칼 means 'a knife' or 'a sword'. 칼+기상=칼기상 is a kind of newly-coined word that means wake up 'on time' without hesitation or delay. There are some examples such as '칼+퇴근(get off the work)=칼퇴근’->get off work on time (no overtime!), ‘칼+군무(group dance)’-> group dance in perfect unison.