• The Bulletin of The Korean Astronomical Society
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• v.35 no.2
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• pp.42.1-42.1
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• 2010

We present ultraviolet (UV) photometric properties of dwarf galaxies in Fornax cluster and Ursa Major group in comparison with Virgo cluster using GALEX data. We construct UV color-magnitude relations (CMRs) of dwarf galaxies matching with available optical photometry and SDSS data. Majority of dwarf galaxies in Fornax cluster show sequence in UV CMRs consistent with that of dwarf elliptical (dEs) in Virgo cluster indicating similar age and metallicity properties of dEs in two clusters. The dS0 sequence in Fornax cluster is not distinct as much as that in Virgo cluster. Dwarf galaxies in outer region of the Fornax cluster show more bluer UV colors with a wide scatter in CMRs, which indicates recent star formation activity. We show that the UV colors of dwarf galaxies are related with the distribution and strength of the X-ray emission in the cluster. In contrast to the Fornax cluster, most dwarf galaxies in Ursa Major group are located in the blue cloud showing recent or on-going star formation, and few galaxies show characteristics of dEs. We discuss relationship between UV properties of dwarf galaxies and different environment of cluster.

• The Bulletin of The Korean Astronomical Society
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• v.44 no.1
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• pp.52.3-52.3
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• 2019

We investigate a relative contribution from short to long-term flaring rate to predicting M and X-class flare probabilities. In this study, we consider magnetic parameters summarizing distribution and non-potentiality by Solar Dynamics Observatory/Helioseimic and Magnetic Imager and flare list by Geostationary Operational Environmental Satellites. A short-term rate is the number of major flares that occurred in an given active region (AR) within one day before the prediction time. A mid-term rate is a mean flaring rate from the AR appearance day to one day before the prediction time. A long-term rate is a rate determined from a relationship between magnetic parameter values of ARs and their flaring rates from 2010 May to 2015 April. In our model, the predicted rate is given by the combination of weighted three rates satisfying that their sum of the weights is 1. We calculate Brier skill scores (BSSs) for investigating weights of three terms giving the best prediction performance using ARs from 2015 April to 2018 April. The BSS (0.22) of the model with only long-term is higher than that with only short-term or mid-term. When short or mid-term are considered additionally, the BSSs are improved. Our model has the best performance (BSS = 0.29) when all three terms are considered, and their relative contribution from short to long-term rate are 19%, 23%, and 58%, respectively. This model seems to be more effective when predicting active solar ARs having several major flares.

• Korean Institute of Interior Design Journal
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• v.21 no.3
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• pp.11-21
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• 2012

In order to increase visitors' viewing satisfaction and viewing behavior in the art museum exhibit by flat works, it is necessary to analyze the characteristics of major evaluation factors, such as 'the number of artworks and their intervals', 'the space of exhibition and the size of walls', and 'compositional change of exhibition spaces', which have a close relationship with each evaluation factors, by focusing on artworks and exhibition space. Thus, to investigate how the characteristic differences of the major evaluation factors in art museums affect visitors' viewing satisfaction and viewing behavior, this study compared the related analytical indicators, and conducted a correlation analysis. The results of this study are summarized as follows: First, the degree of concentration on artworks (which has been selected as a collective assessment indicator of visitors' satisfaction) increased when the exhibition space of art museum is display by less artworks and they have big interval in the large wall. Second, visitors' viewing satisfaction and qualitative viewing behavior increased when the exhibition space of art museum are simple and they change to simpler step by step. These findings imply that there is a high correlation between visitors' visio-perceptual experiences and viewing behavior, and that visitors' viewing satisfaction and viewing behavior can be predicted partially in the certain exhibition environment from this correlation.

• Journal of Aerospace System Engineering
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• v.2 no.1
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• pp.37-45
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• 2008

KARI has jointly developed COMS bipropellant propulsion system with EADS Astrium, UK. It is well known at the moment about American or even German efforts for space development and space propulsion activities. On the contrary UK's capability for space development hasn't been recognised well in Korea. The major space activities relevant to the development of chemical and electric propulsion systems in UK, in reference to our space propulsion programme are addressed in detail. In addition the collaboration in prospect between two countries is proposed.

• Korean Institute of Interior Design Journal
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• no.15
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• pp.31-38
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• 1998

The purpose of this study was to analyze the tendency of the current diversified apartment planning. This study was examined by 13 newspapers from January 1th 1995 to 30th 1997. The major findings in this study were summarized as follows: 1. The strategy of major apartment construction co. was diversified into space planning interior image facilities and utilities and outdoor space design. 2. The trend of space planning was diversified into apartment for 3 generation apartment with its own inside gardeen apartment with kitchen facing south multi-story apartment, apartment with round shape room irregular shaped apartment 3. The trend of interior image was diversified into Korean style natural style casual elegantstyle modern style and classical style.

• Korean Journal of Mathematics
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• v.27 no.4
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• pp.1149-1157
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• 2019

We prove the Frenet type formulae for smooth one-parameter family of 2-planes or 3-planes in the Lorentz-Minkowski space 𝕃⁶. We consider two cases separately: the planes are spacelike or the planes are timelike.

• The Bulletin of The Korean Astronomical Society
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• v.24 no.2
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• pp.114-114
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• 1999

• Bulletin of the Korean Space Science Society
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• 1994.09a
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• pp.31-31
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• 1994

• The Bulletin of The Korean Astronomical Society
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• v.42 no.1
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• pp.27.3-27.3
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• 2017

One of the major discoveries in extragalactic astrophysics made over the past few years is the detection of ultra-diffuse galaxies, a new type of galaxies which appear to be far more numerous than normal galaxies, and which are giants in terms of size, yet dwarfs in terms of luminosity. These galaxies point to the huge discovery potential of the last niche that remains to be explored in observational parameter space: the sky at extremelylow surface brightness. Implications for objects in the Solar System, stellar physics, the interstellar medium, galaxies and cosmology will be addressed, along with the major challenges for pushing the frontiers in ground- and space-based observations.

• The Korean Journal of Air & Space Law and Policy
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• v.2
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• pp.157-188
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• 1990

The objective of this presentation is to describe major air transport problems which international civil aviation is faced with at present and those which may be encountered in the last decade of the 20th century. ICAO's role in tackling these problems as well as some aspects of cooperation between Contracting States and ICAO are also being discussed.