I flew through Seoul to Tokyo from Europe (had a meeting in Seoul for a day), and was planning to go scuba diving in the weekends while in Japan. So, I had a big bag with scuba-gear (ss bp/w & LH for the divers around) with me.

After checking in in Seoul, I headed towards security, when the check-in lady came running after me yelling "mr. Voop, mr. Voop" Following her to just next to her counter we went into an enclosure of sorts, where there was a huge X-ray thingie and a few security folks, looking puzzled at my (locked) bag. They asked if I could open it, which I did. When they saw what it was, they smiled, and sent me on my merry way.

Apparantly, they have big, hidden in-line screeners there, and try to catch people before they get too far away if there's something that they want a closer look at. Fine procedure, I think