And one night he saw an orchid growing between rocks and decided to adopt the penname 'Nangye'. He passed Saengwonsi and first in Mungwa gwageo exams at the age of 28 and 34. He then has successively filled various government posts including Jiphyeonjeon, Saganwon, Saheonbu and Sejasigangwon Munhak, where he met Chungnyeong daegun. As soon as Sejong ascends the throne in 1418, he appoints Bak Yeon to an agency affiliated with Yejo, which oversees music-related affairs. Bak Yeon organized music into three groups: aak, dangak and hyangak. Domestic production of musical instruments for aak was done under his direction. Bak Yeon helped Sejong to improve the music. He has contributed greatly to the completion of music from the early Joseon Dynasty by producing musical notes and Pyeongyeong. The Jongmyo jerye, which includes Jeongdaeeop and Botaepyeong was composed by Bak Yeon and is also listed in 'Nangyeyugo(蘭溪遺藁)' in 39 petitions, including the production of musical notes, the correction of the original notes, the claim to revise the axis system and the publication of music. However, in the Sejo Sillok, Jeongdaeeop and Botaepyeong is recorded as king Sejong's work. On 22 August 1443, When Pak Yeon was 60 years old, his position was suddenly changed from Yejo chamui(禮曹參議) to Jungchuwon busa(中樞院副使), which oversees the palace in shifts. Soon after, the king Sejong announces the creation of Hunminjeongeum on 30 December 1443. Some scholars argue Bak Yeon, who is well versed in rhymes such as Yullyeo Sinseo(律呂新書), Hongmu Jeong-un(洪武正韻), fully understands Sasung Chil-eum(四聲七音) and appealed to king Sejong in his first petition of Nangyeyugo(蘭溪遺藁) to correct the custom and sound by teaching people the Samganghaengsil(三綱行實) and Oeumjeongseong(五音正聲), might have taught king Sejong the Korean alphabet Hangul during this period and proclaimed it in the name of king Sejong.