https://thetreeg.com/ko/2026/06/13/2026-active-learning-summer-intensive-%ed%94%84%eb%a1%9c%ea%b7%b8%eb%9e%a8-%ec%95%88%eb%82%b4/ 2026-06-13T10:07:52Z 더트리그룹 ko 2026 Active Learning Summer Intensive 프로그램 안내 2026-06-13T10:01:58Z Blog