• Transactions of the Korean Society of Machine Tool Engineers
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• v.15 no.1
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• pp.1-7
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• 2006

A method of the volumetric error measurement and calibration of NC machine tools is studied using an artifact method. In this study, a hole-pate is designed and machined using stainless steel. We tested and applied the hole-plate artifact in a commercial CMM(Coordinate Measuring Machine), after calibration of the hole-plate using a precise CMM. It has been shown that not only the measurement of geometric error components but also the 2D length error calculation in a working volume is available using the hole-pate artifact method. The results of study can also be used in NC machine with touch probe as the same method in CMM.

• Journal of the Korean Institute of Telematics and Electronics
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• v.19 no.2
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• pp.23-30
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• 1982

In this paper, two methods (Kalman filter and Conventional) are investigated to reduce the bias error in the INS (Intertial Navigation System) vertical channel. The schemes by these methods show better performance (estimation error and response) than the others commonly used. Comparison results show that the scheme by Kalman filter method gives much better performance than the Conventional method.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.175-180
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• 2003

Ultrasonic pulse velocity method is applied many times for measuring surface crack depth of concrete in case of diagnosis of concrete structures. By the way, this method has an error accompanying measured surface crack depth of concrete because there are many uncertainty factors. So, it is necessary to study for an error of this method affected by these uncertainty factors. Two error factors(uncertainty factors) are tested and analyzed in this study. One is for an error according to measuring the propagation time of ultrasonic wave and the arrangement distance of transducers. Another is for an error according to positioning the transducer as a distance to surface crack from the transducer.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.57 no.3
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• pp.291-295
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• 2008

We have developed an evaluation technique for ratio errors of current transformer (CT) comparator by using the precise standard capacitors. By applying this technique for equivalent circuit of CT comparator evaluation system, we can obtain the calculated and measured ratio errors in the CT comparator. Thus we can evaluate ratio errors of CT comparator by comparing the calculated and measured ratio errors. Because this method requires only the standard capacitors, it is simple and easy method to reliability and accuracy maintenance of CT comparator. The method was applied to CT comparator under test with the ratio error ranges of $0{\sim}{\pm}10%$. The ratio error of the CT comparator under test theoretically obtained in this method are consistent with that measured for same CT comparator under test by using wide ratio error CT within an estimated expanded uncertainty (k = 2) in the overall ratio error ranges.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.11
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• pp.99-109
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• 2004

This paper proposes precision evaluation method for the positioning error of three-DOF translational parallel mechanism. The proposed method uses conventional CMM as metrology equipment to measure the position of end-effector. In order to obtain accurate measurement data from CMM, the transform relationship between the coordinate system of the parallel mechanism and the CMM coordinate system must be identified. For this purpose, a new coordinate referencing (or coordinate system identification) technique is presented. By using this technique accurate coordinate transformation relationships are efficiently established. According to these coordinate transformation relationships, an equation to calculate error components at any arbitrary position of the end-effector is derived. In addition, mathematical fitting models to represent the position error components in the two-dimensional workspace of the parallel mechanism are also constructed based on response surface methodology. The proposed error evaluation method proves its effectiveness through the experimental results and its application to real three-DOF parallel mechanism.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.9
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• pp.167-173
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• 2004

The heterodyne He-Ne laser interferometer is the most widely used sensing unit to measure the position error. It measures the positioning error from the displacement of a moving reflector in terms of the wave length. But, the wave length is affected by the variation of atmospheric temperature. Temperature variation of 1$^\circ C$ results in the measuring error of 1ppm. In this paper, for measuring more accurately the position error of the ultra precision stage, the refractive index compensation method is introduced. The wave length of the laser interferometer is compensated using the simultaneously measured room temperature variations in the method. In order to investigate the limit of compensation, the stationary test against two fixed reflectors mounted on the zerodur$\circledR$ plate is performed firstly. From the experiment, it is confirmed that the measuring error of the laser interferometer can be improved from 0.34${\mu}m$ to 0.11${\mu}m$ by the application of the method. Secondly, for the verification of the compensating effect, it is applied to estimate the positioning accuracy of an ultra precision aerostatic stage. Two times of the refractive index compensation are performed to acquire the positioning error of the stage from the initially measured data, that is, to the initially measured positioning error and to the measured positioning error profile after the NC compensation. Although the positioning error of an aerostatic stage cannot be clarified perfectly, it is known that by the compensation method, the measuring error by the laser interferometer can be improved to within 0.1${\mu}m$.

• The Journal of Korea Robotics Society
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• v.3 no.3
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• pp.176-185
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• 2008

In this paper, new filtering method for sensor registration is provided to estimate and correct error of registration parameters in multiple sensor environments. Sensor registration is based on filtering method to estimate registration parameters in multiple sensor environments. Accuracy of sensor registration can increase performance of data fusion method selected. Due to various error sources, the sensor registration has registration errors recognized as multiple objects even though multiple sensors are tracking one object. In order to estimate the error parameter, new nonlinear information filtering method is developed using minimum mean square error estimation. Instead of linearization of nonlinear function like an extended Kalman filter, information estimation through unscented prediction is used. The proposed method enables to reduce estimation error without a computation of the Jacobian matrix in case that measurement dimension is large. A computer simulation is carried out to evaluate the proposed filtering method with an extended Kalman filter.

• Journal of Korea Society of Digital Industry and Information Management
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• v.10 no.4
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• pp.63-70
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• 2014

Method a target estimation in spatial are mobile wireless communication using network cell and GPS. It have much error that mobile wireless communication depend on cell size. GPS method can't find a target in shadow and inner area. In this paper, we estimate a target as direction of arrival method using adaptive array antenna system. Adaptive array antenna system can obtain desired signal to remove other signal This paper studied digital beamforming method in order to estimation a target. Proposed method is modified optimum weight and antenna error correction to estimation an optimal receive signal. Digital beamforming method decided a signal phase and amplitude from received signal on array antenna element. But if it is not to do error correction of received signal, system performance have decreased. Firstly, we proposed modified optimum weight in order to finding desired target. Secondly, we are error correction of antenna incident signals by optimal weight before digital beamforming method. Thirdly, throughly simulation, we showed that system performance of proposed method compare proposal method with general method. It have improved resolution of estimation target to good performance more proposed method than general method.

• Journal of Mechanical Science and Technology
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• v.20 no.1
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• pp.51-58
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• 2006

To compensate for the motion errors in hydrostatic tables, a method to actively control the clearance of a bearing corresponding to the amount of error using actively controlled capillaries is introduced in this paper. The design method for an actively controlled capillary that considers the output rate of a piezo actuator and the amount of error that must be corrected is described. The basic characteristics of such a system were tested, such as the maximum controllable range of the error, micro-step response, and available dynamic bandwidth when the capillary was installed in a hydrostatic table. The tests demonstrated that the maximum controllable range was $2.4\;{\mu}m$, the resolution was 27 nm, and the frequency bandwidth was 5.5 Hz. Simultaneous compensation of the linear and angular motion errors using two actively controlled capillaries was also performed for a hydrostatic table driven by a ballscrew and a DC servomotor. An iterative compensation method was applied to improve the compensation characteristics. Experimental results showed that the linear and angular motion errors were improved to $0.12{\mu}m$ and 0.20 arcsec, which were about $1/15^{th}$ and $1/6^{th}$ of the initial motion errors, respectively. These results confirmed that the proposed compensation method improves the motion accuracy of hydrostatic tables very effectively.

• The Journal of the Acoustical Society of Korea
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• v.21 no.3
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• pp.221-229
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• 2002

In thin paper, error tolerance of each array element which satisfies error tolerance of beam pattern is decided by using the Monte-Carlo method. Conventional deterministic method decides the error tolerance of each element from the acceptance pattern by testing all cases, but this method is not suitable for the analysis of large number of array elements because the computation resources increase exponentially as the number of array elements increases. To alleviate this problem, we applied new algorithm which reduces the increment of calculation time increased by the number of the array elements. We have validates the determined error tolerance region through several simulation.