In general, attenuation at frequencies over 20GHz is mainly due to absorption by satmospheric gases, rain, and snow. Among this factors rain become an important limiting factor. Rain attenuation is highly influenced by rainfall-intensity and it varies over time and space. Thus it is requeired to obtain spatial and temporal data of rainfall-intensity for precise prediction of rainfall attenuation. In this paper, rainfall intensity of thiry-two measurement sites in South Korea excluding JeiJdo Islands over recent ten years is obtained and the regional relation between rainfall-intensity and percent of time is analyzed. Also we present the new method about rainfall-intensity cumulative distribution.