The 4th Annex 69 Experts Meeting was held in Seoul, Korea. Thirty-six participants from 11 countries attended the meeting. Dr. Hui Zhang (on behalf of Prof. Edward Arens), Prof. Bjarne Olesen, and Prof. Richard de Dear introduced updates of Subtasks A, B, and C, as well as leading discussion about the next step work. It was also agreed among the whole team that Annex 69 will hold a joint seminar with Annex 66 during the next experts meeting.