• Journal of the Korean Mathematical Society
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• v.40 no.2
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• pp.273-286
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• 2003

Let $F^{\alpha}$G be a twisted group algebra. A subalgebra of $F^{\alpha}$G generated by all class sums of partition P of G is called a projective class algebra in $F^{alpha}$G associated with partition P. In this paper we study various partitions of G determined by actions of certain operator groups on G and construct projective class algebras depending on the actions. With regard to projective class algebras, we investigate structures of associated skew group algebras and fixed group algebras.

• Journal of the Chungcheong Mathematical Society
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• v.31 no.4
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• pp.475-486
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• 2018

We study free actions of finite nonabelian groups on 3-dimensional nilmanifolds with the first homology ${\mathbb{Z}}^2{\bigoplus}{\mathbb{Z}}_2$ which yield an orbit manifold reversing fiber orientation, up to topological conjugacy. We show that those nonabelian groups are $D_4$(the dihedral group), $Q_8$(the quaternion group), and $C_8.C_4$(the $1^{st}$ non-split extension by $C_8$ of $C_4$ acting via $C_4/C_2=C_2$).

• Journal of the Korean Mathematical Society
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• v.56 no.1
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• pp.285-287
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• 2019

• Bulletin of the Korean Mathematical Society
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• v.50 no.4
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• pp.1069-1077
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• 2013

Several authors investigated the properties which are invariant under the passage from a group to its nonabelian tensor square. In the present note we study this problem from the viewpoint of the classes of groups and the methods allow us to prove a result of invariance for some geometric properties of discrete groups.

• Archives of Plastic Surgery
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• v.44 no.1
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• pp.65-71
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• 2017

Background This study evaluated dynamic changes in eyebrow position related to aging. Methods Female participants were recruited and separated into two groups aged 20-30 years (the younger group, n=20; mean age, 24.8 years) and 50-70 years (the older group, n=20; mean age, 55.8 years). Photogrammetry was used to determine the eyebrow position at the medial canthus (MC), lateral limbus, lateral canthus, and lateral end point (EP) for 6 actions: smooth opening (the reference action) and closing of the eye, forward gaze, maximum opening and closing of the eye, and maximum frown. Videos were also recorded. Results No differences in eyebrow position were detected at the MC when opening or closing the eyes smoothly, gazing straight ahead, or closing the eyes maximally. For all 6 actions, the position of the lateral EP in the older group was significantly lower than in the younger group (P=0.003), and the smallest degree of vertical movement at this point was found in both age groups (P<0.001). Vertical movement at the 4 landmarks of the eyebrows decreased with aging. Conclusions Eyebrow position was unchanged at the MC with aging, except at maximal eye opening and maximal frown. No differences in eyebrow position were observed between the younger and older groups when eyes were maximally closed, except at the EP. It is important to focus on correction of the lateral EP for periorbital rejuvenation.

• Journal of applied mathematics & informatics
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• v.41 no.6
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• pp.1237-1256
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• 2023

The tree products of groups with amalgamation subgroups are generalizations of the free products of groups with amalgamation subgroup. The aim of this paper is to construct a tree called the standard tree where the tree products of groups with amalgamation subgroups act without inversions and then find the quotient of this action. Furthermore, we show that if the amalgamation subgroups are finite and the factor groups act on disjoint trees then there exists a tree called the fiber tree where the tree products of groups with amalgamation subgroups act without inversions and find the quotients of this action. If each factor is a tree products with amalgamation subgroups, we get a new fiber tree and the corresponding factors.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.7
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• pp.4498-4510
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• 2015

The purpose of this study is to investigate effective teaching media for infants' teaching-learning process by comparing the effects of multimedia fairytale activities and picture fairytale listening activities on infants' prosocial actions. Following the purpose of this study, we studied any effect to infants' prosocial actions from multimedia fairytale activities by dividing in two groups. This study was conducted with 5-year-old infants (total 40; 20 experimental group & 20 comparison group) in D daycare center in Daejeon. Verifying data tool were time series corresponding t-test, independent t-test and multi-variant analyses. As a result, multimedia fairytale listening activities are more effective for infants' prosocial actions. It has meaningful difference in the interpersonal relationship skills and early childhood education adapt which is sub-area of infant's prosocial actions. So, for various and high-quality early childhood education, using multimedia teaching media is more effective than existing teaching media.

• Journal of the Korean Mathematical Society
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• v.39 no.1
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• pp.149-161
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• 2002

We study the torsions in the integral homology of the double loop space of the compact simple Lie groups by determining the higher Bockstein actions on the homology of those spaces through the Bockstein lemma and computing the Bockstein spectral sequence.

• The Journal of the Korea institute of electronic communication sciences
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• v.9 no.1
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• pp.123-130
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• 2014

The aim of this study was to determine the effect of action observational physical training on upper extremity function and activities of daily living in stroke patient. 19 hemiparetic patients participated in this study and were randomly selected into an experimental group and a control group. An experimental group observed performance actions of purposeful activity task through a video and imitated actions with the traditional occupational therapy, and a control group only observed actions with the traditional occupational therapy. Traing was performed 3 times a week and 30 min for each round for 4 weeks. WMFT were performed for an upper extremity function and MBI were performed for activities of daily living. As a result, WMFT and MBI showed significant difference between before and after in two groups but didn't show significant difference between two groups.

• Journal of the Korean Mathematical Society
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• v.34 no.2
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• pp.453-467
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• 1997

A transitive permutation representation of a group G is said to be multiplicity-free if all of its irreducible constituents are distinct. The character corresponding to the action is called the permutation character, given by $(1_H)^G$, where H is the stabilizer of a point. Multiplicity-free permutation characters are of interest in the study of centralizer algebras and distance-transitive graphs, and all finite simple groups are known to have such characters. In this article, we extend to the alternating groups the result of J. Saxl who determined the multiplicity-free permutation representations of the symmetric groups. We classify all subgroups H for which $(1_H)^An, n > 18$, is multiplicity-free.