They look like the type of trinkets you can pick up in Korean gift shops to this day. Koreans policing up brass from US ranges (off the battlefields during the war I would imagine) and turning it into semi-cultural souveniers is pretty common. As late as 96 you could go down range to the little brass shops and get all kinds of brass items, adn those little pipes were pretty common.

The Bugle looks like it may have been a capture item, but during the war the Koreans were very ingenious in making items that they could sell to GI's who missed out on the better battlefield souveniers.