• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.82-85
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• 2003

The sapphire wafers for blue light emitting devices were manufactured by the implementation of the surface machining technology based on micro-tribology. This process has been performed by Micro-lapping process. The sapphire crystalline wafers were characterized by DCXD(Double Crystal X-ray Diffraction). The sample quality of crystalline sapphire wafer at surface has a FWHM(Full Width at Half Maximum) of 250 arcsec. This value at the sapphire wafer surfaces indicated 0.12${\mu}{\textrm}{m}$ sizes. Surfaces of sapphire wafers were mechanically affected by residual stress and surface default. Also Surfaces roughness of sapphire wafers were measured 2.1 by AFM(Atom Force Microscope).

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.5
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• pp.410-416
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• 2001

KLN thin films were fabricated on Pt coated Si(100) wafer using an rf-magnetron sputtering method. The grown KLN thin film consists of 4-fold grains. In this experiment, the structure of 4-fold grained thin film was investigated using XRD and SEM measurements. Pt layer was also deposited using the rf-magnetron sputtering method,. XRD measurement showed that he Pt thin film has Gaussian distribution form with strong (111) direction orientation. The KLN thin film has preferred-orientation of (001) direction, and the peak consists of 2 separate peaks; one with broad FWHM and the other with narrow FWHM. The sharp peak is due to single crystal, and combining with Em results, the 4-fold grain consists of singel crystals with c-axis normal to substrate.

• Journal of the Optical Society of Korea
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• v.18 no.2
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• pp.101-109
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• 2014

In this paper, four apodization functions are proposed for silicon-on-insulator (SOI) strip waveguides with sidewall-corrugated gratings. The effects of apodization functions on the full width at half maximum (FWHM), the side-lobe level, and the reflectivity of the reflection spectrum are studied using the coupled-mode theory (CMT) and the transfer-matrix method (TMM). The results show that applying proposed apodization functions creates very good filtering characteristics. Among investigated apodized waveguides, the apodization functions of Polynomial and z-power have the best performance in reducing side-lobes, where the side-lobe oscillations are entirely removed. Four functions are also used for precise adjustment of the bandwidth. Simulation results show that the minimum and maximum values of the FWHM are 0.74 nm and 8.48 nm respectively. In some investigated functions, changing the apodization parameters decreases the reflectivity which is compensated by increasing the grating length.

• Nuclear Engineering and Technology
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• v.52 no.11
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• pp.2572-2580
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• 2020

Emerging gamma ray detection applications that utilize neutron-based interrogation result in the prompt emission of high-energy (>2 MeV) gamma-rays. Rapid imaging is enabled by scintillators that possess high density, high atomic number, and excellent energy resolution. In this paper, we evaluate the bright (50,000 photons/MeV) oxide scintillator, cerium-doped Gd₂Al₂Ga₃O₁₂ (GAGG(Ce)). A silicon photomultiplier (SiPM) array is coupled to a GAGG(Ce) scintillator array (12 × 12 pixels) and integrated into a coded-aperture based gamma-ray imaging system. A resistor-based symmetric charge division circuit was used reduce the multiplicity of the analog outputs from 144 to 4. The developed system exhibits 9.1%, 8.3%, and 8.0% FWHM energy resolutions at 511 keV, 662 keV, and 1173.2 keV, respectively. In addition, a pixel-identification resolution of 602 ㎛ FWHM was obtained from the GAGG(Ce) scintillator array.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07a
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• pp.121-124
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• 2004

We have grown GaN layers with in-situ SiN mask by metal organic chemical vapor deposition(MOCVD) and study the physical properties of the GaN layer. We have also investigate the effect of the SiN mask on its optical property. By inserting a SiN mask, (102) the full width at half maximum(FWHM) decreased from 480 arcsec to 409 arcsec. The PL intensity of GaN with SiN mask improved 2 times to that without SiN mask. We have thus shown that the SiN mask improved significantly the physical and optical properties of the GgN layer.

• Journal of Ocean Engineering and Technology
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• v.22 no.2
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• pp.72-77
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• 2008

The application of infrared thermography for detecting defects under the surface of a material was studied. Defects in a specimen were made by back-drilled circular holes. To get alarge temperature difference at the surface, a halogen lamp was used for surface heating. We confirmed that the defect location had a good relationship with the maximum temperature difference. The sizes of the defects could be calculated by means of the FWHM. The value of the FWHM of a temperature difference decreased with time. Therefore in an extremely short time after the heating, the true defect size could be measured.

• Bulletin of the Korean Chemical Society
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• v.22 no.8
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• pp.807-815
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• 2001

Two-dimensional (2D) correlation method, which generates the synchronous and the asynchronous 2D spectrum by complex cross correlation of the Fourier transformed spectra, is an analysis method for the changes of the sample spectrum induced by vari ous perturbations. In the present work, the 2D electronic correlation spectra have been simulated for the cases where the sample spectrum composed of two gaussian bands changes linearly. When only the band amplitudes of the sample spectrum change, the synchronous spectrum shows strong peaks at the band centers of the sample spectrum, but the asynchronous spectrum does not make peaks. When the sample spectrum shifts without changing intensity and width, the synchronous spectrum shows peaks around the initial and final positions of the band maximum and the asynchronous spectrum shows long peaks spanning the shifting range. The band width change produces the complex 2D correlation spectra. When the sample spectrum shifts with band broadening, the width change by 50% of full width at half maximum (FWHM) does not give so large an effect on the correlation spectrum as the spectral shift by one half of FWHM of the sample spectrum.

• 대한방사선방어학회:학술대회논문집
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• 2011.04a
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• pp.168-169
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• 2011

• 대한방사선방어학회:학술대회논문집
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• 2010.04a
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• pp.212-213
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• 2010

• Journal of Astronomy and Space Sciences
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• v.33 no.2
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• pp.137-146
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• 2016

The correlation between meteorological data collected at the optical wide-field patrol network (OWL-Net) Station No. 1 and the seeing of satellite optical observation data was analyzed. Meteorological data and satellite optical observation data from June 2014 to November 2015 were analyzed. The analyzed meteorological data were the outdoor air temperature, relative humidity, wind speed, and cloud index data, and the analyzed satellite optical observation data were the seeing full-width at half-maximum (FWHM) data. The annual meteorological pattern for Mongolia was analyzed by collecting meteorological data over four seasons, with data collection beginning after the installation and initial set-up of the OWL-Net Station No. 1 in Mongolia. A comparison of the meteorological data and the seeing of the satellite optical observation data showed that the seeing degrades as the wind strength increases and as the cloud cover decreases. This finding is explained by the bias effect, which is caused by the fact that the number of images taken on the less cloudy days was relatively small. The seeing FWHM showed no clear correlation with either temperature or relative humidity.