Korean Job Discussion Forums

[Enigma]

Let me preface this by saying that I know almost nothing about birds, so please forgive my ignorance.
I've done a lot of hiking all over Korea and usually when I see birds, they are a combination of black, white and/or brown. Usually they are those ggachis (the black and white Korean magpies), white storks, hawks or little finches (?) and I've seen a handful of woodpeckers. However I rarely see anything very colourful.
I live on the coast of Gangwondo in Donghae and do a lot of hiking in the hills and mountains in the area behind my apartment. On many occasions I've seen these birds that are predominantly yellow with a bit of black trim and possibly some white, although I'm not certain as I've never been able to get close to them. They are usually solitary, but a few times I've seen them in pairs, and they are slightly smaller than the magpies you see everywhere here.
I realize this is a terrible description and doesn't give you much to go on, but does anyone have any idea what they might be?

Thanks