Exploratory Study of TAC-302 in Detrusor Underactivity Patients With Overactive Bladder.

Key Inclusion Criteria: * To have Lower Urinary Tract Symptoms for at least 12 weeks prior to study entry * To have at least 1 urinary urgency episodes per day, and diurnal urinary frequency of 8 or more per day. * To meet the detrusor underactivity criteria by urodynamic study Key Exclusion Criteria: * Neurogenic bladder by the central nervous system diseases. * StageIII or more cystocele of pelvic organ prolapse quantification system (women) * Prostate volume ≥30mL (Men) * Any symptoms of Urinary tract infection (UTI)