• Title/Summary/Keyword: finite group

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THE GROUP OF UNITS OF SOME FINITE LOCAL RINGS I

  • Woo, Sung-Sik
    • Journal of the Korean Mathematical Society
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    • v.46 no.2
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    • pp.295-311
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    • 2009
  • The purpose of this paper is to identify the group of units of finite local rings of the types ${\mathbb{F}}_2[X]/(X^k)$ and ${\mathbb{Z}}_4[X]/I$, where I is an ideal. It turns out that they are 2-groups and we give explicit direct sum decomposition into cyclic subgroups of 2-power order and their generators.

Finite-element analysis of the center of resistance of the mandibular dentition

  • Jo, A-Ra;Mo, Sung-Seo;Lee, Kee-Joon;Sung, Sang-Jin;Chun, Youn-Sic
    • The korean journal of orthodontics
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    • v.47 no.1
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    • pp.21-30
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    • 2017
  • Objective: The aim of this study was to investigate the three-dimensional (3D) position of the center of resistance of 4 mandibular anterior teeth, 6 mandibular anterior teeth, and the complete mandibular dentition by using 3D finite-element analysis. Methods: Finite-element models included the complete mandibular dentition, periodontal ligament, and alveolar bone. The crowns of teeth in each group were fixed with buccal and lingual arch wires and lingual splint wires to minimize individual tooth movement and to evenly disperse the forces onto the teeth. Each group of teeth was subdivided into 0.5-mm intervals horizontally and vertically, and a force of 200 g was applied on each group. The center of resistance was defined as the point where the applied force induced parallel movement. Results: The center of resistance of the 4 mandibular anterior teeth group was 13.0 mm apical and 6.0 mm posterior, that of the 6 mandibular anterior teeth group was 13.5 mm apical and 8.5 mm posterior, and that of the complete mandibular dentition group was 13.5 mm apical and 25.0 mm posterior to the incisal edge of the mandibular central incisors. Conclusions: Finite-element analysis was useful in determining the 3D position of the center of resistance of the 4 mandibular anterior teeth group, 6 mandibular anterior teeth group, and complete mandibular dentition group.

PROJECTIVE SCHUR ALGEBRAS AS CLASS ALGEBRAS

  • Choi, Eun-Mi;Lee, Hei-Sook
    • Bulletin of the Korean Mathematical Society
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    • v.38 no.4
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    • pp.803-814
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    • 2001
  • A projective Schur algebra associated with a partition of finite group G can be constructed explicitly by defining linear transformations of G. We will consider various linear transformations and count the number of equivalent classes in a finite group. Then we construct projective Schur algebra dimension is determined by the number of classes.

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ON PROJECTIVE REPRESENTATIONS OF A FINITE GROUP AND ITS SUBGROUPS I

  • Park, Seung-Ahn;Park, Eun-Mi
    • Journal of the Korean Mathematical Society
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    • v.33 no.2
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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.

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