• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.20 no.4
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• pp.446-451
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• 2011

Recent trends for the miniaturization and weight reduction of portable electronic parts have driven uses of subminiature components. Assembly of the miniaturized components requires subminiature screws of which pitch sizes are micrometer scale. To produce such subminiature screws with high precision threads, not only a precision forming technology but also a high-precision measurement technology is required. The present study covers the development of a vision inspection system for precision screws for the automatic measurement of subminiature screws with high speed and reliability. In this study, the feeding unit that transfers the subminiature screws to the inspection unit is investigated through finite element(FE) analysis. The vibration characteristics of the feeding unit are predicted through FE analyses, from which we can determine whether the subminiature screw can be stably fed into the inspection unit or not. The effects of several design parameters on the vibration characteristics are also discussed.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.11a
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• pp.29-30
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• 2022

The unit-water content has a very significant effect on the durability of the construction structure and the quality of concrete. Although there are various methods for measuring the unit-water content, there are problems of time required for measurement, precision, and reproducibility. Recently, there is an FDR sensor capable of measuring moisture content in real time through an apparent dielectric constant change of electromagnetic waves. In addition, various artificial intelligence techniques that can non-linearly supplement the accuracy of FDR sensors are being studied. In this study, the accuracy of unit-water content measurement was compared and evaluated using machine learning and deep learning techniques after normalizing the data secured in concrete using frequency domain reflectometry (FDR) sensors used to measure soil moisture at home and abroad. The result of comparing the accuracy of machine learning and deep learning is judged to be excellent in the accuracy of deep learning, which can well express the nonlinear relationship between FDR sensor data and concrete unit-water content.

• The Mathematical Education
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• v.49 no.3
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• pp.375-387
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• 2010

The focus of this article is the strategies young children use to solve rectangular covering tasks before they have been taught area measurement. seventy nine children from Grade 1 to 4 were observed while they solved various array-based tasks, and their drawing and explanation were collected and analyzed. Children's solution strategies were classified into incomplete covering, inadequate array, array constructed from moveable unit, measurement of one dimension, measurement of two dimension, and calculation. Implications for the learning of area measurement are addressed.

• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.2 no.4
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• pp.52-63
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• 2003

This study proposes a change from the currentexpected price integrated system, which is based on the standard of estimated unit manpower and material, to a new actual construction cost integrated system. In order to implement it, the standard method of measurement organization system as well as the communication area standard of estimated unit manpower and material should be changed Moreover, the work breakdown structure and itemized structure should be assorted.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1881-1886
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• 2005

This paper proposes a novel approach of a precision attitude determination algorithm using UVF (Unit Vector Filter) measurements. The proposed method is superior to the conventional QUEST measurements based approaches because the estimation performance can be greatly enhanced by selecting brighter stars having better noise characteristics. The performance comparison with QUEST measurements is made to verify the usefulness of the proposed algorithm.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.74-78
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• 2002

Ultra-Precision CNC polishing system including on-machine measurement system, a corrective polishing algorithm is developed. The unit removal profiles for various polishing tools and analyzed and tested and dwell time distributions and residual errors for a target removal shape are calculated. The corrective polishing algorithm is tested with various workpieces. This result will be used for the software development of the CNC polishing system.

• Journal of the Korea Institute of Building Construction
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• v.24 no.3
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• pp.319-329
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• 2024

This study examined domestic and international regulations concerning concrete unit weight, along with an evaluation of unit weight in concrete poured on construction sites. Fluctuations in unit weight were observed to correlate with concrete quality issues such as material separation, bleeding, and latency. A word cloud analysis, centered on the concept of concrete quality, further highlighted the significant influence of unit weight. Comparative analysis between Korea and Japan revealed few substantial differences in unit weight management and measurement techniques. However, calculation of concrete unit weight at delivery, using the unit volume mass method, indicated considerable variability among random on-site samples. Notably, the unit weight often exceeded the recommended standard. These findings emphasize the necessity for strict adherence to unit weight standards by all stakeholders involved in concrete production and construction, including ready-mix concrete (REMICON) producers, construction firms, and inspectors. To ensure consistent quality of cast concrete on-site, the establishment of a more comprehensive and practical system is recommended, incorporating measures such as on-site inspections.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.9
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• pp.83-89
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• 2013

Power distribution system has been changed from radial system to closed loop or mesh system due to connection of distributed generation growth. Data from distribution equipments which are installed at distribution line is required to be accurate for the performance of DMS(Distribution Management System). This paper analyzes the voltage measurement data from distribution equipment. However, the results of the analysis are confirmed to have some errors in voltage measurement data from distribution equipment. These errors come from aging of voltage sensor in distribution equipment and inaccurate data transfer to FRTU(feeder remote terminal unit) through the controller. The main problem is that the voltage measurement data of distribution equipment can not be assessed after it's first installation at the distribution line. The voltage measurement accuracy assessment system is to assess the voltage measurement data from distribution equipment on hot-line. This study had a field test to verify the performance of system.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.1
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• pp.120-128
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• 2000

One of the major limitations of productivity and quality in metal cutting is the machining accuracy of machine tools. The machining accuracy is affected by geometric errors, thermally-induced errors, and the deterioration of the machine tools. Geometric and thermal errors of machine tools should be measured and compensated to manufacture high quality products. In metal cutting, the machining accuracy is more affected by thermal errors than by geometric errors. This paper models of the thermal errors for error analysis and develops on-the-machine measurement system by which the volumetric error are measured and compensated. The thermal error is modeled by means of angularity errors of a column and thermal drift error of the spindle unit which are measured by the touch probe unit with a star type styluses and a designed spherical ball artifact (SBA). Experiments, performed with the developed measurement system, show that the system provides a high measuring accuracy, with repeatability of $\pm$2${\mu}{\textrm}{m}$ in X, Y and Z directions. It is believed that the developed measurement system can be also applied to the machine tools with CNC controller. In addition, machining accuracy and product quality can be improved by using the developed measurement system when the spherical ball artifact is mounted on the modular fixture.

• Physical Therapy Korea
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• v.17 no.3
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• pp.1-10
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• 2010

The purpose of this study was to measure intra-rater and inter-rater reliability and range of motion for measurement of passive shoulder internal rotation range of motion and to compare anterior glide distance of humeral head in three methods. Fifty healthy subjects and fifty patients with shoulder musculoskeletal pain were recruited for this study. The subjects' passive shoulder internal rotation range of motion was measured by visual estimation, manual stabilization, and pressure biofeedback unit methods. In two trials, measurements were performed on each subject by two examiners. Intraclass correlation coefficient (ICC(3,1)) was used to determine the reliability of each measurement. The intra-rater reliability of the three methods was excellent (ICC=.77~.93) in both groups. The inter-rater reliability of the visual estimation method was poor (ICC=.20, .29), the manual scapular stabilization method was poor and fair (ICC=.09, .50), and the pressure biofeedback unit method was excellent (ICC .86, .75) in the experimental and control groups. In the experimental group, the difference of examined range of motion by each examiner was significant in the visual estimation method and manual scapular stabilization method, but there was an insignificant difference between the groups is the pressure biofeedback unit method. This result suggests that the intra-rater and inter-rater reliability of a pressure biofeedback unit was better than the other methods. The difference in distance of the anterior glide of humeral head was insignificant among all the methods. The pressure biofeedback unit method was the most reliable method, so it is proposed to be a new and reliable method to measure internal rotation range of motion.