Here is the first way.
11 eleven [yolhana]
12 twelve [yoltul]
13 thirteen [yolset]
14 fourteen [yolnet]
15 fifteen [yoldasot]
16 sixteen [yolyosot]
17 seventeen [yolilgop]
18 eighteen [yolyodol]
19 nineteen [yolahop]
20 twenty [smul]
Here is the second way.
11 eleven [sibil]
12 twelve [sibi]
13 thirteen [sipsam]
14 fourteen [sipsa]
15 fifteen [sibo]
16 sixteen [simryuk]
17 seventeen [sipchil]
18 eighteen [siphal]
19 nineteen [sipgu]
20 twenty [isip]
Then, let's have a conversation.
A: 동무는 몇시에 상점으로 갑니까?
Tong-mu-nun-myot-si-e-sang-jo-mu-ro-gam-ni-kka?
(What time do you go to the shop?)
B: 11시 15분에 갑니다.
Yol-han-si-si-bo-bu-ne-gam-ni-da.
(At 11:15)