With the recent development of the industry level, product diversity and completely new products have been released, and product reliability has become a more important evaluation measure.

Reliability refers to the nature of a part or system performing the required function without failure under a given environmental condition.

After the reliability evaluation of the new product, reliability evaluation under various conditions for the re-manufactured product is required.

Methods for reliability evaluation include analysis of product life using field data, accelerated life evaluation under various conditions, and zero-failure testing.

There are various environmental conditions for product's usage, and due to this, the industry must ensure reliability by considering multiple failure factors as well as single failure factors.