Can't add director credit

You can only do it this way. Other wise staff will have to add it manually.
Have you saved the submission for later and generated a contribution number?
Post it here.

Bradley,

For the time being, submit the name this way.

Kim, U. Son 

(I'm assuming an IMDb name page does not exist for this person.)

After the name page has been processed and published (U. Son Kim), go to the IMDb Contact Us page and submit a report so a representative can correct the item manually.

https://help.imdb.com/contact

Click the following buttons/drop-down menu items on the form.

IMDb Fan/Contributor questions -> Names & biographical Data -> Change name -> Email

In the Explanation box, indicate that because of the error message involving character combinations, the correct name should be without the period after the first initial (U). You can also include the URL of this GetSatisfaction discussion.

I hope this helps. Please write back if you need any more assistance.

Thanks for the help.  I have submitted the name as you suggested.