I. Personal Information

(1) Your age?

_______year old

(2) When did you start smartphone use?

1. Elementary school

2. Junior high school

3. High school

4. University and after

(3) How many hours do you use smartphone in a day?

1. Less than 3 hours

2. 3 ~ 5 hours

3. 5 ~ 7 hours

4. 7 ~ 9 hours

5. More than 9 hours