Yes. Unplug it from the wall outlet immediately. Do not use it.
A burning smell or smoke indicates a serious electrical or mechanical fault. This is not a user-serviceable issue.
After unplugging, do not attempt to open, repair, or modify the unit yourself. Contact the Coway service center directly for instructions.
HEADS UP: For future prevention, always use a dedicated 120V, 60Hz grounded outlet. Never use a damaged power cord or plug, and don't run the cord under carpets or furniture where it can be damaged.