1)I understand the DSi Ware downloads are region locked...
You should be able to access the DSi Ware store for the Americas from Korea, as this is an online program. Please note that the credit card used to purchase Nintendo Points, needs to match the region you are trying to get points from, not the region you are living in. In this case, a U.S. credit card would be required to purchase U.S. Nintendo Points for your DSi.
2)I notice the power adapter for the American DSi is only compatible with 120V...
If you are going to be in South Korea for a long period of time, you may want to get a South Korean version of the DSi AC Adapter. As long as it's the official adapter made by Nintendo for use with the systems in South Korea, it will work with your American DSi. Please note that we don't have release date information for outside the America's, so we don't know what the release date is for the DSi in South Korea. You would likely need to wait until you are in South Korea to find this adapter to purchase. Your other option would be a step-up or step-down transformer, which are available at most electronics or travel stores.
Nice answers from anyone traveling abroad with a Nintendo DSi. It isn't really an exclusive for NWR boards, but I think it is nice information.
Another answer from the tech forums at Nintendo for the first question...alittle more detail.
Hello,
Just like the Wii Shop, the region is tied to where your system was designed to be used. So for example, if you purchased a North American Wii, and you took it to Europe, it would still access the North American Wii Shop and only accept North American currency.
As you might imagine, this can be a problem if someone accidentally (or perhaps intentionally) purchases a system from another country, brings it back home, and then tries to purchase content online. Whoops.