How is the national electoral register created?

South Korea, [Public Official Election Act], Act No. 4739, March 16, 1994 (last amended Act No. 14839, July 26, 2017), accessed 30 September 2018

Article 37 (Preparation of Electoral Register)

(1) Whenever an election is held, the head of a Gu (including a Gu that is not an autonomous Gu), Si (referring to a Si with no Gu established therein), or Gun (hereinafter referred to as "Gu/Si/Gun") shall survey, for each voting district, persons who have the right to vote (including foreigners under Article 15 (2) 3 in cases of the elections of local council members and the head of a local government; excluding persons enrolled in the overseas electoral register determined pursuant to Article 218-13 or the register of reported overseas absentees of another Si/Gun/Gu), and who is registered as a resident in the relevant district pursuant to Article 15, as of 28 days before the presidential election day and 22 days before the election day of members of the National Assembly, local council members, or the head of a local government (hereinafter referred to as the "basis date for preparation of electoral register"), and shall prepare the electoral register within five days from the basis date for preparation of the electoral register (hereinafter referred to as the "period for preparation of electoral register"). In such cases, persons enrolled in the register of reported overseas absentees determined pursuant to Article 218-13 shall be marked with such fact in the column of remarks in the electoral register.

(2) The electoral register shall include the elector's name, address, sex, date of birth, and other necessary matters.

(3) No one may enter him/her in two or more electoral registers in the same election.

(4) The head of a Gu/Si/Gun shall, upon preparing the electoral register, immediately send a certified copy thereof (including a copy of computerized materials for preparation of the electoral register) to the competent Gu/Si/Gun election commission.

(5) Where the number of electors in a voting district exceeds 1,000, the electoral register may be divided into fascicles in means that each fascicle can contain approximately the same number of electors.

(6) The electoral register as provided for in paragraph (1) may be prepared through a computer system. […]

National Election Commission, Preparation of Voter Lists [web content], accessed 30 September 2018

“Whenever an election is held, the head of the relevant Gu/Si/Gun prepares a voters lists for each precinct based on the resident register (Korean citizens) and register for domestic residence (non-Korean citizens, only used in local elections) as a computerized database.”