Clinical Trial on the Safety and Efficacy of Optimized Transcranial Direct Current Stimulation for the Swallowing Function in Patients With Post-Stroke Dysphagia

Inclusion Criteria: * men and women \>19 years old * patients with stroke confirmed by neuroimaging * first-time stroke patients * patients in subacute or chronic phases of stroke with 3 weeks or more after onset * stroke patients with confirmed dysphagia through Videofluoroscopic Swallowing Study (VFSS). Exclusion Criteria: * patients with recurrent stoke, traumatic brain injury, spine cord injury, and degenerative brain disease, such as Parkinson's disease, etc. * patients with deteriorated cognitive function unable to perform the clinical trial as instructed * patients with evidence of delirium, confusion, or other impairment of consciousness * patients with uncontrolled medical disease or surgical conditions * patients ineligible for Transcranial direct current stimulation (due to scalp condition, metallic material at the electrode attachment area, presence of a pacemaker or cochlear implant) * patients with previous experience within the last year using a stimulation device similar to the one use in this clinical trial or who have participated in related clinical trials * patients with severe neurologic disorder with concomitant major psychiatric disorder such as major depressive disorder and dementia * patients with history of uncontrolled epilepsy within 6 months * patients with medical contraindications for neuroimaging test, such as MRI; * patients who are taken contraindicated medications or require medication changes during the trial period that could influence cognitive/motor function changes via brain activation changes * patients who are pregnant, breastfeeding, or planning pregnancy during the trial period * patients considered medically ineligible for participation in the present trial beyond the criteria listened above.