This paper develops a formal approach to investigate the evolution of a Korean traditional pattern, Bosangwhamun. The approach employs the structure of symbolic memes embedded in the pattern as a framework of hierarchical decomposition of a pattern to describe an evolutionary development process of a given pattern with a set of rules in shape grammar as style changes. Further, the formal descriptions of the given pattern become the basis for generating its variations. With this process, the validity of the rules and their appropriateness in the representation of Bosangwhamun are examined.