This is the 15019th most frequent Korean word.
발달에
"발달에" means "in development" or "of development."
In this sentence, '발달에' refers to the area or extent of development, specifically the development of skills.
그의 기술 발달에 많은 시간이 걸렸다.
It took a lot of time for his skill development.
Here, '발달에' pertains to the development progress, in this case, the growth or advancement in education.
아이들의 교육 발달에 관심이 많다.
I am very interested in the development of children's education.
In this instance, '발달에' indicates the influence on the development process, specifically the enhancement of brain functions.