• Korean Journal of Mathematics
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• v.11 no.2
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• pp.147-153
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• 2003

We investigate some properties on right(resp. left) duo $po$-semigroups.

• Bulletin of the Korean Mathematical Society
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• v.36 no.1
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• pp.139-146
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• 1999

It is known that a right nilpotent congruence $\beta$ on a finite algebra A is also left nilpotent [3]. The question on whether the left nilpotency class of $\beta$ in less than or equal to the right nilpotency class of $\beta$is still open. In this paper we find an upper limit for the left nilpotency class of $\beta$. In addition, under the assumption that 1 $\in$ typ{A}, we show that $(\beta]^k=[\beta)^k$ for all k$\geq$1. Thus the left and right nilpotency classes of $\beta$ are the same in this case.

• Korean Journal of Mathematics
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• v.14 no.2
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• pp.241-248
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• 2006

We define a G-fuzzy congruence, which is a generalized fuzzy congruence, and characterize the G-fuzzy congruence generated by a left and right compatible fuzzy relation on a semigroup.

• Journal of the Chungcheong Mathematical Society
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• v.24 no.3
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• pp.449-456
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• 2011

In this paper, we considered the congruence relation, isomorphism and obtained some properties of HS-algebras.

• The Pure and Applied Mathematics
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• v.4 no.2
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• pp.131-135
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• 1997

We give the relation between the semilattice congruence N and the set of prime ideals of the ordered $\Gamma$-semigroup M.

• The Pure and Applied Mathematics
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• v.12 no.4 s.30
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• pp.253-274
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• 2005

An additive regular Semiring S is left inversive if the Set E+ (S) of all additive idempotents is left regular. The set LC(S) of all left inversive semiring congruences on an additive regular semiring S is a lattice. The relations $\theta$ and k (resp.), induced by tr. and ker (resp.), are congruences on LC(S) and each $\theta$-class p$\theta$ (resp. each k-class pk) is a complete modular sublattice with $p_{min}$ and $p_{max}$ (resp. With $p^{min}$ and $p^{max}$), as the least and greatest elements. $p_{min},\;p_{max},\;p^{min}$ and $p^{max}$, in particular ${\epsilon}_{max}$, the maximum additive idempotent separating congruence has been characterized explicitly. A semiring is quasi-inversive if and only if it is a subdirect product of a left inversive and a right inversive semiring.

• Communications of the Korean Mathematical Society
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• v.13 no.1
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• pp.1-6
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• 1998

The paper refers to ordered semigroups in which $x^2 (x \in S)$ are left ideal elements. We mainly show that this $po$-semigroup is left regular if and only if S is a union of left simple subsemigroups of S.

• Journal of the Korean Institute of Intelligent Systems
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• v.17 no.1
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• pp.100-111
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• 2007

We introduce the concept of intuitionistic fuzzy G-equivalence relations (congruence), and we obtain some results. Furthermore, we prove that $IFC_G(K)$ is isomorphic to $IFN^*(K)$ for any group K. Also, we prove that($IFC_{G,({\lambda},{\mu})}/{\sim},\;*$) and ($IFNG_{({\lambda},{\mu})}(K),\;{\circ}$) are isomorphic.

• Korean Journal of Legislative Studies
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• v.23 no.2
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• pp.67-108
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• 2017

How well citizens are represented by their representatives holds critical importance in representative democracy. While previous studies of ideological congruence have largely focused on Western established democracies, there was not as much attention paid to young democracies including, South Korea. This article investigates ideological congruence in South Korea based on multiple survey data sources collected from 2002 to 2016. When it comes to unidimensional Left-Right ideology, the distance between citizens and governments, unlike its citizen-assembly counterpart, has widened since 2000 sending a negative signal to the norm of representative democracy. As to multidimensional issue positions, however, it turns out that ideological congruence in South Korea has varied along issues such as aids to North Korea and Welfare spending. These results provide both citizens and parties with some important implications. For citizens, they are required to distinguish which party or candidate is more representative of the issue they value the most beyond a simple Left-Right line; for parties, they are required to deal with how to represent their supporters as well as today's increasing independents by strengthening their organizational capacity and providing effective party programs.

• The Mathematical Education
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• v.46 no.3
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• pp.273-292
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• 2007

The purpose of this study was to find out how second, fourth and sixth graders understood the main contents related to spatial sense in the Seventh National Mathematics Curriculum. For this purpose, this study examined students' understanding of the main contents of congruence transformation (slide, flip, turn), mirror symmetry, cubes, congruence and symmetry. An investigation was conducted and the subjects included 483 students. The main results are as follows. First, with regards to congruence transformation, whereas students had high percentages of correct answers on questions concerning slide, they had lower percentages on questions concerning turn. Percentages of correct answers on flip questions had significant differences among the three grades. In addition, most students experienced difficulties in describing the changes of shapes. Second, students understood the fact that the right and the left of an image in a mirror are exchanged, but they had poor overall understanding of mirror symmetry. The more complicated the cubes, the lower percentages of correct answers. Third, students had a good understanding of congruences, but they had difficulties in finding out congruent figures. Lastly, they had a poor understanding of symmetry and, in particular, didn't distinguish a symmetric figure of a line from a symmetric figure of a point.