The Seoul National University AMS [SNU-AMS] system has been operated since early 1999 just after completion of the installation work in December 1998 and extensive testing of the accuracy and reproducibility of the system has been carried out, and ca 1000 unknown samples have been measured so far. We obtained a precision of 4‰ for modern ages, and an accuracy of ca 40 yr. was demonstrated by analyzing samples which were previously dated with a conventional technique and by other AMS laboratories. In this colloquium, a brief description for the basic principle of the accelerator mass spectrometry will be given, followed by some intersesting applications made so far to the Korean archaeology ,and also a few examples of geological applications such as dating of Siberian permafrost for the paleo-climate studies.