초록 열기/닫기 버튼
Objective: The objective of this study is to investigate the effect of implementing of the two-consecutive-daytime shift system on the working conditions including the reduction of working hours as well as workers' health in a car assembly factory in Korea. Background: The two-consecutive-daytime shift replaces day-night shift system in order to reduce night-time working hours and improve the workers' health conditions. The effect of changing shift system is not clearly established yet although there are studies investigating short-term effects. Thus investigating the long-term effects of two-consecutive-daytime shift system can provide the insights on the effectiveness of the new shift system and its influence on the workers' welfare. Method: Questionnaire surveys were conducted in a car-part assembly factory in 2015, 2016 and 2019. In the year of 2015, 2016, the shift system was day-night shift whereas two-consecutive day shift system was already in place in the year of 2019. Total number of 137 (year of 2015), 142 (year of 2016), and 126 (year of 2019) workers participated in the survey on the working environment including working hours, labor intensity and the workers' health conditions, such as, musculoskeletal symptoms, sleep disorders, digestive disorders. The differences before and after the change of shift system are compared by a series of statistical task along with some qualitative analysis on free-form comments. Results: The two-consecutive daytime shift system brought positive results of shorter working hours, increased spare time, rest time and day off. The workers satisfied with their work as well as working hours (p <0.001). Compared to the previous shift system, the health index (PSQI) nighttime decreased from 10.5 to 9.3 (p <0.001), and the daytime sleepiness also decreased from 12.3 to 9.1 (p <0.001). Similarly, the insomnia score decreased statistically significantly from 12.3 to 9.0 (p <0.001) in the new twoconsecutive- daytime shift system. In addition, digestive symptoms and musculoskeletal symptoms decreased statistically significantly on the criteria of NIOSH. Change of the shift system influenced on the working conditions, which were focused on the efficiency of the production. The improvement of equipment relieved the workload of lifting, which showed that the physical loads on the waist (p =0.0189) and shoulders (p =0.063) were significantly decreased. On the other hand, the improvement of working conditions increased the efficiency of the production system, and resulted in an increased workload level. Although the ergonomic assessment reduced the inappropriate posture of the waist and shoulders to the point of statistical difference, the overall level of action was not changed as for the statistical difference. The subjective fatigue increased and the movement of the hand and arm also increased. Conclusion: The introduction of consecutive daytime two shift shows positive results in worker health indicators, work and leisure life. However, there was an evidence of intensified work intensity in the process of increasing the efficiency of production in the shorter working hours than the previous shifts system. Application: The findings of this study provides a basis for applying two-consecutivedaytime shift system on a factory.
