A smart measurement system for an on-line gamma monitoring has been developed to overcome the problems of a conventional system which cannot automatically restore the previous-lost data of several posts by a radio telemetry. It is similar to the conventional system except for a new electronic circuit board and an integrated operation program. The new electronic circuit board is able to store the radiation data with a time tag of 6 or more months if the recording interval time is 10 s. The operation program automatically sends the time correction command to the six monitoring posts for a daily synchronization between the monitoring posts and the central control computer as a Korean mean time. The previous-lost radiation data for 6 or more months could be restored by using two components with the functions of a time tag and a daily synchronization without any additional equipment. It was tested for more than 1 year, from which the test results, the data collection rate was dramatically improved without any tedious manual work, which was almost about 100% for 1 year. The smart measurement system has been applied for an effective gamma monitoring around the nuclear facilities at KAERI since it was developed and tested in 2003.