• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 춘계학술대회 논문집
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• pp.297-302
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• 1997

Linear displacement accuracy is one of the most important factors that determine machine tool accuracy. The laser interferometer has been usually recommended for the measurement of linear displacement accuracy. In this paper, microcomputer aided measurement and compensation system has been developed forthe pitch error in a CNC machine tool. For accurate pitch error calculation, the analysis code for the pitch error has been also implemented according to the international standards(ISO). The PC based automatic compensation system for the pitch error is also implemented. A new algorithm for calculating optimum value for pitch error compensation is proposed, minimizing the deviation at each target points. The development system has been applied to a practical CNC maching center and the performance has been demonstrated.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 추계학술대회 논문집
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• pp.229-232
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• 1997

In this paper, the case study of reducing rotational errors is 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. For the most case, the electrical runout of sensor target is big even in well-finished surface; this runout can cause a rotation error amplified by feedback control system. The adaptive feedforward method based on LMS algorithm is discussed to compensate this kind of runout effects, and investigated its effectiveness by numerical simulation and experimental analysis. The rotor orbit size in both bearings is reduced about to 5 pin due to lX rejection by feedforward control up to 50,000 rpm.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 추계학술대회 논문집
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• pp.683-686
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• 2000

A new approach to the task of aligning a robot using camera is presented in this paper. We apply an elitist GA to find the joints angles of manipulator to reach target position instead of using nonlinear least error method. Since it employs parallel search and have good performance in solving optimization problems. In order to improve convergence speed, the floating coding method and geometry constraint conditions are used. Experiments are carried out to exhibit the effectiveness of vision-based control using elitist genetic algorithm.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 추계학술대회 논문집
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• pp.380-384
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• 1997

For improving the motion accuracy of hydrostatic table, corrective machining algorithm is proposed in this paper. The algorithm consists of three main processes. Reverse analysis is performed firstly to estimate rail profile from measured linear and angular motion error, in the algorithm. For the next step, correctwe machining information is decided as referring to the estimating rail profile. Finally, motion errors on correctively machined rail are analized by using motion error analysls method proposed in the previous paper. These processes can be rtcrated if the analized motion errors are worse than target accuracy. In order to verify the validity of the algorithm theoretically, motion errors by the estimated rail after corrective machining are compared with motion errors by true rail assumed as the measured value. Estimated motion errors show good agreement with assumed values, and it is confirmed that the algorithm IS effective to acquire the corrective machming information to improve the accuracy of hydrostatic table.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.133-136
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• 2003

In these days, the reliability analysis and prediction are applied for many industrial products and many products require guaranteeing the quality and efficiency of their products. In this study reliability prediction for core units of machine tools has been performed in order to improve and analyze its reliability. ATC(Automatic Tool Changer) and interface Card of PC-NC that are core component of the machine tools were chosen as the target of the reliability prediction. A reliability analysis tool was used to obtain the reliability data(failure rate database) for reliability prediction. It is expected that the results of reliability prediction be applied to improve and evaluate its reliability. Failure rate, MTBF (Mean Time Between Failure) and reliability for core units of machine tools were evaluated and analyzed in this study.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.1239-1242
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• 2003

The target of this paper is the manufacturing system of mould plant and the object of system development is the reduction of lead times and the improvement of product quality. From the existing MES framework. we found the module to apply in the mould plant, designed and developed the function of the module. Also. as the environment of development is based on internet, we can check and analysis correctly the status of mould plant from remote site.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.181-184
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• 2003

Recently, the fieldbus becomes an indispensable component for many automated systems. In the fieldbus system, realtime data containing sensor values and control commands has a tendency to rapidly lose its value as time elapses after its creation. In order to deliver these data in time, the fieldbus network should be designed to have short delay compared to the maximum allowable delay. Because the communication delay is affected by performance parameters such as target rotation timer of token passing protocol, it is necessary to select proper parameter settings to satisfy the real-time requirement for communication delay. This paper presents the timer selection method for Profibus token passing networks using genetic algorithm (GA) to meet the delay requirements.

• 한국정밀공학회지
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• 제22권8호
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• pp.50-56
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• 2005

This paper is described a development of an optical fiber displacement sensor. The optical fiber sensor using an intensity modulated measures the displacement between target and sensor. A prototype sensor is composed of a transmitting part, a receiving part and a signal processing circuit. The experiment was conducted not only the sensor performance but also factors that affect intensity. The main performance of this sensor is resolution of 0.37um and the non-linearity $0.7\%$ FS and the dynamic bandwidth of about 6.3kHz. As a result of rotation test, the prototype sensor showed an equivalent performance to a commercial eddy current sensor.

• 한국정밀공학회지
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• 제19권12호
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• pp.27-32
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• 2002

The intensity modulated type (reflective method) optical fiber sensor is a well -known method and widely applied to the displacement measurements and other industrial purposes. This type sensor has the advantages of relatively cheap cost, small sensor size and easiness of operation. The sensitivity of the sensor is very dependent of several error terms; the variation in the intensity of the light source and the changes in the surface reflectivity of the object. An optical fiber coupled displacement probe with a new compensation method is presented in this paper. The proposed displacement sensor can measure the displacements of the target surface independent of surface reflectivity error that is caused by the materials and surface processing grade.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 춘계학술대회 논문집
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• pp.921-926
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• 1997

SOI(Silicon On lnsulator) technology is many advantages in the gabrication of MOS(Metal-Oxide Semiconductor) and CMOS(Complementary MOS) structures. These include high speed, lower dynamic power consumption,greater packing density, increased radiation tolearence et al. In smiple form of bonded SOL wafer manufacturing, creation of a bonded SOI structure involves oxidizing at least one of the mirror polished silicon surfaces, cleaning the oxidized surface and the surface of the layer to which it will be bonded,bringing the two cleanded surfaces together in close physical proximity, allowing the subsequent room temperature bonding to proceed to completion, and than following this room temperature joining with some form of heat treatment step,and device wafer is thinned to the target thickness. This paper has been performed to investigate the possibility of the bonded SOI wafer manufacturing Especially, we focused on the bonding quality and thinning method. Finally,we achieved the bonded SOI wafer that Si layer thickness is below 3 .mu. m and average roughness is below 5.angs.