• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.21 no.8
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• pp.708-713
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• 2011

U.S. nuclear regulatory commission(NRC) regulatory guide(RG) 1.20 requires a comprehensive vibration assessment program(CVAP) for use in verifying the structural integrity of reactor vessel internals(RVI) for flow-induced vibrations prior to commercial operation. The CVAP program consist of vibration and fatigue analysis, a vibration measurement program, an inspection program, and a correlation of their results. One of the main purposes of the analysis program is to select measurement locations, however measurement locations can not be determined by only analysis results, therefore we developed selection criteria of measurement locations for advanced power reactor 1400(APR1400) RVI CVAP, It will be used to select measurement locations and instrument types for APR1400 RVI CVAP.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.272-275
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• 2003

Theodolite measurement system is non-contacted 3-dimensional measurement system. The system accuracy is 0.5 mm or better for distance 0 ~ 100 m. And the system is used for the measurement of a product for middle and large scale. This study was performed for finding the measurement error factors of the system. We could know that the main error factors are temperature, illumination and expertness. And we could find the measurement errors are $\pm$ 0.045 mm at temperature conditions is 2$0^{\circ}C$ and $\pm$ 0.012 mm at illumination condition is 300 lux. Also the results had significant differences by combinations of operator's expertness.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.2
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• pp.60-69
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• 2005

In electrostatic suspension system of thin plates like a silicon wafer or an aluminum disk for hard disk applications, the lateral restoring force exerted on a suspended object plays an important role since the lateral motion of the suspended object, owing to the inherently stable restoring forces, can be passively stabilized without any active control of it. This paper reports about the measurement apparatus of the lateral restoring force originating from a relative translation of the suspended object with respect to the electrodes-for-suspension. An approximate calculation of the lateral force in disk-shaped objects, the structure of the measurement apparatus, a measurement method, stabilization condition and the guideline in designing the measurement apparatus are described. Experimental results obtained by using a 3.5-inch aluminum disk as a suspended object are presented as well in order to assess the magnitude of lateral force and stiffness, and also verify the usefulness of the measurement apparatus.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.1409-1416
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• 2006

In measuring, uncertainty in measurement is essential to improve measuring reliability. Currently, however, in measuring impact sound insulation of floors, there are no guidelines to estimate uncertainty in measurement. In addition, the concept of uncertainty in rating is required to recognize the relation between measuring and rating. Therefore, through this paper, the efforts have been made to establish uncertainty in measurement and rating of light impact insulation of floors. The result of estimating of uncertainty in measurement and rating in our laboratory is considered reliable, considering ${\pm}0.46{\sim}1.44dB$ of uncertainty in measurement and 1 dB of uncertainty in rating.

• 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.

• 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.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.436-439
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• 2005

In general a square master and a dial gauge are used to measure the axis squareness on the spot. This method is a comparison measurement and its accuracy depends on the square accuracy wholly. Therefore the accuracy of a square master is very important and it is impossible that the accuracy of a square measurement is superior to the accuracy of a square master. In this paper, the new method of square measurement is proposed for measuring square without a square master and easily. This method is an absolute measurement by using a reversal method and can be used to measurement the accuracy of a square master.

• Current Optics and Photonics
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• v.7 no.4
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• pp.378-386
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• 2023

A wideband instantaneous frequency measurement (IFM) system is been proposed, designed and analyzed. Phase modulation to intensity modulation conversion is implemented based on the stimulated Brillouin scattering (SBS) effect, and the microwave frequency can be measured by detecting the change in output power. Theoretical analysis shows that the frequency measurement range can be extended to 4f_b by adjusting the two sweeping signals of the phase modulators with a difference of 2f_b. The IFM system is set up using VPI transmission maker software and the performances are simulated and analyzed. The simulation results show that the measurement range is 0.5-45.96 GHz with a maximum measurement error of less than 9.9 MHz. The proposed IFM system has a wider measurement range than the existing SBS-based IFM system.

• Journal of the Korean Society for Precision Engineering
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• v.31 no.11
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• pp.981-986
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• 2014

Printed electronics devices are made of several sets of printed patterns. The quality or printability of the printed patterns determines the electrical performance of such devices. Moreover, control of the printability determines the reliability of such devices. Despite its importance, few studies have been reported for the measurement of the printed patterns to evaluate their printability. In this study, a measurement method is proposed for printed patterns, including the definition of the properties to be measured, and the related software is described. The proposed method measures the width, pinholes, and edge waviness and evaluates the printability of the patterns quantitatively. The proposed measurement method could be an efficient tool to evaluate and enhance the printability of printed patterns in printed electronics.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.8
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• pp.40-47
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• 2001

Optical measurement methods make it possible to detect object displacements with high resolution and noncontact measurements. Also, they are very robust against EMI noises and have long operation range. An optical triangulation sensor is one of widely used displacement measurement sensors for its sub-micron resolution, fast response, simple structure, and low cost. However. there are several errors caused by inclinations of a surface. speckle effects, power fluctuations of light sources, and noises of detectors. In this paper, in order to minimize error effects, we performed error analysis and proposed a new structure. Then, we setup a new modeling method and verify it through simulations and experiments. Based on the new model. we propose a new sensor structure and establish design criteria. Finally, we design a signal processing system to overcome a resolution-limited problem of light detectors. The resolution of the proposed system is 0.2${\mu}{\textrm}{m}$ in 5mm operating range.