araso (아라소) and arata (아라타) are incorrect spelling of 알았어. 알았다. By the way, if someone who is not acquainted with me or close to me say "알았다." Then I may think the person is very impolite and don't have any respect for me. Maybe this videoclip will be a help to you. http://www.youtube.com/watch?v=pniA-K5vt2U

oh yes i didn't kwon how to write it so .. >.<

u may mean 알았어 & 알아다