• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 추계학술대회논문집
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• pp.79-82
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• 2004

In general, compressors for refrigerators are major noise source in home environment. The vibration originated from a pump of a compressor can make noise through suspension springs and a LDT(Line Discharge Tube). Especially for the inverter motor driven compressor, the vibration is more serious than it of the constant speed compressors. Because the operation frequency range of an inverter motor driven compressor is very wide from 1600 rpm to 4200 rpm. In this paper, we propose the numerical model to reduce vibration by designing weight balancers and grommets. Results for analytical investigations on the exciting force and moment at the pump mass center, weight balancers and exciting frequency variation are presented.

• 한국소음진동공학회논문집
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• 제21권9호
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• pp.834-841
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• 2011

Obtaining the real exciting force is important for the analysis of structural vibration or sound radiation to represent the actual condition. But in most cases, it is so difficult to get the actual force signals by direct measurement using sensors due to complex geometry. This paper suggests advanced source identification method which can be applied to the prediction of radiated noise considering correlations between measured signals. This method was implemented to the identification of the fan force in the refrigerator. The analysis of structural vibration and radiated noise caused by the fan force was also performed. The comparison between predicted SPL and measured SPL of the radiated noise by the refrigerator fan showed good agreement.

• 소음진동
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• 제8권6호
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• pp.1150-1157
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• 1998

In this Paper, we present an efficient method for finite element vibration analysis of constantly rotating structures with cyclic symmetry, which are deformed to some considerable extent by centrifugal force, Coriolis force and operating load, and vibrate due to several types of exciting forces. A structure with cyclic symmetry is composed of circumferentially repeated substructures with the same geometry. Being only one substructure modeled. the dynamic characteristics of the structure can be analyzed systematically. rapidly and exactly using discrete Fourier transform by means of a computer with small memory.

• 대한조선학회 특별논문집
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• 대한조선학회 2009년도 특별논문집
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• pp.59-64
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• 2009

The propeller induced forces acting on a hull are surface forces and bearing forces. The bearing forces are the forces acting directly on the propeller which are transferred to the hull through the propeller bearings. The surface forces are those which act by fluid pressure directly on the various hull surfaces. Because the surface force is main source to oscillate stern constructions and deckhouse, the estimation of surface force is very important to predict response of forced vibration of that. The estimation methods were statistical analysis method, theoretical analysis method and method through model test.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.107-109
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• 2007

This paper presents a dynamic force analysis of switched reluctance motor using 2D-transient finite element method. The main exciting of the vibration is the electiromagnetic force in the stator that is calculated Maxwell stress method. The advantage for elimation of vibration of 12/8 SRM was explained by comparing the radial force of 12/8 and 6/4 SRM in both time and frequency domain. In order to effective mitigate the vibration during turning off process, effects of different commutation method were investigated.

• 한국정밀공학회지
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• 제10권2호
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• pp.161-169
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• 1993

The elimination of chatter vibration is necessary to improve the precision and the productivity of the cutting operation. A new mathematical model of chatter vibration is presented in order to predict the dynamic cutting force from the static cutting data. The dynamic cutting force is analytically expressed by the static cutting coefficient and the dynamic cutting coefficient which can be determined from the cutting mechanics. The stability analysis is carried out by a two degree of freedom system. The chatter experiments are conducted by exciting the cutting tool with an impact hammer during an orthogonal cutting. A good agreement is shown between the stability limits predicted by theory and the critical width of cut determined by experiments.

• 해양환경안전학회지
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• 제13권3호
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• pp.213-217
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• 2007

폰툰형 초대형 부체구조물은 해양공간의 활용에 있어서 가장 많이 고려되고 또한 적극적으로 연구되어지는 분야이다. 폰툰형 부체구조물의 해상에서의 유탄성 변형은 입사하는 파와 접하는 풍상측에서 가장 큰 값을 나타내고 있다. 본 연구에서는 폰툰형 부유체에 작용하는 파랑강제력을 감소시키고자 개발된 부유식 수평 몰수평판의 효과를 수치해석적인 방법에 의하여 그 특성을 파악하고자 한다. 유한차분법을 토대로 한 수치계산법을 적용하고, 적용된 수치계산법을 실험값과 비교함으로서 프로그램의 신뢰성을 확인한다. 검증된 수치계산법을 이용하여 본 연구에서 실시하고자 하는 폰툰형 부유체에 작용하는 파랑강제력의 계산을 수행하고 그 결과에 대하여 논의한다.

• Journal of Advanced Marine Engineering and Technology
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• 제18권5호
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• pp.56-67
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• 1994

The installation methods of diesel engines in ships would be largely classified into two groups : one is the direct mounting system fixing engine directly into double bottom of the hull, and the other is the resilient mounting system having vibration absorbers between engine and ship body such as rubber plate to prevent shocks or vibration transmission. The direct mounting system is generally used for large-sized low speed diesel engines, because the resilient mounting system has difficulties in reducing the natural frequency of engine itself under normal speed. On the contrary, the resilient mounting system is often used for medium or high speed engines for marine propulsion and generator that have light weight and high revolution speed. Recently, it is even applied to engines having relatively low speed(300-400rpm) for fishing boats. Although many researches for the resilient mounting system have been carried out, many problems in applying these results directly to marine vessels because most of these have been used for automobiles. Up to now we have had to depend on the professional foreign company in design and the supply of parts for the resilient mounting system of marinediesel engines utterly. In preseut study, the exciting forces of engines effecting to resilient mounting were examined, and patterns of vibration and evaluation procedure for force transmission from resilient mounting to the body of hull were established. Also, these results were applied to the analysis of free and forced vibration for the rubber-type resilient mounting systems of marine diesel engines. Besides, after changing the various design parameters, such as locations, angles, dynamic characteristics and the number of resilient mountings, the influences on resilient mounting system were also examined.

• 한국항만학회지
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• 제8권1호
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• pp.17-22
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• 1994

The wave interaction with flexible membrane such as PVC and fabrics is studied to prove its applicability to portable breakwaters. To obtain the wave exciting force acting on flexible membrane, eigen-function expansion method is employed. The effect of flexible is involved in body boundary condition in which x-directional displacement of membrane is obtained by solving the linear membrane equation. Displacement of membrane is assumed to be small compared to wavelength, therefore the tensile force of membrane remains constant. As the numerical examples, transmission and reflection coefficients according to the change of tensile forces are investigated. The hydrodynamic force on membrane, the dynamic tension in the mooring lines and the vertical displacement profile of membrane are also calculated. It is suggested that the flexible membrane can be used to engineering material for the future coastal/ocean applications.

• 한국정밀공학회지
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• 제10권4호
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• pp.216-226
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• 1993

Three dimensional cutting is considered as an equivalent orthogonal cutting through the plane containing both the cutting velocity vector and the chip flow velocity vector in dynamic cutting process. An analytical expression of dynamic cutting force is obtained from the cutting parameters determined by the static cutting. Particular attention is paid to the energy supplied to the vibratory system of cutting tool with two degree of freedom. In this approach, the phase lag of the horizontal vibration of the tool behind the vertical vibration and the direction angle of the fluctuating cutting force is considered in point of stability limits. Chatter vibration can be effectively suppressed by relatively increasing the spring constant and the damping coefficient of the cutting system in the vertical cutting force direction. A good agreement is found between the stability limits predicted by theoretical value and experimental results.