• 대한수학회지
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• 제45권6호
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• pp.1647-1659
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• 2008

Let R be a ring with identity, X the set of all nonzero, nonunits of R and G the group of all units of R. First, we investigate some connected conditions of the zero-divisor graph $\Gamma(R)$ of a noncommutative ring R as follows: (1) if $\Gamma(R)$ has no sources and no sinks, then $\Gamma(R)$ is connected and diameter of $\Gamma(R)$, denoted by diam($\Gamma(R)$) (resp. girth of $\Gamma(R)$, denoted by g($\Gamma(R)$)) is equal to or less than 3; (2) if X is a union of finite number of orbits under the left (resp. right) regular action on X by G, then $\Gamma(R)$ is connected and diam($\Gamma(R)$) (resp. g($\Gamma(R)$)) is equal to or less than 3, in addition, if R is local, then there is a vertex of $\Gamma(R)$ which is adjacent to every other vertices in $\Gamma(R)$; (3) if R is unit-regular, then $\Gamma(R)$ is connected and diam($\Gamma(R)$) (resp. g($\Gamma(R)$)) is equal to or less than 3. Next, we investigate the graph automorphisms group of $\Gamma(Mat_2(\mathbb{Z}_p))$ where $Mat_2(\mathbb{Z}_p)$ is the ring of 2 by 2 matrices over the galois field $\mathbb{Z}_p$ (p is any prime).

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제18권3호
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• pp.633-652
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• 2024

Software testing is an important phase as it ensures the software quality. The software testing process comprises of three steps: generation, execution, and evaluation of test cases. Literature claims the usage of single and multiple 'Unified Modeling Language' (UML) diagrams to generate test cases. Using multiple UML diagrams increases test case coverage. However, the existing approaches show limitations in test case generation from UML diagrams. Therefore, in this research study, we propose an approach to generate the test cases using UML State Chart Diagram (SCD), Activity Diagram (AD), and Sequence Diagram (SD). The proposed approach transforms UML diagrams into intermediate forms: SCD Graph, AD Graph, and SD Graph respectively. Furthermore, by integrating these three graphs, a System Testing Graph (STG) is formed. Finally, test cases are identified from STG by using a traversal algorithm such as Depth First Search (DFS) that is an optimization method. The results show that the proposed approach is better compared to existing approaches in terms of coverage and performance. Moreover, the generated test cases have the ability to detect faults at the unit level, integration, and system level testing.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권7호
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• pp.2649-2666
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• 2015

In the dynamic cloud computing environment, to ensure, under the terms of service-level agreements, the maximum efficiency of resource utilization, it is necessary to investigate the online dynamic management of virtual machine resources and their operational application systems/components. In this study, the feasibility and properties of the division of virtual machine resources on the cloud platform, using the virtual machine cluster as the management unit, are investigated. First, the definitions of virtual machine clusters are compared, and our own definitions are presented. Then, the feasibility of division using the virtual machine cluster as the management unit is described, and the isomorphism and reconfigurability of the clusters are proven. Lastly, from the perspectives of clustering and cluster segmentation, the dynamics of virtual machines are described and experimentally compared. This study aims to provide novel methods and approaches to the optimization management of virtual machine resources and the optimization configuration of the parameters of virtual machine resources and their application systems/components in large-scale cloud computing environments.

• 한국콘텐츠학회논문지
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• 제17권12호
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• pp.1-10
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• 2017

오픈 데이터는 전세계적으로 많은 관심을 받고 있다. 우리나라 정부는 데이터 개방에 많은 노력을 기울이고 있다. 그러나, 공공 데이터의 양적 증가에도 불구하고 데이터에 대한 부족함이 여전히 지적되고 있다. 본 논문은 공공 데이터를 의미적으로 연결해 데이터 공유 및 활용을 향상시키기 위한 방법을 제안한다. 첫째, 대한민국 행정구역의 정의와 행정구역 사이의 관계를 의미적으로 표현하기 위한 지식 모델을 제안한다. 행정구역은 국가의 영역을 국가 행정상의 목적에 따라 구분한 단위이다. 행정구역 지식모델은 지방자치법을 기준으로 행정구역체계의 구조, 행정단위별 관계를 정의한다. 둘째, 대한민국 행정구역 데이터에 대한 지식그래프를 소개한다. 공공 데이터를 의미적 수준에서 연결시키는 기준정보로써 행정구역 지식그래프의 특징과 이기종 공공데이터 연계 및 데이터 품질 개선을 위한 방법을 소개한다. 마지막으로 행정기관 데이터의 연계 결과를 통해 행정구역 지식그래프의 응용 방법을 살펴본다. 행정기관 명칭은 기관별로 상이하게 활용하고 있기 때문에 행정구역 그래프를 통한 데이터 식별 및 정제와 더불어 데이터 품질 개선에 효과적인 접근 방안으로 고려할 수 있다.

• 한국주거학회논문집
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• 제18권2호
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• pp.121-128
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• 2007

The investigation of the apartment housing as a dwelling type has become the most important and popular research subject to understand the housing culture in Korea. In their methods of typological analysis, it is found that most studies represent each unit plan as a simplified architectural drawing. This type of typology, however, has difficulties in processing a large scale of data set because each representation of a plan contain too many informations. To deal with this problem, this study suggests a new graph-theoretical method by which apartment plans can be represented in a more simple and effective way. This new method is also tested against the sample plans from Gangnam-gu area in Seoul to reveal the design logic hidden in plan configuration. Through a series of analyses, it is verified that there exist a design strategy that guides the particular pattern of zoning and allocation of each room in the plan.

• Journal of Electrical Engineering and information Science
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• 제2권6호
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• pp.43-47
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• 1997

A procedure presented in this paper generates test sequences to check the conformity of an implementation with a protocol specification, which is modeled as a deterministic finite state machine (FSM). Given a FSM, a common procedure of test sequence generation, first, constructs a directed graph which edges include the state check after each transition, and produces a symmetric graph G* from and, finally, finds a Euler tour of G*. We propose a technique to determine a minimum-cost tour of the transition graph of the FSM. The proposed technique using Multiple Unique State Signature (MUSS) solves an open issue that one MUIO sequence assignment may lead to two more edges of unit cost being replicated to from G* while an optimal assignment may lead to the replication of a single edge of high cost. In this paper, randomly generated FSMs have been studied as test cases. The result shows that the proposed technique saves the cost 4∼28% and 2∼21% over the previous approach using MUIO and MUSP, respectively.

• 정보과학회 컴퓨팅의 실제 논문지
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• 제23권8호
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• pp.473-480
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• 2017

최근 들어 플래시 메모리 Solid State Driver(SSD)와 같은 반도체 기반 저장장치가 고성능으로 발전하면서 저장장치 내부 컨트롤러의 CPU와 메모리 같은 자원을 응용의 요구에 맞추어 최적으로 활용해보고자 하는 움직임이 있었다. 이러한 개념을 스토리지 내 프로세싱 방식(In-Storage Processing, ISP)이라고 한다. ISP의 기능이 탑재된 저장장치에서는 호스트에서 수행하던 연산의 일부를 나누어 처리할 수 있으므로 호스트의 부하가 줄어들고 저장장치 내에서 데이터가 가공되어 처리되기 때문에 호스트까지의 데이터 전달 시간이 줄어든다. 본 논문에서는 이러한 ISP 기능을 활용하여 그래프 질의 처리를 최적화하기 위한 방식을 제안하고, 제안된 최적화 그래프 처리 방식이 graph500 벤치마크의 성능을 최대 20%까지 향상 시켰음을 보여준다.

• 충청수학회지
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• 제23권4호
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• pp.657-661
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• 2010

We study a singular function which we call a generalized cylinder convex(concave) function induced from different generalized dyadic expansion systems on the unit interval. We show that the generalized cylinder convex(concave)function is a singular function and the length of its graph is 2. Using a local dimension set in the unit interval, we give some characterization of the distribution set using its derivative, which leads to that this singular function is nowhere differentiable in the sense of topological magnitude.

• 의료ㆍ복지 건축 : 한국의료복지건축학회 논문집
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• 제21권3호
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• pp.25-35
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• 2015

Purpose: Signs that are installed at unnoticeable places or that disconnect before the destination can bring errors of location information delivery. Therefore, this study aims to find out the spatial relation between structure of space and signs in the perspective of visual exposure possibility, operating arrangement and assesment by applying spatial structure theory. Methods: Effectiveness of organization of guidance signs was evaluated after the four way-finding factors(Plan Configuration, Sign System, Perceptual Access, Architectural Difference) that G.D.Weisman suggested were interpreted by spatial structure theory(J-Graph analysis, Space Syntax, Visual Graph Analysis) under the premise that it is closely related to the structure of space. Results: 1) Because the south corridor that connects each department of outpatient division is located in the hierarchy center of the space, and walking density is expected to be high, guidance signs need to be organized at the place with high integration value. 2) The depth to the destination space can be estimated through J-Graph analysis. The depth means a switch of direction, and the guidance signs are needed according to the number. 3) According to visibility graph analysis, visual exposure can be different in the same hierarchy unit space according to the shape of the flat surface. Based on these data, location adjustment of signs is possible, and the improvement effect can be estimated quantitatively. Implications: Spatial structure theory can be utilized to design and evaluate sign systems, and it helps to clearly understand the improvement effect. It is desirable to specify design and estimation of sign systems in the order of J-Graph analysis${\rightarrow}$Space Syntax Theory${\rightarrow}$visibility graph analysis.

• 한국컴퓨터정보학회논문지
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• 제19권5호
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• pp.19-25
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• 2014

본 논문은 평면상의 거리가 1인 인접 정점들에 대해 서로 다른 색을 칠할 경우 최대로 필요한 색인 채색수를 찾는 문제를 연구하였다. 지금까지 채색수 상한 값은 $4{\leq}{\chi}(G){\leq}7$로 알려져 있으며, Hadwiger-Nelson은 ${\chi}(G){\leq}7$, Soifer는 ${\chi}(G){\leq}9$를 제안하였다. 먼저, 최소로 필요로 하는 채색수를 구하는 알고리즘을 제안하고, Hadwiger-Nelson의 정육각형 그래프를 대상으로 채색수를 구한 결과 ${\chi}(G)=3$이 될 수 있음을 보였다. Hadwiger-Nelson의 정육각형 그래프를 12개 인접 정점으로 가정할 경우 ${\chi}(G)=4$를 구하였다. 또한, Soifer의 8개 인접 정점 정사각형 그래프에 대해 채색수를 구한 결과 ${\chi}(G)=4$임을 보였다. 결국, 제안된 알고리즘은 최소 차수 정점부터 색을 배정하는 단순한 다항시간 규칙을 적용하여 평면의 최대 채색수는 ${\chi}(G)=4$임을 제안한다.