Decisions on reliability screening rules and burn-in policies are determined based on the estimated reliability. The variability in a semiconductor manufacturing process does not only causes quality problems but it also makes reliability estimation more complicated. This study investigates the nonuniformity characteristics of integrated circuit reliability according to defect density distribution within a wafer and between wafers then develops optimal burn-in policy based on the estimated reliability. New reliability estimation model based on yield information is developed using a spatial stochastic process. Spatial defect density variation is reflected in the reliability estimation, and the defect densities of each die location are considered as input variables of the burn-in optimization. Reliability screening and optimal burn-in policy subject to the burn-in cost minimization is examined, and numerical experiments are conducted.

Community analysis of oribatid mites was conducted in unburned and burned area of Samcheok-si, Gangwon province with differential burn severity that occurred in April 2000. Except control site, four sites (T1, T2, T3 and C2) were selected according to burn severity and subsequent recovery following a year after fire form T1 (heavily burned) to Control (unburned). This study analyzes the abundance, species richness, diversity and evenness, similarity, dominant species, and MGP types of oribatid mites. Oribatid mites were sampled 8times from each site from 2005 to 2007. Total of 40 families, 58 genus, 123 species and 4,638 individuals were founded. Species richness and abundance of oribatid mites decreased as burn severity increased. Diversity index of control site was higher than all other sites and decreased as the burn severity increased. Similarity between control and C2 sites was highest among the sites and cluster analysis showed control and C2 as closely related followed by T3, T2 and T1 respectively. MGP-I analysis revealed oribatid mites of all sites as GP type. MGP-II analysis showed control as G type and all other sites as GP type.