• The Transactions of the Korea Information Processing Society
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• v.5 no.9
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• pp.2256-2270
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• 1998

The development of a high perfoffilance index system is crucial for the retrieval of information from large sets o[ data. In this study, a minimal perfect hash function (MPHF), which hashes m keys to m buckets with no collisions, is revisited. The MOS algorithm developed bv Heath is modified to be successful for computing MPHFs of large sets of keys Also, a system for generating MPHFs for large sets of keys is developed. This system computed MPHFs for several large sets of data more efficiently than Heath's. The application areas for this system include those for generating MPHFs for the indexing of large and infrequently changing sets of data as well as information stored in a medium whose seek time is very slow.

• Korean Journal of Mathematics
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• v.7 no.1
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• pp.117-121
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• 1999

In this paper, we introduce $m$-open(closed) mappings by $m$-sets, and obtain a number of their properties. In particular, $m$-open(closed) mappings are used to extend known results for ${\alpha}$-open mapping, semi-open mappings and preopen mappings.

• Korean Journal of Mathematics
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• v.17 no.3
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• pp.249-255
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• 2009

In [5], we introduced the concepts of IVF m-preopen sets and IVF m-precontinuous mappings on interval-valued fuzzy minimal spaces. In this paper, we introduce the concept of IVF m-preopen mapping and investigate characterizations for IVF mprecontinuous mappings and IVF m-preopen mappings.

• Korean Journal of Remote Sensing
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• v.29 no.2
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• pp.219-233
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• 2013

In this study, spatio-temporal variations of Land Surface Emissivity (LSE) of the three LSE data sets in the Asian-Oceanian regions were addressed. The MODerate Resolution Imaging Spectroradiometer (MODIS) LSE, Cooperative Institute for Meteorological Satellite Studies (CIMSS) LSE, and Kongju National Univ. (KNU) LSE data sets were used. The three data sets showed very similar emissivity in the Tibetan Plateau, desert in the Middle East and Australia, and low latitude regions irrespective of season. The emissivity of $12{\mu}m$ was systematically greater than that of $11{\mu}m$, in particular, in the Tibetan Plateau, desert over Middle East and Australia. In general, they showed a weak seasonal variation in the low latitude regions although the emissivity was different among them. However, the three data sets showed quite different spatial and temporal variations in the other regions of Asian-Oceanian regions. The KNU LSE showed a systematic seasonal variation with a high emissivity during summer and low emissivity during winter but the other two LSE data sets showed irregular seasonal variations without regard to the regions. And the annual mean correlations of $11{\mu}m$ and $12{\mu}m$ between KNU LSE and MODIS LSE (KNU LSE and CIMSS LSE; MODIS LSE and CIMSS LSE) were 0.423 and 0.399 (0.330, 0.101; 0.541, 0.154), respectively. The relatively low correlations and strong inter-month variations, in particular, in $12{\mu}m$, indicated that consistency in spatial variation was very low. The comparison results showed that caution should be given before operational use of the LSE data sets in these regions.

• Journal of Communications and Networks
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• v.12 no.4
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• pp.330-333
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• 2010

In this paper, using binary (N, M, L, $\epsilon$) low correlation zone (LCZ) sequence sets, we construct new quaternary LCZ sequence sets with parameters (2N, 2M, L, $2{\epsilon}$). Binary LCZ sequences for the construction should have period $N\;{\equiv}\;3$ mod 4, L|N, and the balance property. The proposed method corresponds to a quaternary extension of the extended construction of binary LCZ sequence sets proposed by Kim, Jang, No, and Chung [1].

• Communications of the Korean Mathematical Society
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• v.35 no.4
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• pp.1057-1073
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• 2020

In this paper, we study some of the factorization aspects of rational multicyclic monoids, that is, additive submonoids of the nonnegative rational numbers generated by multiple geometric sequences. In particular, we provide a complete description of the rational multicyclic monoids M that are hereditarily atomic (i.e., every submonoid of M is atomic). Additionally, we show that the sets of lengths of certain rational multicyclic monoids are finite unions of multidimensional arithmetic progressions, while their unions satisfy the Structure Theorem for Unions of Sets of Lengths. Finally, we realize arithmetic progressions as the sets of distances of some additive submonoids of the nonnegative rational numbers.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.8 no.4
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• pp.284-287
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• 2008

In this paper, we introduce multi-intuitionistic fuzzy sets and intuitionistic fuzzy hybrid sets. The basic operations between such structures are defined. The use of these structures in the definition of intuition is tic fuzzy variants of P systems and their properties are presented.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.8 no.3
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• pp.202-206
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• 2008

We introduce the concept of interval-valued minimal structure which is an extension of the interval-valued fuzzy topology. And we introduce and study the concepts of IVF m-continuous and several types of compactness on the interval-valued fuzzy m-spaces.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.10 no.1
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• pp.54-58
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• 2010

We introduce the concepts of interval-valued fuzzy $m{\alpha}$-open sets and interval-valued fuzzy $m{\alpha}$-continuous mappings. And we study some characterizations and properties of such concepts.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.11 no.1
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• pp.33-37
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• 2011

We introduce the concepts of interval-valued fuzzy m${\beta}$-open sets and interval-valued fuzzy m${\beta}$-continuous mappings. And we study some characterizations and properties of such concepts.