* -아/어 봤다 = have had the experience of doing something. Used for interesting or unusual experience. * -ㄴ 적이 있다/없다 = have (ever /never) done something. Strictly factual. -아/어 봤다 usually indicates a personal experience stressing the unique, one time nature of it. -ㄴ 적이 있다 focuses on the occurrence of an action or event. You can use it for anything people might experience. (There is also -는 적이 있다 and -ㄹ 적이 있다 for present tense and tenseless cases.) For example, 1. A: 너 스위스 가 봤어? B: 응: 작년에 갔었어/가 봤어. Have you ever been to Switzerland? Yes, I went there last year. 2. A: 너 금년 들어서 아팠던 적 있어? B: 아니, 없어. Have your even fallen ill this year? No, never. 3. (police interrogation) 8월 1일 이후로 피해자을 만난 적이 있습니까? = Have you ever met with the victim since August 1st?