• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.26-27
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• 2008

본 연구는 투명전도성전극(TCO)인 ITO를 대체하기 위해 ZnO에 $Al_2O_3$, $SiO_2$, $TiO_2$의 불순물을 도핑하여 박막의 전기적 및 광학적 특성에 관한 연구를 하였다. 불순물 도핑은 2wt.%로 진행 하였고, 동일한 전압과 두께로 그 특성을 비교 하였으며, 특성으로는 UV-Vis를 이용한 광투과율 측정과 광투과율을 이용한 박막의 광학적 밴드갭과 굴절률을 계산 하였다. 전기적 특성으로는 4-Point Probe로 면저항과 비저항값을 측정하였다.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.8
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• pp.727-732
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• 2008

In this work, the etch characteristics of $VO_2$ thin films were investigated using inductively coupled plasma (ICP) of $Cl_2/Ar$ gas mixtures. To analyze the plasma characteristics, a quadrupole mass spectrometer (QMS), an optical emission spectroscopy (OES), and a Langmuir probe measuring system were used. The surface reaction of the $VO_2$ thin films was investigated using X-ray photoelectron spectroscopy (XPS). It was found that an increase in Ar fraction in the $Cl_2/Ar$ plasma at fixed gas pressure, input power, and bias power resulted in increasing $VO_2$ etch rate which reached a maximum value of 87.6 nm/min at 70-75 % Ar. It was confirmed that the etch rate of the $VO_2$ films was mainly controlled by the ion flux. On the basis of measuring results, we will discuss possible etching mechanism of $VO_2$ film in the $Cl_2/Ar$ plasma.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.419-420
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• 2008

In this work, we report several experimental data capable of evaluating the phase transition characteristics of (InTe)x(GeTe)y (x = 0.1, 0.3, y =1) pseudo-binary thin films. (InTe)x(GeTe)y phase change thin films have been prepared by thermal evaporator. The crystallization characteristics of amorphous (InTe)x(GeTe)y thin films were investigated by using nano-pulse scanner with 658 nm laser diode (power : 1~17 mW, pulse duration : 10~460 ns) and XRD measurement. It was found that the crystalline speed of In-Ge-Te thin films are faster than $Ge_2Sb_2Te_5$[1] and also the crystalline temperature is higher. Changes in the optical transmittance of as-deposited and annealed films were measured using a UV-VIS-IR spectrophotometer and four-point probe was used to measure the sheeresistance of InGeTe films annealed at different temperature.

• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.3
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• pp.566-574
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• 1988

A study is described for obtaining real time in situ size and velocity measurements of the spray-droplet using crossed-beam interferometry. The optical arrangement is similar to dual-beam laser Doppler velocimetry(LDV). Droplets passing trough the probe volume scatter light to the collecting lens placed at 90.deg. off-axis angle. The dual-beam light scatter is analyzed by the geometric optics theory to relate the scattered fringe pattern to droplet diameter. The droplet size measurement is based upon the signal visibility. As the system is based on the Doppler effect, a single component of velocity is velocity is extracted concurrent with the size information. The validity of the method is evaluated by comparing its performance to widely accepted but limited technique, the collection method. By using 90.deg. off-axis scatter detection angle, the measurement of the droplet size and velocity distributions, and the local correlations between droplet sizes and velocities in relatively dense spray environments are made possible.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.2
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• pp.68-75
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• 1996

More accurate inspection method for facilities of nuclear power plants is required to guarantee the continuous and stable energy supply. The portion of inspection for pipes and pressure vessels is relatively big in the power plants. Conventional inspection methods using ultrasonic wave, x-ray and eddy current for nondestructive testing in nuclear power plants have been performed as the method of contact with objects to be inspected. With this reason these methods have been taken relatively much time, money and manpower. And the area to be inspected is limited by the location of probe or film. These difficulties make the inspection into a time-consuming work. We propose an optical defect detection method using phase shifting realtime holographic interferometry. This method has an advantage that the inspection can be performed at a time for relatively wide area illuminated by the laser beam, a coherent light source and can help an inspector recognize not only defects but also the high stressed areas. In this paper we show that the quantitative measurement using holographic interferometry and image processing for defect in pressure vessels is possible.

• Korean Journal of Optics and Photonics
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• v.14 no.1
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• pp.44-50
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• 2003

This paper describes the thermal effect at Nd:YAG using a laser-diode side-pumping. To detect the depolarization loss and the retardation caused by the thermal effect, a λ/4 plate is inserted between the polarizer and the Nd:YAG laser material. Using a CCD has allowed detection of the variation of the beam pattern that could analyze the change of the refractive index of the Nd:YAG laser material by the thermal effect. Through the change of the probe beam power, we know that 21% of the pumping power was converted into heat in the material. The depolarization loss was 24.7% under a temperature of $25^{\circ}C$ of the laser material and a pumping power of 15 W. The inhomogeneous distribution showed that the retardation angle was 7$^{\circ}$ in the center of the material and 19$^{\circ}$ on the edge of it. It is confirmed that the thermal effect is analyzed at the each point of the laser material and it suggests an effective method to reduce the thermal effect on the LD side-pumped laser material.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.11 s.176
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• pp.64-71
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• 2005

In order to measure surface roughness profile, stylus type equipments are commonly used, but the stylus keeps contact with surface and damages specimens by its tip pressure. Therefore, optics based measurement systems are developed, and light phase interferometer, which is based on light interference phenomenon, is the most noticeable research. However, light interference based measurements require translation mechanisms of nano-meter order in order to generate phase differences or multiple focusing, thus the systems cannot satisfy the industrial need of on-the-machine and in-process measurement to achieve factory automation and productive enhancement. In this research, we focused light reflectance phenomenon rather than the light interference, because reflectance based method do not need translation mechanisms. However, the method cannot direct]y measure surface roughness profile, because reflected light consists of several components and thus it cannot supply surface height information with its original form. In order to overcome the demerit, we newly proposed an image processing based algorithm, which can separate reflected light components and conduct parameterization and reconstruction process with respect to surface height information, and then confirmed the reliability of proposed algorithm by experiment.

• Proceedings of the KWS Conference
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• 2006.05a
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• pp.266-268
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• 2006

The effects of the brazing temperature and homogenizing time for brazed specimens on the joint of Ni-based superalloys such as Haynes 250, Inconel 617 and Hastelloy-X were investigated. The brazing alloy is nickel base MBF 15. The foil had a thickness of $38{\mu}m$, which was used two sheets of that for the all experiments. The experimental brazing was carried out by a brazing process in a vacuum of approximately $2{\times}10^{-5}$ Torr, an applied pressure of about 0.74MPa and the three kinds of brazing temperatures were 1100, 1150, and $1190^{\circ}C$ for a holding time of 5 to 1440 minutes. Microstructural observations were made on the cross-sectional samples by using an optical microscope(OM), scanning electron microscope(SEM), and electron probe X-ray microanalyzer(EPMA). The tensile tests were performed at room temperature with a cross head speed 1.5 mm/min according to ASTM E8M. The results show that excellent joint tensile strengths of as high as 788MPa were obtained when processed at $1190^{\circ}C$ for 5 minutes.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.1
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• pp.51.3-51.3
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• 2017

To investigate the connection between radio activity and AGN outflows, we present a study of ionized gas kinematics by using [O III] ${\lambda}5007$ emission line along the radio jet for six radio AGNs. These AGNs are selected based on the radioactivity (L1.4GHz ${\geq}$ 1039.8 erg s-1) as well as optical properties as type 2 AGNs. By using the high spatial resolution of the Red Channel Cross Dispersed Echellette Spectrograph at the Multiple Mirror Telescope, we investigate in detail the [O III] and stellar kinematics. We spatially resolve and probe the central AGN-photoionization sizes, which is important in understanding the structures and evolutions of galaxies. We find that the typical central AGN-photoionization sizes of our targets are in range of 1.8-3.8 kpc. We study the [O III] kinematics along the radio jets to test whether there is a link between gas outflows in the narrow-line region and radio jet emissions. Contrary to our expectation, we find no evidence that the gas outflows are directly connected to radio jet emission.

• Journal of Technologic Dentistry
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• v.25 no.1
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• pp.63-70
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• 2003

The microstructure and hardness of a porcelain fused Au-Pt-Cu-In alloy was investigated using optical microscopy, secondary electron microscopy, electron probe microanalyzer, transmission electron microscope, and vickers hardness. The hardness of the heat-treated Au-Pt-Cu-In quartenary alloy reached a maximum value in 30 min at 550$^{\circ}C$ in the range of 150 to 950$^{\circ}C$. In the aged Au-Pt-Cu-0.5In alloy at 550$^{\circ}C$, the hardness of the alloy rapidly increased until 30min with increasing aging time and after that it was remained nearly constant value. Based on above results, glazing and final aging of the porcelain fused Au-Pt-Cu-0.5In alloy were performed at 920 and 550$^{\circ}C$, respectively. The hardness of Au-Pt-Cu-0.5In alloy glazed at 920$^{\circ}C$ was 90 Hv and that of the alloy aged for 30 min at 550$^{\circ}C$ increased to 160 Hv. This indicates that a ceramic-metal crown with high strength can be manufactured using the glazing at 920$^{\circ}C$ and followed final aging at 550$^{\circ}C$ for 30 min.