According to Naver dictionary,
볼거리 [볼꺼리] vs 갈기다 [갈기다]
일당 [일땅] vs 일다 [일:다] (For this pair, I guess it is because 일 in the second one is long. If that is true, since many Koreans do not differentiate between long and short sounds, is it OK to pronounce 일다 as 일따?)
Anyway I am confused by the sound change after ㄹ, and similarly after some other sounds like ㅁ.
Can someone explain this?