Single-frequency Differential GPS Accuracy Improvement via Local Area Ionospheric Time Delay model Development Jan 1, 1999· Doohee Yun Changdon Kee · 0 min read Last updated on Jan 1, 1999 Authors Doohee Yun Ph.D Authors Changdon Kee Professor ← GPS 반송파를 이용한 정밀 측위 Jan 1, 1999 헬리콥터 비행시험을 통한 DGPS 성능평가 Dec 1, 1998 →