What does "kwukyel" mean in regards to Chinese language characters?
kwukyel or gugyeol is a Korean system to write Chinese characters phonetically that predates Hangul. As for 丷 itself, to quote from Wiktionary: 


  This is a kwukyel note. Kwukyel was a system formerly used in Korea whereby correct interpretation of texts written in Classical Chinese was aided by small interspersed notes such as this one. The notes represent Korean morphemes but were only used within Chinese text.