 4. Urodynamic study A multi-channel urodynamic study using Euet Sensik will be performed including cystometry, urethral pressure measurement, abdominal leak point pressure ALPP measurement, residual urine measurement. Patients with stress urinary incontinence due to intrinsic sphincter deficiency will be selected. Criteria for selection are: absence of involuntary contractions during leakage caused by a stress maneuver; low ALPP 60 cmH2O; maximum urethral closure pressure MUCP 20-30 cmH2O. Patients with voiding dysfunction will be excluded residual urine volume 100ml. 