Drinfeld comultiplication and vertex operators

For the current realization of the quantum affine algebras, Drinfeld gave a simple comultiplication of the quantum current operators. With this comultiplication, we study the related vertex operators for the case of U-q((s) over cap I-n) and give an explicit bosonization of these new vertex operators. We use these vertex operators to construct the quantum current operators of U-q((s) over cap I-n) and discuss its connection with quantum boson-fermion correspondence.