This line is your problem
add_action( 'widgets_init', 'ohsik_widgets_init', 12);
You are deregistering your sidebar correctly. For some reason you are registering it, or something. I don’t see the need or use for this.
The other possibility that I’m thinking of for using this code is that somewhere you are registering your own custom sidebars.
If that is the case, you are most probably reusing the ID of the sidebar you have deregistered. Try changing the ID to 12 of your new sidebar. You can not reuse ID’s. All ID’s needs to be unique