We entered US on 07-01-2011 on Green card lottery.I’m studying PhD in S. Korea. My wife in dependent visa accompanies me in S. Korea. I’ve completed 4 years of my studies. To complete my degree, I may need 6 mths-1 yr. We’re leaving US on 07-29-2011. We’re planning to come back in every 6 mths to maintain our status. Is it okay if we do so? Or there would be some trouble at the port of entry while we re-enter the US next time? What should be better for us to maintain our status? Do you think we should apply for the re-entry permit?? If so, what are the processes required to apply for the permit? Can we apply for the re-entry from Korea or we should come here to apply for the re-entry? Also do we need to wait for the re-entry permit before we travel outside the country if we apply in US?