• Nuclear Engineering and Technology
• /
• v.54 no.7
• /
• pp.2599-2605
• /
• 2022

The Korea Retrospective Dosimetry network (KREDOS) performed an inter-laboratory comparison to confirm the harmonization and reliability of the results of retrospective dosimetry using mobile phone. The mobile phones were exposed to ¹⁹²Ir while attached to the human phantoms in the field experiment, and the exposure doses read by each laboratory were compared. This paper describes the reference dosimetry performed to present the reference values for inter-comparison and to obtain additional information about the dose distribution. Reference dosimetry included both measurement using LiF:Mg,Cu,Si and calculation via MCNP simulation to allow a comparison of doses obtained with the two different methodologies. When irradiating the phones, LiF elements were attached to the phones and phantoms and irradiated at the same time. The comparison results for the front of the phantoms were in good agreement, with an average relative difference of about 10%, while an average of about 16% relative difference occurred for the back and side of the phantom. The differences were attributed to the different characteristics of the physical and simulated phantoms, such as anatomical structure and constituent materials. Nevertheless, there was about 4% of under-estimation compared to measurements in the overall linear fitting, indicating the calculations were well matched to the measurements.

• Proceedings of the KSRS Conference
• /
• 2005.10a
• /
• pp.178-181
• /
• 2005

The positioning accuracy of the Global Positioning System (GPS) has been improved considerably during the past two decades. The main error sources such as ionospheric refraction, orbital uncertainty, antenna phase center variation, signal multipath, and tropospheric delay have been reduced substantially, if not eliminated. In this study, the GPS data collected by the GPS receivers that were established as continuously operating reference stations by International GNSS Service (IGS), Ministry of the Interior (MOl), Central Weather Bureau (CWB), and Industrial Technology Research Institute (ITRI) Of Taiwan are utilized to investigate the impact of atmospheric water vapor on GPS positioning determination. The surface meteorological measurements that were concurrently acquired by instruments co-located with the GPS receivers include temperature, pressure and humidity data. To obtain the influence of the GPS height on the proposed impact study. A hydrodynamic ocean tide model (GOTOO.2 model) and solid earth tide were used to improve the GPS height. The surface meteorological data (pressure, temperature and humidity) were introduced to the data processing with 24 troposphere parameters. The results from the studies associated with different GPS height were compared for the cases with and without a priori knowledge of surface meteorological measurements. The finding based on the measurements in 2003 is that the surface meteorological measurements have an impact on the GPS height. The associated daily maximum of the differences is 1.07 cm for the KDNM station. The impact is reduced due to smoothing when the average of the GPS height for the whole year is considered.

• Proceedings of the KSRS Conference
• /
• 2003.11a
• /
• pp.625-627
• /
• 2003

In this study, the Global Positioning System (GPS) data collected by the GPS receivers that were established as continuously operating reference stations by Central Weather Bureau and Industrial Technology Research Institute of Taiwan are utilized to investigate the impact of atmospheric water vapor on GPS positioning determination. The surface meteorological measurements that were concurrently acquired by instruments co-located with the GPS receivers include temperature, pressure and humidity data. To obtain the influence of the baseline length on the proposed impact study, four baselines are considered according to the locations of the permanent GPS sites. The length of the shorter baseline is about 66km, while the longer is about 118 km. The results from the studies associated with different baseline lengths and ellipsoid height were compared for the cases with and without a priori knowledge of surface meteorological measurements. The finding based on 66 days measurements is that the surface meteorological measurements have a significant impact on the positioning determination for the longer baseline case. The associated daily maximum differences are 1.1 cm and 1.4 cm for the baseline and ellipsoid height respectively. The corresponding biases are -8.1 mm in length and -7.3 mm in el lipsoid height.

• Bulletin of the Korean Chemical Society
• /
• v.30 no.1
• /
• pp.133-136
• /
• 2009

A newly designed Ag/$Ag^+$ reference electrode in a quartz tube with a tungsten tip junction (W-tip-Quartz- REF) was fabricated and its electrochemical performance was compared with a conventional Pyrex tube-based Ag/$Ag^+$ reference electrode (Py-REF). The results of the electrochemical potential measurements with the W-tip-Quartz- REF and the Py-REF in the LiCl-KCl eutectic melts for a wide temperature range proved that the oxide layer on the surface of the tungsten metal tip provided a high ionic conduction. Stability of our newly designed W-tip- Quartz-REF was tested by measuring a junction potential for 12 hours at 700${^{\circ}C}$. The results of the cyclic voltammetric measurement indicated that the Ag/$Ag^+$ reference electrode in the quartz tube with a tungsten tip junction can provide a good performance for a wide temperature range.

• Journal of Advanced Navigation Technology
• /
• v.19 no.4
• /
• pp.299-304
• /
• 2015

This paper introduces development of the MATLAB GUI based software for generating GPS RINEX observation file. The purpose of this software is to generate GPS measurements of reference station or dynamic user, which are similar to the real GPS receiver data, accurately and efficiently. This software includes two data generation modes. One is Precision mode which generates GPS measurements as accurate as possible using post-processing data. The other is Real-time mode which generates GPS measurements using GPS error modeling technique. GPS error sources are calculated on the basis of each data generation mode, and L1/L2 pseudorange, L1/L2 carrier phase, and Doppler measurements are produced. These generated GPS measurements are recorded in the RINEX observation version 3.0 file. Using received GPS data at real reference station, we analyzed three items to verify software reliability; measurement bias, rate of change, and noise level. Consequently, RMS error of measurement bias is about 0.7 m, and this verification results demonstrate that our software can generate relatively exact GPS measurements.

• Ecology and Resilient Infrastructure
• /
• v.8 no.1
• /
• pp.22-31
• /
• 2021

Surface image velocimetry (SIV) is a noncontact velocimetry technique based on images. Recently, studies have been conducted on surface velocity measurements using drones to measure a wide range of velocities and discharges. However, when measuring the surface velocity using a drone, reference points must be included in the image for image correction and the calculation of the ground sample distance, which limits the flight altitude and shooting area of the drone. A technique for calculating the surface velocity that does not require reference points must be developed to maximize spatial freedom, which is the advantage of velocity measurements using drone images. In this study, a technique for calculating the surface velocity that uses only the drone position and the specifications of the drone-mounted camera, without reference points, was developed. To verify the developed surface velocity calculation technique, surface velocities were calculated at the Andong River Experiment Center and then measured with a FlowTracker. The surface velocities measured by conventional SIV using reference points and those calculated by the developed SIV method without reference points were compared. The results confirmed an average difference of approximately 4.70% from the velocity obtained by the conventional SIV and approximately 4.60% from the velocity measured by FlowTracker. The proposed technique can accurately measure the surface velocity using a drone regardless of the flight altitude, shooting area, and analysis area.

• Wind and Structures
• /
• v.19 no.1
• /
• pp.75-88
• /
• 2014

The computational fluid dynamic is used to explore new aspects of the hill flow. This analysis focuses on flow dependency and the comparison of results from measurements and simulations to show an optimization turbulent model and the possibility of replacing measurements with simulations. The first half of the paper investigates a suitable turbulence model for determining a suitable site for a wind turbine. Results of the standard k-${\varepsilon}$ model are compared precisely with the measurements taken in front of the hilltop, The Reynolds Stress Model showed exact results after 1.0 times of hill steepness but the standard k-${\varepsilon}$ model and standard k-${\omega}$ model showed greater underestimation. In addition, velocity flow over Pha Taem hill topography and the reference geometry shape were compared to find a suitable site for a turbine in case the actual hill structure was associated with the trapezoid geometric shape. Further study of geometry shaped hills and suitable sites for wind turbines will be reported elsewhere.

• The Journal of the Acoustical Society of Korea
• /
• v.19 no.1E
• /
• pp.13-21
• /
• 2000

In this paper, we present the description and results of experimental study of the sound power measurements based on International Standards ISO 3741 and 3745. The sound power emitted by a calibrated reference sound source was measured in a reverberation room and a free field over a reflecting plane, using the precision methods of International Standards ISO 3741 direct method and ISO 3745, respectively. The sound power measurements carried out in this study give accurate estimation and also show that both methods for determining the sound power levels of a sound source in a reverberation room and a free field over a reflecting plane, according to the ISO 3741 and 3745, respectively, have proved equally good.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.26 no.3
• /
• pp.514-520
• /
• 1997

The purpose of this study is to provide the reference data for estimating body composition and developing equations for prediction of percent body fat. This study was designed of two aspects: Comparison of percent body fat measurements between two operators. comparison of percent body fat measurements among four instruments. Percent body fat of college girls(n=71) aged 18-24 was measured by skinfold thickness, near-infratred interactance(Futrex-5000), and bioelectrical impedance analysis (TBF-105, Spectrum II). All measurements were duplicated & measured by two operators. The results are summarized as follows: Percent body fat observed from two operators had no significant difference. There was significant difference from four instruments. However, we found close relation between Skinfold thickness & TBF-105, Spectrum II & Near-infrared interactance. Four instruments have several assumptions and limitations. Therefore, many researches for developing new equations are required for Korean people.

• Journal of Radiation Protection and Research
• /
• v.41 no.3
• /
• pp.211-215
• /
• 2016

Background: The moderated neutron calibration fields using $^{241}Am$-Be sources and a graphite moderator have been constructed at the Facility of Radiation Standard (FRS) in the Japan Atomic Energy Agency (JAEA). Materials and Methods: The neutron spectra of the fields were evaluated by the Monte-Carlo calculations and measurements using the Bonner Multi-sphere Spectrometer. Results and Discussion: The fields have continuous neutron spectra from several MeV to thermal neutron energy, with fluence-averaged energies of 0.84 MeV and 0.60 MeV. Reference values of fluence rates and ambient/personal dose equivalent rates were determined from neutron spectra by measurements. Conclusion: Currently, the fields are available for calibration or performance test of neutron measuring instruments.