Thank you for the question. It sounds like you would like to automatically log into your account when your start your iMac. OS X Mavericks has the same functionality as Mountain Lion for automatic login.
You can change these settings in System Preferences>Users & Groups. Follow the steps in the article below, and in step 4, be sure to select the account you would like to automatically log into when you start your iMac (the title of the article says Mountain Lion, but the steps are the same for Mavericks):
I believe this is the solution for the what you described, but if it is not, please clarify the functionality you are looking for.
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