The only ‘Z’ I can find that fits neatly in a K-drama glossary. There’s no ‘z’ consonant sound in Korean so it’s pronounced ‘chombie’.
In Korean film the Zombie has been enthusiastically appropriated from its American home and some contagion to TV is inevitable. Movies like Train to Busan and #Alive have made Korean actors deservedly feted for the extreme physicality of their Zombie representations, well supported by the virtuosity of Korean make-up artists, designers and technicians. This aspect of the Korean film and TV industry is meta explored in Vincenzo when the performance artist in the plaza trains the other residents in the dark arts of playing a Zombie for a Mission Impossible (TV) like caper to unmask a greedy banker.
K-dramas are all about the romance so the ‘go-to’ metaphysical entity is typically the Gwisin (ghost/spirit), a normality disrupting figure but one also able to channel human emotions such as regret, longing, jealousy, and, crucially, love: as well as being simple to cast and tech-lite to portray by K-drama convention. However, hard core Zombie action in K-drama has caught on relatively recently, probably in part facilitated by international streamers who are less interested in financing romances and more interested in feeding international audiences’ taste for East Asian horror.
Zombie Detective is a KBS mainstream romance outlier from 2020 in the vein of US flick Warm Bodies in which a zombie tries to behave like a human. Zombie hordes start with the magnificent Kingdom in 2019, a sageuk / Zombie mashup, followed in 2020 by Sweet Home, which features human transformation but into a diverse and highly creative range of monsters and a top notch acting cast. Happiness in 2021, a Han Hyo-joo vehicle, brings back the 28 Days Later style Zombie bio-origin logic that featured in Kingdom and drives the US movie World War Z, and 2022 sees K-Zombies go to High School in All of Us Are Dead. Maybe one Zombie infestation a year is all the market can take.