• 한국소음진동공학회논문집
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• 제16권3호
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• pp.240-246
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• 2006

In the air-conditioner, refrigerant induced noise and vibration can be increased when the airflow rate is reduced in order to decrease the noise at the low mode. Through the test and analysis of this kind of noise, it can be verified that the main reasons of refrigerant induced noise are the velocity and flow Induced force of the refrigerant at the inlet of the evaporator, So, in order to reduce this velocity, quality at the evaporator inlet should be minimized. And, in order to reduce flow induced force of the refrigerant, sudden change of fluid flow must not be occurred. So, in this paper, we will review the characteristics of refrigerant cycle and find how the quality and flow induced force can be minimized.

• 전력전자학회논문지
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• 제5권2호
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• pp.200-207
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• 2000

근래 에어컨, 냉장고 및 세탁기와 같은 가전 전기제품에도 전력소비의 저감, 저속운전에 의한 소음저감 및 인간에게 보다 안락한 기능을 제공하기 위하여 인버터 시스템의 적용이 증가되고 있다. 그러나 인버터 시스템은 PWM에 의해 불필요하게 발생되는 전자기소음의 저감과 소음의 질에 대한 감성소음의 개선이 요구된다. 본 논문에서는 브러쉬없는 직류전동기로 구동되는 왕복동식 압축기에 대하여 고정 PWM과 랜덤 PWM의 전자기소음 분석을 통하여 인버터 냉장고에 랜덤 PWM을 적용함으로써 전자기소음의 저감 및 감성소음의 개선효과가 있음을 실험을 통하여 검증하였다.

• 한국소음진동공학회논문집
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• 제18권2호
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• pp.263-271
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• 2008

Compressor radiated noise is one of the dominant noise for the outdoor unit of the air conditioner. Therefore, air conditioner makers are trying to reduce it continuously. Even though noise absorption and isolation technology are one of the important parts for reducing the noise from the compressor, it is usually treated to the substitute technology when the noise from the compressor is very difficult to reduce by the compressor noise control only. In this paper, we focus on the property of the sound insulation for the cabinet and measure it applying the theory of the sound transmission loss and insertion loss of the simple enclosure. The insertion loss is evaluated by the experiments according to the thickness and the aperture of the partition in the cabinet.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 추계학술대회 논문집
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• pp.332-335
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• 2014

Applying damping sheets or dampers (dynamic or mass) can reduce noise from vibrating structure as well as vibration. However, this approach requires increases of weight and cost. If one can reduce structural noise by only modifying the structural shape, which would be the best practice. It is natural that the noise characteristics change when the structure is modified, but the recent experiment on the sunroof frame showed that the modification of the frame beads results in change of the structural damping, so that the corresponding noise can be reduced. In this context, the reason why the structural damping and the related noise upon an impact excitation is changed is theoretically investigated. The change of dynamic and damping characteristics of the strip panels when their shapes are modified is experimentally found and it is shown that such behaviours can be predicted by computer simulation. Some experimental specimen, mainly strip-type panels, are examined for the numerical verification, and especially damping ratios are investigated.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2000년도 전력전자학술대회 논문집
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• pp.53-56
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• 2000

An Electrical equipment is the noise source which makes a noise. So the optimally designed filter should be inserted in the equipment in order to reduce the noise. The noise source impedance is varied according to the frequency It effects on the CE noise. Knowing the magnitude of its impedance and inserting an EMI filter in the equipment we can estimate the insertion loss of the filter. SO it helpful in designing the EMI filter. The measurement method of a noise source impedance is proposed and verified by experiment.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1995년도 춘계학술대회논문집; 전남대학교, 19 May 1995
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• pp.94-99
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• 1995

In order to improve the sound quality and reduce the noise of engines and vehicles efficiently, it is important to quantify the subjective noise characteristics objectively. The exhaust noises of the passenger vehicles have been measured for the subjective assessments. This paper outlines the objective data by which engine noise can be assessed and the salient features of subjective assessments before proposing an approach by which targets for internal vehicle noise may be set. The method to objectify the subjective assessments has been proposed considering three components - Loudness, Harmonic content, Impulsiveness - which have influence on the subjective assessments.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 추계학술대회논문집 I
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• pp.488-493
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• 2001

In accordance with the tendance to construct high-rise apartment buildings, the transporting elevators tend to speed up to 90-105m／min and to drive more frequently. So, the problem of noise produced by the elevator operation has been treated as an important subject. In this research, the actual conditions of noise and vibration which generated and transmitted by the elevator operation in apartment buildings were measured and analysed. And the several noise and vibration control design which helps reduce noise were examined.

• 소음진동
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• 제9권6호
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• pp.1145-1151
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• 1999

Sensitivity analysis and structural modification technique are used to reduce the interior noise of a passenger car. The sensitivity analysis for the noise level at the rear seat shows that the stiffness change at the front lower member and the rear roof rail are sensitive. Using the structural modification method, we verified that the reinforcements at those members decrease the noise transfer function from the body to the rear seat. The combined application of the sensitivity analysis and structural modification method can decrease the noise level effectively.

• 한국철도학회:학술대회논문집
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• 한국철도학회 1999년도 춘계학술대회 논문집
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• pp.218-225
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• 1999

Speed-up and mass reduction of EMU(Electrical multiple unit) causes increase of interior noise. One of the best ways to reduce the interior noise is to identify noise sources. In this study, we evaluated interior noise by contribution analysis. This method is to predict the interior noise contribution of carbody by using transfer function between acceleration and sound pressure. The plan of the interior noise reduction based on the test results was also presented.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 추계학술대회 논문집
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• pp.1794-1798
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• 2008

Inside noise level of a running train in open field is the summation of air borne noise and structure-borne noise. Anti-roll bar is the major transmission path of vibration from bogie. And this vibration gives an effect to the structure borne noise. In this paper, the effect of anti-roll bar is investigated. Structure borne noise is analyzed in terms of changing the mounting position of anti-roll bar to reduce inside noise levels.