A high-pressure in-situ permeation measuring system was developed to evaluate hydrogen permeation properties of polymer sealing materials under hydrogen environments up to 100 MPa. This system could perform real-time monitoring of hydrogen permeation following high-pressure hydrogen injection, employing the volumetric method for quantitative measurement. By utilizing a self-developed permeation-diffusion analysis program, this system enabled precise evaluation of permeation properties, including permeability, diffusivity and solubility. To apply the developed system to high-pressure hydrogen permeation tests, hydrogen permeation properties of ethylene propylene diene monomer (EPDM) materials containing silica fillers, specifically designed for use in high-pressure hydrogen environments, were evaluated. Permeation measurements were conducted under pressure conditions ranging from 5 to 90 MPa. Results showed that as pressure increased, hydrogen permeability and diffusivity decreased while solubility remained constant regardless of pressure. Finally, the reliability of this system was confirmed through uncertainty analysis of permeation measurements, with all results falling within an uncertainty of 10.8%.

Most temperature indicators that use thermocouples as sensors include an internal thermometer for compensating room temperature variations. This thermometer measures ambient temperature, which is then converted to a thermoelectric voltage. This voltage is added to the electromotive force measured in the thermocouple sensor and then converted back to temperature. Although precise calibration of the indicator can be conducted in a controlled room-temperature environment, additional uncertainty arises due to room temperature compensation during actual measurements. To address this issue, we calibrated temperature indicator at the ice point. In this experiment, the indicator was placed in an environment where the temperature varied between 8 and 38oC, demonstrating its dependency on ambient temperature. In a second set of experiments, we shorted the thermocouple input terminal to verify whether the indicator correctly indicated the ambient temperature. This study proposed a method to assess additional uncertainty that must be considered when using a thermocouple connected to an indicator calibrated with an external ice point in a laboratory. It also highlights additional steps and factors to consider during the calibration of temperature indicators that employ internal temperature compensation.

As per ISO376 : 2011, creep uncertainty can be measured directly or indirectly. In this regard, this paper seeks to provide a comparison between direct and indirect creeps computed from hysteresis. All computations for direct and indirect creeps were done using equations from ISO376 : 2011. Five force measuring devices were experimentally examined for this purpose. Results showed that the behaviors of direct and indirect creeps were quite different. The relative creep that was directly measured was constant. On the other hand, the relative creep that was indirectly estimated varied with the applying force. Therefore, the directly measured creep cannot be replaced by the indirect one. This paper proposes a method to use a representative value for indirect creep, as the maximum of the creep. For the force measuring devices that had good hysteresis characteristics, the directly and indirectly measured creeps were comparable. However, for the force measuring devices with poor hysteresis characteristics, the indirectly estimated creep was much higher than the directly measured creep. Therefore, it is highly recommended to measure the creep directly for the force measuring devices characterized by poor hysteresis.

The International System of Units (acronym: SI) is founded on seven base units (meter, kilogram, second, ampere, kelvin, mole, and candela) corresponding to seven base quantities (length, mass, time, electric current, thermodynamic temperature, amount of substance, and luminous intensity). SI was formally established in 1960 by the 11th CGPM. It has been revised from time to time in response to requirements of users and advances in science and technology. However, the most significant revision is going to be done in November 2018 by the 26th CGPM. Four base units (kilogram, ampere, kelvin, and mole) will be given new definitions linking them to exactly defined values of Planck constant, elementary charge, Boltzmann constant, and Avogadro constant, respectively. In this paper, historical background for the revision of SI is described and scientific principle of redefinition is explained. The procedure used to redefine meter from the speed of light in a vacuum is used as an example. After this revision, uncertainties of many other fundamental constants will be eliminated or reduced. From May 20, 2019 (World Metrology Day), the revised SI will come to practice.