This trial is a multi-center, randomized, double-blind, placebo-controlled, parallel, phase II clinical trial and aimed at osteoarthritis of the knee.

Patients who signed informed consent voluntarily and eligible for this study are assigned randomly to one of 3 groups after 2 week-Washout period.

1. st group (experimental) : WIN-34B 450mg BID
2. nd group (experimental) : WIN-34B 900mg BID
3. rd group (Comparator) : Placebo BID

Patients will take WIN-34B or Placebo BID for 12 weeks. Based on baseline, after 4 weeks(Visit 3) and 12 weeks(Visit 5), Researchers check patients' physical examination, questionnaire, laboratory experiment.

After 8 weeks(Visit 4), researchers check adverse effects and current medication status via telephone interview.

After 12 weeks(Visit 5) patients stop taking drugs and after 16 weeks(Visit 6) researchers check patients' physical examination, questionnaire, adverse effects and current medication status.

Inclusion Criteria:

1. Being between 35 and 80 years of age
2. Diagnosed with Osteoarthritis of the knee at least 3 months
3. Diagnosed with Osteoarthritis of the knee, based on ACR criteria
4. Able to communicate with researchers and write questionnaires
5. At the screening visit, checking 100mm Pain VAS at least 80mm
6. At randomization(Visit 2), checking 100mm Pain VAS over 50mm
7. Agreeing to participate and signing informed consent voluntarily

Exclusion Criteria:

1. Previous intra-articular injection on knee within 3 months
2. Previous knee surgery within 6 months or scheduled procedures
3. Other diseases that could affect or interfere with the therapeutic outcomes
4. Experiencing habitual use of psychotropic, narcotic analgesic drugs over 1 week
5. Diagnosed with gastrointestinal diseases, unable to stop medicines during the study
6. At the screening visit, identified liver dysfunction
7. At the screening visit, identified renal dysfunction
8. Patients who cannot take NSAIDs
9. Pregnancy and breast-feeding (women of childbearing age need pregnancy test)
10. Physicological or mental disorders, including drug-takers
11. Orthopedic diseases that could affect or interfere with the therapeutic outcomes
12. Inappropriate for the study