• Journal of the Korea Safety Management & Science
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• v.9 no.1
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• pp.119-131
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• 2007

Engineer and quality statistician use different terms and techniques but they have same meaning and concept. The terms accuracy and precision are frequently used by engineer and scientist in the department of R&D and production technology. This paper makes a contribution to the interpretation of statistical quality techniques by the use of accuracy and precision. Engineer and scientist who have six sigma black belt and statistical background can use efficiently and effectively accuracy and precision in a manner consistent with statistical usage according to this study.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.3
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• pp.82-88
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• 1997

In this paper, the development of a precision CNC lathe prototype for mirror surface machining is presented. To obtain high precision machining accuracy, a hydrostatically supported precision spindle and a sliding guideway with turcite pad are adopted as the motion elements. The machining accuracy of the prototype machine, and the motional accuracy of its motion elements are tested and evaluated to confirm the validity of the application of these elements on the prototype. The hydrostatic spindle shows 0.09 .mu. m of rotational accuracy and the guideway shows about 0.8 .mu. m/170mm of horizontal straightness. The sur- face roughness of cupper and aluminium cylinder machined by the prototype machine with diamond tool are 0.07 .mu. m and 0.10 .mu. m Rmax respectively. From these results, it is verified that the prototype lathe is avail- able for high precision machining.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.221-225
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• 2001

Recently, high accuracy and high precision are required in various industrial fields that are composed of semiconductor manufacturing apparatus and ultra precision positioning apparatus and information system and so on. The positioning technology is a very important one among them. This technology has been rapidly developed, its field needs for positioning accuracy to high as submicron. It is expected that accuracy with 10 nm in precision working and accuracy with 1 nm in ultra precision working are reached at the beginning of 2000s. Recently, to accomplish this positioning technology, many researches are concerned about it and make efforts it. This paper contain design technology of ultra precision 2-axis(X-Y Delta) stage for materialize to positioning accuracy with submicron, where, Delta stage is design as optimum against load and disturbance. And computer simulation is performed for stability and dynamic characteristic of Delta stage.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.7
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• pp.94-100
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• 2010

This paper describes the design and evaluation procedure of an ultra-precision rotary table for freeform generating machined tools. Design of the thrust and journal hydrostatic bearings and experimental evaluation of the table were performed. To get the compact size and less lost motion direct drive servomotor with ultra precision encoder. From the considered design, following performance were confirmed by experiment. The total stiffness of the prototype rotary table was 483.6 $N/{\mu}m$ and 97.6 $N/{\mu}m$ for axial and radial direction, respectively. Rotational accuracy of the table was investigated by capacitive sensor and reversal measurement technique, and 0.10 ${\mu}m$ radial direction and 0.05 ${\mu}m$ axial direction of the rotational accuracy were confirmed. The micro resolution of the table was also investigated with displacement of capacitive sensor, and $0.5/10000^{\circ}$ of micro resolution was confirmed. Index accuracy of the table was evaluated by the autocollimator and polygon mirror, and the $\pm0.39$ arcsec accuracy and $\pm0.16$ arcsec repeatability of the table were confirmed. Those are under the general requirements of ultra precision rotary tables for freeform generating machined tools.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.1
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• pp.63-68
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• 2018

At present, ultra-precision cutting technology has been studied in Korean research institutes, focusing on development of ultra-precision cutting tool technology and ultra-precision control engineering. However, the developed technologies are still far behind advanced countries. It focuses on metals including aluminum, copper and nickel, and nonmetals including plastics, silicone and germanium which require high precision while using a lathe. It is hard to implement high precision by grinding the aforementioned materials. To address the issue, the ultra-precision cutting technology has been developing by using ultra-precision machine tools very accurate and strong, and diamond tools highly abrasion-resistant. To address this issue, this study aims to conduct ultra-precision cutting by using ECTS (Error Compensation Tool Servo) to improve motion precision of elements and components, and compensate for motion errors in real time. An IR camera is used for analyzing cutting accuracy differences depending on the heat generated in diamond tools in cutting to examine the heat generated in cutting to study cutting accuracy depending on generated heat.

• Design & Manufacturing
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• v.2 no.1
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• pp.33-38
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• 2008

As consumer in optics, electronics, aerospace and electronics industry grow, the demand for ultra precision aspherical surface lens increases higher. Precision turning with single-diamond tools has a long history of development for fabrication of optical quality surfaces since the advent of aerostatic rotary spindles and precise linear motion guide ways. To enhance the precision and productivity of ultra precision aspherical surface micro lens, the following specification of ultra precision grinding system is required: the highest rotational speed of the grinder is 100,000rpm and its turning accuracy is $0.1{\mu}m$, positioning accuracy is $0.1{\mu}m$. The development process of the grinding system for the ultra precision aspherical surface micro lens for optoelectronics industry is introduced. In the work reported in this paper, an intelligent grinding system for ultra precision aspherical surface machining was designed by considering the factors affecting the surface roughness and profiles accuracy. An aerostatic form was adopted to build the spindle of the workpiece and the spindle of grinder and ultra precision LM guide way was adopted in this system. And this paper deals with mirror grinding of an aspheric surface micro lens by resin bonded diamond wheel and spherical lens of BK7. It results was that a form accuracy of $0.6{\mu}m$ P-V and a surface roughness of $0.006{\mu}m$ Rmax.

• Journal of Korean Society for Atmospheric Environment
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• v.16 no.3
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• pp.265-275
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• 2000

By using thermal desorption/gas chromatograph/flame ionization detector(TD/GC/FID), this study was carried out to evalute an accuracy and a precision on Benzene(B), Toluene(T), o-Xylene(X) analysis in an industrial hygiene laboratory. Limits of detection of TD/GC/FID on B, T, X were showed 13.75ng/sample or less. For the accuracy of the method by concentration levels, overall bias was showed 7.7% as an absolute value, and the pooled coefficient of variation showed 3.51%. For the precision on repeatability of peak area and retention time between within-run and between-run of analytical system, it is showed the results of within-run gave better than those of between-run. Also the accuracy by sorbents(Tenax TA and Chromosorb 106)was evaluated, and the precision on reproducibility between MDHS72 and this study was compared. It is showed it is possible for TD/GC/FID to evaluate accurately B, T, X concentration levels of less than 1ppm at indoor or outdoor of workplaces in Korea.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.05a
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• pp.617-620
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• 2000

Recently, High accuracy and precision are required in various industrial field especially, semiconductor manufacturing apparatus, Ultra precision positioning apparatus, Information field and so on. Positioning technology is a very important one among them. Is such technology has been rapidly developed, this field needs the positioning accuracy as high as submicron. It is expected that the accuracy of 10nm and 1nm is required in precision work and ultra precision work field, respectively by the beginning of 2000s. High speed and low vibration are also needed. This work deals with the design method and control system of Ultra precision positioning apparatus. We will examine the control performance and stability before manufacturing the real apparatus by using MATLAB SIMULINK based or pre-designed controller and system modeling.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.4
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• pp.55-61
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• 2012

Very important content in performance evaluation of machine tool is positioning accuracy and repeatability precision measurements of feed mechanism. A study analyses the measurement method and uncertainty factors by ISO-based test method. Reliable results can't be derived without the notion of measurement uncertainty. The reason is that the measured value includes a lot of uncertain factors. Finding the factor that affects the measurement of parameter is important for estimation of measurement precision. In this paper, the evaluation of uncertainty analysis about positioning accuracy and repeatability precision measurements of high precision feed mechanism is presented to evaluate the important factors of uncertainty.

• Journal of Information Processing Systems
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• v.18 no.3
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• pp.293-301
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• 2022

Direction of arrival (DOA) estimation of space signals is a basic problem in array signal processing. DOA estimation based on the multiple signal classification (MUSIC) algorithm can theoretically overcome the Rayleigh limit and achieve super resolution. However, owing to its inadequate real-time performance and accuracy in practical engineering applications, its applications are limited. To address this problem, in this study, a DOA estimation algorithm with high parallelism and precision based on an analysis of the characteristics of complex matrix eigenvalue decomposition and the coordinate rotation digital computer (CORDIC) algorithm is proposed. For parallel and single precision, floating-point numbers are used to construct an orthogonal identity matrix. Thus, the efficiency and accuracy of the algorithm are guaranteed. Furthermore, the accuracy and computation of the fixed-point algorithm, double-precision floating-point algorithm, and proposed algorithm are compared. Without increasing complexity, the proposed algorithm can achieve remarkably higher accuracy and efficiency than the fixed-point algorithm and double-precision floating-point calculations, respectively.