REALIZATION AND UNCERTAINTY EVALUATION OF THE ITS-90 FIXED-POINTS FOR THE ESTABLISHMENT OF TEMPERATURE STANDARDS AT KRISS

摘要

In past 20 years KRISS prepared the fixed-points cells for the realization of the ITS-90. Home-made fixed-points was realized using the conventional methods and were estimated the uncertainties for the realization of the fixed points. The uncertainty factors from the impurities of samples, immersion depth of sensor, pressure variation of cells, and temperature gradient was analysed in detail and especially the uncertainty of the AC thermometer bridge arising from the noise factor and non-linearity was measured. The expanded uncertainty for the fixed-points with the coverage factor k=2 was ±0.06mK at the triple point of water and, increased in accordance with the temperature increase, was ±2.34 mK at the freezing point of silver.