A randomized, parallel, multicenter, active-controlled with 48 weeks of treatment period. Patients will be randomized to receive clevudine alone for 48 weeks or clevudine for 24 weeks followed by 24 weeks of clevudine in addition to monthly HBV vaccination.The purpose of this study is to investigate efficacy of combination of clevudine and HBV vaccine over clevudine alone in patients with chronic hepatitis B infection.