Does anyone know where can I find Korean alphabet which tells if a vowel or consonant is voiced or unvoiced, aspirated or not? Thanks.
I can tell you right now.
(Always) Voiced: all vowels, ㄴ, ㅁ, ㅇ(final), ㄹ
(Conditionally) Voiceless: ㄱ, ㄲ, ㄷ, ㄸ, ㅂ, ㅃ, ㅅ, ㅆ, ㅈ, ㅉ, ㅊ, ㅋ, ㅌ, ㅍ, ㅎ
(Strongly) Aspirated: ㅋ, ㅌ, ㅍ, ㅅ, ㅊ, ㅎ
Not (strongly) aspirated: ㄱ, ㄷ, ㅂ, ㅈ
Not aspirated: ㄲ, ㄸ, ㅃ, ㅆ, ㅉ
Note that Korean doesn't really phonemically contrast voicing, so it's not weird if a voiced consonant comes out voiceless, or vice versa. It happens all the time.
Asking if a Korean stop consonant is voiced or not is akin to asking if English /p/ is aspirated or not. It is sometimes, and it is sometimes not. For example, "pin" is usually aspirated, but "spin" is usually not. So is English /p/ aspirated? Yes and no. Is Korean ㅂ voiced? Yes and no.
Refer to the wikipedia for more info about Korean phonology.