To study the confinement characteristics of dimensionally similar discharges (ρ * experiments) in JT-60U L-mode plasmas, transport simulations have been carried out with three different transport models; i.e., the Bohm-type, the Current-Diffusive-Ballooning-Mode and the Multi-Mode models. For all models the electron temperature is in good agreement (within 15% in the electron stored energy). If the thermal diffusivity of ions is around two times of that of electrons, it seems that the simulation results could reproduce the experimental ion temperature. We have compared diffusion coefficients to study the characteristics of the ρ * scaling of each transport model. In the Bohm-type model it is found that the simulation results yield the Weak-Gyro-Bohm characteristics for electrons and ions, even though the Bohm-type thermal diffusivity is incorporated. This can be accounted for by the factor q 2 / L T * in the diffusion coefficient. In the CDBM model, the simulation results clearly show the Gyro-Bohm charac...