Behind the phenomenal success of the TV drama series “Descendants of the Sun,” which recorded nearly 40 percent viewership ratings, was the soundtrack that enhanced the completeness of the drama. Aired in 2016 on KBS, "Descendants of the Sun" depicts the love story between Army Captin Yoo Si-jin (Song Joong-ki) and Kang Mo-yeon (Song Hye-kyo), a medical doctor, in the fictional land of Uruk. The...