Abstract
요약
1. Introduction
2. Method
2.1 Research design
2.2 Subject of Research
2.3 Research variables
2.4 Data analysis method
3. Results
3.1 Comparison of general characteristics of subjects
3.2 Comparison of physical and psychological characteristics of fubjects
3.3 Factors influencing on using time of smartphone of subjects
4. Discussion
5. Conclusion
REFERENCES