• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 1998년도 춘계학술대회 학술발표 논문집
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• pp.3-6
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• 1998

We introduce the notion of TL-p-subgroups that is an extension of the notion of fuzzy p-subgroups and show that a torsion TL-subgroup of an Abelian group with T=∧ can be written as the intersection of its minimal TL-p-subgroups.

• 충청수학회지
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• 제32권1호
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• pp.87-95
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• 2019

The homothety classes of lattices in a two dimensional vector space over a nonarchimedean local field form a regular tree ${\mathcal{T}}$ of degree q + 1 on which the projective linear group acts naturally where q is the order of the residue field. We show that for any finite regular combinatorial graph of even degree q + 1, there exists a torsion free discrete subgroup ${\Gamma}$ of the projective linear group such that ${\mathcal{T}}/{\Gamma}$ is isomorphic to the graph.

• Clinical and Experimental Pediatrics
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• 제48권1호
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• pp.75-80
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• 2005

목 적 : 일본이나 우리나라처럼 좌식생활을 많이 하는 동아시아국가에서는 경골 내염전이 많은 것으로 알려져 있다. 경골 내염전이나 지나친 경골 외염전은 미용적인 문제, 기능적인 문제, 정신적인 문제를 일으킬 수 있으며, 성인에서 퇴행성관절염과 연관성이 있는 것으로 보고되고 있다. 이에 제주지역 정상소아를 대상으로 경골 염전의 정도를 알아보기 위하여 본 연구를 시행 하였다. 방 법 : 제주지역 아동을 대상으로 1-12세 사이의 521명, 1,042족을 대상으로 복사 통과 각도를 측정하였으며 나이를 6개월 간격으로 구분하여 분석하였다. 평균 복사 통과 각도의 변화 양상을 적합하기 위하여 2차 회귀 모델과 선형회귀 모델을 사용하였다. 2차 회귀분석에 대해 가장 높은 결정계수를 보여주는 7세가 서로 다른 통계모형에 적합하는 기준점으로 사용되었다. 결 과 : 전체 아동의 평균 복사 통과 각도는 $0.10{\pm}5.79^{\circ}$이었으며, 남아의 평균 복사통과각도는 $0.90{\pm}5.49^{\circ}$, 여아의 평균 복사 통과 각도는 $-0.80{\pm}5.97^{\circ}$이었다. 평균 복사 통과 각도는 1세에 $4.25{\pm}4.04$에서 나이가 들면서 점차 감소하여 4년 7개월에 $-1.98^{\circ}$로 가장 낮은 값을 보였으며 이후 나이가 들면서 점차 증가하여 7세 이후는 $0.67{\pm}1.10^{\circ}$로 일정하게 유지되었다. 결 론 : 영아기의 경골 내염전은 정상적인 성장 발달 과정에서 저절로 좋아지는 것으로 알려져 있다. 그러나 본 연구에서는 우리나라 아동의 경우 오히려 1세 이후 복사 통과 각도가 해마다 감소하여 4년 7개월에서 최저 각도를 보이고 이후 다시 점차 증가하여 7세 이후에 더 이상 교정되지 않고 경골 외염전이 서양 아동들에 비해 약 $10^{\circ}$ 정도 감소한 상태에서 지속되었다. 이는 우리의 전통적인 생활 방식 특히 무릎을 꿇어앉는 습관에 기인하는 것으로 보인다. 따라서 관절과 보행의 이상을 예방하기 위하여 아동기에 경골 염전의 이상을 조기 발견하여 자세를 교정하여주고 필요한 경우에는 조기에 치료를 해줄 필요가 있다고 생각된다. 아울러 우리나라 아동기의 경골 염전에 대한 연구가 보다 폭넓게 이루어져야 될 것으로 생각된다.

• East Asian mathematical journal
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• 제39권3호
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• pp.349-354
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• 2023

The motivation in this paper comes from the recent results about Bell inequalities and topological insulators from group theory. Symmetries which are interested in group theory could be mainly used to find material structures. In this point of views, we study group extending by adding one relator which is easily called an equation. So a relative group extension by a adding relator is aspherical if the natural injection is one-to-one and the group ring has no zero divisor. One of concepts of asphericity means that a new group by a adding relator is well extended. Also, we consider that several equations and relative presentations over torsion-free groups are related to zero divisors.

• 대한수학회보
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• 제42권4호
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• pp.807-815
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• 2005

Let R be a ring with identity, X the set of all nonzero, nonunits of Rand G the group of all units of R. We will consider two group actions on X by G, the regular action and the conjugate action. In this paper, by investigating two group actions we can have some results as follows: First, if G is a finitely generated abelian group, then the orbit O(x) under the regular action on X by G is finite for all nilpotents x $\in$ X. Secondly, if F is a field in which 2 is a unit and F $\backslash\;\{0\}$ is a finitley generated abelian group, then F is finite. Finally, if G in a unit-regular ring R is a torsion group and 2 is a unit in R, then the conjugate action on X by G is trivial if and only if G is abelian if and only if R is commutative.

• 대한수학회지
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• 제40권2호
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• pp.225-239
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• 2003

(G, <) is an ordered group if'<'is a total order relation on G in which f < g implies that xfy < xgy for all f, g, x, y $\in$ G. We say that (G, <) is centrally ordered if (G, <) is ordered and ［G,D］ $\subseteq$ C for every convex jump C $\prec$ D in G. Equivalently, if $f^{-1}g f{\leq} g^2$ for all f, g $\in$ G with g > 1. Every order on a torsion-free locally nilpotent group is central. We prove that if every order on every two-generator subgroup of a locally soluble orderable group G is central, then G is locally nilpotent. We also provide an example of a non-nilpotent two-generator metabelian orderable group in which all orders are central.

• 호남수학학술지
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• 제39권4호
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• pp.637-647
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• 2017

Elastica is known as classical curve that is a solution of variational problem, which minimize a thin inextensible wire's bending energy. Studies on elastica has been conducted in Euclidean space firstly, then it has been extended to Riemannian manifold by giving different characterizations. In this paper, we focus on energy of the elastic curve in a Lie group. We attepmt to compute its energy by using geometric description of the curvature and the torsion of the trajectory of the elastic curve of the trajectory of the moving particle in the Lie group. Finally, we also investigate the relation between energy of the elastic curve and energy of the same curve in Frenet vector fields in the Lie group.

• Earthquakes and Structures
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• 제8권2호
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• pp.305-377
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• 2015

The problem of earthquake induced torsion in buildings is quite old and although it has received a lot of attention in the past several decades, it is still open. This is evident not only from the variability of the pertinent provisions in various modern codes but also from conflicting results debated in the literature. Most of the conducted research on this problem has been based on very simplified, highly idealized models of eccentric one-story systems, with single or double eccentricity and with load bearing elements of the shear beam type, sized only for earthquake action. Initially, elastic models were used but were gradually replaced by inelastic models, since building response under design level earthquakes is expected to be inelastic. Code provisions till today have been based mostly on results from one-story inelastic models or on results from elastic multistory idealizations. In the past decade, however, more accurate multi story inelastic building response has been studied using the well-known and far more accurate plastic hinge model for flexural members. On the basis of such research some interesting conclusions have been drawn, revising older views about the inelastic response of buildings based on one-story simplified model results. The present paper traces these developments and presents new findings that can explain long lasting controversies in this area and at the same time may raise questions about the adequacy of code provisions based on results from questionable models. To organize this review better it was necessary to group the various publications into a number of subtopics and within each subtopic to separate them into smaller groups according to the basic assumptions and/or limitations used. Capacity assessment of irregular buildings and new technologies to control torsional motion have also been included.

• 대한수학회논문집
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• 제18권2호
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• pp.367-374
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• 2003

Let N be a Closed n-manifold with residually finite, torsion free $\pi$$_1$(N) and finite H$_1$,(N). Suppose that $\pi$$\_$k/(N)=0 for 1 < k < n-1. We show that N is a codimension-n PL fibrator if and only if N does not cover itself regularly and cyclically up to homotopy type, provided $\pi$$_1$(N) satisfies a certain condition.

• 호남수학학술지
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• 제40권2호
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• pp.265-280
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• 2018

In this study, we firstly define equations of motion based on the traditional model Newtonian mechanics in terms of the Frenet frame adapted to the trajectory of the moving particle in Lie groups. Then, we compute energy on the moving particle in resultant force field by using geometrical description of the curvature and torsion of the trajectory belonging to the particle. We also investigate the relation between energy on the moving particle in different force fields and energy on the particle in Frenet vector fields.