The judgment below is reversed and the case is remanded to Seoul High Court.

The grounds of appeal are examined (to the extent of supplement in case of supplemental appellate briefs not timely filed).

1. When an international application (hereinafter referred to as “PC international application”) as prescribed by the Patent Cooperation Treaty (hereinafter referred to as “PC international application”) is filed within one year thereafter on the basis of the priority claim after filing a patent application in Korea first, the designated State may be deemed to be the Republic of Korea;

(hereinafter referred to as "PCT self-designated application"). In such cases, the conditions and effect of the priority claim shall be governed by the statutes of the Republic of Korea.

[Article 8(b)(b) of the PCT. A person seeking a patent may claim priority on the invention described in the specification or drawings initially attached to an application filed earlier (hereinafter “Earlier application”) for a patent having the right to obtain a patent, on the basis of the invention described in the specification or drawings initially attached to the application.

(1) Article 55(1) of the Patent Act applies to an invention identical to an invention described in the initial specification, etc. of an earlier application claiming the relevant priority (hereinafter referred to as “Earlier application”) among inventions described in a patent application claiming priority, the patent application shall be deemed to have been filed at the time the earlier application was filed (hereinafter referred to as “priority date”). Therefore, if the inventor claims priority while filing a subsequent application containing a professional engineer of an earlier application, the patent application shall be deemed to have been filed as the filing date of the part identical to the earlier application among the inventions described in an earlier application claiming the priority as the filing date of the earlier application.

The purpose of this domestic priority system is to protect the inventor's accumulated performance as a patent in consideration of the fact that the technology development is constantly conducted.

A person who has made an invention or his successor shall have the right to obtain a patent under the conditions as prescribed by the Patent Act.