ABSTRACT
In most of production systems, such as assembly lines of a semiconductor plant, manufacturing processes of a chemical factory or process controls in power plants, the human operators follow the standard operation procedure (SOP) to perform their tasks. However, some errors many occur and result in product deficiency or system breakdown. Comparing the equipment errors and human errors, the former is more obvious whereas most of the human errors except few significant ones that cause an accident are hidden in the operating process. Such latent human errors have to be clarified by some special techniques, otherwise the exist in the process and may gradually damage the system.
