• Journal of The Korean Astronomical Society
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• v.42 no.4
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• pp.93-103
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• 2009

This article reports the spectral behavior of CH Cygni, using data obtained in October 2005 and June 2006. In these epochs, CH Cygni showed emission lines of H I, Fe II, [Fe II], [O III], [N II], [Ne III] and [S II]. Many of these lines were more enhanced since 2004. The underlying M-type spectrum was removed to get the intrinsic emission profile, and the resulting profiles were deconvoluted into several Gaussian components. Also, the radial velocities for all the lines that appeared in these spectra of CH Cygni were measured. The resultant lines were compared with each other and with those obtained in 2004; the findings are explained in terms of an accretion disk and jets.

• The Bulletin of The Korean Astronomical Society
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• v.35 no.1
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• pp.91.2-91.2
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• 2010

We present far-ultraviolet (FUV) observations of comet C/2001 Q4 (NEAT) obtained with Far-ultraviolet Imaging Spectrograph (FIMS, also called SPEAR) around perihelion between 8 and 15 May 2004. Several important emission lines, including S I (1425, 1474 ${\AA}$), C I (1561, 1657 ${\AA}$), CO (1087.9, 1340-1680 ${\AA}$) were detected. Especially, the spectral features of CO are its electronic transitions belongings to the A-X, C-X systems. We also obtained radial profile of S I, C I, H I $Ly{\beta}$ with line fitting from central coma. The production rate of several spectral lines calculated from observed FUV photon flux. FUV spectral images of S I, C I, H I $Ly{\beta}$ emission lines were obtained.

• 한국연소학회:학술대회논문집
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• 2007.05a
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• pp.176-183
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• 2007

An experimental study was performed to investigate the effects of mixing quality, inlet pressure, nozzle diameter on CO emission and radiation characteristics in porous ceramic fiber radiant burners. Observations of combustion characteristics occurring inside the burner system which was insulated fiber mat, were investigated by measuring temperature, CO emission and radiation characteristics. Combustion was achieved at the firing rate of $88{\sim}99$ kcal/hr, inlet pressure of $100{\sim}250$mm$H_2O$. CO emissions were found to be strongly dependent on the operating conditions. There was a tendency that CO concentration increased as the firing rate increases. The reason for rise of CO concentration is that it becomes the relatively rich condition. The fiber burner exhibit significant both spectral intensity peaks in the bands at 2.5${\mu}m$ and 4.0${\mu}m$ relatively, There is a small difference in the variable mixing tube. However spectral intensity increased with the firing rate.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.1
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• pp.68.2-68.2
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• 2018

Spectroscopic observations commonly use a slit or fiber; however, non-slit spectroscopy enables us to observe a larger number of targets in one frame of image. Hence, it has been adopted as an observational mode for observatories like HST and JWST. Slitless spectroscopy requires wavelength calibration solutions in order to distinguish and measure the absorption / emission lines from the spectra with high accuracy. We installed the Volume Phase Holographic (VPH) grating to SQUEAN camera on the McDonald 2.1m telescope and obtained images with spectral resolutions of ~ 100 and 200. In order to derive the wavelength calibration, we measured the distances between the 0th order images and spectral features of various quasars. The distances are converted to wavelengths using the known wavelengths of the emission lines. We tested several different methods of spectral extraction and peak estimation of emission lines. We will present the results for the wavelength calibration and suggest the reliable methods to find the solution.

• Journal of Advanced Navigation Technology
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• v.10 no.4
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• pp.333-341
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• 2006

This paper analyzes the spectral power properties of various time hopping UWB signals and shows that the power spectral densities of the various signals could have to be determined by the PSD of the pulse used in the signal. The pulse design method by which the FCC emission mask can be utilized fully is proposed. The method combines the arbitrary derivative Gaussian pulse linearly. The coefficients of the linear combination are calculated by the LSE(Least Square Error) method. Various parameters such as the number of coefficients and the types of the basic pulses are considered when calculating the PSD and pulse shapes of the new pulses.

• The Bulletin of The Korean Astronomical Society
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• v.44 no.1
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• pp.82.1-82.1
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• 2019

Recent analyses of spectro-images of Saturn observed by Visual and Infrared Mapping Spectrometer (VIMS)/Cassini revealed altitudinal distributions of the spectral structure of haze in Saturn's south-polar regions (Kim et al., 2018) and at $55^{\circ}N$ latitude (Kim et al., 2012). However, other regions of Saturn still have not been investigated. We derived series of high-spatial resolution VIMS images of Saturn's limb at various latitudes. Using our developed code, the altitudinal intensity profiles of $3.3-{\mu}m$ emission and H3+ through different latitudes were plotted. Then we obtained the averaged vertical spectra of $3.3-{\mu}m$ emission which is all blended with fluorescent methane and hydrocarbon haze. The vertically-resolved spectra were measured from the limb of Saturn in 50km intervals to see altitudinal variance. We will present a comparison of spectral structures of $3.3-{\mu}m$ emission with different latitudes. Further investigation using radiative transfer to extract adjacent fluorescent CH4, C2H6, and H3+ is needed to derive spectral structure of pure haze. We look forward to a better understanding of aging process in a global view.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.1
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• pp.33-39
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• 2007

This paper is aimed at the development of a software that predicts the surface temperature profiles of three-dimensional objects on the ground by considering the spectral solar radiation through the atmosphere. The spectral solar radiation through the atmosphere is modeled by using the well-known LOWTRAN7 code which analyzes the detailed spectral transmission characteristics by considering the atmospheric gas layers. In this paper, the transient temperature distribution over a cylinder is calculated by using the semi-implicit method. The spectral radiative surface properties such as the absorptivity and emissivity of the objects are used to model the effects of the solar irradiation and the surface emission. Both the detailed spectral modeling and the simple total modeling for the solar radiation absorption show fairly good agreement with each other by showing less than 3% difference in surface temperature.

• Journal of Astronomy and Space Sciences
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• v.33 no.2
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• pp.109-117
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• 2016

We explain the results of Yu et al. (2015b) of the novel sharpness angle measurement to a large number of spectra obtained from the Fermi gamma-ray burst monitor. The sharpness angle is compared to the values obtained from various representative emission models: blackbody, single-electron synchrotron, synchrotron emission from a Maxwellian or power-law electron distribution. It is found that more than 91% of the high temporally and spectrally resolved spectra are inconsistent with any kind of optically thin synchrotron emission model alone. It is also found that the limiting case, a single temperature Maxwellian synchrotron function, can only contribute up to 58⁺²³₋₁₈% of the peak flux. These results show that even the sharpest but non-realistic case, the single-electron synchrotron function, cannot explain a large fraction of the observed spectra. Since any combination of physically possible synchrotron spectra added together will always further broaden the spectrum, emission mechanisms other than optically thin synchrotron radiation are likely required in a full explanation of the spectral peaks or breaks of the GRB prompt emission phase.

• The Bulletin of The Korean Astronomical Society
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• v.40 no.1
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• pp.49.3-50
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• 2015

Synchrotron radiation of relativistic electrons is an important radiation mechanism in many astrophysical sources. In the sources where the synchrotron cooling timescale is shorter than the dynamical timescale, electrons are cooled down below the minimum injection energy. It has been believed that such fast-cooling electrons have a power-law distribution in energy with an index -2, and their synchrotron radiation has a photon spectral index -1.5. On the other hand, in a transient expanding astrophysical source, such as a gamma-ray burst (GRB), the magnetic field strength in the emission region continuously decreases with radius. Here we study such a system, and find that in a certain parameter regime, the fast-cooling electrons can have a harder energy spectrum. We apply this new physical regime to GRBs, and suggest that the GRB prompt emission spectra whose low-energy photon spectral index has a typical value -1 could be due to synchrotron radiation in this moderately fast-cooling regime.

• Journal of the Korean Institute of Navigation
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• v.23 no.2
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• pp.61-66
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• 1999

It is being more and more difficult to suppress emissions from electronic products using PCB(Printed Circuit Board) to the limit. Therefore, the exact evaluation of the emission from PCB has been more important to reduce the required time and the cost at the design phase of the products, especially on board ship's equipments. This research has evaluated the emission radiated from PCB based on the theoretical approach of SDA(Spectral Domain Analysis), which is available to analyze microwave stripline, coplanar line, patch antenna, etc. According to the theoretical results, it has been clearly shown that the emission radiated from PCB is reduced as the thickness of PCB is thinner, the permittivity of PCB is higher, the length of stripline is shorter, and the frequency is lower.