Issuance of Zero-Rated Tax Invoices for Goods Exported via Express Courier (FedEx, DHL, etc.)

I am an employee of a corporation, and I would like to know if it is possible to issue a zero-rated tax invoice even when goods are exported via express courier. We have goods that were exported from Incheon to Vietnam via FedEx. Is it possible to issue a zero-rated tax invoice after issuing a Purchase Confirmation, the same as when goods are exported by sea? Is the same possible for goods exported via DHL? If goods are carried out personally via hand-carry, can a zero-rated tax invoice be issued following the same procedure?