Here are some common first names in Korea 
(I dont wanna put gender on them, but if you wanna use them just ask what they are for)

( more names might be added )

The theme is J

Ji :

Ji-woo ( 지우 )

Ji-yoo ( 지유 )

Ji-yoon ( 지윤 )

Ji-eun ( 지은 )

Ji-soo :) ( 지수 )

Ji-min :) ( 지민 )

Ji-seong :) ( 지성 )

Ji-seung ( 지슬 ) 

Ji-won ( 지원 )

Ji-seul ( 지슬 )

Jin :

Jin-mi ( 진미 )

Jin-hee ( 진희 )

Ju / Joo :

Ju-hee ( 주희 )

Ju-won ( 주원 )

Jung / Jeong :

Jungkook :) ( 정국 )

Jung-won :) ( 정원 )

Jung-min ( 정민 )

Jung-eun ( 정은 )

Jung-hee ( 정희 )

Jung-hyun ( 정현 )

Jae :

Jae-won ( 재원 )

Jae-min ( 재민 )

Jay-hyun :) ( 재현 )