The occurrence of emergence agitation (EA) in pediatric patients who have received sevoflurane anesthesia is a common postoperative problem. Among various strategies for reducing the incidence and severity of EA, the use of pharmacological agents at the end of anesthesia is thought to be the most convenient and easily applicable method in clinical situation. The one of typical agents that can be administered in this way is propofol. Previous studies demonstrated that the use of propofol 1mg/kg at the end of anesthesia could reduce the incidence of EA with low incidence of postoperative nausea and vomiting. However, it was also demonstrated that the use of propofol 1mg/kg at the end of anesthesia could delay the emergence time. The purpose of this study is to compare the preventive effect on EA and the emergence time between propofol 1mg/kg and propofol 0.5mg/kg administered at the end of sevoflurane anesthesia.

Inclusion Criteria:

1. children (3-12 years old) scheduled for elective strabismus surgery undergoing general anesthesia.
2. ASA 1-2

Exclusion Criteria:

1. Patients with developmental disability, mental retardation, neurologic disorder, ongoing neurologic medication such as anticonvulsant, previously undergoing general anesthesia, a recent history of upper respiratory infection, parents difficult to read or understand the informed consent.