The talk is concerned with generally symmetric hyperbolic-parabolic systems with Korteweg-type dispersion. Referring to those classical efforts, we formulate a new structural condition for the Korteweg-type dispersion and develop the dissipative mechanism of "regularity-gain type". As an application, it is checked that several concrete model systems (e.g., the compressible Navier-Stokes (-Fourier)-Korteweg equations) satisfy the general structural conditions. This is a joint work with Professors Shuichi Kawashima and Yoshihiro Shibata.