1. They are distinguishable when a vowel syllable is attached after it. For example. both 빗 and 빚 sound [빋] /bit/ when they are independent or followed by consonant syllable. With an attached vowel syllable 이, 을, 빗이 => [비시] , 빗을 => [비슬] , 빚이 => [비지] , 빚을 => [비즐] , 2. Please give me the example of /t/ of ㄴ word 3. ㄹ sound is quite different from /ʒ/ or Chinese r sound. Refer to https://www.youtube.com/watch?v=0ZhOeA0RD9o ㄹ sound is similar to /r/ at initial position of syllable like 라디오, 다리, 사람 ㄹ sound is similar to /l/ at final position of syllable like 물, 불, 이불 마리 is pronounced like /mari/ 몰리 is pronounced like /moli/

Based on my limited understanding, it does not seem to be the problems that you mentioned. For instance, ᄉ is pronouned as /s/ (s)；ᄌ is pronouned as /t͡ɕ/ (j) [unless there is a sound change when such consonant is located at the word-end (받침)] ㄴ is pronouned as /n/ (n) [unless there is a nasal-sound change] ㄹ is pronouned as something between /ɾ ~ l/ (r,l) （there is no such sound like /ʒ/ in KR） It is suggested to refer to the wikipedia for references. https://zh.wikipedia.org/wiki/朝鮮語 === 좋은 하루를 지내세요.／I wish you a good day.