• Communications of the Korean Mathematical Society
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• v.35 no.1
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• pp.63-81
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• 2020

In this paper we consider certain classes of generalized level 2 Eisenstein series by simple differential calculations of trigonometric functions. In particular, we give four new transformation formulas for some level 2 Eisenstein series. We can find that these level 2 Eisenstein series are reducible to infinite series involving hyperbolic functions. Moreover, some interesting new examples are given.

• Korean Journal of Mathematics
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• v.4 no.2
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• pp.101-115
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• 1996

In this paper, we will show that the minimal number of generators of any four dimensional, faithful, $\mathcal{B}$(Schur algebra of size 4)-module is two. This result can be applied to classify the isomorphism classes of the class {$\mathcal{B}{\ltimes}N^2{\mid}N$ is a faithful, $\mathcal{B}$-module with $dim_k(N)=4$}.

• Bulletin of the Korean Mathematical Society
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• v.52 no.6
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• pp.2035-2045
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• 2015

Meridian surfaces in the Euclidean 4-space are two-dimensional surfaces which are one-parameter systems of meridians of a standard rotational hypersurface. On the base of our invariant theory of surfaces we study meridian surfaces with special invariants. In the present paper we give the complete classification of Chen meridian surfaces and meridian surfaces with parallel normal bundle.

• The Korean Journal of Mycology
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• v.8 no.1
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• pp.29-32
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• 1980

More than 100 of higher fungi were collected and identified at the bamboo forest of Damyang, Chonlanam-Do, during July to October, 1979. They include two classes, four oders, 13 families, 21 genera and 25 species. Among them, Leucocoprinus otsuensis Hongo, Lepiota atros­quamulosa Hongo and Rhodophyllus mycenoides Hongo were found to be new in Korea.

• Journal of Species Research
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• v.7 no.2
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• pp.181-186
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• 2018

We investigated five ciliate species from soil, estuary and marine habitats in eastern Gangwon-do Province, South Korea. Morphology was studied through observation of living specimens as well as silver preparations. The species were classified into five genera, five families, five orders and four classes. Aspidisca aculeata, Hemiurosoma similis, Litonotus alpestris, Stentor roeselii and Vorticella infusionum are first records in Korea, and among them, the genus Hemiurosoma is recorded for the first time. Here, we provide short descriptions with microphotographs of these species.

• Journal of applied mathematics & informatics
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• v.40 no.1_2
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• pp.259-266
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• 2022

The present investigation is concerned with certain subclasses of alpha-convex functions with fixed point and defined with subordination in the unit disc E = {z :| z |< 1}. The estimates of the first four coefficients for the functions in these classes are obtained. The results due to various authors follow as special cases.

• Journal of Species Research
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• v.6 no.2
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• pp.101-118
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• 2017

In an investigation of indigenous prokaryotic species in Korea, a total of 57 bacterial strains assigned to the classes Betaproteobacteria and Gammaproteobacteria were isolated from diverse environments. Samples were collected from fresh water, natural caves, soil, paddy fields, lakes, sea water, jeotgal (fermented seafood), salt flats, soil from abandoned mines, plant roots, digestive organs of both Japanese crested ibis (Nipponia nippon) and Burmese python (Python molurus bivittatus) and tidal flats. From the high 16S rRNA gene sequence similarity (>98.7%) and formation of robust phylogenetic clades with closely related species, it was determined that each strain belonged to an independent and predefined bacterial species within either the Betaproteobacteria or Gammaproteobacteria. There is no official report or publication that describes these 57 proteobacterial species in Korea. Overall, in the class Betaproteobacteria there were 16 species in 12 genera of 4 families in the order Burkholderiales and two species in two genera of one family in the order Neisseriales. Within the class Gammaproteobacteia, there were five species in four genera of four families in the order Alteromonadales, 12 species in 11 genera of one family in the order Enterobacteriales, four species in four genera of three families in the order Oceanospirillales, 11 species in four genera of two families in the order Pseudomonadales, two species in the order Vibrionales and five species in five genera of one family in the order Xanthomonadales. Gram reaction, colony and cell morphology, basic biochemical characteristics, isolation source and strain IDs are described in the species description section.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.15 no.2
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• pp.124-136
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• 1990

This paper presents a catalog of AND-EXOR expressions for representative function of four-variable NP-equivalence classes. Minimality is defined as minimizing first the number of product terms and then the total number of literal in the expression. Also, the propoerties of minimum expressions are discussed. Using this as a base, We compare minimum expressions of AND-OR type two-variable circuit with minimum expressions of AND-EXOR type two-variable circuit which used algorithm in this paper. As a results it was found that in the case of AND-OR type minimum expressions, number of product terms is under 8, and in the case of AND-EXOR type minimum expressions all functions are formed in which number of product terms is under 6, and generally number of product term is considerably small to realize four-vaiable function toward ADN-EXOR type minimum expression circuit. Algorithm suggested in this paper are realized on Sun 3/50, and through this, logic function under four-variable can get minimum immedately by a catalog suggested in this paper. As for five-variale function, we can do shanon-development a part of the function with suitable variable, and by applying four-variable minimum of this paper on this, it can be possible to get minimum in a short time and it can be said that it is possible to apply this method to functions over 6 variable.

• Agricultural and Biosystems Engineering
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• v.3 no.1
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• pp.1-9
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• 2002

Garlic is one of the major seasoning vegetables in Korea and consumed mostly in a form of peeled cloves. Conventional Korean standards for garlic grading consist of four classes according to the size of bulb and its shape. Sorting and grading of garlic are manually done but could be in the process of automated mechanization using machine vision system in the near future. The proportion of mass of cloves in a garlic bulb to the volume of the bulb (g/ml) was determined to find out the best way of representing both the quantity and quality of cloves in each bulb. Garlic bulb was assumed as an ellipsoid and its major and minor axis and its height were measured to calculate its volume. The mass proportions and density of a garlic bulb and cloves were measured for four domestic varieties of garlic to propose it as a standard for Korean garlic grading machine.

• Communications of the Korean Mathematical Society
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• v.25 no.1
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• pp.11-18
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• 2010

The work in this paper was motivated by [3], where Eschenbach and Li listed four 4 by 4 sign patterns, conjectured to be nilpotent sign patterns of nilpotence index at least 3. These sign patterns with no zero entries, called full sign patterns, are shown to be potentially nilpotent of nilpotence index 3. We also generalize these sign patterns of order 4 so that we provide classes of n by n sign patterns of nilpotence indices at least 3, if they are potentially nilpotent. Furthermore it is shown that if a full sign pattern A of order n has nilpotence index k with $2{\leq}k{\leq}n-1$, then sign pattern A has nilpotent realizations of nilpotence indices k, k + 1, $\ldots$, n. Hence, the four 4 by 4 sign patterns in [3, page 91] also allow nilpotent realizations of nilpotence index 4.