The consonants on the end of a Korean orthographic syllable is called a "final." (받침) These "finals" only have seven phonetic values which are ㅇ, ㅁ, ㄴ, ㄹ, ㅂ, ㄷ, ㄱ. The rule is ㄱ,ㄲ,ㅋ => ㄱ ㄴ => ㄴ ㄷ,ㅅ,ㅆ,ㅈ,ㅊ => ㄷ ㄹ => ㄹ ㅁ => ㅁ ㅂ,ㅍ => ㅂ o => o Thus, 빛 is pronounced as 빋 The ㅊsound can be pronounced with 이,을 빛이 => 비치 빛을 => 비츨