• The Journal of the Korean dental association
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• v.50 no.1
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• pp.22-30
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• 2012

The methods for the occlusal force measurement have long been developed. The occlusal analyzing equipment utilizing the pressure-sensitive film (Prescale) is useful for the assessment and comparison among large group of patients. On the other hand, the apparatus which uses the grid-based sensor sheet (T-scan) can be a useful assistant for acquiring the well-balanced occlusion. The device that can process the electrical input from the strain gauge which is attached to the tooth surface can collect the dynamic data of actual masticatory force. This device has been developed for the measurement of actual mastication with the food bolus and it can be a useful method for the comparison before and after the restorative treatment. Occlusal force measurement can be applied for the analysis of therapeutic action, diagnosis of crack- tooth syndrome, temporomandibul ar disease, and idiopathic implant loosening.

• Korean Journal of Optics and Photonics
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• v.15 no.6
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• pp.539-546
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• 2004

An improved low coherence interferometer system and a new analysis method for the accurate measurement of the optical path difference error of an AWG (Arrayed-Waveguide Grating) are described. The use of software simplifies the experimental setup by eliminating the hardware (clock generator). In addition, the actual distances between the peak positions of the adjacent interference signals are calculated using interpolation methods. The wavelength transmission characteristics of the AWG are calculated assuming the measured phase errors. The calculated AWG characteristic is quite similar to the actual measurement result, confirming accuracy of the proposed measurement setup.

• Journal of Korean Society of Water and Wastewater
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• v.33 no.5
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• pp.389-394
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• 2019

In order to determine the location of average concentration and distribution status of dissolved oxygen in the rectangular aeration tank of the sewage treatment plant was analyzed and the difference of dissolved oxygen concentration was remarkable at each location. Compared with the computational fluid dynamics analysis, it was found that the results were consistent with the measurement results by showing the difference of dissolved oxygen concentration between the locations. Based on the measured data, the representative location of dissolved oxygen in aeration tank was selected by using statistical analysis method and the representative location was expressed in three-dimensional coordinates(LWH : 25%, 50%, 33%) from flow direction and left wall. Also the difference between the dissolved oxygen concentration at the actual measurement location and the average concentration value of the entire aeration tank was founded, and the equations for calibrating the automatic measurement data considering the actual measurement location were calculated.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.10
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• pp.102-108
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• 2004

In this paper, we studied a vibration problem that is critical and common to most precision measurement systems. For micro mechanical part measurements, results obtained from the vision-based precision measurement system may contain errors due to the vibration. In order to defeat this generic problem, for the current study, a PC based image processing technique was used first, to assess the effect of the vibration to the precision measurement and second, to develop an in-situ calibration algorithm that automatically compensate the measurement results in real time. We used a set of stereoscopic CCD cameras to acquire the images for the dimensional measurement and the reference measurement. The mapping function was obtained through the in-situ calibration to compensate the measurement results and the statistical analysis for the actual results is provided in the paper. Based on the current statistical study, it is expected to obtain high precision results for the micro measurement systems.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.10
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• pp.172-181
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• 1999

The objective of this research is to develop a measurement error model for sculptured surfaces in On-Machine Measurement (OMM) process based on a closed-loop configuration. The geometric error model of each axis of a vertical CNC Machining center is derived using a 4${\times}$4 homogeneous transformation matrix. The ideal locations of a touch-type probe for the scupltured surface measurement are calculated from the parametric surface representation and X-, Y- directional geometric errors of the machine. Also, the actual coordinates of the probe are calculated by considering the pre-travel variation of a probe and Z-directional geometric errors. Then, the step-by-step measurement error analysis method is suggested based on a closed-loop configuration of the machining center including workpiece and probe errors. The simulation study shows the simplicity and effectiveness of the proposed error modeling strategy.

• Journal of Magnetics
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• v.20 no.1
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• pp.40-46
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• 2015

This study investigated the accuracy of magnetic resonance angiography (MRA) and computed tomography angiography (CTA) in terms of reflecting the actual vascular length. Three-dimensional time of flight (3D TOF) MRA, 3D contrast-enhanced (CE) MRA, volume-rendering after CTA and maximum intensity projection were investigated using a flow model phantom with a diameter of 2.11 mm and area of $0.26cm^2$. 1.5 and 3.0 Tesla devices were used for 3D TOF MRA and 3D CE MRA. CTA was investigated using 16 and 64 channel CT scanners, and the images were transmitted and reconstructed by volume-rendering and maximum intensity projection, followed by conduit length measurement as described above. The smallest 3D TOF MRA measure was $2.51{\pm}0.12mm$ with a flow velocity of 40 cm/s using the 3.0 Tesla apparatus, and $2.57{\pm}0.07mm$ with a velocity of 71.5 cm/s using the 1.5 Tesla apparatus; both images were magnified from the actual measurement of 2.11 mm. The measurement with the 16 channel CT scanner was smaller ($3.83{\pm}0.37mm$) than the reconstructed image on maximum intensity projection. The images from CTA from examination apparatus and reconstruction technique were all larger than the actual measurement.

• International Journal of Precision Engineering and Manufacturing
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• v.2 no.2
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• pp.73-80
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• 2001

The objective of this research is to develop a measurement error model for sculptured surface in On-Machine Measurement(OMM) process based on a closed-loop configuration. The geometric error model of each axis of a vertical CNC machining center is derived using a 4$\times$4 homogeneous transformation matrix. The ideal locations of a touch-type probe for the sculptured surface measurement are calculated from the parametric surface representation and X-, Y- directional geometric errors of the machine. Also the actual coordinates of the probe are calculated by considering the pre-travel variation of a probe and Z-directional geometric errors. Then, the step-by-sep measurement error analysis method is suggested based on a closed-loop configuration of the machining center including workpiece and probe errors. The simulation study shows the simplicity and effectiveness of the proposed error modeling strategy.

• Proceedings of the Korean Geotechical Society Conference
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• 2001.03a
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• pp.223-230
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• 2001

Nine different types of the reinforced railroad roadbeds which . are located in between Suwon-Chunan station of Kyongbu line were constructed in order to increase the bearing capacity of railroad roadbed and to improve the ridability as a part of speed-up project of conventional railroad systems. Each three sections were composed of weathered granite soil, crushed stone and furnace slag(HMS25), and fully instrumented with earth pressure cells, settlement plates and geophones to monitor the behavior of roadbeds under actual train loads. Field measurement has continued since October 31, 2000 and presently with rather longer measurement interval. The measurement data such as settlement, earth pressure and vibration levels are currently under analysis process. In this paper, only cumulative measurement data of railroad roadbeds were introduced. In the near future, comprehensive measurement data and result of analysis will be presented and design technique for the reinforced railroad roadbed will be proposed as a final product of this study.

• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.9 no.2
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• pp.35-41
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• 2010

The balance coefficients between telecommunication lines are specified in the technical standard and the power induction computation method varies in the order of 100 times in magnitude according to the amount of impedance. The results of actual balance measurements, differing from time to time with the measurement circuit or increasing proportionally as the induction voltage increases, appeared as a measurement error because of not using the standard measurement circuit. This article investigates such errors and proposes the use of a standard balance measurement circuit and a measurement device impedance under the domestic notification standard and the ITU-T international standard.

• Transactions of the Korean hydrogen and new energy society
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• v.32 no.6
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• pp.642-648
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• 2021

In this paper, an experimental study was conducted on the performance of the cooling tower. In order to improve reliability in the cooling tower performance test, the measurement uncertainty of the instrument was estimated. Measurement uncertainty refers to the uncertainty of a measurement, estimates the range in which the expected value of the measurement can be within a certain confidence level, and suggests a range in which the measured representative value is incorrect. Therefore, the measurement result of the performance experiment is not an actual value, but a reasonable estimated value. The measurement uncertainty for the test was calculated and the measured results were presented.