• 한국소음진동공학회논문집
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• 제19권11호
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• pp.1202-1213
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• 2009

Muffler sound quality of a vehicle has widely been evaluated using commercial softwares. However, the commercial softwares are providing only simple sound quality index. To get better sound quality evaluation method of the muffler, a new approach is suggested based on the subjective sound quality test. The suggested subjective sound quality evaluation method is refined with the fuzzy theory. The developed method is applied for the evaluation of various kinds of vehicle muffler sounds.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 춘계학술대회논문집
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• pp.383-386
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• 2003

This paper deals with transmission loss of 3-dimensional rectangular plenum lined chamber. There are three kinds of rectangular plenum lined chamber: throughflow type, flow-reversal type, and end-in/side-out type. The combination of above three types of rectangular plenum lined chamber is used for the commercial HVAC system and automobile exhaust system. However, the ambiguity and complexity of sound absorbing material property and 3-dimensional property have impeded research. In this paper, the transmission loss of three kinds of rectangular plenum lined chamber is derived and calculated. The effect of increase of sound absorbing material is also considered. Analytical solution is calculated by using the locally-reacting property of sound absorbing material.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 추계학술대회논문집 II
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• pp.866-870
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• 2001

Measurement techniques for in-duct acoustic source parameters can be classified into the direct method and the load method, according to whether it utilizes an extra external source or not. It is reported that the load methods yield the negative source resistance and the purpose of this paper is to clarify that the time-varying nature of the source is the main cause of this physically implausible result. For this purpose, the direct and load methods for measuring the source characteristics of a simplified fluid machine are simulated using the time domain numerical analysis. In the numerical simulations, the method of characteristics is employed and the source characteristics are calculated from the resultant data. It is shown that the load method results in negative source resistance for some frequencies, whereas the direct method yields positive values for all frequencies considered. It is found that the result of load method is quite sensitive to the change of cylinder pressure or valve profile in contrast to the direct method.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2008년 영문 학술대회
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• pp.266-271
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• 2008

Generation mechanisms of pressure waves from the H-IIA launch vehicle are analyzed numerically. The Mach wave radiated downstream from wavy shearlayer of supersonic exhaust plume is revealed to be the dominant noise source. Reflecting from the constructions of the launch-pad, the Mach wave turns to propagate to the vehicles. It was also found that the fluctuating supersonic plume entering into the flame duct is the dominant noise source that appears in the flame duct. Then, the pressure wave propagates through the flame duct and is ejected outside to the vehicle.

• International Journal of Automotive Technology
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• 제2권4호
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• pp.135-145
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• 2001

DEUTZ AG, co-founded in 1864 by Nicolaus August Otto, the inventor of the four-stroke cycle engine, has developed the new 2013 engine for commercial vehicles on the basis of the tried and tested 1012 and 1013 series. With 4 and 6 cylinder models, the engine covers the power range between 100 and 190 kW. At the time of their introduction to the market, the engines will meet the exhaust emission legislation of EURO IV and incorporate the potential for EURO IV, Further engineering targets were. (Compactness, Favourable power/cost relation, Low weight, Low fuel consumption and Low noise level). All targets could be accomplished in a relatively short development period via the application of modem simulation tools and test methods. In this paper, the design configuration of the engines is described with particular emphasis on measures for noise emission reduction and the combustion system including injection and turbo charging. Furthermore, we demonstrate the engine's potential to fullfill the European emission legislation EU4, which comes into force in 2005.

• 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.

• 오토저널
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• 제11권1호
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• pp.57-67
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• 1989

본 연구에서는 음향 인텐시티법을 가솔린 엔진에 직접 적용하여, 각각의 중심주파수별 음향인텐시티 응답특성을 1/3옥타브 밴드로 구하였고, 오버올 레벨 및 최대 인텐시티레벨을 갖는 중심주파수에서의 음향 인텐시티 방사특성을 등고선 및 3차원 표시로 나타내었다. 또한 그 결 과를 분석 및 고찰하여 엔진의 중요 소음원을 검출하므로써 이 수법이 소음대책에 유효하다는 것을 검증하였다. 연구 결과, 오버올 레벨에서는 아이들링 상태의 경우 엔진 전면부에서, 2,000 rpm 상태의 경우 엔진 우측부에서 가장 높은 음향 인텐시티가 방사되었으며, 최대 인텐시티레 벨을 갖는 중심주파수에서는 오일팬과 흡, 배기매니홀드가 100Hz에서 가장 높은 음향 인텐시티를 나타내었다.

• 한국음향학회:학술대회논문집
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• 한국음향학회 1994년도 FIFTH WESTERN PACIFIC REGIONAL ACOUSTICS CONFERENCE SEOUL KOREA
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• pp.662-667
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• 1994

This paper presents the design and construction details of a soundproof enclosure for housing 20 KVA diesel generator-set. As the generator had to be installed close to the hospital building, it was desirable to reduce the transmission of noise by housing the generator in such an enclosure. The diesel engine being an air cooled one, it was essential to supply fresh air into the enclosure for its cooling. Forced inflow of air is provided through an inlet duct located in such a way that the incoming fresh air is thrown close to the inlet of cooling fan of the engine. The high velocity air stream, which heats up while passing over the engine head, escapes to the atmosphere through a rectangular outlet duct with enlarges inlet that receives hot air from the engine. The air ducts were designed specially and have been provided with acoustic lining for sound absorption. The masonary enclosure has been provided with double glazed fixed windows and double doors. The exhaust pipe of the engine fitted with a muffler has been taken out through the enclosure wall facing away from the hospital. Acoustic performance studies conducted in terms of attenuation provided by the enclosure at different frequencies have also been presented and discussed. The noise control measures adopted for building the sound-proof enclosure have been found to be quite effective as the noise levels inside the hospital building are now within the acceptable limits.

• Journal of Advanced Marine Engineering and Technology
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• 제17권4호
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• pp.49-62
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• 1993

It has been a principle research topic on the diesel engine development to increase the efficiency and the performance of engine to satisfy the user's needs for high reliability and durability. However, recently with the worldwide concerns at the global climate change and environmental protection, the main target in the diesel engine research has been changed to solve the exhaust emission problem in order to satisfy the strict emission regulations. To reduce the pollutant for the diesel engine, the researchs on the combustion chamber is the most important and has to be performed first of all. The diesel fuel injection system plays major role to air-fuel mixing process and influences engine output, themal efficiency, reliability, noise, and emissions. The experimental studies were conducted by varying the various parametric conditions and the results were campared with the computation and calculated results by using the fuel injection simulation program developed during previous research. From the experiments, the matching technique of a fuel injection pump and nozzle was conducted to understand under the various parametric conditions. Also, the relations between needle lift and wave propagation characteristics in high pressure pipe were examined. The basic design data from the experimentations and computation works would be applied to actual design works of diesel fuel injection system.

• 대한기계학회논문집B
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• 제31권6호
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• pp.507-513
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• 2007

This study represents the temperature uniformity in catalytic converter. Present research model type is a monolithic catalytic converter. This type was been widely used for complying the regulations of pollutant emissions from automobiles. The mean experimental parameters are engine speed and ceramics monolith in the catalytic converter. The experimental test engine model used was the 124.1cc motorcycle engine. The experimental study using thermal imaging method shows the megaphone type model has larger effective area than the basic model. The rate of effective area in the basic model is about 8.9 % and the megaphone type model are 41.52 %, 34.60 %, 33.43 %, 25.43 %, 17.82 % according to the diffuser angle $4^{\circ}\;to\;8^{\circ}$. In conclusion, the megaphone type monolithic converter has higher efficiency of reducing the pollution with less noise compared to the basic shape. We believe this will be very important as a design guide of the advanced motorcycle.