• 대한수학회지
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• 제33권2호
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• pp.387-397
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• 1996

Let G be a finite group and F be a field of characteristic $p \geq 0$. Let $\Gamma = F^f G$ be a twisted group algebra corresponding to a 2-cocycle $f \in Z^2(G,F^*), where F^* = F - {0}$ is the multiplicative subgroup of F.

• 대한수학회논문집
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• 제10권2호
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• pp.275-284
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• 1995

In this paper various G-module structures on M and all possible extensions of M by G will be studied, whence equivalence classes of extensions of M by G and those of extensions which are compatible with the given G-module structures of M will be determined explicitly. Further the difference between extensions and compatible extensions will be pointed out.

• 대한수학회보
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• 제33권2호
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• pp.303-310
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• 1996

The Gottlieb group of a compact connected ANR X, G(X), consists of all $\alpha \in \prod_{1}(X)$ such that there is an associated map $A : S^1 \times X \to X$ and a homotopy commutative diagram $$ S^1 \times X \longrightarrow^A X $$ $$incl \uparrow \nearrow \alpha \vee id $$ $$ S^1 \vee X $$.

• 대한수학회보
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• 제52권2호
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• pp.557-570
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• 2015

Let $\mathbb{G}$ be a von Neumann algebraic locally compact quantum group, in the sense of Kustermans and Vaes. In this paper, as a consequence of a notion of amenability for actions of Lau algebras, we show that $\hat{\mathbb{G}}$, the dual of $\mathbb{G}$, is co-amenable if and only if there is a state $m{\in}L^{\infty}(\hat{\mathbb{G}})^*$ which is invariant under a left module action of $L^1(\mathbb{G})$ on $L^{\infty}(\hat{\mathbb{G}})^*$. This is the quantum group version of a result by Stokke [17]. We also characterize amenable action of Lau algebras by several properties such as fixed point property. This yields in particular, a fixed point characterization of amenable groups and H-amenable representation of groups.

• 대한수학회보
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• 제48권5호
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• pp.1015-1021
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• 2011

A point of a Riemann surface X is said to be its fixed point if it is a fixed point of one of its nontrivial holomorphic automorphisms. We start this note by proving that the set Fix(X) of fixed points of Riemann surface X of genus g${\geq}$2 has at most 82(g-1) elements and this bound is attained just for X having a Hurwitz group of automorphisms, i.e., a group of order 84(g-1). The set of such points is invariant under the group of holomorphic automorphisms of X and we study the corresponding symmetric representation. We show that its algebraic type is an essential invariant of the topological type of the holomorphic action and we study its kernel, to find in particular some sufficient condition for its faithfulness.

• 아동학회지
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• 제28권5호
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• pp.91-108
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• 2007

This study investigated the attachment representation, self-perception, and social competence of preschoolers of interracial families in rural areas. Participants were 60 3- to 5-year-old preschoolers with Korean father-other Asian national mother group and 91 3- to 5-year-old preschoolers with Korean father-Korean mother group in rural areas. Results were that 58% of preschool children of interracial families were securely attached, 30% were insecure-disorder type, and 12% were insecure-avoidance type. Preschool children of interracial families were rated by their teachers as showing more withdrawn behaviors and prosocial behaviors than preschool children of Korean parents. A sex difference in the interracial family group showed boys with more withdrawn behaviors than girls.

• 대한수학회보
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• 제10권2호
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• pp.63-68
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• 1973

• 한국초등과학교육학회지:초등과학교육
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• 제40권1호
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• pp.100-112
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• 2021

Based on the importance of visual representation for scientific understanding, this study applied visual thinking in elementary science classes. This study analyzed elementary students' visual thinking and investigated the instructional influences. Students' perceptions on the class applying visual thinking were also investigated. The subject were 38 fourth grade students, 18 in experimental group and 20 in control group. For the unit of 'Shadow and mirror', on-line and off-line blended classes were applied in both group because of COVID-19. The experimental group student were asked to construct their own visual thinking, while the control group students used traditional workbook. The results were as follows. First, students' visual thinking can be classified into three different types, which are 'activity recall type', 'result summary type', and 'core concept representation type' based on what they represent rather than how they represent. Second, applying visual thinking in science class showed significant effects on science academic achievement, science related attitude, and creative academic efficacy. Third, students' perceptions on applying visual thinking in science classes were very positive. Students perceived visual thinking activities were interesting and helpful for understanding science. Educational implications of applying visual thinking in elementary science classes were discussed.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권8호
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• pp.3873-3887
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• 2018

In this paper, we propose a novel method to recover images corrupted by impulse noise. The proposed method uses two stages: noise detection and filtering. In the first stage, we use pixel values, rank-ordered logarithmic difference values, and median values to train a neural-network-based impulse noise detector. After training, we apply the network to detect noisy pixels in images. In the next stage, we use group-based weighted couple sparse representation to filter the noisy pixels. During this second stage, conventional methods generally use only clean pixels to recover corrupted pixels, which can yield unsuccessful dictionary learning if the noise density is high and the number of useful clean pixels is inadequate. Therefore, we use reconstructed pixels to balance the deficiency. Experimental results show that the proposed noise detector has better performance than the conventional noise detectors. Also, with the information of noisy pixel location, the proposed impulse-noise removal method performs better than the conventional methods, through the recovered images resulting in better quality.

• ETRI Journal
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• 제28권2호
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• pp.219-222
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• 2006

Virtual source location information (VSLI) has been newly utilized as a spatial cue for compact representation of multichannel audio. This information is represented as the azimuth of the virtual source vector. The superiority of VSLI is confirmed by comparison of the spectral distances, average bit rates, and subjective assessment with a conventional cue.