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Stay With Me - Chanyeol & Punch (Goblin)
If - Taeyeon (Hong GIl Dong)
Can You Hear Me - Taeyeon (Beethoven Virus)
Because I'm a Girl - IU (Road Number One)
Reset - Tiger JK (School 2015)
Suddenly - Kim Bokyung (City Hunter)

And although I didn't finish watching Boys Over Flower, that series has a whole bunch of amazing OSTs.
Ben - Like a Dream ( Another Oh Hae Young )
Sam Kim - Who Are You ( Goblin ) 
Lena Park - More Than Anyone in the World ( Spy Myung Wol ) 
Hyorin - Crazy Of You ( Master's Sun ) 
Baek Ji Young - That Woman ( Secret Garden ) 
Davichi - Forgetting You ( Moon Lovers )
Tiger JK - Reset  ( Who Are You: School 2015 )
M Signal - I Dont Know ( Heartstrings ) 
Chen - Best Luck ( It's Okay, That's Love )
Baekhyun - Beautiful ( EXO Next Door ) 
Tiger Moth (Acoustic) - Monsta X (Shopping King Louis)
Flower - Seo In Guk (Tomorrow With You)
Like A Dream - Ben (Another Miss Oh)
My Destiny - Lyn (My Love From Another Star)
My Time Towards You - Alex (Bubblegum)
Who Are You - Sam Kim (Goblin)
Hope Its Not A Dream - Lee Young Hoon (Falling For Innocence)
Stay With Me - Chanyeol & Punch (Goblin)
EXO (Chen-Baekhyun-Xiumin) - For You (Scarlet Heart)
Tiger Moth (Acoustic) - Monsta X (Shopping King Louis)
Various Artists - Return (I Hear Your Voice)
Jang Jae In - Auditory Hallucination (Kill Me Heal Me)
Yoon Mi Rae - Always (Descendants of The Sun)
Basick, INKII - In the Illusion (W Two Worlds)
The Black Skirts - Wait More (Another Oh Hae Young)

I'm just crazy for good OSTs  ^^
Will Be Back - Im Sun Hae (Moon Lovers: Scarlet Heart Ryeo)
One Day of Love - Park Wan Kyu (The Princess' Man)
Auditory Hallucination - Jang Jae In Feat. NaShow (Kill Me Heal Me)
Bad Guy, Jang Hye Jin & MC Sniper (Faith)
I Miss You ~ Bogoshipda - Kim Bum Soo (Stairway to Heaven)
Thorn Love - 4MEN (Empress Ki)
Once Again - Mad Clown, Kim Na Young (‎Descendants of The Sun)
For You It's Separation For Me It's Waiting - Jae Joong (Sungkyunkwan Scandal)
Hurt, Ali (Rooftop Prince)
A Walk in a Dreamy Road - Jang Nara (Dong Yi)
Stranger - Bobby Kim (Doctor Stranger)
Incurable Disease - Navi ft Kebee of Eluphant (Secret)
Leave - Park Bo-young (Oh my ghost)
Echo - Every Single Day (I Hear Your Voice)
Back In Time - Lyn (The Moon Embracing The Sun)
Because I Miss You - Hwang Chiyeul // Beige (Moonlight Drawn by Clouds)
Wing Of Goryeo - (Moon Lovers: Scarlet Heart Ryeo)
The Wind - Park Wan Kyu (Empress Ki)
ALWAYS - Yoonmirae (‎Descendants of The Sun)
This Love - DAVICHI (‎Descendants of The Sun)
Puppet Scarecrow - Jung Il Woo (49 days)
Secret Paradise - Jang Jane In (Scholar Who Walks the Night)
Angel - Super Junior (Haru)
Destiny Sonata - Jung Dongha (Fated to love you)
The Way We Loved - Sihwan Park (Emergency Couple)
The Scent of Flower - Choi Jin Hyuk (Emergency Couple)
Because I'm Stupid - Kim Hyun Joong (Boys Over Flowers)
Non-Fiction - Every Single Day (Pinocchio)
Best Luck - CHEN - EXO (It's Okay, That's Love)
I Love You - Yoon Mi Rae (It's Okay, That's Love)
Hope And Hope - Kim Na Young – (Marriage Not Dating)
Something Happen To My Heart - Ast'1 And T-Max (Boys Over Flowers)
Aebyeolri -  Im Hyung Joo (Dong Yi)
Because My Steps Are Slow, Shin Yong Jae, 4MEN (Faith)
Love Is - Park Jang Hyeon, Park Hyeon Gyu (The Heirs)
Chicago typewriter .. satellite 
moon lovers ...almost all
I think i will be here all day. My music list has over 100 songs (although not all korean) but i will name 20 (no particular order) - hopefully some that aren't mentioned already.

For You - BTOB (Cinderella and the four knights)
My Love - Monsta x (Hello, Mr Right)
Once Again - Mad Clown/Kim Na Young (DOTS)
Round and Round - Heize (Goblin)
Stay With Me - Punch/Chanyeol (Goblin)
Auditory Hallucination - Jang Jae In (KMHM)
Hurt - Kim Jong Jin (Cruel City)
Goodbye Day - Ulalasession (The Bridal Mask)
Goodbye My Love - Ailee (Fated to Love You)
Will it Hurt - Dong Soo (Wild Romance)
Without Words - Jang Geun Suk (You're Beautiful)
Moment - Lee Chang Min (Heirs)
I can't live without you - Lee Changmin/Dahee (The best Lee Soon Shin)
My Love - Lee Jong-Hyun (Gentlemans Dignity)
Breath - Mad Soul Child (Special Affairs Team 10)
Eternal Love - Michael Learns to Rock (Healer)
You're falling into me - No Brain (Thumping Spike 2)
Bang Bang Boom - T-Max (Boys over flowers)
Because i'm stupid - SS501 (BOF)
Jaywalking/Wake up - Eye Candy(SUFBB OST)