the galgo (or yangjang-go or yang-go) is a traditional korean drum. the drum has an hourglass-shaped wooden body and two drum heads of identical diameter, similar to the "janggu". compared to the "janggu", the "galgo" is fitted with a sound-adjusting funnel different from that of the "janggu". the "galgo" also uses thinner drum skins and is struck with two bamboo sticks called "chae" but mallet shaped "gungchae" is not used. the pitch of the drum can be controlled on both sides of the drum rather than only one pitch per-side for the janggu. this instrument is popular after the rule of king yeongjo in the joseon dynasties, and is always mentioned in the jinyeoneuigwe (historical records of the palace). however, today, the "galgo" has fallen out of use by traditional music performers. until 2015, if one wishes to see this instrument, normally it will be in the national center for korean traditional performing arts, but today it can also be seen as part of the traditional band of the republic of korea army when it performs in military tattoos, since a modern example has been recently manufactured in the traditional manner for the band.