I'm not an expert, but there no Z in Korean. Although, J is often used in place of where a Z would be. So maybe the word you heard is 직진 (Jikjin) which I think means straight.

직진 means "going straight, " not just straight. 직 means "straight," and 진 means "going forward." 직진 is often used for driving straight. i.e. 직진하세요: Go straight / Drive straight.

직진 means "going straight, " not just straight. 직 means "straight," and 진 means "going forward." 직진 is often used for driving straight. 직진하세요: Go straight / Drive straight.