• Bulletin of the Korean Mathematical Society
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• v.48 no.5
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• pp.1093-1103
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• 2011

We give the characterizations of the classes of matrix trans-formations ($m(\phi),{\ell}_p$), ($n(\phi),{\ell}_p$) ([5, Theorem 2]), (${\ell}_p,m(\phi)$) ([5, Theorem 1]) and (${\ell}_p,n(\phi)$) for $1{\leq}p{\leq}{\infty}$, establish estimates for the norms of the bounded linear operators defined by those matrix transformations and characterize the corresponding subclasses of compact matrix operators.

• The Pure and Applied Mathematics
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• v.16 no.3
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• pp.259-269
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• 2009

We introduce the concept of intuitionistic fuzzy minimal structure which is an extension of the intuitionistic fuzzy topological space. And we introduce and study the concepts of intuitionistic fuzzy M -continuity, intuitionistic fuzzy Mopen mappings and several types of intuitionistic fuzzy minimal compactness on intuitionistic fuzzy minimal spaces.

• Journal of applied mathematics & informatics
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• v.42 no.1
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• pp.85-92
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• 2024

In this work we give the necessary and sufficient conditions for f-biharmonic curves in three-dimensional generalized symmetric spaces.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2005.11a
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• pp.130-131
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• 2005

A study developing the dry powder fire extinguishing system inside the simulated machinery spaces of small ship was performed. Fire tests were conducted inside the compartments having volums 8$m^3$, 2.9$m^3$ and 4.5$m^3$ respectively. The openings and fans were established on the walls of the compartments. Diesel oil was used for the test fuel. In addition fire extinguishing nozzles using dry powder were installed downward at ceiling and horizontally at the wall or conner. All fires in the test were extinguished under system activation and there was no reignition.

• Bulletin of the Korean Mathematical Society
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• v.31 no.2
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• pp.297-308
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• 1994

In [5], M. Cwikel and J. Peetre showed that some Banach couples are Calderon pairs and every K-monotone cones in that couples can be constructed by the Peetre K-method. With the help of theorem 4 in [3], we can extend the above result to the K-monotone spaces. In [4], M. Cwikel provided the proof of therem 4 in [3] and also mentioned that some theorems in [5] which were stated in terms of K-monotone cones can be extended to K-monotone spaces. But M. Cwikel and J.Peetre's results only cover the case when over bar A = over bar B. We extend this result to the case when over bar A.neq. over bar B. In this case, we need a condition stronger than that the K-monotone space.

• Kyungpook Mathematical Journal
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• v.46 no.1
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• pp.1-9
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• 2006

M. Reni has shown that there are at most nine mutually inequivalent knots in the 3-sphere whose 2-fold branched covering spaces are mutually homeomorphic, hyperbolic 3-manifolds. By observing that the Z-homology sphere version of M. Reni's result still holds, M. Mecchia and B. Zimmermann showed that there are exactly nine mutually inequivalent, knots in Z-homology 3-spheres whose 2-fold branched covering spaces are mutually homeomorphic, hyperbolic 3-manifolds, and conjectured that there exist exactly nine mutually inequivalent, knots in the true 3-sphere whose 2-fold branched covering spaces are mutually homeomorphic, hyperbolic 3-manifolds. Their proof used an argument of AID imitations published in 1992. The main result of this paper is to solve their conjecture affirmatively by combining their argument with a theory of strongly AID imitations published in 1997.

• Korean Journal of Remote Sensing
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• v.26 no.6
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• pp.675-680
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• 2010

Temperature is one of the main issues in climate change, and the urban heat island effect in highly developed urban areas is an important issue that we need to deal with. This study analyzed the extent of the cooling effects of urban green spaces. The study used a surface temperature map of Seoul. It found that the cooling effects of green space was observed within limited distances, although it varied a little depending on the parks investigated. The cooling effect distance ranged from 240m to 360m, averaging about 300m. It also found the size of an urban green space does not make much difference in cooling the surrounding areas. Although further investigation with diverse urban areas should be conducted on this matter, the results did imply that many small green spaces in the neighborhood are more effective than a single big green space in mitigating the heat island effects of cities.

• Journal of the Korean Mathematical Society
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• v.60 no.1
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• pp.33-69
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• 2023

Let α ∈ (0, ∞), p ∈ (0, ∞) and q(·) : ℝⁿ → [1, ∞) satisfy the globally log-Hölder continuity condition. We introduce the weak Herz-type Hardy spaces with variable exponents via the radial grand maximal operator and to give its maximal characterizations, we establish a version of the boundedness of the Hardy-Littlewood maximal operator M and the Fefferman-Stein vector-valued inequality on the weak Herz spaces with variable exponents. We also obtain the atomic and the molecular decompositions of the weak Herz-type Hardy spaces with variable exponents. As an application of the atomic decomposition we provide various equivalent characterizations of our spaces by means of the Lusin area function, the Littlewood-Paley g-function and the Littlewood-Paley $g^*_{\lambda}$-function.

• Journal of the Korean Magnetics Society
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• v.20 no.2
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• pp.52-60
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• 2010

The changes of magnetic flux density distribution and the degree of magnetic anomaly on the ground surface by underground fracture zones and empty spaces had been investigated through the variations of the measuring heights. The magnetic flux density distributions were monitored for the ground surfaces of fracture zones, empty spaces and tunnels by fluxgate-type magnetometer. The fracture zones showed the magnetic anomaly with (+) and (-) peak-pairs in the magnetic flux distribution measured at 0.15 m height from the ground surface, and this anomaly disappeared at the height of 1.15 m. The underground empty spaces and tunnels showed the decrease of magnetic flux densities, where the degree of this density decrease diminished with the increase of the underground depth. And, the existence and size of underground empty spaces, such as tunnels and sink holes, could be monitored by the phenomena of this decreasing flux density.

• Journal of the Korean Institute of Intelligent Systems
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• v.21 no.1
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• pp.128-131
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• 2011

In this paper, we introduce and study the concept of fuzzy r-$M^*$ preopen mappings between fuzzy r-minimal spaces. We also investigate the relationships among fuzzy r-M precontinuous mappings, fuzzy r-$M^*$-preopen mappings and several types of fuzzy r-minimal compactness.