 Multi-center, randomized, double-blind, placebo-controlled, parallel-group design, Phase 3 pivotal study to investigate the efficacay and safety of 50 mg, 100 mg and 150 mg udenafil tablets compared with placebo in men with ED. This study consisted of a 4-week, treatment free run-in period followed by a treatment period of 12 weeks, with an on-demand dosing regimen. 