Time evolution of the slope for the global attenuation curves from the four different models (dynamic, dynamic-no-scattering, static, and static-no-scattering) of the MW-like galaxy simulation. The inclination angle is color-coded in each panel. Here, all models with A_v < 0.01 are excluded. The gray thick lines represent the time evolution of the slope of the average extinction curves for the static and dynamic dust models in the left and right panels, respectively. The value of slope for the static dust model corresponds that of the MW (Pei 1992; Li et al. 2008).