• Publications of The Korean Astronomical Society
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• v.30 no.2
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• pp.737-739
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• 2015

To accommodate today's higher education student, fewer textbooks are printed and more are becoming digital. Keeping with the modern era, hybrid versions of textbooks have all end-of-chapter assessment content moved to digital learning systems such as MindTap$^{TM}$ by Cengage $Learning^{(R)}$. In this work, we introduce new pedagogical strategies to combat academic e-cheating, specifically cheating on assessments given in online astronomy courses. The strategies we present in this work are employed in Horizons: Exploring the Universe, Hybrid, 13th Edition, and Universe, Hybrid, 8th Edition, by Seeds, Backman, and Montgomery.

• The Pure and Applied Mathematics
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• v.12 no.1
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• pp.33-45
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• 2005

We introduce the category ISet(H) of intuitionistic H-fuzzy sets and show that ISet(H) satisfies all the conditions of a topological universe except the terminal separator property. And we study the relation between Set(H) and ISet(H).

• Journal of the Korean Society of Industry Convergence
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• v.3 no.4
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• pp.293-296
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• 2000

We have accumulated the knowledge of the phenomena of external nature under the gravity fields of the earth, but have not the data of the natural phenomena under the high or low gravity fields. It is necessary to research the phenomena of the combustion, heat transfer and the behavior of the living animals under the high or low gravity fields. This paper introduces the mysterious universe in high and low gravity fields from the experimental study by Arai et al.

• Journal of The Korean Astronomical Society
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• v.9 no.1
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• pp.9-14
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• 1976

Godel models of the universe filled with fluid are studied in the framework of the Einstein-Cartan theory of gravitation. It is assumed that the models admit a group of motions simply transitive on space-time. The combined effects of spin and rotation(vorticity) are studied with a particular attention to whether the held equations impose any restriction on alignement of spin direction (a polarized spin distribution). The solutions are found explicitly in a closed form, which show that spin components are vanishingly small except in the direction of z-axis (the compass of inertia) in which they can assume an arbitrary distribution.

• The Bulletin of The Korean Astronomical Society
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• v.46 no.1
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• pp.27.2-27.2
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• 2021

The unknown excess emission in the near-infrared is thought to be related to the evolution of galaxies in the early epoch of Universe. Due to its extremely faint brightness, it can be observed only in space. Many infrared space missions have been tried to trace the origin of the Cosmic Infrared Background through the measurement of its absolute brightness and its spatial fluctuation. In addition, the infrared observations can address questions ranging from the origin of first galaxies in the Universe to the formation of stars. I will overview the Korean infrared space missions and introduce the status of the recent international collaboration mission, SPHEREx.

• The Bulletin of The Korean Astronomical Society
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• v.28 no.2
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• pp.50-50
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• 2003

• The Bulletin of The Korean Astronomical Society
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• v.37 no.1
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• pp.32.2-32.2
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• 2012

Gamma Ray Bursts (GRBs) are the most energetic events in the universe, and are known to arise from the death of massive stars in many cases. Their extreme brightness makes it possible to detect them at very high redshift (z > 6.5), well into the epoch of re-ionization, providing us with an opportunity to investigate the deaths of the first stars when the universe was much younger than 1 Gyr. Here, we report the discovery of GRB 100905A, a GRB at $z$ - 7.5 (age of the universe at 700 Myr). Our observation revealed a strong spectral break between z and J band, allowing us to estimate its photometric redshift. Its gamma-ray light curve shows a very short duration of about 0.7 sec, the shortest duration event at z > 5. Investigation of this and three other known GRBs at z > 6.5 reveals that they are all short duration bursts. This is puzzling, considering that GRBs from death of massive stars do not show short duration. We suggest two possible explanations for this: (i) the BAT light curves of the high redshift GRBs suffered from observational selection effect where we are only observing the very tip of the light curve; (ii) the stars in the early universe had a peculiar nature that are different from ordinary stars at lower redshifts.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.1
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• pp.34.2-34.2
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• 2017

A small wide-field imaging telescope is a powerful instrument to survey the Universe: wide-field image can monitor the variability of many sources at a time, e.g. young stellar objects and active galactic nuclei, and it can be an effective way to locate transient sources without precise positional information such as gravitational wave sources or some gamma-ray bursts. In February 2017, we installed a 0.25 m f/3.6 telescope on the McDonald 0.8 m telescope as a piggyback system. With a $4k{\times}4k$ CCD camera, the telescope has a $2.35{\times}2.35deg$ field-of-view. Currently, it is equipped with Johnson UBVRI filters and 3 narrow-band filters: $H{\alpha}$, OIII and SII. We will present the installation process, and the telescope performance such as detection limit and image quality based on the data from commissioning observations. We will also discuss possible scientific projects with this system.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.1
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• pp.50.1-50.1
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• 2017

We present our study of the correlation between star formation rate(SFR) and merging activities of nearby galaxies(d<150Mpc). Our study uses 265 UV-selected galaxies which are not classified as AGN. The UV selection is made using the GALEX Atlas of Galaxies (Gil de Paz+07) and the updated UV catalog of nearby galaxies (Bai+15). We use deep R band optical images reaching to $1{\sigma}$ surface brightness detection limit ${\sim}27mag/arcsec^2$ to classify merger features by visual inspection. We also estimated unobscured SFR($SFR_{NUV}$) and obscured SFR($SFR_{W4}$) using Near-UV continuum and 22 micron Mid-IR luminosity respectively as a indicator of star forming activity. The fraction of galaxies with merger features in each SFR bin is obtained to see if how the fraction of galaxies with merging features($F_m$) changes as a function of SFR. As a result, for 203 late type galaxies(LTGs), we found that merger fraction increases from ~8% up to 50% with $SFR_{W4}$, while for 229 LTGs $SFR_{NUV}$ shows relatively consistent fraction(~18%) of merger fraction. For early type galaxies(ETGs), we could also find no significant correlation between $F_m$ and SFR(both $SFR_{NUV}$ and $SFR_{W4}$). This result suggests that a main driver of star forming activity of UV bright galaxies, especially for obscured late types, is mergers.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.1
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• pp.69.4-70
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• 2018

KAOS30 is an automatic observing software for the wide-field 10-inch telescope as a piggyback system on the 30-inch telescope at the McDonald Observatory in Texas, US. The software has four packages in terms of functionality and is divided into communication with Telescope Control System (TCS), controlling of CCD camera and filter wheel, controlling of focuser, and script for automation observing. Each interconnect of those are based on exe-exe communication. The advantage of this distinction is that each package can be independently maintained for further updates. KAOS30 has an integrated control library that combines function library connecting each device and package. This ensures that the software can extensible interface because all packages are access to the control devices independently. Also, the library includes the ASCOM driver platform. ASCOM is a standard general purpose library that supports Application Programming Interface (API) of astronomical devices. We present the software architecture of KAOS30, and structure of interfacing between hardware and package or package and package.