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조민환
- Journal of the Korea Society of Computer and Information
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- v.4 no.4
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- pp.40-46
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- 1999
The task scheduling has an effect on system execution time in a precedence constrained task graph onto the multiprocessor system. This problem is known to be NP-hard. many people made an effort to obtain near optimal schedule. We compared modified critical path schedule with many other methods(CP, MH, DL Swapping) For testing this subject, we created randomly a directed acyclic task graph with many root nodes and terminal nodes simulation result convinced for us that the modified critical path algorithm is superior to the other scheduling algorithm.
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Ahn, Jinhyun;Im, Dong-Hyuk
- Journal of Information Processing Systems
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- v.16 no.1
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- pp.201-209
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- 2020
The graph data structure is popular because it can intuitively represent real-world knowledge. Graph databases have attracted attention in academia and industry because they can be used to maintain graph data and allow users to mine knowledge. Mining reachability relationships between two nodes in a graph, termed reachability query processing, is an important functionality of graph databases. Online traversals, such as the breadth-first and depth-first search, are inefficient in processing reachability queries when dealing with large-scale graphs. Labeling schemes have been proposed to overcome these disadvantages. The state-of-the-art is the 2-hop labeling scheme: each node has in and out labels containing reachable node IDs as integers. Unfortunately, existing 2-hop labeling schemes generate huge 2-hop label sizes because they only consider local features, such as degrees. In this paper, we propose a more efficient 2-hop label size reduction approach. We consider the topological sort index, which is a global feature. A linear combination is suggested for utilizing both local and global features. We conduct experiments over real-world and synthetic directed acyclic graph datasets and show that the proposed approach generates smaller labels than existing approaches.
https://doi.org/10.3745/JIPS.04.0159 인용 PDF KSCI

Kim Jung-Hwan
- The KIPS Transactions:PartA
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- v.13A no.2 s.99
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- pp.163-170
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- 2006
Most scheduling problems including DAG(Directed Acyclic Graph)-based are known to be NP-complete, so many heuristic-based scheduling algorithms have been researched. HEFT and CPOP are such algorithms which have been devised to be effective in heterogeneous environment. We proposed, in the previous research, three scheduling algorithms which are effective in realistic global heterogeneous environment: CPOC, eCPOPC and eCPOP. In this paper, the heuristics which are used in the above five algorithms will be systematically analyzed. Those algorithms will be also studied experimentally using various benchmarks. Experimental results show that the eCPOC generates better schedules than any other algorithms and the heuristics which are used in the proposed algorithms are effective in the global heterogeneous environment.
https://doi.org/10.3745/KIPSTA.2006.13A.2.163 인용 PDF KSCI

Man Jung Han
- Journal of the Korean Chemical Society
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- v.22 no.3
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- pp.173-183
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- 1978
Bulk polymerization of propylene sulfide with o-sulfobenzoic anhydride as initiator was carried out and the polymerization proceeded by a zwitterionic mechanism. Chemical and spectroscopic investigation of the purified polymer revealed that the polymer contained two end groups-thiolester of benzoic acid o-sulfonate anions and acyclic tert-sulfonium ions which were formed by termination of episulfonium ions with sulfide groups in the polymer chains. The concentration of sulfonate anions was nearly the same as the concentration of acyclic tert-sulfonium ions, as expected for macrozwitterions. The cocatalysis mechanism by a trace of water was excluded and the other possible mechanisms were discussed on the basis of end group analysis.
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