• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 춘계학술대회 논문집
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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.

• 지질공학
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• 제15권2호
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• pp.145-154
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• 2005

본 연구는 우리나라에서 발생하는 산사태 유형의 대부분을 차지하는 토석류 산사태를 대상으로 사면하부로 이동되는 사태물질의 이동거리를 산정하기 위한 기법을 개발하기 위하여 수행되었다. 이를 위하여 최근 산사태가 발생한 지역 중 지질특성이 서로 다른 3개 지역에 서 선정한 24개 산사태를 대상으로 사태물질 이동범위의 정 밀 현장조사와 토질 실내시험 을 수행하고, 그 결과를 토대로 인공신경망을 적용하여 이동거리 산정기법을 제안하였다. 인공신경망 분석을 위한 입력자료는 개개 사면의 경사변화율, 원지반 투수계수, 건조밀도, 간극율, 사태물질의 체적, 측정한 확산거리 등 6개 항목이다. 인공신경망을 이용해 도출된 결과는 각 입력치에서 추론율이 우수하게 나타나 대부분 오차율 $10\%$이내 에 분포하고, 일부경우는 오차율 $5\%$와 $2\%$내에 분포하기도 한다. 이는 학습율이 대단히 좋은 것으로 해석 될 수도 있으나, 학습 자료가 24개 로서 비교적 적은 수이기 때문에 반드시 우수하다고 단정 할 수는 없다. 단, 본 연구에서 획득한 입력자료의 분포범 위가 전국 3개 지역에 걸친 넓은 범위임을 고려하면 대체로 우수한 추론율이라고 할 수도 있다. 향후 산정 결과의 신뢰도를 향상시키기 위해서는 더 많은 자료의 조사 및 해석이 수행되어야 할 것이다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.1775-1780
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• 2003

A hybrid finite element analysis was used to analyze the influence of ring gear rim thickness and spline number on the static properties of an epicyclic gear system with manufacturing errors. Both of these parameters affected the bearing force and critical stress. The effect of changes in the rim thickness on the load sharing between the gears depended on the type of manufacturing error. Ring flexibility improved the load sharing between planetary gears only in systems with planet tooth thickness or planet tangential errors; for other types of error, ring flexibility worsened the load sharing. To improve load sharing, rim thickness and spline number should be controlled within a specific range. The effect of the ring gear boundary condition was more apparent in a system with errors than in a normal system.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 춘계학술대회 논문집
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• pp.637-642
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• 1995

For measuring the error motion of ultra-precision spindle, eliminating the geometric errors is a must. Unless it is achieved, geometric errors will be dominant in data. Here, the roundness error and alignment error between spindle and sensor are to be removed. That's because typical error range of such spindle is muchless than geometric one. A capacitive transducer of cylidricalshape was developed, which takes full advantage of the spatial-averaging effect by using large area compared tpo the geometric error. This idea was first proposed by Chapman and here it is modified for better performance with nomical gap of 50 .mu. m and with newly designed guards which encompass the respective sensor to rectify the electrical field distribution in good shape. The measurement system is made to get the orbit of Ultra-Precision Air Spindle which is supposed to have its runout under 1 .mu. m. The Calibration data of this sensor is presented and the spindle orbit from 2000rpm to 5500rpm is showed. It is quite reasonable to use this sensor in the range of 60 .mu. m with an accuracy of several tens of nm.

• 한국공작기계학회논문집
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• 제17권1호
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• pp.106-112
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• 2008

In this paper, It does the profile measurement of the cam of diesel engine SOHC of the actual object. It uses the measurement of run-out method. This method is that the surface of the object is measured by the sensor when the object rotate, and calculated and displayed by the computer the signal which acquired by sensor. When we acquire the signals, we have two error because of motion and contacting between cam and probe. In this paper, we compensate the motion error while simply liner equation. And we have a solution that we change the figure of probe when we have a contacting error. We compared the data measuring on developed automatic cam profile measuring system with the data measured on CMM.

• 소성∙가공
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• 제5권2호
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• pp.115-121
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• 1996

Recently it is attempted to manufacture gears by various cold forging methods to meet requirements of mass production and uniform qualities. Compared to machined gears cold forged ears reveal higher tooth strength and better surface roughness but they reveal lower geometrical accuracies. Therefore in the present study a series of experiments are performed to investigate relations between geometrical accuracies of dies and billet and those of the final product. The geometrical accuracies of forged gears are considered through functional gear-element tolerances by measuring pitch error profile error lead error radial error tooth thickness and rolling test. Results of the experiments can be summarized as follows: (1) involute spur gears of KS 5(or AGMA7) accuracies can be made,(2) concentricity of die set should be maintained within 0.01mm (3) clearance between the billet and die set should be less than 0.1mm (4) con-centricity and radial runout should be less than 0.08mm and 0.1mm respectively. However it is thought that FEM analysis of elastic/thermal deformations of dies and the billet is necessary for a better understanding of the findings obtained through the present study.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2002년도 추계학술대회 논문집
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• pp.468-473
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• 2002

This paper presents the methodology for measuring eccentricity of the cylindricaliy machined part using CCS(Cylindrical Capacity Spindle Sensor) signal in the CNC turning process. In order to investigate the relationships between CCS orbits and eccentricities, the initial conditions for various eccentricity state and machining process is applied to the experimental strategy. AS a result, it is considered the linearities of CCS signal and magnitude of eccentricity of machined cylindrical surfaces based on the possibility as a automatic detection apparatus for the CNC lathe.

• 한국소음진동공학회논문집
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• 제14권11호
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• pp.1176-1181
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• 2004

In high-capacity disk drives with ever-growing track density, the allowable level of position error signal(PES) is becoming smaller and smaller. In order to achieve the high TPI(track per inch) disk drive, it is necessary to improve the writing accuracy during the servo track writing(STW) Process through the reduction of track mis-registration sources. Among the main contributors of the non-repeatable runout(NRRO) PES, the disk vibration and the head-stack assembly vibration is considered to be one of the most significant factors. Also the most contributors of repeatable runout(RRO) come from the contributors of NRRO which is written-in at the time of STW process. In this paper, the effect of NRRO on servo written-in RRO is Investigated by experimentally, and the experimental result shows that the written-in RRO can be effectively reduced through a STW process under low dense medium condition such as semi-vacuum.

• 대한기계학회논문집A
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• 제27권11호
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• pp.1949-1957
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• 2003

A hybrid finite element analysis was used to analyze the influence of ring gear rim thickness and spline number on the static properties of a planetary gear system with manufacturing errors. Both of these parameters affected the bearing force and critical stress. The effect of changes in the rim thickness on the load sharing between the gears depended on the type of manufacturing error. Ring flexibility improved the load sharing between planetary gears only in systems with planet tooth thickness or planet tangential errors; for other types of error, ring flexibility worsened the load sharing. To improve load sharing, rim thickness and spline number should be controlled within a specific range. The minimum rim thickness limit should be determined considering not only the critical stress but also the load sharing. The effect of the ring gear boundary condition was more apparent in a system with errors than in a normal system.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2002년도 춘계학술대회 논문집
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• pp.161-166
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• 2002

Recently, researches on precision machining of nato-order, especially in the field of optical components and semi-conductors have been under development very actively. A accuracy of machining and positioning in a critical issue in ultra-precision machining. This paper proposes a new positioning system which can give excellent dynamic characteristics and reduce errors in horizontal, vertical, pitching, and yawing motions. In this paper, we suggest a connecting mechanism (the couplings) to reduce motion errors such as chatter and runout while preserving the positioning accuracy. We verified the good performance in the new connecting systems with various coupling types, which we classified into the fixed type, the spring type, the aeroctatic-nozzle type, and the aeroctatic-porous type according to the way of reducing the chatter and error.