• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2009년도 춘계학술대회 논문집
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• pp.92-97
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• 2009

The performance of cooling fan is affected by many peripheral parts, such as radiator, condenser, engine block and etc. Higher power has been requested in more confined automobile engine room. Thus, cooling performance becomes very important to remove the heat generated from the automobile engine more efficiently. In this paper, the performance of cooling fan including effects of engine block is investigated by using a fan tester based on the ASHRAE and the AMCA standards. A flow rate - gap distance curves and a flow rate - engine block constant curves are obtained from this study.

• 대한조선학회 특별논문집
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• 대한조선학회 2013년도 특별논문집
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• pp.55-59
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• 2013

Transverse vibrations of ship's aft end and deckhouse among the various modes of hull structures are induced mainly by transverse exciting forces and moments of main engine such as ${\times}$ and h-moment. Avoidance of resonance should be made in a intial design stage in case there is a prediction for resonance between main engine and transverse modes of deckhouse. This study shows a case of change in type of main engine from 12 cylinders to 10 without modification of hull structures in engine room requested by a shipowner of 8,600 TEU class container carrier and proposes a guide to the effective ways of structural arrangement for avoiding resonance between transverse exciting force and surrounding structures of main engine in engine room through case studies.

• 한국소음진동공학회논문집
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• 제20권4호
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• pp.348-354
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• 2010

In the beginning of vehicle development, it is difficult to define the concept of engine mounting system. With only the property of vehicle, we have to find the direction of engine mounting system. And it is important to find common mounts for several engine variation in order to reduce the cost and manage mounts efficiently. This paper introduces the software which has developed for engine mounting system analysis. And its function and usefulness are explained in paper. The examples have correlated between the analysis model and real model to raise the accuracy during development of engine mounting system are shown in paper.

• Journal of Advanced Marine Engineering and Technology
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• 제4권1호
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• pp.2-22
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• 1980

In the earlier days, when the diesel engine was used for ship propulsion, its shaft had often been broken by uncertain causes. Bauer suggested, for the first time in 1900, that it resulted from the torsional vibration of the shaft system. From 1901 to 1902, Gumbel and Frahm found out that shaft failures were caused by the resonance of the shaft system in critical speed. Since that time, valuable theories, empirical formulae and methods of vibration analysis were introduced by many investigators such as Geiger, Holzer, Lewis, Carter, Porter, Constant, Timoshenko, Dorey, Den Hartog, Tuplin, Ker Wilson, Bradbury etc. But, as the calculation of the damping energy involves very complicated and uncertain factors, the estimated amplitude of the torsional vibration is incorrect and uncertain. Besides, as high-powered engines have been installed on large vessels or special vessels and exciting force has been increased, new problems of the torsional vibration have continuously occurred. Although we can calculate the approximate natural frequencies or estimate their amplitude and additional stress in the design stage, through the above mentioned studies, the results of the calculations are unsatisfactory, and so much time is needed to carry out the calculation by hand. The authors have developed a computer program to calculate its natural frequencies, the amplitudes and additional stresses of the torsional vibration in the marine diesel engine shafting. In developing the computer program, the authors have paid the special attention to the calculation of the damping energy. To verify the reliability of the developed computer program, the torsional vibration of several propulsion shaftings which are driven by the diesel engine has been analyzed. The results calculted by the authors' computer program show good agreements with those of the actual measurements and are better than the results of engine maker's calculation.

• Journal of Advanced Marine Engineering and Technology
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• 제16권5호
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• pp.85-96
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• 1992

Engine enclosures are widely adopted to reduce the noise emission in various fields of application. The radiated noise, which is due to the vibration of enclosure's outer surface, is composed of two kinds of sound power with different path of propagation. One is the 'structure-borne sound power' which stems from the engine's vibratory force applied to the structure of enclosure through the mounting parts of engine etc., while the other is the 'air-borne sound power' which is originated by the sound power radiated from the engine surface to the inner space of enclosure that should excite the vibration of enclosure from inside. In order to get a most efficient engine enclosure is required a profound consideration upon the above structure-borne and air-borne noise, since the guiding principle of countermeasure for each noise is quite different. The controlling of input vibration and its isolation are major subject for the structure-borne sound power and the specifications of absorbing member and damping panels are the major interests for the air-borne sound power. Hence it seems very efficient to separate the total sound power into two categories with a great accuracy when one think of further reduction of engine noise from the exciting enclosure, however, its separating methods have not been made clear for many years. Then author proposes a new practical separation method of two propagation path's contribution to the total radiation sound power for the enclosure under the engine operating condition.

• 한국추진공학회지
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• 제13권3호
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• pp.1-8
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• 2009

본 연구에서는 비행 중 PW4000 엔진의 축류압축기에서 발생된 서지 현상이 엔진성능에 미치는 영향에 대하여 연구하였다. 이륙조건에서는 항공기의 엔진성능이 급격히 변화하므로 순항할 때 보다 자주 서지가 발생할 수 있다고 판단된다. EPR은 서지 발생과 동시에 급격히 저하하는 것으로 나타나 민감도가 가장 컸다. 엔진 rpm과 Wf도 EPR과 거의 동일한 경향이었으며, Vibration 변화는 크지 않았으나 N1 Vibration 변화가 상대적으로 크게 나타났다. 따라서 비행 중 EPR, N1 rpm, Wf 값이 급격히 저하되고 EGT가 비선형적으로 상승하는 상태를 서지 발생 감지에 적용할 수 있을 것으로 판단된다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 춘계학술대회논문집
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• pp.855-860
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• 2001

In this study, the improvement work to reduce the steering wheel vibration of a forklift truck is performed. The forklift truck newly developed possesses a trans-axle type power train to achieve a compact and low-price design. The forklift truck is directly subjected to a high-level engine vibration through hard mounted trans-axle housing. The engine vibration shakes the whole system of the forklift truck, and then a high level local vibration of steering wheel could not be avoided. As the results, the vibration source and path mechanisms are experimentally identified and then an improvement design is proposed to minimize the steering wheel vibration.

• 한국자동차공학회논문집
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• 제18권6호
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• pp.138-144
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• 2010

If the vibration is occurred in a large-sized bus roof, it makes people annoying and complaining the quality of a large-sized bus. So in design stage, it must be considered. To assess vibration at the roof which is equipped with air conditioner in design stage, finite element model is constructed. Computer simulation analysis and experimental method are performed. The dynamic characteristics of the large-sized bus are found by using eigenvalue method. It is related with dynamic behavior. The running conditions of a large-sized bus are velocity and road condition which followed experimental conditions. And the frequency response of a large-sized bus is well correlated with analysis result. Modal participation method is used for finding major modes at each peak. Using this method, we found that front and rear suspension system, engine mounting system and roof structure are the major reasons of the roof vibration. To reduce vibration level of roof in a large-sized bus, spring stiffness of front and rear suspension system, spring stiffness of engine mounting system and roof structure are properly combined. From this study, the vibration characteristics of the roof structure of a large-sized bus can be to a satisfactory level.

• 한국소음진동공학회논문집
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• 제25권12호
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• pp.815-821
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• 2015

Maritime safety has been more critical recently due to the occurrence of shipboard accidents involving prime movers. As such, the propulsion shafting design and construction plays a vital role in the safe operation of the vessel other than focusing on being cost-efficient. Smaller vessels propulsion shafting system normally install high speed four-stroke diesel engine with reduction gear for propulsion efficiency. Due to higher cylinder combustion pressures, flexible couplings are employed to reduce the increased vibratory torque. In this paper, an actual vibration measurement and theoretical analysis was carried out on a propulsion shafting with V18.3L engine installed on small car-ferry and revealed higher torsional vibration. Hence, a rubber-block type flexible coupling was installed to attenuate the transmitted vibratory torque. Considering the flexible coupling application factor, reduction gear stability due to torque variation was analyzed in accordance with IACS(International Association of Classification Societies) M56 and the results are presented herein.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2013년도 춘계학술대회 논문집
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• pp.273-278
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• 2013

This paper presents optimal design procedures of mount based on a magnetorheological (MR) fluid to isolate the vibration in heavy diesel engine system. At first, frequency response and force-displacement transmissibility methods are used to get required damping force that is necessary for effective vibration isolation. From this result, a new type of high damping force engine mount is proposed and the governing equation of Bingham plastic behavior of MR fluid in flow path is mathematically derived under cylindrical coordinates. Finally, parametric design optimization featuring finite element is performed using ANSYS software to get the required damping force in MR mount system which can be used to reduce engine vibration. Damping force of the MR mount is then determined as an objective function in this analysis based on ANSYS. Furthermore, Magnetic analysis is then applied in this process.