Byoung-Hoon, Kim Choi, Jong-Suk KO SANG IL 2024-01-13T07:00:59Z 2024-01-13T07:00:59Z 2021-09-29 https://pubs.kist.re.kr/handle/201004/103824 English beacon localization indoor GPS ultrasonic Unscented Kalman Filter (UKF) Improved Active Beacon System using Multi-modulation and Unscented Kalman Filter for Indoor Localization Conference 1 URAI2006 URAI2006 KO