Jin Wan Chung

Report on CIPM key comparison of the second phase of multiples and submultiples of the kilogram (CCM.M-K5)

In order to show equivalence of mass standard determination among NMIs of CIPM member countries, key comparisons of mass standards have been carried out under the auspices of the CCM. At each NMI, mass standards are derived from one kilogram by means of the multiples and submultiples methods. The pilot laboratory, NMIJ, prepared five sets of transfer standards. Any set of transfer standard consists of five pairs of mass standards with nominal values of 200 mg, 1 g, 50 g, 200 g and 2 kg. The nominated twenty participants have been divided into four groups and the corresponding four sets of transfer standards have been circulated within the groups simultaneously while the remaining set has been kept at the pilot laboratory for the stability evaluation. The pilot laboratory measured the volumes, the centres of gravity and the magnetic properties, susceptibilities or magnetism, of the standards before the circulation and has reported these values to the participants. The pilot laboratory has also verified the stability of all travelling standards in advance. Nineteen laboratories have reported final results to the pilot. Nine participants belong to EURAMET, three belong to COOMET but two of them also belong to EURAMET, four belong to SIM, and five belong to APMP. Table 2 shows all the results associated with their uncertainties reported by the participants. As shown in table 3 the majority of the instabilities of the transfer standards during their circulation were less than the claimed uncertainties of the participants except for few standards of small mass, 1 g and 200 mg. These instabilities are considered for uncertainty evaluation within the group. All reported results among different groups have been linked based on the average values of transfer standards before and after the circulation. Figures 3 to 7 show the comparison results of all the participants for five nominal mass values respectively. The plotted results are expressed in relation to the median as reference values. Tables 10 to 19 show the differences and associated expanded uncertainties referred to a confidence level of 95% between any combination of the laboratories in the form of matrices. They show a few outliers, one at 2 kg and 200 g, three at 50 g, and two at 200 mg. 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 CCM, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

Magnetic properties comparison of mass standards among seventeen national metrology institutes

The ubiquitous technology of magnetic force compensation of gravitational forces acting on artifacts on the pans of modern balances and comparators has brought with it the problem of magnetic leakage from the compensation coils. Leaking magnetic fields, as well as those due to the surroundings of the balance, can interact with the artifact whose mass is to be determined, causing erroneous values to be observed. For this reason, and to comply with normative standards, it has become important for mass metrologists to evaluate the magnetic susceptibility and any remanent magnetization that mass standards may possess. This paper describes a comparison of measurements of these parameters among seventeen national metrology institutes. The measurements are made on three transfer standards whose magnetic parameters span the range that might be encountered in stainless steel mass standards.

Development of a new dynamic gas flow-control system in the pressure range of 1 Pa–133 Pa

A new flow-control system (FCS-705) has been developed at Korea Research Institute of Standards and Science. The system is intended for calibration of vacuum gauges in the pressure range of 1 Pa-133 Pa by comparison method. This paper describes some basic characteristics of the system including; (1) the design and construction of the system, (2) the generation of stable pressures in the chamber, (3) achieving high upstream pressure limit by installing a short duct in the by-pass pumping line, and (4) investigation of the gas flow regimes within the short duct.

Final report on APMP.M.M-K2.1: Bilateral comparison of four stainless steel mass standards (500 g, 20 g, 2 g and 100 mg) between KRISS and NPLI

This report describes a bilateral comparison of 500 g, 20 g, 2 g and 100 mg stainless steel mass standards between Korea Research Institute of Standards and Science (KRISS) and National Physical Laboratory, India (NPLI), which is registered in the KCDB as APMP.M.M-K2.1. These nominal values were chosen as they followed the nominal values of CCM.M-K2. This bilateral comparison was piloted by KRISS. The Measurement Standard Laboratory (MSL), New Zealand has provided a linkage analysis of this bilateral comparison to CCM.M-K2. The set of four weights was circulated between KRISS and NPLI laboratories in June 2010 and received back from the last participant in July 2010. NPLI has tried to improve their calibration and measurement capabilities (CMCs) for mass below 1 kg. KRISS participated in both this comparison and CCM.M-K2, providing the link between the NPLI results and the key comparison reference value of CCM.M-K2. 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 CCM, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

Final report of the APMP comparison of mass standards: APMP.M.M-K6 (SUB) multiples mass key comparison

This report summarizes the results of a comparison of mass standards conducted between eleven participating members, including the pilot laboratory, of the Asia-Pacific Metrology Program (APMP). One set of five weights with nominal mass values 10 kg, 500 g, 20 g, 2 g and 100 mg were used as traveling artifacts. These nominal values were chosen as they followed the nominal values of CCM.M-K2. The program was piloted by the National Physical Laboratory, New Delhi, India (NPLI), and the Center for Measurement Standards, Industrial Technology Research Institute (CMS-ITRI), Taiwan, Korea Research Institute of Standards and Science (KRISS), Korea, and Measurement Standards Laboratory (MSL), New Zealand, have provided all other help to successfully organize and run the comparison. The set of five weights was circulated among all the participating laboratories in July 2004 and received back from the last participant in March 2007. The final report of this comparison is being given in this document. 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 CCM, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).