• Communications of the Korean Mathematical Society
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• v.27 no.4
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• pp.689-699
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• 2012

(S, *) is a semigroup S equipped with a unary operation "*". This work is devoted to a class of unary semigroups, namely E-$inversive$ *-$semigroups$. A unary semigroup (S, *) is called an E-inversive *-semigroup if the following identities hold: $$x^*xx^*=x^*$$, $$(x^*)^*=xx^*x$$, $$(xy)^*=y^*x^*$$. In this paper, E-inversive *-semigroups are characterized by several methods. Furthermore, congruences on these semigroups are also studied.

• Bulletin of the Korean Mathematical Society
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• v.44 no.2
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• pp.241-246
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• 2007

For the evaluation algebra $F[e^{{\pm}x}]_M\;if\;M=\{{\partial}\}$, then $$Der_{non}(F[e^{{\pm}x}]_M)$$ of the evaluation algebra $(F[e^{{\pm}x}]_M)$ is found in the paper [15]. For $M=\{{\partial},\;{\partial}^2\}$, we find $Der_{non}(F[e^{{\pm}x}]_M))$ of the evaluation algebra $F[e^{{\pm}x}]_M$ in this paper. We show that there is a non-associative algebra which is the direct sum of derivation invariant subspaces.

• Honam Mathematical Journal
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• v.27 no.3
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• pp.389-397
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• 2005

Let K be an absolutely real abelian number field with $G=Gal(K/{\mathbb{Q}})$. Let E be a subfield of K and ${\Delta}=Gal(K/E)$. Let $C_K$ and $C_E$ be the group of circular units of K and E respectively. In [G], Greither has shown that if G is cyclic then $C_K^{\Delta}=C_E$. In this paper we show that the same result holds in function field case.

• Kyungpook Mathematical Journal
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• v.55 no.4
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• pp.885-892
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• 2015

In this paper, we mainly obtain the following assertions: (1) If T is a quasi-*-n-paranormal operator, then T is finite and simply polaroid. (2) If T or $T^*$ is a quasi-*-n-paranormal operator, then Weyl's theorem holds for f(T), where f is an analytic function on ${\sigma}(T)$ and is not constant on each connected component of the open set U containing ${\sigma}(T)$. (3) If E is the Riesz idempotent for a nonzero isolated point ${\lambda}$ of the spectrum of a quasi-*-n-paranormal operator, then E is self-adjoint and $EH=N(T-{\lambda})=N(T-{\lambda})^*$.

• Korean Journal of Mathematics
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• v.32 no.3
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• pp.533-544
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• 2024

Given a groupoid (X, *) and a real-valued function d : X → R, a new (derived) function Φ(X, *)(d) is defined as [Φ(X, *)(d)](x, y) := d(x * y) + d(y * x) and thus Φ(X, *) : R^X → R^X2 as well, where R is the set of real numbers. The mapping Φ(X, *) is an R-linear transformation also. Properties of groupoids (X, *), functions d : X → R, and linear transformations Φ(X, *) interact in interesting ways as explored in this paper. Because of the great number of such possible interactions the results obtained are of necessity limited. Nevertheless, interesting results are obtained. E.g., if (X, *, 0) is a groupoid such that x * y = 0 = y * x if and only if x = y, which includes the class of all d/BCK-algebras, then (X, *) is *-metrizable, i.e., Φ(X, *)(d) : X² → X is a metric on X for some d : X → R.

• Asia pacific journal of information systems
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• v.20 no.4
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• pp.1-23
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• 2010

Some researches insist that, to participate in an e-partnership, a distributor needs a given level of trust to reduce the perceived risk of an e-partnership to his/her own threshold. However, other researches insist that if a distributor has only a given level of trust in his/her suppliers, irrelevant of the perceived risk level, he/she participates in the e-partnership. Thus, from the perspective of a distributor, this study built a trust model in which these two viewpoints were reflected. And then this study examined whether or not perceived risk mediates an influence of trust to e-partnership. The proposed trust model was tested with 265 questionnaires about a distributor-supplier e-partnership in food wholesale markets. The analysis results Indicated that perceived risk partially had a mediating effect between trust and e-partnership Intention. That is, of the two risk types, only perceived performance risk mediated an influence from competence trust to e-partnership intention. Relational risk did not play a mediating role between goodwill trust and e-partnership intention. This result Implies two managerial meanings. First, a distributor Intends to engage In e-partnership with his/her supplier, irrelevant of relational risk's level if goodwill trust level surpasses his/her own threshold. Thus, suppliers should concentrate more effort in developing goodwill trust than in reducing relational risk. To develop goodwill trust, they should endeavor to establish mutual interests and individual trust with their distributor, and to utilize institutional trust bases. Second, a distributor requires a certain competence In his/her suppliers to sufficiently reduce performance risk caused bye-partnership. Thus, to develop competence trust in e-partnership, suppliers should improve on any lack of competence and build a good reputation.

• The Journal of Korean Association of Computer Education
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• v.10 no.5
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• pp.71-79
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• 2007

The purpose of this research is to show that elements of learning information's record(learning time and the score of practice test) have a significant effect on the correctness of decision when they are applied to e-Learning based on CAT with SPRT model. Especially, the score of practice test can be used in the real e-learning environment as its effect showed approximately 90% improvement. Therefore, if we apply learning information's record to SPRT in evaluation, we can evaluate the learner's ability more precisely and quickly, contributing to the enhancement of the individualization of learners. If an algorithm with variables from learning information's record can be developed, a better e-Learning evaluation program will be made in the future.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.9
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• pp.855-862
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• 2009

This paper contains the signal receiving algorithm for Galileo E5 AltBOC signal and the development of Galileo E5 signal receiving software. The software runs the process from signal acquisition to extracting measurement data to get navigation solution. It uses logged IF data file as an input. In signal acquisition stage, 1ms and delayed 1ms data are used for reducing correlation ross from secondary code and navigation bit conversion. Signal tracking stage is made of two stages which are coarse tracking and fine tracking. It is for taking advantage of AltBOC characteristic and resolving ambiguity problem due to BOC modulation. The functions of software are verified by signal processing using logged IF data from commercial GNSS simulator.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1994.04a
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• pp.171-171
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• 1994

Cephem ring의 C-7위치에 aminothiazoly lmethoxyimino기를 가진 화합물들이 항균활성을 증가시키고, G(-)균의 외막투과성을 촉진시킬뿐 아니라 광범위항균 spectrum을 갖게 하고 $\beta$-lactamase에 안정하며 PBP(penicillin binding protein)에 대한 결합친화성을 증가시킨다는 보고에 따라 본 저자는 C-7위치에 cefotaxime구조와 같이 aminothiazolylmethoxyimino acetamido moiety를 고정시키고 항균활성을 증가시키기 위하여 약리활성이 기대되는 5-(substituted)-2H-tetrazole유도체들을 합성하여 C-3 위치에 도입시킨 새로운 화합물 7$\beta$-〔(z)-2-(2-aminothiazol-4-yl)-2_(methoxyimino)acetamido〕-3-〔5-(substituted)tetrazol-2-yl〕 methyl-3-cephem-4-carboxylic acid 유도체를 합성하여 B. subtilis ATCC 6633, M. luteus ATCC 1004, E. coli KCTC 1039, E. coli ESS, K. pncumonia KCTC 1560, P. aeruginosa IF0 13130, S. typhimurium KCTC 1925, S. typhimurium SL 1102, 및 C. albicans ATCC 10231 등의 균과 fungus에 대하여 기존의 cefotaxime과 cefazoline을 대조물질로 사용하여 항균력을 비교하였다. 이들 화합물들은 대체적으로 M. luteus ATCC 6633, E. coli ESS, S. typhimurium SL 1102 균에 대해서는 cefotaxime보다 항균력이 우수하였으나 P. aeruginosa IF0 13130에 대해서는 항균력이 저하되었고 cefazolin보다는 대체적으로 항균력이 우수하였다.

• Journal of applied mathematics & informatics
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• v.22 no.1_2
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• pp.435-440
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• 2006

Let G be a simple graph with vertex set V(G) and edge set E(G). A subset S of E(G) is called an edge cover of G if the subgraph induced by S is a spanning subgraph of G. The maximum number of edge covers which form a partition of E(G) is called edge covering chromatic number of G, denoted by X'c(G). It is known that for any graph G with minimum degree ${\delta},\;{\delta}-1{\le}X'c(G){\le}{\delta}$. If $X'c(G) ={\delta}$, then G is called a graph of CI class, otherwise G is called a graph of CII class. It is easy to prove that the problem of deciding whether a given graph is of CI class or CII class is NP-complete. In this paper, we consider the classification of nearly bipartite graph and give some sufficient conditions for a nearly bipartite graph to be of CI class.