• 대한수학회보
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• 제21권2호
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• pp.67-75
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• 1984

Let X be a topological space. We consider a groupoid G over X and the quotient groupoid G/N for any normal subgroupoid N of G. The concept of groupoid (topological groupoid) is a natural generalization of the group(topological group). An useful example of a groupoid over X is the foundamental groupoid .pi.X whose object group at x.mem.X is the fundamental group .pi.(X, x). It is known [5] that if X is locally simply connected, then the topology of X determines a topology on .pi.X so that is becomes a topological groupoid over X, and a covering space of the product space X*X. In this paper the concept of the locally simple connectivity of a topological space X is applied to the groupoid G over X. That concept is defined as a term '1-connected local subgroupoid' of G. Using this concept we topologize the groupoid G so that it becomes a topological groupoid over X. With this topology the connected groupoid G is a covering space of the product space X*X. Further-more, if ob(.overbar.G)=.overbar.X is a covering space of X, then the groupoid .overbar.G is also a covering space of the groupoid G. Since the fundamental groupoid .pi.X of X satisfying a certain condition has an 1-connected local subgroupoid, .pi.X can always be topologized. In this case the topology on .pi.X is the same as that of [5]. In section 4 the results on the groupoid G are generalized to the quotient groupoid G/N. For any topological groupoid G over X and normal subgroupoid N of G, the abstract quotient groupoid G/N can be given the identification topology, but with this topology G/N need not be a topological groupoid over X [4]. However the induced topology (H) on G makes G/N (with the identification topology) a topological groupoid over X. A final section is related to the covering morphism. Let G$_{1}$ and G$_{2}$ be groupoids over the sets X$_{1}$ and X$_{2}$, respectively, and .phi.:G$_{1}$.rarw.G$_{2}$ be a covering spimorphism. If X$_{2}$ is a topological space and G$_{2}$ has an 1-connected local subgroupoid, then we can topologize X$_{1}$ so that ob(.phi.):X$_{1}$.rarw.X$_{2}$ is a covering map and .phi.: G$_{1}$.rarw.G$_{2}$ is a topological covering morphism.

• 한국초전도학회:학술대회논문집
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• 한국초전도학회 2002년도 High Temperature Superconductivity Vol.XII
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• pp.31-31
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• 2002

• 대한수학회지
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• 제43권3호
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• pp.491-506
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• 2006

In this paper, we extend the concept of the group ${\varepsilon}(X)$ of self homotopy equivalences of a space X to that of an object in the category of pairs. Mainly, we study the group ${\varepsilon}(X,\;A)$ of pair homotopy equivalences from a CW-pair (X, A) to itself which is the special case of the extended concept. For a CW-pair (X, A), we find an exact sequence $1\;{\to}\;G\;{\to}\;{\varepsilon}(X,\;A)\;{to}\;{\varepsilon}(A)$ where G is a subgroup of ${\varepsilon}(X,\;A)$. Especially, for CW homotopy associative and inversive H-spaces X and Y, we obtain a split short exact sequence $1\;{\to}\;{\varepsilon}(X)\;{\to}\;{\varepsilon}(X{\times}Y,Y)\;{\to}\;{\varepsilon}(Y)\;{\to}\;1$ provided the two sets $[X{\wedge}Y,\;X{\times}Y]$ and [X, Y] are trivial.

• Korean Journal of Mathematics
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• 제19권2호
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• pp.181-189
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• 2011

Let G be a group and X be a nonempty set and H be a subgroup of G. For a given ${\phi}_G\;:\;G{\times}X{\rightarrow}X$, a group action of G on X, we define ${\phi}_H\;:\;H{\times}X{\rightarrow}X$, a subgroup action of H on X, by ${\phi}_H(h,x)={\phi}_G(h,x)$ for all $(h,x){\in}H{\times}X$. In this paper, by considering a subgroup action of H on X, we have some results as follows: (1) If H,K are two normal subgroups of G such that $H{\subseteq}K{\subseteq}G$, then for any $x{\in}X$ ($orb_{{\phi}_G}(x)\;:\;orb_{{\phi}_H}(x)$) = ($orb_{{\phi}_G}(x)\;:\;orb_{{\phi}_K}(x)$) = ($orb_{{\phi}_K}(x)\;:\;orb_{{\phi}_H}(x)$); additionally, in case of $K{\cap}stab_{{\phi}_G}(x)$ = {1}, if ($orb_{{\phi}_G}(x)\;:\;orb_{{\phi}H}(x)$) and ($orb_{{\phi}_K}(x)\;:\;orb_{{\phi}_H}(x)$) are both finite, then ($orb_{{\phi}_G}(x)\;:\;orb_{{\phi}_H}(x)$) is finite; (2) If H is a cyclic subgroup of G and $stab_{{\phi}_H}(x){\neq}$ {1} for some $x{\in}X$, then $orb_{{\phi}_H}(x)$ is finite.

• Journal of Genetic Medicine
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• 제6권1호
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• pp.67-73
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• 2009

목 적 : 터너증후군 환자들에게는 다양한 핵형과 표현형이 나타나지만 우리나라에서는 그 연관성에 대한 연구가 미미한 실정이다. 그리하여 본 연구에서는 터너증후군으로 진단받은 환자들의 염색체 이상, 임상양상, 동반 질환에 대해 조사하였다. 대상 및 방 법 : 경북대학교병원에서 터너증후군으로 진단받은 환자 92명을 대상으로 염색체 핵형을 분류하였으며, 그 중 62명을 대상으로 임상 양상 및 동반 질환을 조사하였다. 결 과 : 핵형이 45,X인 환자는 54.3%였고. 섞임증 및 구조 이상이 나머지를 차지하였다. 섞임증의 경우 45,X에 비하여 Turner stigmata의 빈도가 낮았다. 46,X,del(Xp) 및 45,X/46,X,del(Xq)에서는 모두 골격 이상이 나타난 반면, 46,X, del(Xq)에서는 나타나지 않았다. 46,X,del(Xp)에서는 성적 유치증이 나타나지 않았지만, 46,X,del(Xq) 및 45,X/46,X,del(Xq)의 경우에는 이차 성징 지연이 지연 및 무월경이 나타났다. 46,X,i(Xq) 및 45,X/46,X,i(Xq)의 경우 이차 성징이 발현되지 않았고 모두 일차 무월경을 보였다. 그 외에 장완의 isochromosome이 있는 경우 청력 장애 및 갑상선 질환이 더 빈번하게 나타났다. 결 론 : 터너증후군 환자들의 핵형과 표현형 사이의 연관성을 조사하는 작업은 성염색체에 위치하는 유전자자리를 예측하는 정보를 얻을 수 있다는 점에서 중요하다고 생각한다.

• Current Photovoltaic Research
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• 제11권2호
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• pp.39-43
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• 2023

Carrier-selective contacts (CSCs) solar cells are considerably attractive on highly efficient crystalline silicon heterojunction (SHJ) solar cells due to their advantages of high thermal tolerance and the simple fabrication process. CSCs solar cells require a hole selective contact (HSC) layer that selectively collects only holes. In order to selectively collect holes, it must have a work function characteristic of 5.0 eV or more when contacted with n-type Si. The VO_x, NiO_x, and CuI_x thin films were fabricated and analyzed respectively to confirm their potential usage as a hole-selective contact (HSC) layer. All thin films showed characteristics of band-gap engergy > 3.0 eV, work function > 5.0 eV and minority carrier lifetime > 1.5 ms.

• BMB Reports
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• 제46권2호
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• pp.86-91
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• 2013

Glucose effects on the vegetative growth of Dictyostelium discoideum Ax2 were studied by examining oxidative stress and tetrahydropteridine synthesis in cells cultured with different concentrations (0.5X, 7.7 g $L^{-1}$; 1X, 15.4 g $L^{-1}$; 2X, 30.8 g $L^{-1}$) of glucose. The growth rate was optimal in 1X cells (cells grown in 1X glucose) but was impaired drastically in 2X cells, below the level of 0.5X cells. There were glucose-dependent increases in reactive oxygen species (ROS) levels and mitochondrial dysfunction in parallel with the mRNA copy numbers of the enzymes catalyzing tetrahydropteridine synthesis and regeneration. On the other hand, both the specific activities of the enzymes and tetrahydropteridine levels in 2X cells were lower than those in 1X cells, but were higher than those in 0.5X cells. Given the antioxidant function of tetrahydropteridines and both the beneficial and harmful effects of ROS, the results suggest glucose-induced oxidative stress in Dictyostelium, a process that might originate from aerobic glycolysis, as well as a protective role of tetrahydropteridines against this stress.

• 한국세라믹학회지
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• 제40권4호
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• pp.346-349
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• 2003

Microwave dielectric characteristics and physical properties of the new Zr$_{1-x}$ (Bn$_{1}$3/Nb$_{2/3}$)xTi $O_4$ (0.2$\leq$x$\geq$ 1.0) system have been investigated as a function of the amount of Bn$_{1}$3/Nb$_{2/3}$ $O_2$substitution. With increasing Bn$_{1}$3/Nb$_{2/3}$ $O_2$ content (x), two phase regions were observed: $\alpha$-Pb $O_2$ solid solution (x<0.4), mixture of the rutile type Zn$_{1}$3/Nb$_{2/3}$Ti $O_4$ and the $\alpha$-Pb $O_2$ solid solution (x$\geq$0.4). In the$\alpha$-Pb $O_2$solid solution region below x<0.4, the Q.f$_{0}$ value sharply increased and the Temperature Coefficient of the Resonant Frequency(TCF) decreased with increasing Bn$_{1}$3/Nb$_{2/3}$ $O_2$ contents while dielectric constant (K) showed nearly same value. In the mixture region above x$\geq$4, the dielectric constant and TCF increased with increasing Bn$_{1}$3/Nb$_{2/3}$ $O_2$ content. Zr$_{1-x}$ (Zn$_{1}$3/Nb$_{2/3}$)xTi $O_4$ materials have excellent microwave dielectric properties with K=44.0, Q.f$_{0}$ : 41000 GHz and TCF =-3.0 ppm/$^{\circ}C$ at x=0.35.=0.35. x=0.35.=0.35.

• 대한수학회보
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• 제57권1호
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• pp.109-115
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• 2020

Recently, Lesieutre constructed a 6-dimensional projective variety X over any field of characteristic zero whose automorphism group Aut(X) is discrete but not finitely generated. As an application, he also showed that X is an example of a projective variety with infinitely many non-isomorphic real structures. On the other hand, there are also several finiteness results of real structures of projective varieties. The aim of this short paper is to give a sufficient condition for the finiteness of real structures on a projective manifold in terms of the structure of the automorphism group. To be more precise, in this paper we show that, when X is a projective manifold of any dimension≥ 2, if Aut(X) does not contain a subgroup isomorphic to the non-abelian free group ℤ ∗ ℤ, then there are only finitely many real structures on X, up to ℝ-isomorphisms.

• 대한수학회지
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• 제56권5호
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• pp.1371-1385
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• 2019

Given a topological space X and a non-negative integer k, ${\varepsilon}^{\sharp}_k(X)$ is the set of all self-homotopy equivalences of X that do not change maps from X to an t-sphere $S^t$ homotopically by the composition for all $t{\geq}k$. This set is a subgroup of the self-homotopy equivalence group ${\varepsilon}(X)$. We find certain homotopic tools for computations of ${\varepsilon}^{\sharp}_k(X)$. Using these results, we determine ${\varepsilon}^{\sharp}_k(M(G,n))$ for $k{\geq}n$, where M(G, n) is a Moore space type of (G, n) for a finitely generated abelian group G.