Hello, Speaking of + (Noun) : (Noun) ~ 에 대해 말한다면, ~ 의 이야기라면.. Speaking of which + (Sentence) : (Sentence) ~ 에 대해 말한다면, (Sentense)의 이야기라면... There is no difference, only the Noun is came or Sencence is came. Hope this help you studying Korean. - I get good grades in school. Speaking of which, how are your grades? / I hope I answered your question well. Speaking of which, I have a question for you too. - 나는 학교에서 좋은 점수를 받았어요. 좋은 점수를 받은 것에 관해, 당신의 점수는 어때요 ? / 나는 당신의 질문에 잘 대답했기를 바래요. 질문에 대답하는 것과 관련하여, 나도 당신에게 질문이 있어요. - "Speaking of traveling, have you ever been to France?" / "Speaking of movies, what is your favorite film?" - 여행에 관해 얘기한다면, 당신은 프랑스에 가본 적이 있어요 ? / 영화에 관해 얘기한다면, 당신이 좋아하는 영화는 무엇인가요 ?

Speaking of which: "얘기 나온 김에 (말 하자면)" would be the perfect fit in many cases. Direct translation lead you to nowhere. Mostly the sentences have to be rephrased and reconstructed in order to sound natural: I get good grades in school. Speaking of which, how are your grades? 저 학교 성적 좋아요. 얘기 나온김에, 당신의 성적은 어때요? It's very similar to "since we are already there" I hope I answered your question well. Speaking of which, I have a question for you too. 답변이 되었나요? 문답하는 김에 저도 질문 하나 해도 될까요? Was the answer sufficient? And now since we are apparently in a QnA session, may I ask a question as well? Speaking of [something]: [something] 얘긴데요/말이에요/ 얘기 하자면 Speaking of traveling, have you ever been to France?" 여행 얘긴데요, 혹시 프랑스에 가보신 적 있으세요? Speaking of movies, what is your favorite film?" 영화 말인데요, 어떤 영화를 가장 좋아하세요?