• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2004.11a
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• pp.143-148
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• 2004

The numerical analysis of the hard disk drive slider is presented. The pressure distribution was calculated using the finite element method. The generalized Reynolds equation was applied in order to include the gas rarefaction effect. The balance of the air bearing force and preload force was considered. The characteristics of the small vibrations near the equilibrium were studied using the perturbation method. Triangular mesh with variable element size was employed to model the two-rail slider. The flying height, pitching angle, rolling angle, stiffness and damping of the two-rail slider were calculated for radial position changing from the inner radius to the outer radius and for a wide range of the slider crown values. It was found that the flying height, pitching angle and rolling angle were increased with radial position while the stiffness and damping coefficients were decreased. The higher values of crown resulted in increased flying height, pitching angle and damping and decreased stiffness.

• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.596-598
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• 2001

This paper presents an analysis of the characteristics in switched reluctance motor (SRM). 2D finite element method (FEM) considering the iron saturation and the actual switching circuit of the SRM drive is applied for the dynamic analysis. The influence of the rotor shape on the radial force and torque ripple is investigated and the optimal shape of rotor pole is proposed to enhance the torque. The radial force characteristics acting on the surface of teeth is investigated by using the Maxwell's magnetic stress tensor method.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.3
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• pp.349-356
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• 2003

The aim of this paper is to investigate the friction characteristics of piston assembly. The friction of piston assembly is composed of ring pack and skirt friction. In this paper, the theoretical models of piston ring pack and piston skirt were presented. The mixed lubrication theory was considered to calculate friction force of piston ring and skirt. from the results, most of friction in piston assembly occurred at the piston ring park. The piston assembly usually showed hydrodynamic lubrication characteristics. but the top and bottom dead centers showed mixed lubrication characteristics. The piston skirt was much affected by radial clearance and load, but ring was significantly influenced by ring tension.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.850-851
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• 2008

This paper compares and investigates the vibration and noise characteristics through simulations of 12/8 and 6/4 switched reluctance motors (SRMs). The radial force which is the main source of vibration is computed from two-dimensional(2D) transient magnetic finite element analysis (FEA) and compared in both time and frequency domain. At the same output power, the radial force of 6/4 SRM is found to be more than two times as that one of 12/8 SRM. Three-dimensional structural finite-element analysis (3D FEA) is used to study the mechanical characteristics. It can be concluded from static structural analysis that the maximum total deformation could be reduced to 1/26 if the motor is designed with 12/8 structure instead of 6/4. The dominant vibration modes are verified by modal analysis.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.04a
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• pp.326-331
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• 2000

In this study, residual stress was investigated experimentally to evaluate damaged layer in high-sped machining. In machining difficult-to-cut material, residual stress remaining in machined surface was mainly speared as compressive stress. The scale of this damaged layer depends upon cutting speed, feed per tooth and radial cutting depth. Damaged layer was measured by optical microscope. The micro-structure of damaged layer was a mixed maternsite and austenite. depth of damaged layer is increased with increasing of cutting temperature, cutting force and radial depth. On the other hand, that is slightly decreased with decreasing of cutting force. The increase of tool wear causes a shift of the maximum residual stress in machined surface layer.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.14 no.5
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• pp.7-12
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• 2005

This paper presents several time series methods to analyze the chatter mechanics by using the power spectrum of these algorithms considering the cutting dynamics. In this study, several time series models such as AR(burg, forwardbackward, geometric lattice, instrument variable, least square, Yule Walker), ARX(1s, iv4), ARMAX, ARMA, Box Jenkins, Output Error were modeled and compared with one another. Finally, it was proven that time series modelings are also a desirable and reliable algorithm than the other conventional methods(FFT) for the calculation of the chatter mode in turning operation. Also, the spectrum of times series methods is a little bit more powerful than the FFT fer the detection of a high noisy and weak chatter mode. The radial cutting force Fy has been used for spectrum and chatter stability lobe analysis in this study.

• Journal of international Conference on Electrical Machines and Systems
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• v.1 no.3
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• pp.336-346
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• 2012

In this paper, a novel bearingless switched reluctance motor (BLSRM) with hybrid stator poles is proposed. The structure and operating principle are presented. In order to describe the design methodology clearly, analytical torque and radial force models are established. Further, basic design procedure is described. The numbers of phases and poles have important influence on the selection of structure. These effects, along with sizing of machine envelope and internal dimensions, make the machine design an insight-intensive effort. Effect of pole arcs and air-gap length on the production of torque and radial force are analyzed in detail. Mechanical design factors such as hoop stress and first critical speed are also considered. Based on the above analysis, the characteristics of the proposed BLSRM are analyzed. A prototype motor is designed and manufactured. The validity of the proposed structure is verified by the experimental results.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.12
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• pp.1986-1991
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• 2016

The vibration soucre of motor has a electromagnetic and mechanical causes. The most widely known, electromagnetic reasons are cogging torque and RMF(Radial magnetic force). Recently, analysis of the cogging torque has been made actively. but analysis of the RMF was not filled. So, in this paper, analyzed RMF. the vibration test were performed for the basic and reduced model of cogging torque and RMF. And it analyzed for the effect of each factor on the vibration. Finally, the vibration was formulated for stator's weight and RMF. To this end, natural, cogging torque and RMF of frequency were analyzed and these relationships were considered.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.2
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• pp.298-303
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• 2016

In this paper, the vibration source of IPM type BLDC motor was analyzed by finite element method. The main causes of the electrical vibration were RMF(Radial magnetic force) and cogging torque. It was designed model of minimized cogging torque and RMF equilibrium. Design models were selected the optimum model using the design of experiment method. And, the vibration experiment was carried out through prototype machine of each model. Finally, the experimental results were compared with the analysis ones.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.1
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• pp.64-69
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• 2012

In this paper, the optimal design of notch and barrier was carried out in order to improve characteristics of constant torque with minimizing the cogging torque occurred by teeth and slot structure. Optimized design was carried out by design of experiment and various characteristics including torque were studied by finite element method(FEM). In addition, in order to verify resonance frequency, natural frequency of the stator was analyzed by modal analysis.