하루에

In a sentence

• 나는 하루에 한 번 운동해요.

  I exercise once a day.

  In this sentence, '하루에' is used to indicate the frequency in a time span, specifically 'in a day'.

• 하루에 몇 시간을 일하세요?

  How many hours do you work in a day?

  Here, '하루에' specifies the time reference about 'in one day' for the question regarding hours worked.

• 하루에 세 끼를 먹는 것이 건강에 좋아요.

  Eating three meals a day is good for your health.

  In this instance, '하루에' refers to the context of daily routine, meaning 'in a day' for maintaining a healthful schedule.