단독 itself is pronounced as [단독] But, when it is followed by ㅁ sound like 무대, 단독무대 is pronounced as [단동무대] The rule: When ㄱ, ㄷ, ㅂ meet ㄴ, ㅁ, they become ㅇ, ㄴ, ㅁ each. Let's see them with examples. 국물 먹는데 말을 걸면 어떡해? Why did you talk to me when I am drinking the stew? 혹시 웃는 얼굴이라는 꽃말을 가진 꽃도 있나? Is there a flower that has the flower language meaning smiling face? 밥만 먹지 말고 이리로 와서 고기 굽는 것 좀 도와 줘. Stop eating and help me roast the meat. 국물 is [궁물] and 먹는데 is [멍는데]. 웃는 is [운는] and 꽃말 is [꼰말]. 밥만 is [밤만] and 굽는 is [굼는].