• The KIPS Transactions:PartC
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• v.11C no.5
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• pp.677-682
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• 2004

In the present paper routing and wavelength assignment (RWA) in optical WDM networks is considered. Previous techniques based on the combination of integer linear programming and graph coloring are complex and require extensive use of heuristics. Such methods are mostly slow and sometimes impossible to get results due to infeasibility. An alternative approach applied to RWA employs on the greedy algorithm for obtaining the maximum edge disjoint paths. Even though this approach is fast, it produces a solution for any connection request, which is very far from the optimal utilization of wavelengths. We propose a novel algorithm, which is based on the maximum flow technique to obtain the maximum quantity of edge, disjoint paths. Here we compare the offered method with previous maximum edge disjoint paths algorithms ap plied to the RWA.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.11A
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• pp.979-986
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• 2005

In optical networks, traffic demands often demonstrate periodic nature for which time-overlapping property can be utilized in routing and wavelength assignment (RWA). A RWA problem for scheduled lightpath demands (SLDs) has been solved by combinatorial optimal solution (COS) and graph coloring, or heuristic sequential RWA (sRWA). Such methods are very complex and incurs large computational overhead. In this paper, we propose an efficient RWA algorithm to utilize the time disjoint property as well as space disjoint property through fast grouping of SLDs. The computer simulation shows that our proposed algorithm indeed achieves up to $54\%$ faster computation with similar number of wavelengths than the existing heuristic sRWA algorithm.

• Journal of the Korea Society of Computer and Information
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• v.16 no.6
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• pp.179-186
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• 2011

This paper suggests the minimum number of vertex guards algorithm. Given n rooms, the exact number of minimum vertex guards is proposed. However, only approximation algorithms are presented about the maximum number of vertex guards for polygon and orthogonal polygon without or with holes. Fisk suggests the maximum number of vertex guards for polygon with n vertices as follows. Firstly, you can triangulate with n-2 triangles. Secondly, 3-chromatic vertex coloring of every triangulation of a polygon. Thirdly, place guards at the vertices which have the minority color. This paper presents the minimum number of vertex guards using dominating set. Firstly, you can obtain the visibility graph which is connected all edges if two vertices can be visible each other. Secondly, you can obtain dominating set from visibility graph or visibility matrix. This algorithm applies various art galley problems. As a results, the proposed algorithm is simple and can be obtain the minimum number of vertex guards.

• Journal of the Korea Society of Computer and Information
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• v.18 no.2
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• pp.69-76
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• 2013

Reader-to-reader interference in RFID system is occurred due to the use of limited number of frequencies, and this is the main cause of read rate reduction in the passive RFID tags. Therefore, in order to maximize the read rate under the circumstances of limited frequency resources, it is necessary to minimize the frequency interference among RFID readers. This paper presents a hybrid FDM/TDM constraint satisfaction problem models for frequency interference minimization problems of the RFID readers, and assigns optimal channels to each readers using conventional backtracking search algorithms. A depth first search based on backtracking are accomplished to find solutions of constraint satisfaction problems. At this moment, a variable ordering algorithm is very important to find a solution quickly. Variable ordering algorithms applied in the experiment are known as efficient in the graph coloring. To justify the performance of the proposed constraint satisfaction problem model, optimal channels for each readers in the passive UHF RFID system are allocated by using computer simulation satisfying various interference constraints.

• Proceedings of the IEEK Conference
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• 2002.07a
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• pp.425-428
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• 2002

The technology of Computer Graphics (CG) has been in great progress for almost 20 years and has proven to be a valuable tool for a broad variety of fields, including nuclear engineering. To work in any hazardous environment for example radiation field is particularly challenging because the danger is not always visually apparent. In this study as the application of CG to nuclear engineering field, we proposed to develop a radiation risk recognition aided system in which various radiation information; radiation risks, radiation distribution, hazard information and so on, were visualized by CG. The system used the server and client system. In the server there were two parts; one (main-server) was the database part having various data and the other (sub-server) was the visualization part visualizing the human phantom by POV-Ray. In the client there was the input and output part. The outputs from the system were various radiation information represented by coloring, circle graph and line graph intuitionally. The system is useful for a broad range of activities including radiation protection, radiation management, dose minimization, and demonstration to the public.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.9
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• pp.1719-1721
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• 2015

In this paper, we investigate a frequency assignment problem from graph theory for military communications. We propose an algorithm based on the graph coloring theory and confirm that we utilize 0.77 times lower number of frequencies. We also propose a hybrid algorithm that facilitates a trade-off between the range and the spectrum utilization gain.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.10A
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• pp.1604-1612
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• 2000

This paper proposes a simultaneous hardware resource allocation and binding algorithm for VLSI design. The proposed algorithm works on scheduled input graph and simultaneously allocates binds functional units, interconnections and registers by considering interdependency between operations and storage elements in each control step, in order to share registers and interconnections connected to functional units, as much as possible. Also, the register allocation is especially executes the allocation optima us-ing graph coloring techniques. Therefore the overall resource is reduced. This paper shows the effectiveness of the proposed algorithm by comparing experiments to determine number of functional unit in advance or to separate executing allocation and binding of existing system.

• ETRI Journal
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• v.39 no.3
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• pp.345-352
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• 2017

Traffic management is a highly beneficial mechanism for satisfying quality-of-service requirements and overcoming the resource scarcity problems in networks. This paper introduces an optimal connection admission control mechanism to decrease the packet loss ratio and end-to-end delay in cognitive radio sensor networks (CRSNs). This mechanism admits data flows based on the value of information sent by the sensor nodes, the network state, and the estimated required resources of the data flows. The number of required channels of each data flow is estimated using a proposed formula that is inspired by a graph coloring approach. The proposed admission control mechanism is formulated as a semi-Markov decision process and a linear programming problem is derived to obtain the optimal admission control policy for obtaining the maximum reward. Simulation results demonstrate that the proposed mechanism outperforms a recently proposed admission control mechanism in CRSNs.

• Journal of the Korea Society of Computer and Information
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• v.7 no.2
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• pp.79-86
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• 2002

This paper presents a low power scheduling and allocation algorithm for multiple supply voltage. The proposed supply voltage scheduling algorithm determines the control step to execute a possible the operation experimentally using another supply voltage level. Also, the switching activity using component library. and the supply voltage allocation method uses the graph coloring technique for low power, the proposed algorithm Proves the effect through various high level benchmark examples to adopt a multiple supply voltage scheduling algorithm for low power.

• The Transactions of the Korea Information Processing Society
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• v.5 no.12
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• pp.3151-3156
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• 1998

대학의 시간표 문제를 해결하기 위해서 시간표의 문제는 종종 그래프 착색 알고리즘으로 표현된다. 각 노드를 강좌로, 에지는 연결된 강좌간에는 동일한 시간에 서로 배정이 불가능한 조건으로 표시한다. 그러나 순수한 그래프 착색 알고리즘은 바로 대학의 시간표 문제에 적용하기 곤란하다. 그 이유는 대부분의 시간표 문제에서 강좌는 한시간 이상으로 존재하고 이들은 반드시 연속된 시간에 배정이 되어야 한다는 등의 제약 조건을 갖기 때문이다. 이 문제를 해결하기 위하여 적용된 것이 가중치 그래프 착색 알고리즘이다. 이 경우 각 노드는 강의 시간의 길이의 값을 갖게 된다. 이와 관련된 기존의 연구가 진행되었으나 탐색의 시간이 지수적으로 증가하거나 해의 질이 뛰어나지는 못하였다 라는 단점을 갖고 있다. 따라서 본 연구에서는 새로운 가중치 그래프의 착색 방법을 제안한다.