Comments on D-brane and SO(2n) enhanced symmetry in type II string

We propose a configuration of D-branes welded by analogous orbifold operation to be responsible for the enhancement of SO(2n) gauge symmetry in type II string compactified on the Dn-type singular limit of K3. Evidences are discussed from the Dn-type ALE and D-manifold point of view. A subtlety regarding the ability of seeing the enhanced SO(2n) gauge symmetry perturbatively is briefly addressed.