Objectives The purpose of this paper is to identify the types of logico-semantic relations that Korean quotation clauses have with their main clauses.
 Methods The clause complexing system of systemic functional linguistics separates the logico-semantic relations of quotation clauses and the Taxis into a optional system. This method can solves the previous problems of mixing the two criteria within the framework of embedded clauses.
 Results First, we argued that the logico-semantic relationship(projection) and clause complexing of quotation clause are independent systems, so that quotation clause can be used as a paratactic, hypotactic, or adverbial clause. we, also, explained that projecting nouns and fact nouns require adjective clauses as complement clause, and some factual cognitive verbs require nominal clauses as complement clause. Second, we explained that Korean quotation clauses can be logically and semantically categorized into locution, idea, and fact projections, respectively. Each of these is governed by the locution verb, the idea verb, and the fact noun in the main clause. In addition, a projecting clause always functions as a proposition or a proposal: thus, projenting clause can be defined as an obligatory bound clause that functions as speech acts of proposition or proposal. Third, from the perspective of systemic functional linguistics, we proposed the morpho-syntactic structures of quotation clauses as paratactic, hypotactic, and adverbial clauses, reflecting the aforementioned logico-semantic types and clause complexing system of quotation clauses.
 Conclusions The clause complexing system of SFL adopted in this paper is expected to provide a more comprehensive explanation than existing grammar theories because it reflects both logical-semantic types and the Taxis.