• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.375-378
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• 1995

Although laser interferometer measurement system has the advantage of range and accuracy, the traditional error measurement methods for geometric errors(two straightness and three angular errors) of a machine tool measures error components one at a time. It may also create an optical path difference and affect the measurement accuracy. In order to identify and compensate for geometric error of a moving body, an on-line measurement system for simultaneous detection of the five error components of a moving axis is required. An on-line measurement system with 5 degrees of freedom was developed for geometric error detection. Performance verification of the system was performed on an error generating mechanism. Experimental results show the feasibility of this system for identifying geometric errors of a side of machine tool.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.23 no.61
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• pp.89-98
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• 2000

For statistical process control, the process data are collected by the measurement system. But, the measurement system may have instrument error or/and operator error. In the measured values of products, the total observed variance consists of process variance and variance due to error of measurement system. In this paper, we design more practical T-s control chart considering estimated measurement error The effects of measurement error on the expected total cost and design parameters are investigated.

• Child Health Nursing Research
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• v.5 no.1
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• pp.48-58
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• 1999

The purpose of this study was to determine the most accurate technique measuring the apical pulse rate, using three counting duration 15, 30 and 60 seconds, and two methods start ‘0’ and start ‘1’. The instrument used in the study was the EKG monitor, stethoscope and stopwatch. Data was analyzed by utilizing SPSSWIN program. General characteristics of the subjects were analyzed by frequency, percentile, mean, SD. The subject of this research is made up of 46 children and 20 nurses. The children were infants, & under the age of 5. They were hospitalised in PICU & NICU in 2 tertiary hospitals in seoul from Jan. 1. 1998 to Sep. 10. 1998. The measurement of starting 1 & measurement of starting ‘0’ used the T-test to find out the measurement error. Apical pulse duration of 15, 30, 60 seconds were used to find out measurement error, the measurement error depend on experience of Nurse were analyzed by using ANOVA. The result of this study are as follows. 1. When comparing the starting poin of apical pulse 0&1, starting with 1 the measurement error is less, but not statiscally significant. 2. When counting the apical pulse by 15, 30,60 sec. ; 60 seconds counting duration was more accurate, but not statistically significant. 3. The mean of measure error ; Group under 100/min, is 10.33 ; from 100 re 119/min, is 8.30 ; from 120 to 139/min, is 4.76 ; from 140 to 159/min, is 6.09 ; above 160, is 17.83. The differences of these groups are statistically significant. When 60sec were counted, under 140/min the mean of measurement error is 3.4. Also when 30 seconds were counted from 140/min to 159/min the measurement error is 7.14, above 160/min the measurement error is 16.4. That measurement mean is the smallest than the other durations. During the 15 sec. count the measurement error was the largest of them all. 4. By the experience of the nurses, the apical pulse count measurement error was discovered. Under a year experience this measurement error was the largest(11.09), 1 year to under 3 years, the error is the smallest(4.86). 3 year to under 6 years the error is 8.33, 5 years above the error is 6.11 but this is not statistical significant. Under a year experience when counting 15, 30, 60 seconds the error is the largest. The group of the nurses from a year to under 3 years, the measurement error is the smallest of all the groups. The result of the study is to determine the technique measuring the apical pulse rate, Hargest (1974), starting point ‘0’ is not proved. When the pulse rate increases the 30 sec measurement rate is accurate. Under 140/min the 60 sec measurement rate is the most accurate. Depending on the nurses experiences, there is a variable difference to the apical pulse rate measurement. Especially new nurses training courses should enforce the children’s pulse rate count and the basic vital signs.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.6
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• pp.607-614
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• 2013

In this study, effect of the sensor gain error is theoretically analyzed and simulated when mixed sequential two-prove method(MTPM) is applied for the precision measurement of straightness error of a linear motion table. According to the theoretical analysis, difference of the gain errors between two displacement sensors increases measurement error dramatically and alignment error of the straightedge is also amplified by the sensor gain difference. On the other hand, if the gain errors of the two sensors are identical, most of error terms are cancelled out and the alignment error doesn't give any influence on the measurement error. Also the measurement error of the straightness error is minimized compared with that of the straightedge's form error owing to close relationship between straightness error and angular motion error of the table in the error terms.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.5
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• pp.93-99
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• 1998

Although laser interferometer measurement system has advantages of measurement range and accuracy, it has some disadvantages when measurement of multi degrees of freedom of motion are required. Because the traditional error measurement methods for geometric errors (two straightness and three angular errors) of a slide of machine tools measures error components one at a time. It may also create an optical path difference and affect the measurement accuracy. In order to identify and compensate for geometric errors of a moving rigid body in real time processes, an on-line error measurement system for simultaneous detection of the five error components of a moving object is required. Using laser alignment technique and some optoelectronic components, an on-line measurement system with 5 degrees of freedom was developed for the geometric error detection in this study Performance verification of the system has been performed on an error generating mechanism. Experimental results show the feasibility of this system for identifying geometric errors of a slide of machine tools.

• Transactions of Materials Processing
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• v.13 no.7
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• pp.594-599
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• 2004

In the sheet metal forming operations, the strain measurement of sheet panel is an essential work which provides the formability information needed in die design, process design, and product inspection. To measure efficiently complex geometry strains, the 3-dimensional automative strain measurement system, which theoretically has a high accuracy but practically has about 3～5％ strain error, is often used. For eliminating the strain error resulted in measuring the strains of formed panels using an automated strain measurement system, the position error calibration method is suggested, which computes accurate strains using the grids with accurate nodal coordinates. The accurate nodal coordinates are calculated by adding the nodal coordinates measured by the measurement system and the position error found using the multiple regression method as a function of the main error parameters obtained from the analysis of strain error in a standard cube. For the verification, the strain distributions of square and dome cups obtained from the position error calibration method are compared with those provided by the finite element analysis and ASAME.

• Journal of Integrative Natural Science
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• v.5 no.3
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• pp.157-162
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• 2012

Measurement error is one of main source of error in survey. It is generally defined as the difference between an observed value and an underlying true value. An observed value with error may be expressed as a function of the true value plus error term. In some cases, the measurement error variance may be also a function of the unknown true value. The error variance function can be rewritten as a function of true value multiplied by a scale factor. This research explore methods for estimation of the measurement error variance based on the data from complex sampling design. We consider the case in which the variance of mesurement error is a linear function of unknown true value, and the error variance scale factor is small. We applied our results to the U.S. Third National Health and Nutrition Examination Survey (the U.S. NHANES III) data for empirical analyses, which has replicate measurements for relatively small subset of initial respondents's group.

• Journal of Korean Society for Quality Management
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• v.35 no.1
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• pp.10-19
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• 2007

ANOVA is widely, used for measurement system analysis. It assumes that the measurement error is normally distributed, which nay not be seen in some industrial cases. In this study the estimates of the measurement system variability and PTR (precision-to-tolerance ratio) are obtained by using weighted standard deviation for the case where the measurement error is non-normally distributed. The Standard Bootstrap method is used foy estimating confidence intervals of measurement system variability and PTR. The point and confidence interval estimates for the cases with normally distributed measurement error are compared to those with non-normally distributed measurement errors through computer simulation.

• Journal of the Semiconductor & Display Technology
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• v.20 no.4
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• pp.114-118
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• 2021

In this research, the dimensional error of the measured specimen according to the measurement method was analyzed for the length, angle, radius of curvature and diameter using a projector which is used in industry. One-way analysis was performed on each data tested 30 times using a statistical technique. Through the experiment, it was found that an error occurred in each data when measuring the length and radius of curvature according to the measurement method, and the null hypothesis that no error occurred when measuring the angle and length was established. Based on this experimental data, the automatic measurement when measuring the projector causes less measurement error, so automatic measurement is recommended when measuring a small product. Also, an optimal measuring method is suggested for securing reliability on formulations of measurement automation.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.9 s.174
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• pp.69-76
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• 2005

The laser interferometer system such as HP5529A is one of the most powerful equipment fur measurement of the straightness error in precision stages. The straightness measurement system, HP5529A is composed of a Wollaston prism and a reflector. In this system, the straightness error is defined as relative lateral motion change between the prism and the reflector and computed from optical path difference of two polarized laser beams between these optics. However, rotating motion of the prism or the reflector used as a moving optic causes unwanted straightness error. In this paper, a compensation method is proposed for removing the unwanted straightness error generated by rotating the moving optic and an experiment is carried out for theoretical verification. The result shows that the unwanted straightness error becomes very large when the reflector is used as the moving optic and the distance between the reflector and the prism is far. Therefore, the prism must be generally used as the moving optic instead of the reflector so as to reduce the measurement error. Nevertheless, the measurement error must be compensated because it's not a negligible error if a rotating angle of the prism is large. In case the reflector must be used as the moving optic, which is unavoidable when the squareness error is measured between two axes, this compensation method can be applied and produces a better result.