• Communications of the Korean Mathematical Society
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• v.31 no.2
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• pp.389-394
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• 2016

Let $f:M{\rightarrow}M$ be a diffeomorphism on a closed $C^{\infty}\;d({\geq}2)$ dimensional manifold M. For $C^1$-generic f, if a diffeomorphism f satisfies the local star condition on a transitive set, then it is hyperbolic.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.2
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• pp.144.2-144.2
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• 2011

A dwarf irregular galaxy IC10 in the Local Group is the nearest starburst galaxy, playing an important role revealing the details of starburst. It is located close to the Galactic plane so that it suffers from severe foreground reddening. Therefore much less is known about the property of this galaxy compared with other galaxies in the Local Group. So are star clusters in this galaxy. We present a photometric study of the star clusters in IC10. 57 star clusters are already found from HST images in previous studies, and we newly found 15 star clusters using Local Group Survey data and SUBARU/Suprime-Cam data. We derive UBVRI integrated photometry of these star clusters from the images from Local Group Survey data and JHKs photometry taken with SUBARU/MOIRCS. Then we derive age and mass of these clusters using the spectral energy distribution fitting with the simple stellar population models. We discuss the photometric and physical properties of these star clusters and its implication.

• The Bulletin of The Korean Astronomical Society
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• v.39 no.2
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• pp.60.2-60.2
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• 2014

Hierarchical structure of star-forming regions is widespread and may be characteristic of all star formation. We studied the hierarchical structure of star-forming regions in the Local Group galaxies (M31, M33, Phoenix, Pegasus, Sextans A, Sextans B, WLM). The star-forming regions were selected from Galaxy Evolution Explorer (GALEX) far-UV imaging in various detection thresholds for investigating hierarchical structure. We examined the spatial distribution of the hot massive stars within star-forming regions from Hubble Space Telescope (HST) multi-band photometry. Small compact groups arranged within large complexes. The cumulative mass distribution follows a power law. The results allow us to understand the hierarchical structure of star formation and recent evolution of the Local Group galaxies.

• The Bulletin of The Korean Astronomical Society
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• v.46 no.1
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• pp.51.1-51.1
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• 2021

Spiral arms greatly affect gas flows and star formation in disk galaxies. We use local 3D simulations of vertically-stratified, self-gravitating, gaseous disks under a stellar spiral potential to study the effects of spiral arms on galactic star formation as well as formation of gaseous spurs/feathers. We adopt the TIGRESS framework to handle radiative heating and cooling, star formation, and ensuing supernova (SN) feedback. We find that more than 90% of star formation takes place inside spiral arms. The global star formation rate (SFR) in models with spiral arms is enhanced by less than a factor of 2 compared to the no-arm counterpart. This supports the picture that spiral arms do not trigger star formation but rather redistribute star-forming regions. Correlated SN feedback produces interarm feathers in both magnetized and unmagnetized models. These feathers live short, have parallel magnetic fields along their length, and are bounded by SN feedback in the lateral direction, in contrast to instability-induced feathers formed in our previous isothermal simulations.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.143-146
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• 2008

Dynamic range of LCD panel can be dramatically improved by adaptive dimming technique. Adaptive control of LED backlight by input signal can reduce the light leakage of LCD panel and achieve high contrast ratio. An algorithm is proposed to distinguish the input signal and get proper luminance level. For lower cost of LCD panel, white light LED is used to accomplish 2D dimming and get better image performance of LCD.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.11 no.5
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• pp.297-306
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• 1986

This paper surveys circuit switching local area networks(LANs) whit topology of ring, mesh, bus and star. Emphasis of this study is given on the conceptual switching technologies of these LANs.

• Journal of the Korean earth science society
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• v.34 no.5
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• pp.407-414
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• 2013

This study presents the global star formation efficiency (SFE) of 272 local star-forming galaxies based on the HI gas mass, stellar mass, star formation rate (SFR), and morphology. The SFE increases as the stellar mass increases while the specific SFR decreases. The SFE is enhanced for galaxies with large H$\acute{a}$ equivalent widths, which is primarily due to the large SFR, not due to the large available amount of gas. The SFE is also enhanced by a factor of ~2 for merging systems compared to the normal spirals, showing that the merger-induced high pressure and density environment are crucial for the active star formation. Based on the SFR scaling relation, I present a SFR calibration formula using the HI gas mass.

• Bulletin of the Korean Mathematical Society
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• v.56 no.3
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• pp.659-666
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• 2019

In this paper, we consider a conjecture of I. N. Herstein for local commutators of symmetric elements and unitary elements of division rings. For example, we show that if D is a finite dimensional division ring with involution ${\star}$ and if $a{\in}D^*=D{\setminus}\{0\}$ such that local commutators $axa^{-1}x^{-1}$ at a are radical over the center F of D for every $x{\in}D^*$ with $x^{\star}=x$, then either $a{\in}F$ or ${\dim}_F\;D=4$.

• The Journal of Asian Finance, Economics and Business
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• v.5 no.3
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• pp.73-80
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• 2018

The growth of Bandung's tourism industry has had a massive impact on the hotel sector. Most tourists visiting Bandung are domestic tourists and tend to be modest spenders fitting the profile of a mid-market (2/3 star) hotel guest. As competition has increased mid-market hotels have come under pressure from upmarket (4/5 star) and budget hotels committed to cutting prices. There is also competition with the mid-market hotel sector, which means that the 2/3 star hotels have to keep innovating in order to remain competitive. This study uses the Service Quality framework to describe customer expectations and identify gaps in hotel services. A questionnaire survey of 105 local tourists who had stayed in 2/3 star hotels in Bandung showed that the most important dimension is responsiveness, following by reliability, assurance, tangibles and empathy. Thus we conclude that local tourists' primary expectations are that hotels will deliver the service they have promised, be responsive to guests' needs and comply with service standards. Furthermore, these findings validate the earlier prediction that comparing 2/3 star hotel with 5/4 start hotel, the customers are having preliminary knowledge on facilities limitation and friendliness. Tourists using 2/3 star hotels tend to be prepared to accept limited facilities and less friendly staff service.

• Publications of The Korean Astronomical Society
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• v.27 no.4
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• pp.331-334
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• 2012

We investigate the role of galaxy environment in the evolution of individual galaxies through the AKARI observations of the merging galaxy cluster A2255. MIR diagnostics using N3-S11 colors are adopted to select star-forming galaxies and galaxies in transition between star-forming galaxies and quiescent galaxies. We do not find particular enhancement of star formation rates as a function of galaxy environment, reflected in cluster-centric distance and local surface density of galaxies. Instead, the locations of intermediate MIR-excess galaxies (-1.2 < N3 - S11 < 0.2) show that star-forming galaxies are transformed into passive galaxies in the substructures of A2255, where the local surface density of galaxies is relatively high.