대규모 고장수목 계산에서 빠른 BDD 생성을 위한 고장수목 축소

초록

It is known that the size of fault tree affects the BDD(Binary Decision Diagram) structure and as the fault tree size decreases, the number of BDD nodes also decreases in general and the BDD generation time is shorter than the other. For two given fault trees which are logically the same each other, the BDD generation time for the smaller fault tree is shorter. Contraction, absorption and extraction rule can be applied for the logically same, but smaller fault tree transformation. As the BDD conversion of fault tree is performed per gate, the aim of fault tree reduction is to reduce the number of gates and to simplify the repeated events. Formulation of fault tree reduction is obtained and three forms of fault tree reduction are recommended before the BDD conversion of fault trees in order to reduce the runtime. The fault tree of an derailment accident is calculated and it is shown that the reduction strategy can be used for huge fault trees in order to reduce conversion runtime in BDD generation.

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