A Study to Compare and Evaluate Intrahepatic cccDNA Reduction After Administrating Clevudine or Entecavir in the Chronic HBV Patients

Inclusion Criteria:

1. Patient who is older than 18.
2. Patient who is HBsAg positive for the previous 6 months and with HBV DNA ≥ 1 x 10^5 copies/mL
3. Patient who is HBeAg negative.
4. Patient with ALT≥1×ULN.
5. Patient who is able to give written informed consent prior to study start and to comply with the study requirements.

Exclusion Criteria:

1. Patient is currently receiving antiviral, immunomodulatory, cytotoxic or corticosteroid therapy.
2. Patient is treated with interferon for the previous 6 months.
3. Patient has been treated previously with clevudine, lamivudine, adefovir, entecavir, telbivudine or any other investigational nucleoside for HBV infection.
4. Patient is coinfected with HCV, HDV or HIV.
5. Patient has evidence of ascites, variceal hemorrhage and/or hepatic encephalopathy.
6. Patient has evidence of decompensated Liver cirrhosis and/or hepatocellular carcinoma.
7. Patient has a history of organ transplantation.
8. Patient has the treatment of nephrotoxicity drugs, competitive drugs for kidney to excrete, and/or hepatotoxicity drugs for the previous 2 months from screening.
9. Patient is pregnant or breast-feeding.
10. Patient has a clinically relevant history of abuse of alcohol or drugs.
11. Patient has a significant immunocompromised, gastrointestinal, renal, hematological, psychiatric, bronchopulmonary, biliary diseases excluding asymptomatic GB stone, neurological, cardiac, oncologic, allergic disease or medical illness that in the investigator's opinion might interfere with therapy. The patient with a benign tumor, excluded if judged by an investigator that the continuation of study would be interfered by the tumor.
12. Patient has creatinine clearance less than 60mL/min as estimated by the following formula: (140-age in years) (body weight [kg])/(72) (serum creatinine [mg/dL]) [Note: multiply estimates by 0.85 for women]