thank u so much

if you go to a funeral, you will see lots of chinese hanja. There is very little rule on how to mix in hanja. In fact, in common life settings you'll hardly see hanja being written in chinese anymore. They are all disguised in hangul. However, chinese hanja will not just disappear altogether from korean society in any near future. words based in hanja tend to be used in formal and serious circumstances while native korean equivalents serve informal situations but this is only a rough rule of thumb.