• Honam Mathematical Journal
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• v.36 no.2
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• pp.425-434
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• 2014

In this paper, we introduce a new concept of a countably sequential space which is a generalization of a sequential space and study some properties of a countably sequential space and relations among the space and related spaces.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.13 no.2
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• pp.147-153
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• 2013

Previously, Park et al. (2005) defined an intuitionistic fuzzy metric space and studied several fixed-point theories in this space. This paper provides definitions and describe the properties of type(${\beta}$) compatible mappings, and prove some common fixed points for four self-mappings that are compatible with type(${\beta}$) in an intuitionistic fuzzy metric space. This paper also presents an example of a common fixed point that satisfies the conditions of Theorem 4.1 in an intuitionistic fuzzy metric space.

• The Mathematical Education
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• v.22 no.1
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• pp.31-33
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• 1983

In this paper, we investigate the properties of the semi-continuous functions on the first axiom space, n-th product space, pseudo-metric space, and proximity space. Counterexample is used when the converse of the theorem is not hold.

• Communications of the Korean Mathematical Society
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• v.33 no.1
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• pp.305-315
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• 2018

This note provides a study of lightlike hypersurfaces of a generalized Robertson-Walker(GRW) space-time with a certain screen distribution, which are integrable and have good properties. Focus is to investigate geometric features from the relation of the second fundamental forms between lightlike hypersurfaces and leaves of the integrable screen distribution. Also, we shall apply those results on lightlike hypersurfaces of a GRW space-time to lightlike hypersurfaces of a Robertson-Walker(RW) space-time.

• Korean Institute of Interior Design Journal
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• no.27
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• pp.145-151
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• 2001

There is so much difference in the way we perceive nature whether from eastern or western, present or past standpoint. however, awareness of coexistence between human beings and nature along with the concept that the most natural is th e most beautiful remain unchanged. The desire to describe the beauty of nature have existed all through the ages, but the (new) naturalism movement was spawned in our time when so much devastation and side effects took place for the expediency of nature, and field of display has been trying new interpretation of nature with direct or applied method. Naturalism trend is studied using the categories such as relationship between human and nature, space concept in western and eastern society, and the definition of view of nature in modern time. Elements of naturalism display are classified into the element of physical properties and element beyond the physical properties, and then methodology on naturalism display is investigated, using the illustration of display examples, in order to know the most essential elements of display, which are the physical properties such as space, light, object, glass, are expressed based on the elemental concept like nature, an accident, dynamic state, variability. As mentioned above, Naturalism display consists of physical properties and phenomenon. How to ive strong impression to a spectator depends on the ability to create effective space applying these elements. The significance of this study comes to surface in a time when the tremendous emphasis is put on the importance of nature and concerns about the role of display has become even greater.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.1
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• pp.96.1-96.1
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• 2012

Various electromagnetic fluctuations are observed in the upstream of Earth's bow shock. Properties of plasmas are important in determining the development of the fluctuations. In this study we analyze the phase space distribution functions of plasmas measured by the Cluster spacecraft to understand how the fluctuations develop. Plasmas in the upstream of Earth's bow shock often consist of multiple components, especially when the fluctuations exist. In addition to the solar wind beams, backstreaming ion beams and diffuse ions are also often observed separately or simultaneously. The solar wind beams are not much perturbed even within the fluctuations. The diffuse ions are more than 10 times hotter than the solar wind beams and the backstreaming beams intermediate between them. The distribution functions of the diffuse and backstreaming ions are anisotropic to the magnetic field. Thus, they may be responsible for the fluctuations associated with temperature anisotropy. We will discuss about the thermalization processes and the relationship between the fluctuations and plasmas.

• Korean Institute of Interior Design Journal
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• v.22 no.1
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• pp.75-84
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• 2013

This study focuses on Gilbert Simondon's individuation theory, a core concept of his technological philosophy, and spatial modality in interactive space as the schema of interactive operation. The study examines spatial modality as the technology of an interaction-enabler that has archi-semiotic characteristics in the designed space by aspects of examples. They are based on ideas and properties of a combined environment and the concept of information, which form Simondon's individuation theory. In the process of technological individuation, spatial modality has the characteristics of archi-semiotics from a combined environment and information. The first of the three properties is representation through semiosis and the information surface. Second is the context by relation works and perception, and third are the symbolic aspects, which could create Placeness by meaning. Combining meaningful constructive and deconstructive spaces could result in space for interactive communication. Spatial modality makes it possible to interact with users and spaces. In fact, it could have a particular semiotic mode of address and become a semiotic and contextual base. As a basic investigation of spatial modality, this study will contribute to interactive space design research.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.1
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• pp.61.3-62
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• 2016

An asteroid family is a group of asteroidal objects in the proper orbital element space (a, e, and i), considered to have been produced by a disruption of a large parent body through a catastrophic collision. Family members usually have similar surface properties such as spectral taxonomy types, colors, and visible geometric albedo with a same dynamical age. Therefore an asteroid family could be called as a natural Solar System laboratory and is also regarded as a powerful tool to investigate space weathering and non-gravitational phenomena such as the Yarkovsky/YORP effects. We carry out time series photometric observations for a number of asteroid families to obtain their physical properties, including sizes, shapes, rotational periods, spin axes, colors, and H-G parameters based on nearly round-the-clock observations, using several 0.5-2 meter class telescopes in the Northern hemisphere, including BOAO 1.8 m, LOAO 1.0 m, SOAO 0.6 m facilities in KASI, McDonald Observatory 2.1 m instrument, NARIT 2.4 m and TUG 1.0 m telescopes. This study is expected to find, for the first time, some important clues on the collisional history in our Solar System and the mechanisms where the family members are being transported from the resonance regions in the Main-belt to the near Earth space.

• The Bulletin of The Korean Astronomical Society
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• v.44 no.1
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• pp.38.3-38.3
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• 2019

We investigate the stellar population properties of nine passive spiral galaxies in the CALIFA survey. They have NUV-r > 5 and no/weak nebular emission lines in their spectra. They lie in the redshift range of 0.001 < z < 0.021 and have stellar mass range of 10.2 < ${\log}(M{\star}/M{\odot})$ < 10.8. We analyze the stellar populations out to two effective radius, using the best-fitting model to the measured absorption line-strength indices in the Lick/IDS system. We compare the passive spirals with S0s selected in the same mass range. S0s cover a wide range in age, metallicity, and [${\alpha}/Fe$], and stellar populations of the passive spirals are encompassed in the spread of the S0 properties. However, the distribution of passive spirals are skewed toward higher values of metallicity, lower [${\alpha}/Fe$], and younger ages at all radii. These results show that passive spirals are possibly related to S0s in their stellar populations. We infer that the diversity in the stellar populations of S0s may result from different evolutionary pathways of S0 formation, and passive spirals may be one of the possible channels.

• The Bulletin of The Korean Astronomical Society
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• v.32 no.2
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• pp.72.1-72.1
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• 2007