As a part of the ongoing BIPM key comparisons BIPM.EM-K11.a and b, a comparison of the 1.018 V and the 10 V voltage reference standards of the BIPM and the Korea Research Institute of Standards and Science (KRISS), Daejeon, Republic of Korea, was carried out in February 2008. One KRISS Zener diode (Fluke 732A) was used as a transfer standard. KRISS measurements were carried out by comparison with the KRISS primary voltage standard consisting of a Josephson Voltage Standard. BIPM measurements were carried out on site, at KRISS by comparison with the BIPM transportable Josephson Voltage Standard. The transfer standard wasn't characterized for the effects of temporal drift and environmental influences as both participants measured the Zener within a short time period. For day to day measurement, the voltage assigned by the BIPM to the transfer standard, U_BIPM, was computed using a linear least-square fit to all of the data from the BIPM and referenced to the mean time of the KRISS measurements. The final result is the simple mean of the daily result over the total period of the comparison (6 days).

The final result of the comparison is presented as the difference between the value assigned to a 1.018 V and 10 V standard by the KRISS, U_KRISS, and that assigned by the BIPM, at the KRISS, U_BIPM, which for the reference date is:

at 1.018 V, U_KRISS − U_BIPM = 70 nV; u_c = 48 nV on 2008/02/26
at 10 V, U_KRISS − U_BIPM = −31 nV; u_c = 100 nV on 2008/02/26,

where u_c is the standard uncertainty associated with the measured difference, including the uncertainty of the representation of the volt at the BIPM, the uncertainty of the representation of the volt at KRISS, both based on K_J-90, and the uncertainty related to the comparison.

This satisfactory result shows that the voltage standards maintained by the KRISS and the BIPM were equivalent, within their stated expanded uncertainties, on the mean date of the comparison.

Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.

The final report has been peer-reviewed and approved for publication by the CCEM, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).