Purpose: The purpose of this study was to identify factors associated with smartphone overdependency in preschool children based on an analysis of mother, child, and their mutual dyadic relationships. Methods: Data were collected from 171 mothers of preschool children enrolled at daycare centers and kindergartens from January to March 2018. The data were analyzed by descriptive statistics, the t-test, analysis of variance with Scheffé post hoc test, Pearson correlation coefficient, and hierarchical regression analysis using SPSS version 24. Results: The self regulation of preschool children (β=-.358, p<.001) was the factor most closely associated with smartphone overdependency. The second most closely associated factor was children's use of a smartphone 0.5-1 hour daily (β=-.249, p=.005). Additional associated factors were mothers' use of a smartphone for 3-4 hours daily (β=.217, p=.002), children's use of a smartphone for less than 0.5 hour daily (β=-.212, p=.006), and children's use of a smartphone for 1-2 days per week (β=-.205, p=.026). Conclusion: Based on the results of this study, it is necessary to try to develop guidelines and programs to prevent smart phone overdependency in preschool children.

The purpose of this study was to verify the mediating effects of academic performance on the relationship between screen time, executive function difficulty, and school adjustment. This study analyzed secondary data of the 8th Panel Survey on Korean Children. The 8th Panel Survey was the first measurement of children's academic performance, executive function difficulty, and school adjustment through large sampling. Accordingly, it is possible to provide a large amount of data that can verify the relationship between them. The respondents were parents and teachers of students. The total number was 1,031. Data were analyzed by descriptive, t-test, analysis of variance, Pearson correlation, and three-steps multiple regression statistics. As a result, screen time has a full mediating effect on school adjustment through academic performance. The executive function difficulty has a partial mediating effect on school adjustment through academic performance. The results of this study will contribute to the development of the school adjustment improvement program.