• Journal of the Korean Vacuum Society
• /
• v.15 no.1
• /
• pp.1-13
• /
• 2006

Vacuum laboratory in Korea Research Institute of Standards and Science (KRISS) was opened in 1983 for establishing and disseminating vacuum standard in Korea. The major three systems such as the ultrasonic interferometer manometer (UIM), the static expansion system (SES) and the dynamic expansion system (DES) with orifice and porous plug conductance are developed. In this study, the standard systems from low to ultra-high vacuum, uncertainty analysis by ISO regulation, and key and bilateral comparison results will be described.

• Proceedings of the KIEE Conference
• /
• 2011.07a
• /
• pp.1075-1076
• /
• 2011

This paper compares performance characteristics and mechanical design specifications of outer rotor radial flux type and double-sided axial flux type permanent magnet generator for 1.5-kW class small scale wind power applications to suggest most suitable type. In order to analyze electromagnetic performances of two different type generators, this paper performs generating performance and efficiency characteristic analysis from electrical parameters obtained by using nonlinear finite element analysis using commercial software, electromagnetic losses characteristics equations and d-q characteristics equation. Considering the derived electromagnetic performance, mechanical design specifications and manufacturing cost, the best suitable model for 1.5-kW class wind power system is determined, and its experiment was performed to validate the suggested analysis method.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.10 no.2
• /
• pp.377-387
• /
• 2009

Digital signatures not only provide a way of guaranteeing the integrity of data but also establish the identity of the signer. However, basic digital signature format which contains only the signature of the signer does not guarantee the correctness of its creation time, and it can not remain valid over long periods. This paper proposes a system which integrates timestamp service into digital signatures. The system provides online services for the creation and verification of long term digital signatures which can give the guarantee of the correctness of their creation times and can be proved to be valid over long periods. The proposed system can be used in the various areas such as e-commerce contracts, document archival services, and invoice applications, which requires long term digital signatures. The proposed system is tested with the KRISS timestamp service system.

• Progress in Superconductivity
• /
• v.9 no.1
• /
• pp.56-61
• /
• 2007

The most recent improvement in the 10 V array system was carried out with focusing on noise reduction. We have evaluated the uncertainty of the 10 V Josephson array system after the improvement. The uncertainty evaluation of 10 V standard included a comparison with a programmable Josephson array system at 1 V. Every contribution to the measurement uncertainty was evaluated in the level of $10^{-10}$. The estimated combined uncertainty was found to be approximately $10^{-9}$ at 10 V, which was limited only by the indirect verifying method. In the near future, a direct comparison with another 10 V Josephson voltage standard is expected to be carried out to provide more accurate uncertainty evaluation for the KRISS Josephson voltage standard.

• Journal of the Korean Society of Costume
• /
• v.55 no.3 s.93
• /
• pp.69-80
• /
• 2005

The anatomical structure of the head and face are influenced by environmental factors. Therefore in this study we had undertaken to determine normal values of the head and face by 3D measurement in the 384 normal Korean male adults to find out craniofacial characteristics of Korean male adults by the age group. From the basic statistical data analysis, vertex-tragion and the length between the pupils were the longest in their twenties and grew shorter in elderly groups. According to the analysis of the craniofacial proportion, the head type of Korean male adults was short-headed. The statistically noticeable differences were found in the measurement of the left and the right sides of face in the age groups of 20, 30, 40, and 50. The results of the factor analysis of the age group showed two groups which were classified to 20, 40, 50 ages and 30, 60 ages. The order of factor analysis was as follows; the perpendicular length, the horizontal length, and the width (from highest).

• Proceedings of the KSME Conference
• /
• 2007.05a
• /
• pp.84-89
• /
• 2007

In order to guarantee the safety of the facility systems, one of the essential components is information on mechanical properties of materials used for the construction. However, acquisition or accumulation of the mechanical property data in industrial fields is limited because this operation does not yield profit, excepting few materials production companies. Corresponding to the urgent needs and poor economical features, the MOCIE has founded the National Center for Standard Reference Data in the KRISS and also designated the Data Center of Mechanical Properties for Metallic Materials (DCMP) as a principal operating section. The DCMP plays roles of collection, edition and evaluation of the mechanical data and development of reference standards. In this study, several functions of the DCMP and standardization procedures of mechanical properties data will be introduced the prospective of standard reference researches will be discussed based on active feedbacks from industrial fields.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.30 no.12 s.255
• /
• pp.1139-1146
• /
• 2006

Light Oil Flow Standard System(LOFSS) in Korea Research Institute of Standards and Science(KRISS) was designed for oil flowmeter calibration. In order to extend the flow range from 120 $m^3/h$ to 200 $m^3/h$, the build-up technique was applied with two positive displacement flowmeters as master flowmeter. The master flowmeters were calibrated against with LOFSS, which has 0.04 % uncertainty of flow quantity determination, then the test flowmeter is calibrated against two master flowmeters. For uncertainty analysis, the repeatability of master flowmeters, the variation of the fluid density and the pipe volume due to temperature change were scrutinized. The contribution of each uncertainty factors to the calibrator and the correlation of each factors were discussed. For investigating the feasibility of uncertainty analysis, a turbine flowmeter as a transfer package was tested with LOFSS and two reference flowmeter. The hypothesis test for both results was coincide with a 95 % significant level. This means that the uncertainty analysis procedure of the calibrator is reasonable and the extension of flow range with master meters was carry out successfully.

• Journal of Astronomy and Space Sciences
• /
• v.30 no.2
• /
• pp.107-112
• /
• 2013

Tissue equivalent proportional counter (TEPC) can measure the Linear Energy Transfer (LET) spectrum and calculate the equivalent dose for the complicated radiation field in space. In this paper, we developed and characterized a TEPC for radiation monitoring in International Space Station (ISS). The prototype TEPC which can simulate a 2 ${\mu}m$ of the site diameter for micro-dosimetry has been tested with a standard alpha source ($^{241}Am$, 5.5 MeV). Also, the calibration of the TEPC was performed by the $^{252}Cf$ neutron standard source in Korea Research Institute of Standards and Science (KRISS). The determined calibration factor was $k_f=3.59{\times}10^{-7}$ mSv/R.

• Korean Journal of Optics and Photonics
• /
• v.15 no.2
• /
• pp.137-141
• /
• 2004

We make a gonioradiometer to realize the scales of total luminous flux and total spectral flux from standards of irradiance and illuminance. Transferring of the photometric scales to a radiometric base has been completed by using a new goniometer to realize a scale of total luminous flux from the scale of illuminance. This is done by measuring the flux emanating from an optical source in different directions and integrating it over an entire imaginary surface surrounding the source. This method is suggested for the realization of the scales of total luminous flux and geometrically total spectral flux. The combined uncertainty of a total flux in the KRISS gonioradiometry is 1 % in the condition of 95% reliance.

• Journal of Positioning, Navigation, and Timing
• /
• v.9 no.3
• /
• pp.261-272
• /
• 2020

A Kalman filter algorithm is used for the generation of an ensemble timescale with three hydrogen masers maintained in KRISS. Allan deviation curves of three pairs of clocks were obtained by a three-cornered hat method and were used as reference curves for determination of parameters of the Kalman filter-based timescale. The ensemble timescale equation of a 3-clock system was established, and the clocks' phases estimated by the Kalman filter were used as the prediction time of each clock in the equation. The weight of each clock was determined inversely proportional to the Allan variance calculated with the clocks' phases. The Allan deviation of the weighted mean was 1.2×10^-16 at the averaging time of 57,600 s. However when we made fine adjustments of the clocks' weight, the minimum Allan deviation of 2×10^-17 was obtained. To find out the reason of the great improvement in the frequency stability, additional researches are in progress theoretically and experimentally.