• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.374-374
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• 2009

We have fabricated pure YBCO films and $BaZrO_3$ doped ones on $CeO_2$ buffered YSZ single crystal substrates using rf-sputtering method. In this work, pure YBCO and 2 vol% BZO doped YBCO target were used to investigate the flux pinning properties of BZO doped YBCO films compared to undoped ones. BZO nanodots within the superconducting materials was known to comprise the self-assembled columnar defects along the c-axis from the bottom of YBCO films up to the top surface, thus can be a very strong pinning sites in the applied magnetic field parallel to them. We will discuss the possibility of growing self-assembled columnar defects in the rf-sputtering method. It is speculated that BZO and YBCO phases can separate and BZO form nanodots surrounded by YBCO epitaxial layers and continuous phase separation and ordering between these two materials, which was well studied in Pulsed Laser Deposition method. For this purpose, some severe experimental conditions such as on-axis sputtering, shorter target-substrate distance, high rf-power, etc was adopted and their results will be presented.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.22 no.1
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• pp.77-84
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• 2013

In this paper, we review two-dimensional measuring methods referring to target patterns. The patterns consist of two linearly-repeated patterns or is designed repeatedly in two-dimension. The repeated properties are reflectivity, refractivity, air-gapping distance, capacitance, magnetic reluctance, electrical resistance and sloping gradient, etc. However, the optical methods are generally used for high speed processing and density, and their encoding principles are treated here. In case of two-dimensional pattern, as there is not inherently error between single units encoding the pattern except for the metrology frame errors, the end-effector position of an object accompanying the pattern can be measured with respect of the global frame without via error. Therefore, it is regarded as a substitute for laser interferometer with severe environmental constraints and has been applied to the high-accurate planar actuator.

• International Journal of Automotive Technology
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• v.6 no.4
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• pp.315-322
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• 2005

This work was performed to investigate the effect of a split injection on spray characteristics of fuel sprays injected from a common rail system. In order to analyze the spray behavior and atomization characteristics at various rates of split injections, the injection durations of pilot and main injections were varied in experiments. The injection rate of split injection was measured to study the effect of the pilot injection on the main injection. By using a Nd:YAG laser and an ICCD camera, the development of the injected spray was visualized at various elapsed time from the start of injection. The microscopic characteristics such as SMD and axial velocity were analyzed by using a phase Doppler particle analyzer system. The results indicate that the ambient gas flow generated by the pilot injection affects the behavior of main spray, whereas the effect of pressure variation on the main spray is little. The spray tip penetration of a main spray with pilot injection is longer than that of the single injection by the effect of ambient gas flow. Also the main spray produces larger droplets than the pilot spray due to a small relative velocity between the droplets and ambient gas.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.9
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• pp.3435-3440
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• 2010

Unlike the electric method capable of checking only product defect, the real time optical metrology is suggested for measuring and visualizing vibration with respect to position of surface acoustic wave in RF device. The measuring limits and conditions for surface acoustic wave is given, and the interference and diffraction due to RF signal are analyzed by optical interpretation. A single mode laser and a 105MHz-center-frequency repeater filter were employed for experiments and theoretical analysis. In this paper, the optical metrology providing visual energy distribution and real time inspection for surface acoustic wave is proposed for development of high quality multi-service and multi-frequency RF module.

• Journal of the Korean Society of Visualization
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• v.1 no.2
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• pp.29-37
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• 2003

During the past five decades or so, the characteristics of turbulent swirling flow have been studied extensively because of its great technological and scientific importance. It is well known that the swirling flow improves heat transfer in duct flow. The reason for this is due to the effect of streamline curvature associated with the tangential velocity component. Although many studies have been carried out to investigate the characteristics of the swirling flow in a circular tube. The experimental methods for measuring the velocity components are by hot-wire or LDV (Laser-Doppler-Velocimetry) measuring single point velocity so far. The present study was aimed to analyse the flow characteristics of swirling flow such as time-mean velocity vector, local velocity turbulence intensity and turbulence kinetic energy by using PIV(Particle-Image Velocimetry). The experiment was carried out for four Reynold numbers $1.0\times10^{4}$, $1.5\times10^{4}$, $2.0\times10^{4}$ and $2.5\times10^{4}$ of the measuring area.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.1
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• pp.92-97
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• 2008

This is a research to apply 1310nm single-mode optical fiber to a temperature sensor. The existing study of optical fiber sensor is complicated because it was made with various equipment. To vary scattering, the variation of optical frequency is measured by using Bragg(lattice) or pulse generator and also bulk system is created by YAG laser but there were some difficulties creating experimental environment and it was a problem that the stability of measured data was low. The temperature sensor system using the suggested sBs(stimulated Brillouin scattering:sBs) from this research is much more simplified straight-line system. To improve the trust and accuracy of noises from optical frequency and unclear results, it was analysed by using Neuro-Fuzzy algorithm. we tried to get more correct data than existing system. sBs measure that optical frequency changed due to the variation of temperature. The analyzed change rate of outcome by Fuzzy theory is 1.1 MHz.

• Journal of Electrical Engineering and Technology
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• v.8 no.5
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• pp.1194-1201
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• 2013

This paper introduces a vision-based automatic system (VAMS) for non-contact measurement of morphometric characteristics of flatfish, such as total length (TL), body width (BW), height (H), and weight (W). The H and W are simply measured by a laser displacement and a load cell, respectively. The TL and BW are measured by a proposed morphological image processing algorithm. The proposed algorithm cans measurement, when the tail of flatfish is deformed, and when it is randomly oriented. In the experiment, the average and maximum measurement errors were recorded, and standard deviations and coefficients of variation (CVs) for the measurements were calculated. From those results, when flatfish the TL measurements had an average of 266.844 mm, a standard deviation of 0.351 mm, a CV of 0.131%, and a maximum error of 0.87 mm with straightened flatfish ($TL_A$ : 267 mm, $BW_A$ : 141 mm), and when flatfish of different sizes were measured, the errors in the TL and BW measurements were both about 0.2 %. Using a single conveyor, the VAMS can process up to 900 fishes per hour. Moreover, it can measure morphometric characteristics of flatfish with a TL of up to 500 mm.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.12 s.117
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• pp.1279-1285
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• 2006

In this study, structural deformation estimation using displacement-strain relationship is investigated. When displacements of a structure cannot be measured directly, estimation of displacements using strain data can be an alternative solution. Additionally, the deformation of the whole structure as well as the displacement at the point of interest can be estimated. Strain signals are obtained front Fiber Bragg Grating(FBG) sensors that have an excellent multiplexing ability. Some experiments were performed on two beams and a plate to which FBG sensors were attached in the laboratory. Strain signals from FBG sensors along a single strand of optical fiber were obtained through wavelength division multiplexing(WDM) method. The beams and the plate structures were subjected to various loading conditions, and deformed shapes were reconstructed from the displacement-strain transformation relationship. The results show good agreements with those measured directly from laser sensors. Moreover, the whole structural shapes of the beams and the plate were estimated using only some strain sensors.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.1
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• pp.59-72
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• 1998

This experimental study was carried out to investigate the characteristics of the in-cylinder eccentricity swirl flow generated by a 4 valve cylinder head with a tangential and a helical intake port. the measurements of the in-cylinder velocity field have been made by a two-channel LDA system. The mean flow coefficient(Cf(meam)), swirl ratio(Rs) and mass flowrate with valve eccentricity ratios and an intake port partition between the two intake ports were measured in the steady flow test fig using the ISM(impulse swirl meter). The experimental results indicated that the mass flowrate through the tangential intake port was 19% and 7.7% more than that of the helical intake port in case of with and without intake port partition respectively. There was a tendency to be a single rotation flow in swirl flow fields formed by a 4 valve cylinder head because of the interaction between the two intake ports. As the intake port partition was not set between flow coefficient(Cf(mean)) was 7.35%.

• The Journal of Engineering Geology
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• v.25 no.1
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• pp.1-8
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• 2015

Deep geological disposal is the preferred storage method for high-level radioactive waste, because it ensures stable long-term storage with minimal potential for human disruption. Because of the risk of groundwater contamination, a buffer of steel and bentonite layers has been proposed to prevent the leaching of radionuclides into groundwater. Quartz is one of the most common minerals in earth's crust. To understand how deformation and dissolution phenomena affect waste disposal, here we study quartz samples at pressure, temperature, and pH conditions typical of deep geological disposal sites. We perform a dissolution experiment for single quartz crystals under different pressure and temperature conditions. Solution samples are collected and the dissolution rate is calculated by analyzing Si concentrations in a solution excited by inductively coupled plasma-atomic emission spectroscopy (ICP-AES). After completing the dissolution experiment, deformation of the quartz sample surfaces is investigated with a confocal laser scanning microscope (CLSM). An empirical formula is introduced that describes the relationship between dissolution rate, pressure, and temperature. These results suggest that bentonite layers in engineering barrier systems may be vulnerable to thermal deformation, even when exposed to higher temperatures on relatively short timescales.