It is an important problem to find out the variation area factors of the postal service cost of various province (city) in the postal management and economy.

There is huge variation in how people are affected by loud sound, however, and this is an area where a number of researchers are conducting studies.

However, due to a considerable variation in land area, 1 population density and climatic, geological and topographical conditions, the extent of forest cover differs greatly among the island states.