How do I replicate the unique crispiness of Korean fried chicken?
It's not so much the dry ingredients as it is the cooking technique, which involves double frying the chicken. 

You'll notice that the recipe you link instructs you to double fry the chicken, and so do others like this one: http://www.seriouseats.com/recipes/2010/04/dinner-tonight-korean-fried-chicken-recipe.html