Wanida Chaichalotorn. Evaluation of mental fatigue from an inspection task : a case of an electronic parts assembly plant. Master's Degree(Industrial Engineering). Chulalongkorn University. Center of Academic Resources. : Chulalongkorn University, 1994.
Evaluation of mental fatigue from an inspection task : a case of an electronic parts assembly plant
Abstract:
Inspection task is a cognitive task requiring high vigilance since the inspector has to interpret incoming information and make decision when an unusual phenomenon is encountered. This task consists of characteristics of monotonous, continuing repetitive and boring activities which may affect the inspection performance and increase mental fatigue. The research was aimed at 1) studying responses of workers who perform an inspection task on electronic parts and investigate correlation between workers' fatigue and inspection performance, 2) comparing cumulative mental fatigue signs of workers between two shifts and paced-condition with two types of rest allowances, and 3) developing fatigue evaluating criteria which include work stresses in real work situation. The study was done between two shifts, morning and night, and two rest allowances (R1) and the defined on (R2). Three operators were measured for mental fatigue two times a day, before work and after work, using critical flicker fusion frequency, reaction time and a subjective scaling questionnaire. To get more details on prolonged work, electromyography and heart rate measurement were introduced for use on one subject. The results were analysed by statistical methods and the fuzzy set theory. The conclusion of the study, from fuzzy analysis, was that rest allowances and shift works resulted in high effects on mental fatigue level of workers. Working with R1 schedule had higher mental fatigue level than R2 schedule. Night shift work also had higher mental fatigue than morning shift work. Machine-paced was recommended for experimentation in a separate study because it needed time to change the workers' attitude, but this study had limited time. It was also concluded that prolonged work in inspection task caused cumulative fatigue and decreased the worker's muscle efficiency. CFF was the most effective criterion for mental fatigue evaluation in this work stituation.