• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.1
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• pp.1-7
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• 2022

In this study, vibration analysis of washing machine dehydration was carried out using laser sensors. The suspension of the washing machine was attached to a jig developed for this study. In addition, 10 laser sensors were attached to the jig. The channels of each laser sensor are composed of five channels: front, rear, left, right, and upper. Data acquisition equipment was used to obtain sensor data. The measured data were processed using signal processing, and interpolation of the data was performed using MATLAB with robust interpolation. Vibration analysis according to unbalanced mass and sensor attachment points was carried out.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.6
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• pp.1819-1826
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• 1996

This paper present the claculating method of optimum correction mass within permissible vibration linits for ratating machinery in two-plane field balancing. Basic technique of this method is based on influence coefficient method, and grphic vector composition that the resultant of two influence vectors obtained by trial mass have to be equilibrium with initial vibration vector in the each correction plane. Genetic algorithm which is a search algorithm based on the mechanism of natural selection and natural genetics is sued for vector composition, and SUMT method is used to objective function which seeks optimum correction mass for balancing a rotor.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.26 no.1
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• pp.114-120
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• 2017

In recent years, applications of high speed rotating bodies have diversified. It is necessary for a device rotating at high speed to be balanced to minimize vibration. It is necessary to reduce the unbalancing factor to evenly wind the yarn. In this study, we also attempted to devise a technique to minimize the unbalance that occurs while assembling the components of spindles and to simplify the balancing procedure in the field. To balance the spindle, the vibration of the rotating spindle was measured using a laser displacement meter. We also performed balancing using the influence coefficient method by considering the phase.

• Journal of KSNVE
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• v.7 no.6
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• pp.1015-1023
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• 1997

Rotordynamic analysis of a multistage turbine pump using finite element method is performed to investigate the effects of seal wear on its system behavior. Stiffness and damping coefficents of the 2-axial grooved bearing are obtained as functions of rotating speed. Stiffness and damping coefficients of plane annuler seals are calculated as functions of rotating speed as well as seal clearance of seals become larger, these stiffness and damping coefficients decrease drastically so that there can be significant changes in whirl natural frequencies and damping characteristics of the pump rotor system. Although a pump is designed to operate with a sufficient seperation margin from the 1st critical speed, seal wear due to long operation may cause a sudden increase in vibration amplitude by resonance shift and reduce seal damping capability.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1996.04a
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• pp.53-59
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• 1996

오늘날 산업현장에서 사용되는 대부분의 기계와 가전 제품에는 회전기계가 중요한 역할을 담당하고 있고, 이러한 회전 요소에서 종종 진동이 발생하여 문제가 되고 있다. 이러한 진동이 발생시키는 원인 중에서도 회전체의 불평형(unbalance)이 대부분이다. 이러한 불평형 중에도 매 운전 사이클마다 불평형의 크기나 위치가 바뀌는 경우에는 평형잡이 기계로는 불평형을 수정할 수 없다. 이를 자동적으로 수정하는 장치로써 Thearle가 볼(steel ball)을 이용한 자동평형장치를 제안하였고, 정상는 2개의 볼을 내장한 1개 또는 2개의 원판을 설치하여 계의 기본적인 진동특성을 조사하였다. 그리고 볼과 저점성유체를 내장한 단일원판의 자려진동에 대한 안정성을 조사한 연구결과도 있다. 본 연구에서는 위의 이론들을 기초로 하여 1) 2개의 원판을 모델한 기본적인 진동거동, 2) 자동 평형장치로서 이용가능한 운전영역과 자려진동의 발생 영역 및 조건, 3) 계의 파라메터, 즉 각가속도, 원판내의 유체의 점성계수 및 볼의 갯수의 변화에 대한 자동평형장치의 성능 등을 실험적으로 조사하였다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.1419-1424
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• 2007

Centrifugal turbo blower is requested highly efficiency and low noise in FCEV, but the noise generated by this machine causes of the most serious problems in the NVH performance. In general, centrifugal turbo blower is dominated by mechanical noise and aerodynamic noise. Mechanical noise is generated by rotation of the bearing, misalignment and unbalance. And aerodynamic noise is generated by the strong intersection between the flow discharged from the impeller and the cut-off in the casing. The first object of this study is to comprehend a noise property of the blower through the noise test. And, second object is to bring up the method that can reduce blower noise.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.11a
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• pp.515-520
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• 2008

This paper develops a mite element model of a polygon mirror scanner motor supported by the sintered bearing and flexible supporting structures to analyze the shock response by using the finite element method and the mode superposition method. The validity of the proposed model is verified by comparing the simulated natural frequencies and shock response with the experimental ones. It investigates the displacement and the stress of the most vulnerable component, i.e. a leaf spring due to shock, and it proposes a robust design of leaf spring of a polygon mirror scanner motor against shock.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.05a
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• pp.843-847
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• 2007

The unbalanced mass of a high precision rotor deteriorates mechanical performance of the rotor. The geometrical center of a rotor generally corresponds to the rotational axis of the rotor. However, this alignment carried out with a stationary rotor does not guarantee the dynamic rotor balance. There have been a number of schemes for the correction of the imbalance published for decades especially in the hard drive industry where the issues are directly affecting manufacturing costs and product performances. Realizing the significance of the problem, the present work tries to refine one of the methods that works by applying external impact during a rotor spins. A systematic way to apply the external impact to a rotating rotor has been introduced to minimize imbalance correction process time.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1998.04a
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• pp.255-260
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• 1998

A detailed rotordynamic design analysis is performed with a turbo-chiller compressor rotor-bearing system. A pinion is machined into a compressor shaft and the pinion is driven by a bull gear to a rated speed of 14,600 rpm. Utilizing a finite element method each bearing loads are calculated considering various gear loadings as well as the rotor weight itself. A Partial bearing and a 3-Lobe bearing are designed as the compressor impeller out-board bearing and in-board bearing, respectively. Finally a complex rotordynamic analysis of the compressor rotor-bearing system is carried out to evaluate the system whirl natural frequencies, stabilities, and unbalance responses.

• International Journal of Fluid Machinery and Systems
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• v.2 no.3
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• pp.254-259
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• 2009

In this paper it was attempted to treat the hydrodynamic journal bearing as a time-based nonlinear reaction source in each step of rotor rotation in order to observe the bearing effect more realistically and accurately in stead of the conventional method of simple linearized stiffness and damping. Lubrication analysis based on finite element method is employed to calculate the hydrodynamic reaction of bearing and Newmark's method was used to calculate the rotor dynamics in the time domain. Simulation for an industrial electrical motor showed remarkable results with differences compared to those by the conventional method in the dynamic behavior of the rotor.