A web robot is a program that downloads and stores web pages. Implementation issues for developing web robots have been studied widely and various web statistics are reported in the literature. First, this paper describes the overall architecture of our robot and implementation decisions on several important issues. Second, we show empirical statistics on approximately 74 million Korean web pages. Third, we monitored 1,424 Korean web sites to observe the changes of web pages. We identify what factors of web pages could affect the changes. The factors may be used for the selection of web pages to be updated incrementally.