• Proceedings of the Korea Concrete Institute Conference
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• 2006.05a
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• pp.566-569
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• 2006

The purpose of this study is to develop digital air meter used pressure sensor for measurement of air content in freshly mixed concrete by pressure method. The digital air meter can enhanced measurement accuracy and uniformity of air content in freshly concretes, according to use of pressure sensor and measuring process automation. Finally, the digital air meter in this study is improved reproducibility and reliability of measurement compared with analog air meter.

• ETRI Journal
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• v.32 no.1
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• pp.154-156
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• 2010

Oscillation-based testing of analog-to-digital converters represents a viable option for low-cost built-in self-testing in mixed-signal design. While numerous papers have addressed implementation issues, little attention has been paid to the measurement accuracy. In this letter, we highlight an inherent measurement uncertainty which has to be considered when deriving the parameters from the oscillation frequency.

• Journal of the Korean Society for Precision Engineering
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• v.32 no.12
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• pp.1039-1047
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• 2015

Contact type sensors (e.g., displacement sensor and strain gauge) were typically used to evaluate the safety and mechanical properties in machines and construction. However, those contact type sensors have been constrained because of measurement problems such as surface roughness, temperature, humidity, and shape. The Digital Image Correlation (DIC) measurement system is a vision measurement system. This measurement system uses the taken image using a CCD camera and calculates the image correlation between the reference image and the deformed image under external force to measure the displacement and strain rates. In this paper, we discuss methods to improve the measurement precision of the digital image correlation measurement system. A tensile test was conducted to compare the precision improvement effects, by using the universal test machine and the DIC measurement system, with the use of subpixel algorithms, i.e., the Coarse Fine Search (CFS) algorithm and the Peak Finding (PF) algorithm.

• The Journal of the Korean dental association
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• v.47 no.5
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• pp.282-290
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• 2009

The purpose of this study was to evaluate the measurement error between conventional films, digital cephalographs and hardcopy. The material consisted of 29 cephalographs which used image modality of Asahi CX-90SP in the Kyung Hee University Dental Hospital. One observer measured fiducial measurements at an interval of four weeks. Measurement error was tested by Dahlberg's formula. A paired t-test was used to detect it between each modality. The results are as follows; 1. The monitor-displayed digital image showed enlargement compared with the conventional image. The cephalometric measurements of the monitor-displayed digital image and conventional image were no statistically significant difference except SNB. 2. In conventional image, measurement errors of linear and angular measurements were 0.23mm, $0.36^{\circ}$, respective. In monitor-displayed digital image, measurement errors of linear and angular measurements were 0.63mm, $0.48^{\circ}$ respective. 3. The reduction ratio of hardcopy was 1.01% compared to the monitor-displayed digital image. Based on the results, it indicates that the digital cephalographs and hardcopy using storage phosphor digital radiography showed the same accuracy as the conventional films in clinical use.

• Journal of Internet Computing and Services
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• v.22 no.4
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• pp.51-63
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• 2021

Recently, virtual communication has become a standard tool due to the outbreak of COVID-19. Likewise online communication is emerging as an essential competency. In this study, we aimed to develop a comprehensive and systematic digital literacy measurement tool reflecting the changes and needs of society. Construct variables were drawn by characterizing existing digital literacy measurement tools. Thirty-four items corresponding to the concept of each variable were developed. The developed measurement tool was then evaluated in the form of surveys from university students belonging to the digital native generation, and the reliability and validity were performed through exploratory and confirmatory factor analysis. The digital literacy measurement tool contained five sub-factors and twenty-five questions. In addition, hierarchical regression analysis was performed to verify the predictive validity of digital literacy sub-factors. Based on these findings, the implication of future research is discussed.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.18 no.2
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• pp.135-141
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• 2000

This study aims to analyze stone's surface roughness measurement accuracy of a high resolution DCS 420 digital camera by digital close-range photogrammetric technique. For this purpose, the surface roughness measurement system was constructed by means of microsoft visual basic 6.0 in windows. As the analysis results of measurement accuracy of digital camera using this system, the roughness error of the normal distance between the best fitting reference surface obtained by least square method and sample points in the ideal plane or surface did not exceed $\pm$0.1 mm

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.4D
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• pp.545-553
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• 2009

This paper describes the result of study on measurement of displacement of structure by means of non-contacting method, close-range digital photogrammetry using digital camera. To apply close-range digital photogrammetry to displacement measurement of structure, correction of lens distortion that interferes geometrical analysis has been carried out and then measuring displacement was performed on load regulated-rahmen. For enhanced applicability of displacement measurement, MIDAS which is a structural analysis program was used for modeling and the result was taken from comparative analysis. As a result of the study, it is showed that close-range digital photogrammetry could supplement several weaknesses of LVDT and cable displacement meter and, especially, economy in the perspective of measuring time could be realized. Close-range digital photogrammetry using digital camera can be applied to the area where requires visual analysis such as 3D modeling of structure, profile replication of measurement of structure as well as measurement of displacement of structure.

• Journal of Advanced Marine Engineering and Technology
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• v.22 no.4
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• pp.468-480
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• 1998

A flow measurement system which is able to measure the instantaneous three-dimensional velocity components and the pressure distribution of fluid flows is developed using a digital image processing system and the stereoscopic photogrammetry. This system consists of two TV cameras a digital image processor and a 32-bit microcomputer. The capability of the developed system is verified by a preliminary test in which three-dimensional displancements of moving particles arranged on a rotating plate are tracked automatically. The constructed system is through the measurement and spatial pressure distribution is also obtained. The measurement uncertainty of this system is evaluated quantitatively. The present technique is applicable to the measurement of an unsteady fluid phenomenon especially to the measurement of three-dimensional velocity field of a complex flow.

• Journal of the Korean Society for Nondestructive Testing
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• v.30 no.3
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• pp.257-260
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• 2010

Advancements in the imaging and computing technology have opened the path to digital holography for non-destructive investigations of technical samples, material property measurement, vibration analysis, flow visualization and stress analysis in aerospace industry which has widened the application of digital holography in the above fields. In this paper, we demonstrate the non-destructive investigation and micro-structure measurement application of digital holography to the small particles and a biological sample. This paper gives a brief description of the digital holograms recorded with this system and illustratively demonstrated.

• Proceedings of the KIEE Conference
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• 1999.11c
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• pp.482-484
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• 1999

In this paper, we propose a voting method for capacitance measurement. Nowadays the measurement system is changing from analog system to digital system. However, capacitance measurement system has a data error because of the noise. The data of general digital measurement system include an internal and external measurement noises that highly affect to the results. Therefore, this paper proposes data compensation method using voting method. Finally, simulation results are used to demonstrate the efficiency of the proposed method.