• Journal of the Korean Mathematical Society
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• v.48 no.2
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• pp.301-309
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• 2011

Let R = $Mat_2(F)$ be the ring of all 2 by 2 matrices over a finite field F, X the set of all nonzero, nonunits of R and G the group of all units of R. After investigating some properties of orbits under the left (and right) regular action on X by G, we show that the graph automorphisms group of $\Gamma(R)$ (the zero-divisor graph of R) is isomorphic to the symmetric group $S_{|F|+1}$ of degree |F|+1.

• Bulletin of the Korean Mathematical Society
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• v.53 no.4
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• pp.1017-1031
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• 2016

Let R be a commutative ring with the non-zero identity and n be a natural number. ${\Gamma}^n_R$ is a simple graph with $R^n{\setminus}\{0\}$ as the vertex set and two distinct vertices X and Y in $R^n$ are adjacent if and only if there exists an $n{\times}n$ lower triangular matrix A over R whose entries on the main diagonal are non-zero such that $AX^t=Y^t$ or $AY^t=X^t$, where, for a matrix B, $B^t$ is the matrix transpose of B. ${\Gamma}^n_R$ is a generalization of Cayley graph. Let $T_n(R)$ denote the $n{\times}n$ upper triangular matrix ring over R. In this paper, for an arbitrary ring R, we investigate the properties of the graph ${\Gamma}^n_{T_n(R)}$.

• Bulletin of the Korean Mathematical Society
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• v.46 no.6
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• pp.1051-1060
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• 2009

In this paper, we give topological properties of collection of prime ideals in 2-primal near-rings. We show that Spec(N), the spectrum of prime ideals, is a compact space, and Max(N), the maximal ideals of N, forms a compact $T_1$-subspace. We also study the zero-divisor graph $\Gamma_I$(R) with respect to the completely semiprime ideal I of N. We show that ${\Gamma}_{\mathbb{P}}$ (R), where $\mathbb{P}$ is a prime radical of N, is a connected graph with diameter less than or equal to 3. We characterize all cycles in the graph ${\Gamma}_{\mathbb{P}}$ (R).

• Bulletin of the Korean Mathematical Society
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• v.54 no.1
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• pp.51-69
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• 2017

We, in this paper, study the commutativity of skew polynomials at zero as a generalization of an ${\alpha}-rigid$ ring, introducing the concept of strongly skew reversibility. A ring R is be said to be strongly ${\alpha}-skew$ reversible if the skew polynomial ring $R[x;{\alpha}]$ is reversible. We examine some characterizations and extensions of strongly ${\alpha}-skew$ reversible rings in relation with several ring theoretic properties which have roles in ring theory.

• Journal of Institute of Control, Robotics and Systems
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• v.8 no.8
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• pp.633-638
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• 2002

We study how the missile autopilot with three loop acceleration structure is related to the aerodynamic characteristics. First, the relationships between the response characteristics of wingless-tail controlled missile and aerodynamics are derived. Next the maximum allowable performance limit of autopilot and the design direction for a missile shape are indicated using the property of zero. The method proposed in this paper may give a help to the missile autopilot system design and determination of the shape of aerodynamic. Also, the validity of proposed method is demonstrated via numerical example.

• The Korean Journal of Rheology
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• v.5 no.2
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• pp.161-169
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• 1993

Glucomannan(G.M.)은 Amorphophallus Konjac C. Koch의 tuber로부터 분리되었고. 이 G.M.은 다시 침전제로 메탄올을 사용하여 4단계로 분별되었다.(F.1, F.2, F.3, F.4,). 각분 별물에 비하여 직선으로부터 벗어남을 보였다. Low shear viscometer로 G.M. 용액의 viscosity를 측정하였고 농도와 zero shear specific viscosity의 logarithm을 도시한 결과 inflection point를 나타내었다. 이것은 G.M. 분자들의 coil overlap의 시작에서 기인한 것이 고 묽은 용액에서 진한 용액으로의 전이행동은 임계농도. C＊=4/[η]에서 일어났고 이때의 zero shear specific viscosity는 10을 나타내었다. 또한 specific viscosity는 묽은 용액에대해 서는 C14로써 변화하였고 진한 요액에서는 C3.0으로변화하였다. G.M.의 고체상태에 대한 유 전성($\varepsilon$＇,$\varepsilon$＂)과 점탄성(C＇,C＂)계수들을 액체질소 온도에서부터 15$0^{\circ}C$ 온도범위에 걸쳐 4단계로 film을 건조시키면서 10Hz에서 측정하였다. G.M. film의 유전성과 점탄성의 허수부 분은 ($\varepsilon$＂, C＂), -10$0^{\circ}C$에서 peak를 나타내었고 이 peak는 hydroxy methyl 기들의 회전 운동에서 생겨난 것이다. 건조시키지 않은 상태의 G.M. film의 유전성과 점탄성의 허수부분 의 값들은 -5$0^{\circ}C$에서 물 분자의 운동에 의하여 생긴 peak를 보였다.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2014.05a
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• pp.242-243
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• 2014

In this study, industrial by-products including blast furnace slag, incineration ash and waste gypsum were used with recycled fine aggregates to manufacture the zero-cement mortar. The replacement ratio of anhydrite gypsum was fixed as 0, 10%, 20% the replacement ratio fo WA1 was fixed as 0.5% and 1.0%, respectively. It could be identified that when the replacement of gypsum was 20% and WA1 of 1.0%, the strength could be in the range of normal strength.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2014.05a
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• pp.222-223
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• 2014

In this study, industrial by-products including blast furnace slag, incineration ash and waste gypsum were used with recycled fine aggregates to manufacture the zero-cement mortar.The replacement ratio of dihydrate gypsum and anhydrite gypsum was fixed as 0 and 10%, the replacement ratio fo WA1 was fixed as 0.5% and 1.0%, respectively. It could be identified that when the replacement of gypsum was 10% and WA1 of 1.0%, the strength could be in the range of normal strength.

• Speech Sciences
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• v.7 no.1
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• pp.171-186
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• 2000

The aim of this paper is to investigate the acoustic characteristics of the French vowel [e] and Korean [i] and to seek a way of understanding them from a phonological point of view. These two vowels have similar distributional properties, i.e. they alternate with zero in some contexts. Therefore, in both languages, they are not found when immediately followed by a nucleus with phonetic content and in word-final positions. We firstly compare the two vowels by measuring the actual frequencies of the formants, pitch and energy using CSL. We also consider whether the realisation of the two vowels is affected by the speed of speech sounds. In order to show that realisation of the two vowels in both languages is not arbitrary, rather predicted, we will introduce the notion of proper government, proposed and developed by Kaye (1987, 1990) and Charette (1991).

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.255-260
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• 2003

Most of the fatigue test were achieved in fully reversed condition that mean stress is zero. But, generally, mean stress can not be zero. This research was achieved the bending fatigue test that changes mean stress to spring steel and was studied relation with the mean stress and the fatigue life. The method to search effect about mean stress was extended S-N graph in two cases. One method was extended S-N graph using modified Miner's rule with considering damage. Another was extended using tendency of S-N graph. The exponential value(${\alpha}$) of mean stress-alternating stress equation is converged between the Goodman's and the Gerber's value even if fatigue life increases.