DESIGN OF A KNOWLEDGE-BASED DIAGNOSIS ASSISTANCE SERVICE SYSTEM FOR ELEVATOR AND ESCALATOR INDUSTRY by CHANG Kam Weng Thesis Supervisor: Dr. WONG Seng Fat Master of Science in Electromechanical Engineering The target of this research is to develop a knowledge-based diagnosis assistance service system (KDASS) for elevator and escalator industry, focusing on repair job, which is the most difficult part to control in maintenance activities. This system was set up by building the IDEF model. To understand the knowledge structure of the elevator and escalator maintenance system, it was applied the methodology of IDEF0 for function model and IDEF1X for the information model. After, it was tried to collect the information by questionnaires and interviews with technicians and set up a system through capturing and converting the expert’s internalized tacit knowledge to explicit knowledge. Survey and interview were done on the technicians with different experiences to achieve this goal. The last step, the captured knowledge was used to establish the KDASS and validate the feasibility and contribution in elevator industry through some case tests.