3.1. Failure function modules
The advantage of using the lookup function of System dynamics is that it can express an unusual distribution. By implementing the average and variance of the daily failure probability during the total life of the failure functions as a system dynamics model, the occurrence of failures during the total life can be simulated. Fig.3(a) and (b) are the average of daily normal / critical failure function, respectively. Modules were constructed as shown in Fig. 4 using the mean and variance of the estimated failure functions. The two failure functions and variance are implemented, and the input/output relationship is briefly shown. The physics at this stage is a number of malfunctioning spare parts or equipment. Both failure functions have the same scale. Critical failure should be classified into physics different from normal failure because it is repaired by arriving at the port immediately after failure. Critical failure and normal failure are separated through integration with other modules (section 4).