• Bulletin of the Korean Space Science Society
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• 2000.10a
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• pp.52-52
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• 2000

No Abstract, See Full Text

• Bulletin of the Korean Space Science Society
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• 1996.11a
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• pp.25-25
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• 1996

No Abstract, See Full Text

• The Bulletin of The Korean Astronomical Society
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• v.42 no.2
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• pp.73.1-73.1
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• 2017

Reverberation mapping is one of the best way to investigate structure and kinematics of broad-line regions around central supermassive black holes of active galactic nuclei (AGN). It is usually used to estimate masses of supermassive black holes. So far, reverberation mapping studies have achieved good results for dozens of AGN by spectroscopic monitoring. However, spectroscopic monitoring is time consuming and high cost. Here, we present result of photometric reverberation mapping with medium-band observation. We monitored five nearby AGN which are already studied, have short time-lag, and show bright H-alpha emission lines. Observation has been performed for ~3 months with ~3 days cadence using three medium-band filters installed in LSGT (Lee Sang Gak Telescope). We found 0.01-0.06 magnitude variations by differential photometry. Also time-lags between continuum light-curves and H-alpha emission line light-curves are calculated using Javelin software. The result shows that our study and previous studies are consistent within uncertainty range. From verification of availability in this study, photometric reverberation mapping could be used as a powerful tool to measure central supermassive black holes for large samples and high-redshift AGN in the future.

• Journal of The Korean Astronomical Society
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• v.29 no.spc1
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• pp.333-335
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• 1996

Here we report the results from spectroscopic observations of soloar active regions in the HeI 10830 ${\AA}$ line at the German Vacuum Tower Telescope(VTT) in Tenerife during the August 199:3 International EFR(Emerging Flux Region) Campaign. Four active regions in various stages of their evolution, i.e., NOAA7558, 7560, 7561, and 7562, were ovserved on 10 August 1993. From the observed HeI 10830 ${\AA}$ spectra in these active regions, spectroscopic quantities such as equivalent width(EW), doppler shift, doppler width, etc., were derived(see Figure l(a)) and the correlation between them were studied(see Figure l(b)). Our main results are as follows: (I)In NOAA7562, which is a young and evolving EFR, the EW is large, while it is small around a simple and roundish spot of NOAA7558. (2)In these active regions, redshift in the 10830 line is dominant when the EW is larger. (3)As the doppler width increases, the line tends to shift redward. (4)When the EW is smaller, it seems to exist another component which have dynamic characteristics different from the redshifting component. In NOAA7560 and NOAA7561, regions which have several small spots, the values of the EW are intermediate. Results (2) and (3) may suggest the possible existence of downflow above active regions, if the HeI 10830 ${\AA}$line is formed in the upper chromopshere, and it is consistent with the earlyer result from the SMM extreme-ultraviolet observation by Klimchuk(1987, Astrophys. J., 323, 368) (to be submitted. to Astronomy and Astrophysics; an extended abstract)

• The Bulletin of The Korean Astronomical Society
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• v.41 no.2
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• pp.63.1-63.1
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• 2016

We observed Ultra-Long GRB 111209A using NASA's 3m InfraRed Telescope Facility (IRTF). The observation was started around 40 min later than T0 = 07:12:08 UT of Swift's BAT, lasted for 24 min. The spectrum was extracted using Spextool package. The NIR SEDs show power law distribution indicating afterglow emission from the GRB according to the fireball model with beta ~ 1.2. Also they do not show thermal emission component compared to the SED of "Christmas burst" GRB 101225A. Because there is no other NIR data with this observation epoch, this data can be compared only with TAROT-R band. It seems NIR data has the same flare which exists in R band as an optical flare.

• Journal of The Korean Astronomical Society
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• v.41 no.4
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• pp.99-107
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• 2008

When a new counting experiment is proposed, it is crucial to predict whether the desired source signal will be detected, or how much observation time is required in order to detect the signal at a certain significance level. The concept of the a priori prediction of the detection limit in a newly proposed experiment should be distinguished from the a posteriori claim or decision whether a source signal was detected in an experiment already performed, and the calculation of statistical significance of a measured source signal. We formulate precise definitions of these concepts based on the statistical theory of hypothesis testing, and derive an approximate formula to estimate quickly the a priori detection limit of expected Poissonian source signals. A more accurate algorithm for calculating the detection limits in a counting experiment is also proposed. The formula and the proposed algorithm may be used for the estimation of required integration or observation time in proposals of new experiments. Applications include the calculation of integration time required for the detection of faint emission lines in a newly proposed spectroscopic observation, and the detection of faint sources in a new imaging observation. We apply the results to the calculation of observation time required to claim the detection of the surface thermal emission from neutron stars with two virtual instruments.

• Advances in nano research
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• v.1 no.2
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• pp.111-124
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• 2013

Surface-enhanced Raman scattering (SERS) effect deals with the enhancement of the Raman scattering intensity by molecules in the presence of a nanostructured metallic surface. The first observation of surface-enhanced Raman spectra was in 1974, when Fleischmann and his group at the University of Southampton, reported the first high-quality Raman spectra of monolayer-adsorbed pyridine on an electrochemically roughened Ag electrode surface. Over the last thirty years, it has developed into a versatile spectroscopic and analytical technique due to the rapid and explosive progress of nanoscience and nanotechnology. This review article describes the recent development in field of surface-enhanced Raman scattering research, especially fabrication of various SERS active substrates, mechanism of SERS effect and its various applications in both surface sciences and analytical sciences.

• Publications of The Korean Astronomical Society
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• v.15 no.spc1
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• pp.73-83
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• 2000

X-ray astronomy deals with measurements of the electromagnetic radiation in the energy range of $E\~0.1-100 keV (\lambda\~0.12-120{\AA})$. The wavelength of X-ray is comparable to the size of atoms, so that the photons in the X-ray range are usually produced and absorbed by the atomic processes. Since the launch of the first X-ray astronomy satellite 'Uhuru' in 1970, technological advances in a launch capability and a detection capability make X-ray astronomy one of the most rapidly evolving fields of astronomical research. Particularly, a spectral resolving power $E/{\Delta}E$ has been increased by an order of 2 - 3 (in the energy range of 0.1 - 10 keV) during the past 30years. In this paper, I briefly review a developing process of the resolving power and spectroscopic techniques. Then I describe important emission/absorption lines in X-ray astronomy, as well as diagnostics of gas property with line parameters.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.2
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• pp.65.5-66
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• 2017

In the history of astronomy, observed data were interpreted very frequently based upon data measured at laboratories. For example, all the spectroscopic observations were understood via spectroscopic measurements on nuclei, atoms, and molecules. Recently, computational astrophysics plays a role of bridging experimental data to observations, in particular via numerical modeling of complex astronomical phenomena. This presentation focuses on computational nuclear astrophysics that connects experimental data on nuclei to high-energy observation data obtained by X-ray and gamma-ray telescopes. As an example case, X-ray burst will be discussed. In this phenomenon, observed X-ray light curves and spectra can be modeled by stellar evolution calculations that take nuclear reactions of rare isotopes as input information. This presentation also works as an introduction to the following presentation that will provide more detailed discussion on the experimental aspect of X-ray burst.

• The Bulletin of The Korean Astronomical Society
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• v.35 no.1
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• pp.78.1-78.1
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• 2010

We present the initial results of rest-frame optical spectroscopy of quasars at 3 < z < 5 from the AKARI space telescope mission program QSONG (Quasar Spectroscopic Observation with NIR Grism). QSONG is an AKARI phase-3 mission program which utilizes the unique capability of spectroscopy at 2.5-5 microns, and is adequate for detecting redshifted Balmer lines. We focus on how to overcome the noise induced from instrumental degradation, and report our measurements of supermassive black hole (SMBH) masses with well calibrated optical mass estimators.