I think you try to hard to attach a single English sound to each hangeul letter. But they aren't 100% comparable! =) Actually, that's just like English letters: for example, how do you explain the difference between the "J" sound in "joy" and the one in "hallelujah"? So, coming back to Korean "ㅅ" sound... In forms like 시 샤 셔 슈 쇼 쉬 it's usually pronounced "sh-" like "shi", "shu". In forms like 사, 새 and 세 it's usually pronounced "s-" like "sa", "sae". At the ending of a word it's often pronounced like a very soft "t", like in "옷" ("ot") or "못" (mot), just to make speaking easier! Nice, isn't it? (But (!) if followed directly by a topic, object or subject marker it turns back to a "s"- or "sh"-sound, for instance "옷을" -- oSeul and "옷이" -- oSHi) So, back to your question: The proper pronounciation is "set" and "sam".