Gasa
Gasa is a form of verse, although its content can include more than the expression of individual sentiment, such as moral admonitions. Gasa is a simple form of verse, with twinned feet of three or four syllables each. Some regard gasa a form of essay. Common themes in gasa were nature, the virtues of gentlemen, or love between man and woman.
The form had first emerged during the Goryeo period., and was popular during the Joseon Dynasty. They were commonly sung, and were popular among yangban women. Jeong Cheol, a poet of the 16th century, is regarded as having perfected the form, which consisted of parallel lines, each broken into two.
Read more about this topic: Korean Poetry