• KSTLE International Journal
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• v.2 no.2
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• pp.93-102
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• 2001

Ball bearings have been widely used for the spindle motor bearing in various kinds of information storage devices. Recently many researchers have been trying to replace ball bearings with fluid film bearings because of their superior NRRO(non-repeatable runout) characteristics. In this study, a numerical analysis has been conducted for the complicate bearing system composed of herringbone groove journal bearing and spiral groove thrust bearing for the spindle motor of the information storage device. At first, spindle motor bearing is modeled as journal bearing part and thrust bearing part separately, and then observed various influences of geometric parameters. Previous studies had considered only the translational motion of the journal bearing. However, this study takes the additional 2-degree of freedom rotation into consideration to attempt to describe the real motion of the spindle bearing. As a result, rotational stiffness coefficients and rotational damping coefficients are obtained. In addition, a spindle bearing system made up of four bearings is modeled and interpreted at once and coefficients of dynamic characteristics of each bearing are obtained. Finally, an eigen analysis of bearing system is made with these results. Through this analysis, it is possible to estimate an unstable condition of the system for given geometric parameters and to propose a method which is able to avoid the unstable condition by a proper adjustment of geometric parameters.

• KSTLE International Journal
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• v.2 no.1
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• pp.59-64
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• 2001

A new bearing concept, the wave journal bearing, has been developed to improve the static and dynamic performance of a hydrodynamic journal bearing. This concept features a wave in bearing surface. Not only straight but also twisted wave journal bearings are investigated numerically. The performances of straight and twisted bearings are compared to a plain journal bearing over a wide range of eccentricity. The bearing load and stability characteristics are dependent on the geometric parameters such as the number of waves, the amplitude and the starting point of the wave relative to the applied load direction. The bearing performance is analyzed for various configurations and for both cases of smooth and wave member notation. The wave journal bearing, especially for the twisted one, offers better stability than the plain journal bearing under all eccentricity ratios and load orientation.

• Proceedings of the KIEE Conference
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• 2006.10b
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• pp.216-220
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• 2006

This paper is presented for the measurement of the bearing stiffness for the spindle motors. BLDC Spindle Motors for the Hard Disk Drive are used by several kinds of the bearings, such as ball bearing, fluid dynamic bearing, and aero dynamic bearing. The spindle motors are attached the platters to read and write the data. Because the platter rotates at high end speed with the load and can be shocked from a suddenly moving, the bearing needs the rated stiffness with the pressure. By the way, it has not been realized to measure the real stiffness for each bearing types. In this paper, we proposed the method of measuring the stiffness for the bearings by using the magnet force. Experimental results show the performance to measure the bearing stiffness of the BLDC spindle motors for an HDD.

• Journal of the Korean Institute of Navigation
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• v.16 no.4
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• pp.35-45
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• 1992

In this study, an interface is developed in compliance with the standards which is made by National M.E.A in U.S.A for transmitting the Marine Gyrocompass information. The interface consists of Bearing Signal Transfer, Bearing Signal Demodulator, Bearing Signal Discriminator, Bearing Counter and, Informatioin Tranmitter. The results are as follows : The transmission of bearing information was achieved successfully on the Marine RADAR by the interface tranmitting for the Marine Gyrocompass. And, newly proposed phase-detector in Bearing Signal Discriminator which method is forcibly reset the previous data of D-T Flip Flop can be solved the problems of the delay in phase discrimination and the unstableness in the boundary areas of input signal.

• Proceedings of the KIEE Conference
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• 2007.11c
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• pp.175-178
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• 2007

This paper is presented for the design of the thrust yoke for the spindle motors. HDD spindle motors are rotated by fluid dynamic bearing which consists of the shaft and the sleeve with the groove to generate the pressure. Because the thrust and journal clearances between shaft and sleeve is too small, around 8um and 2.5um, respectively, it is very difficult to design the bearing to come up to the disks to read and write the data. By the way, it is also so hard to overcome the load of the disks with only the thrust bearing. So, the paper is proposed for the trust yoke to come up to the disks considering of the force of the thrust bearing. In this paper, we proposed the thrust yoke with an unique fluid dynamic bearing in comparison with the motors without thrust yoke. Experimental results show the performance of the thrust yoke of the spindle motors for an HDD.

• Earthquakes and Structures
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• v.11 no.5
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• pp.841-859
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• 2016

Bridge bearings are important connection elements between bridge superstructures and substructures, whose health states directly affect the performance of the bridges. This paper systematacially presents a new method to identify the bridge bearing damage based on the neural network theory. Firstly, based on the analysis of different damage types, a description of the bearing damage is introduced, and a uniform description for all the damage types is given. Then, the feasibility and sensitivity of identifying the bearing damage with bridge vibration modes are investigated. After that, a Radial Basis Function Neural Network (RBFNN) is built, whose input and output are the beam modal information and the damage information, respectively. Finally, trained by plenty of data samples formed by the numerical method, the network is employed to identify the bearing damage. Results show that the bridge bearing damage can be clearly reflected by the modal information of the bridge beam, which validates the effectiveness of the proposed method.

• Journal of IKEEE
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• v.26 no.2
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• pp.319-328
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• 2022

Bearing plays an important role in the operation of most machinery, Therefore, when a defect occurs in the bearing, a fatal defect throughout the machine is generated. In this reason, bearing defects should be detected early. In this paper, we describe a method using Convolutional Neural Networks (SN-CNNs) based on continuous wavelet transformations and Switchable normalization for bearing defect detection models. The accuracy of the model was measured using the Case Western Reserve University (CWRU) bearing dataset. In addition, batch normalization methods and spectrogram images are used to compare model performance. The proposed model achieved over 99% testing accuracy in CWRU dataset.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.3
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• pp.528-533
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• 2005

The purpose of the study is to develop ship's bearing sensor using GPS receiver which can play a role as a ship's secondary compass. In this research, two GPS receivers are used to determine the bearing in real time. Then we investigated the bearing accuracy associated with the error pattern of two GPS receivers. Especially, the results are as follows the investigation on the system design of GPS-Compass, the modeling to compute heading of sailing, the analysis on bearing accuracy with the error pattern, the defining possibility to play a role as a ship's secondary compass.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.799-805
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• 1996

In many cases, the magnetic farce model is linearized at the origin in designing the controller of a magnetic bearing system. However. this linear assumption is violated by the unmodeled nonlinear effect such as sensor dislocation and backup bearing dislocation. Therefore, a direct probe into the nonlinear magnetic force model in an active magnetic bearing system is necessary. To analyze the nonlinear magnetic force model of a magnetic bearing system, phase plot analysis which is to plot the numerical solution of the nonlinear equation in several initial points in the interested region is applied. Phase plot analysis is used to observe a nonlinear dynamic system qualitatively (not quantitatively). With this method, we can get much useful information of the nonlinear system. Among this information, a bifurcation graph that represents stability and locations of fixed points is essential. From the bifurcation graph, a stability criterion of magnetic bearing system is derived.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.6
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• pp.146-151
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• 2016

In this paper, we present a method for estimating the ratio of CPA distance to velocity of underwater target using target bearing information in CPA situation. This ratio can be estimated by previous research which is Envelope CPA using proximity sensor but it has low performance if the target is close to receiver sensor or bigger interference caused by multi-path effects. Therefore we propose a Bearing CPA technique using a target bearing information as a way to overcome.