Standart deviation

I would like to ask a question regarding standart deviation.I have a model.I need standart deviations ,which dynare gives, to measure volalitility. Forexample I have two endogenous variables K and Y. After estimation model I have standart deviations of these two variables.But I need standart deviation of the Y/K.Thefore I define Y/K as a new variable write inside model. Because my model is log-linearized form and the steady states are zero in this form , steady state value of Y/K is equal 0/0 so model is not working.How can I calculate the steady state value of ratio of two endogenous variables?. I try to calculate standart deviation from irf of variables ;however, I know this is wrong method. I will be very happy if you help me

If your model is log-linearized, then Y/K is not the right concept anymore, because the Y and K in your model are already in logs, not in levels. Do you want the standard deviation of the ration in percent? If yes, you need
which is the log-linearization of the ratio.