Article 42 of "National Calibration Laboratory Designation System Operation Guidelines" provides that those who possess or use the measuring instruments should calibrate the relevant measuring instrument periodically to improve the national measurement standards according to the provisions of Article 14 of Framework Act on National Standards and the traceability among the measuring instruments used in all the fields in the country and to do that, they may determine and operate the calibration subjects and application scope as bylaw"

The reason why the calibration should be made in the industrial fields is because the test and measurement should be made with the measuring instrument that maintains the acceptable accuracy. The accuracy can be validated based on the tolerance required in the specification. Such accuracy test is achieved by comparing and calibrating periodically using the higher standards. Therefore, the calibration subject should be set based on the confidence if the performance of the subject to be measured can be maintained within the tolerance required by individual object. However, there is the case that the calibration is not needed for the performance or structure of the measuring instrument, or the national measurement standards are not established or the appropriate calibration method is not developed (Ex: surface characteristics, non-invasive test filed, etc.

Clause 2, Article 42 of "National Calibration Laboratory Designation System Operation Guidelines" provides that those who possess and use the measuring instruments should establish the standards scientifically and reasonably considering the precision and accuracy, stability, purpose of use, environment and frequency of use, etc. when they want to set the calibration cycle by themselves. However, in the event that they cannot determine their calibration cycle scientifically and reasonably, the calibration cycle published separately by Director of Korean Agency for Technology and Standards shall be applied." However, the standard calibration cycle determined in the detailed operating rule is the calibration cycle that estimates the period to maintain the precision and accuracy of that measuring instrument when it is used under the most common situation. It provides the standard calibration cycle for total 448 types of measuring instrument in 25 measurement fields but it is recommended that each industry using the measuring instrument or those who possess it should adjust the cycle considering the accuracy and stability of the measuring instrument, purpose of use, environmental condition and frequency of use.

That means that as the work environment, measurement range and range of tolerance may be varied by department although the same business site, establishing the calibration cycle uniformly is unreasonable, and to establish the appropriate calibration cycle, it is desirable to establish the calibration cycle based on the data investigated the actual condition of use and the measured value by department for certain period. Therefore, the matter that should be considered the most basically is securing the measurement data accumulated in the past, which is the basis of cycle adjustment.