to moving mass and compressive axial forces are derived by using Hamilton's principle. Influence of system parameters such as the speed ratio. the mass ratio and the Rayleigh coefficient is discussed on the response of the moving system. The effects of compressive axial forces are also included in the analysis. The results are presented and compared with the available solutions of a rotating shaft subject to a moving mass and a moving load.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 추계학술대회논문집
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• pp.188-192
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• 2004

The purpose of this study is to develop an air spring mount that has high damping characteristic. The new type air spring mount has a polyurethane core in the center. By adding the core, the air spring mount shows excellent damping effect and good resistance to lateral force. This study includes both the analytical study and the experimental study of the new type air spring mount.

• 대한기계학회논문집
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• 제19권5호
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• pp.1280-1290
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• 1995

In order to investigate the compression wave propagating in a high-speed railway tunnel, a numerical calculation was applied to the wave phenomenon occurring in a model tunnel. Unsteady, one-dimensional inviscid or viscous flows were solved by an explicit TVD scheme, and the calculated flows were compared with the results of measurement in real tunnels. Tunnel noises caused by emission of the compression wave were characterized in terms of excess pressure of compression wave, pressure gradient in the wave front and width of the compression wave. Calculated attenuation, pressure gradient and width of compression wave with the propagating distance agreed with the results of measurement in the real tunnels. The results also show that tunnel noises are proportional to the train velocity entering the tunnel.

• 한국철도학회:학술대회논문집
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• 한국철도학회 1999년도 춘계학술대회 논문집
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• pp.200-207
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• 1999

The purpose of this research is to setup the design procedure of low noise rolling stocks. Noise sources are identified at a field test, and the contribution of noise sources to each part of car interior is ensured by sound intensity measurement technique. Added material to each section of the carbody makes it possible to identify absorption or reflection performance of each part to the anterior random noise. Such experimental tests to the exterior noise intruding through the floor represent that the best countermeasure on the floor is to implement reflecting material which can properly interfere noise. Design procedure of low noise rolling stocks is set through several experiments.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 추계학술대회논문집
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• pp.69-74
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• 2006

It is known that the various noise sources which are engine, transmission, tire, intake system, etc exist at vehicle driving status. Specially noises which cannot be expected by a driver induce unpleasantness to all passengers. These noises are difficult to distinguish noise sources or specifications because of too many vehicle parts. Therefore in this paper, study on abnormal noise of bush on suspension system is performed by the measurement and analysis of the noises of bushings that are generated artificially. The measured noises are analyzed by two points-view of spectrum and sound quality. Finally, it is shown that the noise sources of bushings on the suspension system which are the pillow ball joint bush of a control arm and the rubber bush of a lower arm could be distinguished by the spectrum distribution and a index value based on tonality.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.759-763
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• 2006

The World Health Organization(WHO) has recommended population of sleep disturbance as one of the environmental health indicators. But the percentage of respondents who felt highly sleep disturbed, that is, %HSD can???thave application to sleep disturbance from instantaneous noise. Therefore, this study has been carried out to present the technique for assessing sleep disturbance on instantaneous noise quantitatively. The study of sleep disturbance on night time instantaneous railway noise has been undertaken. Noise monitor has been in operation from 22 hours to 7 hours during 6 nights at 12 locations. To assess instantaneous noise induced sleep disturbance, it was decided to measure body movement by actiwatch. %motility was used as indicators of sleep disturbance. %motility is the expected value of probability of motility value during 7 epochs (105s) of any noise event. The measures of instantaneous motility have been related to measures of instantaneous railway noise events. The relationship shows that %motility is a good predictor for assessing sleep disturbance and Korean is more sensitive to noise than European although the railway noise have been considered in this study. This study can be extended to assessing long-term sleep disturbance and give a guideline far policy decision.

• 한국소음진동공학회논문집
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• 제22권10호
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• pp.985-993
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• 2012

In this paper, a new method is proposed to estimate the sound pressure generated from gasoline direct injection (GDI) engine. There are many noise sources as much as components in GDI engine. Among these components, fuel pump, fuel injector, fuel rail, pressure pump and intake/exhaust manifolds are major components generated from top of the engine. In order to estimate the contribution of these components to engine noise, the total sound pressure at the front of the engine is estimated by using airborne source quantification (ASQ) method. Airborne source quantification method requires the acoustic source volume velocity of each component. The volume velocity has been calculated by using the inverse method. The inverse method requires many tests and has ill-condition problem. This paper suggested a method to obtain volume velocity directly based on the direct measurement of sound intensity and particle velocity. The method is validated by using two known monopole sources installed at the anechoic chamber. Finally the proposed method is applied to the identification and contribution of noise sources caused by the GDI components of the test engine.