New 5-digit zone code (new postcode) will replace the current 6-digit postcode which has been used for postal automation in 2014. New postcode will be used for processing various works to distinguish location and area in the entire country. For example, it new postcode will be used to denote different administration areas, firefighting and police jurisdiction, weather forecast areas, emergency medical facility areas, social welfare institution areas, election districts, school districts, statistical areas, courier and delivery business areas, and etc. Therefore, the relevant authorities must be cosider for the feasibility and applicability of assigning the new postcode. In postal service, postal process will be affected a lot by new postcode because a postcode has been related with delivery area of a postman. Therefore, we propose assignment scheme for new postcode which will impact less to postal process. Then, we present how we used geographic data for efficient assignment and analysis of the results.