• Journal of The Korean Astronomical Society
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• v.33 no.2
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• pp.81-88
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• 2000

The international ultraviolet explorer (IUE) spectra of a low dispersion $\~6{\AA}$, have been investigated for two Seyfert 1 galaxies, Mrk 335 and NGC 4051, well known for the line variability. The electron densities of broad line region (BLR) of these variable Seyfert 1 galaxies have been derived, which showed a non-linear abrupt variation from $10^8$ to $10^{10} cm-3$ within a month. We also found the excitation (or temperature) changes in the Mrk 335 BLR from the IUE broad line profiles analysis, but no such evidence in the NGC 4051. The large amount of mass inflow activity through the bar or spiral structure of host galaxies, may trigger the density change in BLR and emission line variability for both objects. Mass of the giant black holes appear to be order of $10^7\;M_{\bigodot}$ for both variable Seyfert l's.

• Publications of The Korean Astronomical Society
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• v.21 no.2
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• pp.101-112
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• 2006

We developed a new program for automatic continuum normalization of Echelle spectrographic data. Using this algorithm, we have determined spectral continuum of almost BOES data. The first advantage of this algorithm is that we can save much time for continuum determination and normalization. The second advantage is that the result of this algorithm is very reliable for almost spectral type of spectrum. But this algorithm cannot be applied directly to the spectrum which has very strong and broad emission lines, for example Wolf-Rayet type spectrum. We implanted this algorithm to the program which was developed in the previous study. And we introduced more upgraded BOES data reduction program. This program has more convenient graphical user interface environment, so users can easily reduce BOES data. Lastly, we presented the result of study on line profile variation of magnetic Ap/Bp stars analyzed using this program.

• Journal of the Korean Society of Propulsion Engineers
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• v.19 no.4
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• pp.24-36
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• 2015

In the present study, numerical predictions of infrared spectrum of rocket plume with considering effect of particles based on approximation theories were performed by using a line-by-line radiation model with radiation databases. The high-resolution radiation databases were used to predict thermal emission spectra of gas molecules within the rocket plume regime. The particles were modeled as soot particles by using 1st term approximation of Mie theory and Rayleigh approximation. The reliability of modeled effect of soot particles using the two approximation theories was verified, and the spectral radiance of rocket plume was predicted based on the verification. The results were improved in the short wavelength range by considering the effect of soot particles.

• The Bulletin of The Korean Astronomical Society
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• v.35 no.1
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• pp.57-57
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• 2010

We report the discovery of a bright mid-infrared (MIR) source with prominent crystalline silicate emission using the space telescope AKARI and Spitzer. This source, IRAS 15099-5856, has a spectacular morphology with a bright central compact source (CCS) surrounded by knots, spurs, and several extended (~4') arc-like filaments. The source is seen only in infrared at ${\geq}10{\mu}m$. The Spitzer MIR spectrum of the CCS shows prominent emission features from Mg-rich crystalline silicates and strong [Ne II] 12.88 ${\mu}m$ and several other faint ionic lines. We model the MIR spectrum as thermal emission from several independent dust components and compare their properties to those of the Herbig Be star HD 100546 which shows very similar MIR spectrum. Our molecular line observations reveal two molecular clouds around the source, but no associated dense molecular cores. We discuss two possible origins for IRAS 15099-5856; a deeply embedded massive young stellar object on the other side of the Galaxy and a disrupted, protoplanetary disk being photoevaporated by the UV radiation from the nearby O star Muzzio 10.

• Journal of the Korean institute of surface engineering
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• v.48 no.3
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• pp.82-86
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• 2015

$Dy^{3+}$- and $Eu^{3+}$-codoped $CaMoO_4$ Phosphors were synthesized by using the solid-state reaction method. The crystal structure, morphology, and optical properties of the resulting phosphor particles were investigated by using the X-ray diffraction, field-emission scanning electron microscopy, and photoluminescence spectroscopy. XRD patterns exhibited that all the synthesized phosphors showed a tetragonal system with a main (112) diffraction peak, irrespective of the content of $Eu^{3+}$ ions. As the content of $Eu^{3+}$ ions increased, the grains showed a tendency to agglomerate. The excitation spectra of the synthesized powders were composed of one strong broad band centered at 305 nm in the range of 220 - 350 nm and several weak peaks in the range of 350 - 500 nm resulting from the 4f transitions of activator ions. Upon ultraviolet excitation at 305 nm, the yellow emission line due to the $^4F_{9/2}{\rightarrow}^6H_{13/2}$ transition of $Dy^{3+}$ ions and the main red emission spectrum resulting from the $^5D_0{\rightarrow}^7F_2$ transition of $Eu^{3+}$ ions were observed. With the increase of the content of $Eu^{3+}$, the intensity of the yellow emission band gradually decreased while that of the red emission increased. These results indicated that the emission intensities of yellow and red emissions could be modulated by changing the content of the $Dy^{3+}$ and $Eu^{3+}$ ions incorporated into the host crystal.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.05a
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• pp.115-118
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• 2003

In this paper, we analysed the technical characteristics of power line communications interfering marine mobile services. The various radio services including marine mobile potentially affected by unwanted radiation from telecommunication networks as PLT, VDSL, ADSL, etc. The radio spectrum is unique resource. In particular, the frequency range below 30MHz has extremely favourable propagation conditions allowing economic long range as well as low power communication radio services. The paper were as follows to identify marine mobile service that are likely to be affected by PLC and evaluate the protection needs and to investigate methods of measuring the emissions from PLC.

• Bulletin of the Korean Chemical Society
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• v.26 no.6
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• pp.903-908
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• 2005

The sharp-line absorption and emission spectra of $(H_{13}O_6)${$trans-[Cr(Me_2tn)_2Br_2]$}$_2Br_2(ClO_4)\;(Me_2$tn = 2,2-dimethyl-1,3-diaminopropane) have been measured between 13000 $cm^{-1}$ and 16000 $cm^{-1}$ at 5 K. The 298 K infrared and visible absorption spectra have also been measured. The nine electronic bands due to spin-allowed and spin-forbidden transitions were assigned. Using observed transitions, a ligand field analysis has been performed to probe the ligand field properties of coordinated atoms in the title chromium(III) complex ion. The zero-phonon line in the sharp-line absorption spectrum splits into two components by 286 $cm^{-1}$, and the large $^2E_g$ splitting can be reproduced by the modern ligand field theory. It is confirmed that nitrogen atoms of the Me2tn ligand have a strong $\sigma$-donor character, but the bromide has weak $\sigma$- and $\pi$-donor properties toward chromium(III) ion.

• Journal of The Korean Astronomical Society
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• v.48 no.2
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• pp.105-112
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• 2015

The symbiotic star V1016 Cygni, a detached binary system consisting of a hot white dwarf and a mass-losing Mira variable, shows very broad emission features at around 6825 Å and 7082 Å, which are Raman scattered O vi λλ 1032, 1038 by atomic hydrogen. In the high resolution spectrum of V1016 Cyg obtained with the Bohyunsan Optical Echelle Spectrograph these broad features exhibit double peak profiles with the red peak stronger than the blue counterpart. However, their profiles differ in such a way that the blue peak of the 7082 feature is relatively weaker than the 6825 counterpart when the two Raman features are normalized to exhibit an equal red peak strength in the Doppler factor space. Assuming that an accretion flow around the white dwarf is responsible for the double peak profiles, we attribute this disparity in the profiles to the local variation of the flux ratio of O vi λλ 1032, 1038 in the accretion flow. A Monte Carlo technique is adopted to provide emissivity maps showing the local emissivity of O vi λ1032 and O vi λ1038 in the vicinity of the white dwarf. We also present a map indicating the differing flux ratios of O vi λλ 1032 and 1038. Our result shows that the flux ratio reaches its maximum of 2 in the emission region responsible for the central trough of the Raman feature and that the flux ratio in the inner red emission region is almost 1. The blue emission region and the outer red emission region exhibit an intermediate ratio around 1.5. We conclude that the disparity in the profiles of the two Raman O vi features strongly implies accretion flow around the white dwarf, which is azimuthally asymmetric.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.173-173
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• 2010

Recently, a patterned sapphire substrate (PSS) has been intensively used as one of the effective ways to reduce the dislocation density for the III-nitride epitaxial layers aiming for the application of high-performance, especially high-brightness, light-emitting diodes (LEDs). In this paper, we analyze the growth kinetics of the atoms and crystalline quality for the undopped-GaN depending on the facets of the pattern fabricated on a sapphire substrate. The effects of the PSS on the device characteristics of InGaN/GaN LEDs were also investigated. Several GaN samples were grown on the PSS under the different growth conditions. And the undoped-GaN layer was grown on a planar sapphire substrate as a reference. For the (002) plane of the undoped-GaN layer, as an example, the line-width broadening of the x-ray diffraction (XRD) spectrum on a planar sapphire substrate is 216.0 arcsec which is significantly narrower than that of 277.2 arcsec for the PSS. However, the line-width broadening for the (102) plane on the planar sapphire substrate (363.6 arcsec) is larger than that for the PSS (309.6 arcsec). Even though the growth parameters such as growth temperature, growth time, and pressure were systematically changed, this kind of trend in the line-width broadening of XRD spectrum was similar. The emission wavelength of the undoped-GaN layer on the PSS was red-shifted by 5.7 nm from that of the conventional LEDs (364.1 nm) under the same growth conditions. In addition, the intensity for the GaN layer on the PSS was three times larger than that of the planar case. The spatial variation in the emission wavelength of the undoped-GaN layer on the PSS was statistically ${\pm}0.5\;nm$ obtained from the photoluminescence mapping results throughout the whole wafer. These results will be discussed in terms of the mixed dislocation depending on the facets and the period of the patterns.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.1123-1126
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• 2003

In this paper, the emission properties of electrodeless fluorescent lamp were discussed using the inductively coupled plasma. To transmit the electromagnetic energy into the chamber, a RF power of 13.56MHz was applied to the antenna and considering the Ar gas pressure and the RF electric power change, the emission spectrum, Ar- I line, luminance were investigated. At this time the input parameter for ICP RF plama, Ar gas pressure and RF power were applied in the range of $10{\sim}60m$ Torr, $10{\sim}300W$ respectively.