• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.11a
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• pp.184-185
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• 2008

Modal analysis is an important and essential process in design of a high speed machining center. Generally, modal analysis of a built-in spindle system has not taken the work piece's shape and dimension into consideration. Since small and long work pieces influence greatly the natural frequency of the entire system, the high speed spindle system which continuously makes small machine parts by long work pieces for improvement of machining time has to consider the machining work pieces. Therefore frequency characteristics of the spindle system with long work pieces are studied in this paper.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.11a
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• pp.182-183
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• 2008

In this study, rotor dynamic analysis have been conducted using three-dimensional solid model. Analysis object has smaller size and higher speed than any general CNC spindle. It is important to consider the real supporting conditions and external forces for whirl behavior analysis. As a results, the bearing stiffness is higher, whirl motion is less than before.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11a
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• pp.312-318
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• 2001

This paper suggests the finite element method to analyze the dynamic characteristics of a rotating HDD system including the supporting structure with general shape. The flexible supporting structure was modeled by tetrahedra elements to produce a finite element model of disk-spindle-shaft-housing system and the dynamic characteristics of the HDD system was investigated due to the change of rotating speed. The validity of the presented method was verified by the modal testing. The supporting structure has an crucial effect on lower modes for HDD system, so that it is required to consider the supporting structure to accurately analyze the dynamic characteristics of HDD system.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11a
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• pp.58-64
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• 2001

An investigation of the TMR(Track Misregistration) requirements to achieve the capacity of 80GBytes／Platter in 7200rpm disk drive system is reported. This paper also gives an overview of the PES(Position Error Signal) characteristics in the 57,500TPI disk drive to estimate the required 95,000TPI-system PES. The TMR measured by PES are presented and decomposed in order to identify the portions and their contributions of the spindle-disk system vibration and HSA(Head-Stack-Assembly) system vibration respectively. A comprehensive review on the servo system is also presented to provide the practical limits of the modem servo architecture into TMR budget design. The decomposed PES energy distribution shows that the spindle-disk pack vibration is one of the top-ranking sources of the total TMR budget and its percentage contribution is about 50％ considering all the other TMR sources.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.05a
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• pp.1011-1015
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• 2000

In this paper, the case studies of reducing rotational errors is theoretically done for a grinding spindle with an active magnetic bearing system. The rotational errors acting on the magnetic bearing spindle are due to mass unbalance of rotor, runout, grinding excitation and unmodeled nonlinear dynamics of electromagnets. The adaptive feedforward method based on LMS algorithm is discussed to compensate output and input disturbances, and investigated its effectiveness by numerical simulation. The feedforward control reduced external excitation and rotational error for specified frequency. The interpolation method using impulse function for cancelling the electrical 'uncut is studied. These methods show their effectiveness for the rotational accuracy of the improving magnetic bearing spindle through some simulation results of the rotational error decreased by them.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.579-585
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• 2003

This paper investigates the whirling, tilting and flying motion of a HDD spindle system supported by FDB experimentally. Experimental setup is built to measure the flying, whirling and tilting motion of the HDD spindle system, and three capacitance probes fixed on the xyz-micrometers measure the displacement of a HDD spindle system in the xyz-directions. This research shows that the tilting and whirling motion is mostly dependent on the centrifugal force and the gyroscopic moment due to the unbalanced mass of a HDD spindle. It also shows that the rotating HDD spindle starts to float to the equilibrium position in the z-direction until the weight of the rotating spindle is equal to the supporting pressure generated in the upper and lower thrust bearing.

• Journal of KSNVE
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• v.10 no.6
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• pp.977-984
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• 2000

Vibration of disk drive spindle is one of the major limiting factors in achieving higher track densities in hard disk drives. Vibration of a BLDC motor is a coupled phenomenon between mechanical characteristics and magnetic origins through the motor air-gap. In this paper, radial magnetic forces for symmetric and asymmetric BLDC motor are calculated with respect to the various rotor eccentricity using analytic method. Based on the results of the radial magnetic forces, transient whirl responses of the spindle motor are analyzed using finite element and transfer matrices. Results show that an asymmetric motor has a worse effects on unbalanced magnetic forces and vibration when mechanical and magnetic coupling exists.

• Proceedings of the Korea Information Processing Society Conference
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• 2021.11a
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• pp.753-755
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• 2021

본 논문에서 기존의 치아가공기는 회전하는 모터를 사용하여 구성하였으나 이러한 모터는 정밀도, 반복정밀도가 50um 이하로 가공물 가공시에 치기공사나 치과의사가 사람에 맞추어 다시 작업을 해야하는 불편함과 시간적, 작업자의 피로도를 높일수 있는데 이러한 모터에 스크류나 밸트를 연결하여 선형적으로 움직일 수 있는 리니어모듈과 리니어모터를 적용하게되면 20um수준의 고정밀의 위치제어가 가능한 5축 치아가공기를 만들 수 있었다. 또한 MEMS센서를 이용하여 스핀들의 상태를 모니터링 하고 임계값을 지정하여 이상 신호 발생시 모터를 멈추어 위험상황에 대해서 인공지능기법을 이용하여 정지하거나 관리자에게 알림을 주어 효과적으로 5축치아가공기를 운영할 수 있도록 하였다.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.11
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• pp.99-107
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• 2009

Since a long work piece influences the natural frequency of the entire system with a miniature high speed spindle, a bar-feeder is used for a long work piece to improve the vibration characteristics of a spindle system. Therefore, it is very important to design optimally support positions between a bar-feeder and a long work piece for a miniature high speed spindle system. The goal of the current paper is to present an optimization method for the design of support positions between a bar-feeder and a long work piece. This optimization method is effectively composed of the method of design of experiment (DOE), the artificial neural network (ANN) and the genetic algorithm (GA). First, finite element models which include a high speed spindle, a long work piece and the support conditions of a bar-feeder were generated from the orthogonal array of the DOE method, and then the results of natural vibration analysis using FEM were provided for the learning inputs of the neural network. Finally, the design of bar-feeder support positions was optimized by the genetic algorithm method using the neural network approximations.

• KIPS Transactions on Software and Data Engineering
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• v.4 no.11
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• pp.479-486
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• 2015

Model checking method is able to check all possible cases automatically and is applicable to specifications or design before actual implementation so that some critical systems have adopted this method actively. However, the current practice of software verification is largely dependant on basic methods such as manual testing because of lack of understanding about this rigorous method and high verification cost. In this paper we conducted an experimental research for the automated verification using the SPIN model checker on an online-game server to study the applicability of the technique in this domain. The results show that we could verify major features of the online-game server party system with 5~7 GB memory and within 10 minutes execution time, and also found a hidden system error that passed existing testing process. This result shows the possibility of rigorous and effective verification with reasonable cost in comparison to manual testing.