Korean Job Discussion Forums

[fancypants]

It's a reduced adverbial clause (an adverbial phrase). When the subject of the main and subordinate clause is the same, you can reduce the main verb of the subordinate clause and omit the causation/time adverb and the "be" verb.
This sounds way more confusing than it really is! It just works on the less is more principle, where you can turn sentences like "Because she was tired, she fell asleep on the train" into "Being tired, she fell asleep on the trian".

Here is a link to an explanation:

http://www.gallaudet.edu/clast/tutorial_and_instructional_programs/english_works/grammar/adverbs/adverbial_clauses.html

And this is from Azargrammar.com, (Understanding and Using English Grammar, blue, chapter eighteen)

http://www.azargrammar.com/assets/advanced/UUEG04_TeachersGuide/UUEG04_TG_Ch18.pdf

Here's another good explanation: http://youtu.be/MMKcVzBMhP0

It's kind of higher level stuff for upper intermediate/advanced students, so if you need this answer for a lower level student, I would tell them to hold their horses for awhile.[/url]