need 2 entry visa or 1??

Hi, I will be travel with my dauther we hold the Canadian passort; We will take teh flight from HK to Seoul but stopover Beijing for 2 hours (this case is need one??) then we wil stay in Seoul for 4 days and will take the flight from seoul to qingtao and stay 4 day go back to hkg. my question is we need to apply for ONE entry or 2 entry?? thanks