Sliding into the next block

Korean syllables prefer to begin with a consonant, and ㅇ at the top of a block is a placeholder meaning 'no sound here'. When the previous block has a consonant to spare, speech moves it over, so the syllables come out as consonant plus vowel. Now at the start of a block, the consonant is released again, and the day 1 rule stops applying: 옷 is [옫] but 옷이 is [오시]. That is the reason the spelling keeps ㅅ. Linking happens inside words and between a word and its particle or ending, which covers almost every sentence you will say.

The ㄹ is the one to watch. At the end of a block it is an l, with the tongue held against the ridge behind the top teeth, as in 일 'one'. Moved to the front of a block it is flicked, much like the quick t in 'water' in American speech, and romanisation switches from l to r to show it. So 일 is il but 일요일 is iryoil. Nothing about the letter has changed, only its position in the syllable.

Linking fills an empty slot at the start of a block, so it only happens when there is something suitable to move. ㅇ as a final is a sound Korean never puts at the start of a syllable, so 영어 keeps its silent ㅇ and does not link. A doubled letter like ㅆ counts as one consonant and moves whole, while a pair of different letters such as ㄺ splits. 맛없어요 is the subtle one: when the join is between two separate words, the first one closes itself off by the day 1 rule, and it is that [ㄷ] which links, giving [마덥써요].