• Mass Spectrometry Letters
• /
• v.9 no.4
• /
• pp.105-109
• /
• 2018

A certified reference material (CRM) for the analysis of inorganic nutrients in nutritional supplements has been developed. Accurate mass fractions of chromium (Cr), iron (Fe), copper (Cu), and zinc (Zn) were determined by isotope dilution inductively coupled plasma mass spectrometry (ID ICP/MS). The measurement results were used to assign certified values for the CRM, which were metrologically traceable to the definitions of the measurement units in the International System of Units (SI). Production of a candidate reference material (RM) and the certification processes are summarized. Each nutrient in the CRM showed good homogeneity, which was estimated using relative standard deviations of the measurement results of twelve bottles in a batch. This CRM is expected to be an important reference to improve reliability and comparability of nutrient analyses in nutritional supplements and related samples in analytical laboratories.

• Korean Journal of Optics and Photonics
• /
• v.21 no.3
• /
• pp.123-128
• /
• 2010

Sum frequency generation was utilized to obtain a yellow laser with the wavelength of 578.4 nm for a probe laser of an Yb lattice clock. The output of an Nd:YAG laser with wavelength of 1319 nm and that of an Yb-fiber laser with wavelength of 1030 nm were passed through a waveguided periodically-poled lithium niobate (WG-PPLN) for sum frequency generation. It is required that the probe laser has a linewidth of the order of 1 Hz to fully resolve the Yb lattice clock transition. Thus, the linewidth of the probe laser was reduced by stabilizing the frequency to a super-cavity. This was made of ULE with a low thermal expansion coefficient, and was mounted on an active vibration-isolation table at the optimal point for the reduced sensitivity to vibration. Also, this was installed in a vacuum chamber, and the temperature was stabilized to 1 mK level. This system was installed in an acoustic enclosure to block acoustic noise. The finesse of the super-cavity was measured to be 380 000 from the photon life time of the cavity.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2009.06a
• /
• pp.267-268
• /
• 2009

Resistance standards from 1 ${\Omega}$ to 100 $k{\Omega}$, with calculable frequency dependencies of up to 1 MHz, have been developed for the calibration of commercial inductance-capacitance-resistance (LCR) meters and impedance analyzers. The resistors are designed on the basis of single bifilar loops. The typical resistance change from dc to 1 MHz is from 200 to $800\;{\mu}{\Omega}/{\Omega}$. According to the measurement results, the frequency dependencies of the resistors are severaltimes lower than the measurement uncertainty of commercial LCR meters.

• Applied Science and Convergence Technology
• /
• v.23 no.3
• /
• pp.103-112
• /
• 2014

The Korea Research Institute of Standards and Science (KRISS) has three major vacuum systems: an ultrasonic interferometer manometer (UIM; Section II, Figs. 1 and 2) for a low vacuum, a static expansion system (SES; Section III, Figs. 3 and 4) for a medium vacuum, and an orifice-type dynamic expansion system (DES, Section IV, Figs. 5 and 6) for high and ultra-high vacuum systems. For each system, explicit measurement model equations with multiple variables are given. According to ISO standards, all of these system variable errors were used to calculate the expanded uncertainty (U). For each system, the expanded uncertainties (k = 1, confidence level = 95%) and relative expanded uncertainty (expanded uncertainty/generated pressure) levels are summarized in Table 4. Within the uncertainty limits, our bilateral and key comparisons [CCM.P-K4 (10 Pa to 1 kPa)] are extensive and in good agreement with those of other nations (Fig. 8 and Table 5).

• Journal of Sensor Science and Technology
• /
• v.7 no.6
• /
• pp.401-408
• /
• 1998

A dual-channel automatic ac-dc voltage transfer error measurement system in which the output voltages of two thermal voltage converters which are ac voltage standard are directly measured at the same time to reduce the output voltage drift is described. Forward-reverse measurement method by using a two-channel scanner is used to cancel the offset voltage of the voltmeters. The agreements of the 4-V TVC comparison results between other national standards institute and Korea Research Institute of Standards and Science were less than about ${\pm}2\;ppm$ in the frequency range of $40\;Hz{\sim}100\;kHz$, and were less than about ${\pm}4\;ppm$ at $200\;kHz{\sim}1\;MHz$. Measurement uncertainty is reduced significantly from ${\pm}4\;ppm$ of manual system to ${\pm}3\;ppm$ of new system(up to 100 kHz) typically and great increase in comparison efficiency has been achieved by this system.

• Journal of the Korean Solar Energy Society
• /
• v.34 no.1
• /
• pp.117-124
• /
• 2014

Airtightness standards using fan pressurization method are normally used for measuring small buildings, detached houses, and apartment units. And, it is easy to conduct airtightness measurement through this fan pressurization method. However, it can be difficult to achieve accurate measurement results for the large buildings as the height and volume of the buildings have been increased. In this paper, we studied the principle of airtightness method by fan pressurization. And, we reviewed the measurement process described in ISO 9972, EN 13829, ASTM E779, ATTMA TS 1, CAN/CGSB 149.15, and JIS A 2201. Then, we categorized the methods' items according by air flow rate (Q) and pressure difference(${\Delta}P$). As a result, we made a comparison analysis on the measurement methods appeared in each standards. And, we achieved 5 test conditions about air flow rate and pressure difference to state requirements for large buildings airtightness measurement.

• Journal of Biomedical Engineering Research
• /
• v.12 no.4
• /
• pp.309-314
• /
• 1991

This paper describes the results of study on the measurement method of TRMS (true root mean square value) In electrosurgical unit. We used three type (direct computing type, indirect computing type, thermal converting type) in the measurement of TRMS. Three types of measurement method were compared with respect to power level, frequencey and crest factor in addition to environmental temperature. In three of them, the thermal converting type was the best for th electrosurgical unit analyzer

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.24 no.3
• /
• pp.253-258
• /
• 2013

In this paper, a free-space material measurement technique is discussed in W-band(75~110 GHz). For the accurate measurement of S-parameters of an MUT(Material Under Test) in free space, a W-band quasi-optical free-space material measurement system, less affected by the measurement environments, is discussed, and GRL(Gated Reflect Line) method for calibrating the measurement system is described. Proposed technique is verified for 'Air' and measurement results for arystal plates of thickness 1.1 mm, 2 mm, 2.75 mm and 5 mm are also shown.

• Bulletin of the Korean Chemical Society
• /
• v.31 no.11
• /
• pp.3139-3144
• /
• 2010

A model system has been established for the evaluation of the uncertainty of the value from measurements of multiple subsamples by isotope dilution mass spectrometry (IDMS). In this report, we apply this model system for the evaluation of measurement uncertainty in determination of folic acid in infant formula. Five subsamples were analyzed by IDMS. The mean of the measurement results of the five subsamples was assigned as the final measurement value. The standard deviation (s) of the results from five subsamples was attributable to repeatability of the measurement. The uncertainty components in the IDMS measurement methods were categorized into two groups. Group I includes uncertainty components which give common systematic effects to all subsamples and do not contribute to the variation among multiple measurements (repeatability). Group II includes uncertainty components that give random effects on the measurement results, and are related with the measurement repeatability. These random effects are attributed to s. Therefore, the uncertainty of the final value was calculated by combining the standard deviation of the mean of multiple measurements, $s/{\surd}n$ (where n = 5), and the measurement uncertainty associated with the uncertainty components that give systematic effects.

• Proceedings of the Korean Magnestics Society Conference
• /
• 2003.12a
• /
• pp.215-215
• /
• 2003