Samick could very well have bought the name from the original nameholder back in 1985. I do know that the Japanese models were manufactured by Matsumoku, and this could have been no later than 1987 when the plant was sold to Singer.
There was at least one US distributor before the shift in production but I cannot find the one sentence in the one article in the one book/magazine that I remember seeing this in.
It would not surpise me if there was a Canadian distributor that in fact also held the trademark.
I have noticed that there seems to be a bit of a gap as far as Vantage is concerned between Japanese and Korean production. I seem to remember reading something about the name being in limbo for a short while between owners. If I finally find that darn paragraph I'll post it here.