• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1993년도 제18회 학술대회 초록집
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• pp.70-76
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• 1993

From the analysis of shaft-bearing indeterminate system, moment and misalingment angle which was generated in bearing were determined. And the influence of span length between bearings on the fatigue life was established. The equation to estimate the cage rotational speed was proposed, and this equation was verified by the measuring of cage speed and shaft speed. And accoding to quasi-static analysis, the spinning speed of ball was determined.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1990년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 26-27 Oct. 1990
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• pp.805-810
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• 1990

Optimal control systems for a radial magnetic bearing are proposed and tested. An electromagnet system model is developed to predict bearing forces as functions of changing coil currents and rotor position. Models of the multi-mass rotor supported by the magnetic bearings are developed and confirmed, and theoretical relationships are expressed in the form of state equation. As a result of computer simulation, the state feedback with optimal procedure is considered to be more effective for magnetic bearing systems than the classical method.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1994년도 추계학술대회 논문집
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• pp.317-322
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• 1994

The design and performance verification of collocated capacitance sensor system for magnetic bearing is presented. Noncollocation between actuators and sensors may cause unstable rotor behavior. The capacitance sensor is not affected by magnetic field. PCB type capacitance sensor is installed between magnetic bearing polse. so, collocation of sensors and actuators can be achieved. Experiment of sensor's static and dynamic charactistics is conducted. Modeling of the rotor system supported by magnetic bearing is made. And performance comparison between simulation and experiment is showed.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 B
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• pp.1039-1041
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• 2003

There are many advantages of the Magnetic Bearing system, compared with conventional contacting bearing systems. Since the spindle in the Magnetic Bearing system is levitated by electro-magnetic forces and rotates without mechanical friction, it can run without lubrication. So, it can run in the extreme circumstances, e.g. a vacuum condition in the space.

• 소음진동
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• 제6권1호
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• pp.71-82
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• 1996

The finite element analysis for rotor bearing systems has been an essential tool for design, identification, and diagnosis of rotating machinery. Among others, the unbalance response analysis is fundamental in the vibration analysis of rotor bearing systems because rotating unbalance is recognized as a common sourve of vibration in rotating machinery. However there still remains a problem in the aspect of computational efficiency for unbalance response analysis of large rotor bearing systems. Gyroscopic terms and local bearing parameters in rotor bearing systems often make matters worse in unbalance response computation due to the complicated dynamic properties such as rotational speed dependency and/or anisotropy. The present paper proposes an efficient method for unbalance responses of multi-span rotor bearing systems. An improved substructure synthesis scheme is introduced which makes it possible to compute unbalance responses of the system by coupling unbalance responses of substructures that are of self adjoint problem with small order matrices. The present paper also suggests a scheme to easily deal with gyroscopic tems and local, coupling or bearing parameters. The proposed method causes no errors even though the computational effort is reduced drastically. The present method is demonstrated through three test examples.

• 동력기계공학회지
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• 제11권2호
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• pp.72-76
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• 2007

Since the magnetic bearing system has unstability inherently it is necessary to measure the displacement for stable operation. Normally the displacement measurement is implemented by using sensors. The sensor for the displacement measurement is selected by precision, installation space, effect of magnetic field and response speed. And the cost of displacement measurement sensor also is considered. At the cost the hall effect sensor has a large advantage comparing with the others. Therefore this study concern about the basis experimental test for the displacement measurement of the magnetic bearing system that uses the hall effect sensor coupled with a tiny permanent magnet. The experimental results confirm the validity and practicability for this displacement measurement sensor.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1999년도 전력전자학술대회 논문집
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• pp.427-430
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• 1999

This paper presents a S-FES(Superconducting magnetic bearing Flywheel Energy Storage System) for the purpose of replacing battery used to store the energy. Especially, the design elements of FES, such as the bearing, wheel material, and power converter, etc., is described. The design and manufacturing techniques of the controllable power converter are proposed to generate the sinusoidal output current in the high speed operation and to get the constant DC voltage in the regeneration mode. The cylindrical permanent magnet synchronous motor with halbach array of Nd-Fe-B permanent magnet which is the high coercivity material is used as the driver of FES. The proposed S-FES system shows the stable rotation characteristics at high speed range about 10,000 rpm. To verify the validity of proposed system, the comparative study with the conventional ball bearing system is proceeded and it is well confirmed with the result of the lower friction loss of S-FES system.

• 한국생산제조학회지
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• 제21권1호
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• pp.175-181
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• 2012

This paper presents a novel dynamic vibration absorber (DVA) to suppress the unbalance response of flexible rotor-bearing systems. The DVA unit consists of two DVAs, an adapter to place the DVAs and an adapter frame to locate the adapter. The essential feature of the proposed DVA unit is to place itself on any desirable location of the shaft without disassembling the rotor-bearing system under consideration. A simulation with a 3D element based commercial rotor dynamic software is made to test the possibility of the proposed DVA on the suppression of unbalance response in rotor-bearing systems. Experiments are performed to validate the proposed DVA unit. The simulation and experiments show that the proposed DVA unit is very effective to suppress the unbalance response in rotor-bearing system at designated rotational speeds of interest.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1993년도 춘계학술대회논문집; 한국과학연구소, 21 May 1993
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• pp.101-106
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• 1993

A new rotor control scheme, the isotropic control of anisotropic rotor bearing system in complex state space, is proposed, which utilizes the concepts on the eigenstructure of the isotropic rotor system. Then the control scheme is applied to an active magnetic bearing system and the control performance is investigated in relation to control energy, transient response, and unbalance response. In particular, it is shown that the proposed method is efficient for control of unbalance response.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.963-967
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• 2007

Flywheel energy storage systems (FESS) have advantages over other types of energy storage methods due to their infinite charge/discharge cycles and environmental friendliness. The system has two radial bearings and one hybrid-thrust bearing. Thrust hybrid-type bearing use permanent magnet to relieve gravity load. The radial bearings were designed to provide sufficient force slew rate considering the unbalance disturbance at the operating speeds. In this paper, we will derive dynamic model of hybrid-type bearing using permanent magnet for thrust bearing and present simulation and stability of the model.