This is the 2126th most frequent Korean word.
원인을
The Korean word "원인을" means "the cause" in English.
In this sentence, '원인을' is the object of the verb '조사하다', meaning 'to investigate'. It denotes the cause of the issue being investigated.
문제의 원인을 조사하고 있습니다.
We are investigating the cause of the problem.
Here, '원인을' again serves as the object, but this time of the verb '찾다', meaning 'to find'. It specifies the cause that has been located.
사고의 원인을 찾았습니다.
The cause of the accident has been found.
In this example, '원인을' operates as the object of the verb '아', meaning 'to know'. It communicates that understanding the reason behind the disease is critical.