Recently public data is opened fast in many fields. It has been used to improve diverse services in private and public sector. To analyze the data, it is necessary to apply systematic design and methods to aggregate, store, and handle it. In this paper we describe the result of experiments for analyzing user trends related with subway usage based on public data. For this work, we firstly describe the design of software architecture and methods about utilizing tools. Open API based on REST is used to aggregate data from public data portals and to handle the data aggregated by Hadoop, MapReduce programing model based open source framework. In this paper information about occupant of railway train, a kind of public open dat,a from the portal operated by Seoul city is used to verify the tools for handling it.