• 천문학회보
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• 제41권1호
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• pp.44.1-44.1
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• 2016

In this paper, we present a catalogue of the spectra of bright stars observed during the sky survey using the Far-Ultraviolet Imaging Spectrograph (FIMS), which was designed primarily to observe diffuse emissions. By carefully eliminating the contamination from the diffuse background, we obtain the spectra of 70 bright stars observed for the first time with a spectral resolution of $2-3{\AA}$ over the wavelength of $1370-1710{\AA}$. The far-ultraviolet spectra of an additional 139 stars are also extracted with a better spectral resolution and/or higher reliability than those of the previous observations. The stellar spectral type of the stars presented in the catalogue spans from O9 to A3. The method of spectral extraction of the bright stars is validated by comparing the spectra of 323 stars with those of the International Ultraviolet Explorer (IUE) observations.

• 천문학회보
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• 제41권1호
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• pp.48.3-49
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• 2016

Current high-resolution IR spectroscopy at ground-based observatories made it possible to observe $3-{\mu}m\;CH_4$ emission lines from the atmospheres of Jupiter, Saturn, and Titan through narrow atmospheric windows avoiding the counterparts of telluric $CH_4$ absorptions if proper Doppler shifts betwen Earth and these planetary objects are provided. We are also expecting low-resolution (R~300) infrared spectra of Jupiter from the upcoming observations by JUNO's infrared $2-5{\mu}m$ spectrograph during the encounter with Jupiter approximately starting from July 4, 2016. Although the spectral resolution is not enough to resolve the $3-{\mu}m$ P, Q, R branch lines of CH4, the gross envelopes of the P, Q, R branches should yield information on rotational temperatures. The rotational temperatures are useful because theycan be regarded as local temperatures, as discussed by Kim et al. (2014). Since the $3-{\mu}m\;CH_4$ emission is mostly formed at micro-bar pressure levels, the derived rotational temperatures represent the local temperatures near the hompause of Jupiter. We discuss possible sciences from the derived homopause temperatures in the auroral and non-auroral regions of Jupiter.

• 천문학회보
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• 제41권1호
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• pp.77.2-77.2
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• 2016

We present preliminary results of the analysis of chemical abundances for seven hypervelocity star (HVS) candidates. These objects are G and K dwarfs in the Galactic disk selected from the Sloan Extension for Galactic Understanding and Exploration. Unlike other HVSs discovered thus far, their stellar orbits and kinematics suggest that they do not originate in the Galactic center or in an accretion event. These factors imply yet-unknown mechanisms that give rise to these kinematically-extreme disk stars. In order to study in detail their progenitors and possible formation mechanisms, we obtained spectra of these stars at a resolving power of R~6000, with the Dual Imaging Spectrograph at the Apache Point Observatory. We derive the abundances of chemical elements, C, Mg, Ca, Ti, Cr, Fe, and Ba from the observed spectra, using MOOG. We compare them with the ones of typical Galactic disk stars and discuss discrepancies between them to search for clues to their origin.

• 천문학회지
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• 제47권2호
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• pp.69-76
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• 2014

We report the detection of an exoplanet candidate in orbit around ${\sigma}$ Persei from a radial velocity (RV) survey. The system exhibits periodic RV variations of $579.8{\pm}2.4$ days. The purpose of the survey is to search for low-amplitude and long-period RV variations in giants and examine the origin of the variations using the fiber-fed Bohyunsan Observatory Echelle Spectrograph installed at the 1.8-m telescope of Bohyunsan Optical Astronomy Observatory in Korea. We present high-accuracy RV measurements of ${\sigma}$ Per made from December 2003 to January 2014. We argue that the RV variations are not related to the surface inhomogeneities but instead a Keplerian motion of the planetary companion is the most likely explanation. Assuming a stellar mass of $2.25{\pm}0.5$ $M_{\odot}$, we obtain a minimum planetary companion mass of $6.5{\pm}1.0$ $M_{Jup}$, with an orbital semi-major axis of $1.8{\pm}0.1$ AU, and an eccentricity of $0.3{\pm}0.1$ around ${\sigma}$ Per.

• 대한전자공학회논문지
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• 제10권5호
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• pp.31-38
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• 1973

잔향시간은 이론적으로 게산하는데는 아직까지 기하음향학이론인 Sabine 의식을 사용하고 있다. 이것은 파동학이론으로 분석할때 한개의 측에 대한 정재파의 잔향시간과 같다. 잔향시간은 정재파기 영향을 크게 받으며 이것을 각 mode에 의한 주파수관계를 계산하여 측파, 사영파 그리고 oblique wave를 산출하였다. 이것은 간단한 구형교실을 model로 하였다. 따라서 감쇄곡선은 스펙토로그라프에 의하여 축파 및 사영파가 oblique wave 보다 잔향시간에 더큰 영향을 준다는 결과를 얻었다. 이것은 잔향시간을 조정하는데 큰도움을 줄것이다.

• 음성과학
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• 제1권
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• pp.213-223
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• 1997

This paper deals with a general review of Mieko S. Han, who made a significant contribution to the studies of Korean phonetics during the 1960' s and early 1970' s. As both a single and joint author, Dr. Han published important papers in both quantity and quality, which have been cited among Korean phoneticians until today. Before Dr. M. Han' s work, professor of USC in the department of East Asian Languages & Cultures, there were only a few phonetics-related publications in Korea, most of which are papers or books based on non-experimental traditional approach. It is known that there was coexistence between traditionalism and structuralism in the field of Korean linguistics. It was, however, fortunate that we had two important phoneticians (M. Han and Chin-W Kim) abroad at that time. Mieko Han' s concern was to investigate experimental characteristics of the system of Korean vowels and consonants using a Spectrograph, which was the single most important tool for analysing phonetic data at that time. Dr. Han conducted her experimental studies on Korean phonetics, mostly funded by the Office of Naval Research, in terms of duration, fundamental frequency, Voice Onset Time (VOT), intensity, and so on. This paper aims to re-appreciate Dr. Han's specific contribution to the study of Korean phonetics since she played an important role as a pioneer of early Korean phonetics. Further, it is highly recommended that Dr. Han's works can be extremely useful for a graduate student, who seriously would like to specialize in Korean phonetics in the first step.

• 천문학논총
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• 제21권2호
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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.

• 천문학논총
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• 제30권2호
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• pp.109-112
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• 2015

We present [$Fe\;{\small{II}}$] ${\lambda}1.257{\mu}m$ spectra toward the interacting binary UY Aur with 0".14 angular resolution, obtained with the Near infrared Integral Field Spectrograph (NIFS) combined with the adaptive optics system Altair of the GEMINI observatory. In the [$Fe\;{\small{II}}$] emission, UY Aur A (primary) is brighter than UY Aur B (secondary). The blueshifted and redshifted emission between the primary and secondary show a complicated structure. The radial velocities of the [$Fe\;{\small{II}}$] emission features are similar for UY Aur A and B: ${\sim}-100km\;s^{-1}$ and ${\sim}+130km\;s^{-1}$ for the blueshifted and redshifted components, respectively. Considering the morphologies of the [$Fe\;{\small{II}}$] emissions and bipolar outflow context, we concluded that UY Aur A drives fast and widely opening outflows with an opening angle of ${\sim}90^{\circ}$ while UY Aur B has micro collimated jets.

• 천문학논총
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• 제30권2호
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• pp.761-763
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• 2015

Colors have been derived from the observed optical spectrum of Mars and Jupiter. It is known that the planets and the Moon emit reflected sunlight and thus their spectra are similar to the spectrum of solar radiation. The question was then why is the color of Mars different from that of other planets, i.e. red, although it would share the same spectrum of reflected sunlight. Can one derive color from the spectrum? Therefore, we observed the optical spectra of the scattered sunlight in day time for the Moon and Mars using a 1-D array spectrograph on the 12-inch reflecting telescope in the Korea Science Academy of KAIST in Busan, Korea. We adopted the International Commission on Illumination (CIE) in 1931 of three spectral sensitivity peaks for the human eye in short, medium and long wavelengths in visible light. The observed spectra were imposed on CIE sensitivities and the color detected by the human eye was derived. The Mars spectrum represents red color and the Moon white. It is a similar color to that which a human would see. This result means that color is easily derived from astronomical spectra. The appearance of the planets surface can be determined for Mars, which is the result of iron oxide.

• 천문학논총
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• 제30권2호
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• pp.269-270
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• 2015

We carried out near-IR photometric and optical spectroscopic observations of V582 Aur, which is a FU Orionis type object, to investigate any periodic and/or aperiodic variations. We obtained light curves on the scale of a night and a year, in J, H and Ks bands with KASINICS (KASI Near Infrared Camera System) attached to the BOAO (Bohyun-san Optical Astronomy Observatory) 1.8-m reflector in Youngcheon, South Korea and examined photometric variations on the two time scales. So far we have not found any periodic brightness variations on the scale of a night. On the other hand, we have found that there seems to be a periodic brightness variation with a period of approximately 45 days. In addition, high-resolution optical spectroscopic observations of V582 Aur were performed from February 2013 to May 2014 with the high-resolution echelle spectrograph BOES attached to the BOAO 1.8-m reflector. We analyzed several spectral lines to understand the physical state of V582 Aur. The P Cyg profiles are clearly shown in the $H{\alpha}$ line and Na I D line.