This paper describes a requirement architecture modeling for the front end of KT-1 export version requirement definition processes to construct SDS(system development specification). The requirement definition process is a highly conceptual process that is difficult to carry out. This paper focuses on how to perform the KT-1 export version requirements definition process including the integration of process, methods and tools for the front-end activity of requirements definition process. This requirement model is structured in four segments, including requirement layering, requirement categorization, life cycle stakeholder and requirement definition process using Computer-Aided Systems Engineering tool(CORE).