D.M.
A.,
Travel is difficult with infants, let alone across the world. But, what has happened is you lost that consistency you had before your move to Seoul and now you have to stop and evaluate the best way to make everyone happy.
If this means, getting your son to sleep in his crib then you have to think about what has changed...
* Big move and time adjustment
* Return to co-sleeping...not a bad habit or a bad thing by the way, but please only do this if it's what works for your whole family.
* Teething, growing and learning about the world around him.
Keep in mind that change with babies, toddlers and kids has to happend gradually. You can't just change to putting him in his crib without expecting him to freak out. Co-sleeping allows infants to feel his/her parents nearby and when you take that away it's a shock and probably kind of scary. You are going to want to start slow and work your way up.
Instead of putting him in his crib wide awake, you might want to find an alternative like rocking and cuddling to sleep or almost asleep and then, placing him in his crib. If he wakes, repeat the rocking and cuddling but put him back in his crib...be consistent. In the crib you might want to put something that is yours like a small piece of a blanket that he can use to pick up the scent of Mommy and be comforted by.
Or many introduce something that most call a 'lovey' or a transitional object. That over time infants begin to identify with sleeping and their sleep spot. It can be a stuffed animal or toy, that is cuddly and soft.
Also, if you choose to co-sleep you might want to think about a mattress on the floor or something that you can use to sleep on with your son, so Dad can get some rest. It's an alternative that has worked for several of my friends with new babies. Co-sleeping doesn't have to be just sleeping in Mom/Dad's bed, but can vary depending on what suits your family and your child's needs. But, then again you should discuss this with your hubby and make sure you both agree with how to handle this transition.
No matter what you do, remember that a baby will not sleep ALL the time consistently through the night and naps will vary as he grows and discovers the world. At 9 months, my son was growing and teething and sleep was almost non-existent for at least a month. But, it passed until our next milestone and age/stage change.
I'm not sure if you're feeding on demand or if your son is on solids...this can also disrupt sleep patterns. Especially if he is in a growth spurt. Food can play a big part into sleep once they start to get older, and need more nutrition to meet their growth.
Good Luck and don't worry, it will get better. Just be patient and loving!