• Journal of Korean Ophthalmic Optics Society
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• v.6 no.2
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• pp.71-75
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• 2001

In this paper, a three-dimensional measuring system of thermoluminescence(TL) spectra based on temperature, wavelength and luminescence intensity was introduced. The system was composed of a spectrometer, temperature control unit for thermal stimulation, photon detector and personal computer for control the entire system. Temperature control was achieved by using feedback to ensure a linear-rise in the sample temperature. Digital multimeter(KEITHLEY 195A) measures the electromotive force of Copper-Constantan thermocouple and then transmits the data to the computer through GPIB card. The computer converts this signal to temperature using electromotive force-temperature table in program, and then control the power supply through the D/A converter. The spectrometer(SPEX 1681) is controlled by CD-2A, which is controlled by the computer through RS-232 communication port. For measuring the luminescence intensity during the heating run, the electrometer(KEITHLEY 617) measures the anode current of photomultiplier tube(HAMAMATSU R928) and transmits the data to computer through the A/D converter. And, we measured and analyzed thermoluminescence of $CaSO_4$ : Dy, P using the system. The measuring range of thermoluminescence spectra was 300K-575K and 300~800 nm, $CaSO_4$ : Dy. P was fabricated by the Yamashita's method in Korea Atomic Energy Research Institute(KAERI) for radiation dosimeter. Thermoluminesce spectra of the $CaSO_4$ : Dy, P consist of two main peak at temperature of $205^{\circ}C$, wavelength 476 nm and 572 nm and with minor ones at 658 nm and 749 nm.

• The Journal of the Korea Contents Association
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• v.16 no.7
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• pp.681-688
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• 2016

This study assess their quality of radiation on analysis of the spectrum of resolution suggesting IEC 61267 in radiation quality that RQA3, RQA5, RQA7, RQA9 and combination of clinical condition using several quality of radiation. In experiments edge method first, the spatial resolution assessment used image of the additional filter and SID is obtained the IEC 62220-1, spatial resolution and sharpness of the obtained image was evaluated in the MTF value 10%(0.1), MTF value 50%(0.5) using a Matlab program. Second, MCNPX simulation used spatial resolution analysis was radiation quality particle fluence and spectrum analysis in energy. As a result, make use of additional filter, image quality evaluation of SID that RQA3 radiation quality combination qualification is higher spatial resolution and sharpness make unused of additional filter and SID 100cm. RQA7 radiation quality combination qualification is higher that spatial resolution make unused of additional filter and SID 150cm. RQA9 radiation quality combination qualification is higher that spatial resolution and sharpness make used of additional filter and SID 180cm. spectrum analysis of radiation quality by reducing consequent errors occurring in the experiment that error due to the reproducibility of the X-ray tube, occur in an error of correction the detector suggest ideal conditions from spectrum analysis through MCNPX simulation. In conclusion, by suggesting spatial resolution and sharpness of result for various radiation quality, It provide basic data that radiation quality condition and quantitative assessment method for laboratory in clinical using detector evaluation.

• Journal of radiological science and technology
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• v.33 no.1
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• pp.51-59
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• 2010

We developed an analysis software that automatically detects incoming isotopes for multi-purpose gamma-ray detectors. The software is divided into three major parts; Network Interface Module (NIM), Spectrum Analysis Module (SAM), and Graphic User Interface Module (GUIM). The main part is SAM that extracts peak information of energy spectrum from the collected data through network and identifies the isotopes by comparing the peaks with pre-calibrated libraries. The proposed peak detection algorithm was utilized to construct libraries of standard isotopes with two peaks and to identify the unknown isotope with the constructed libraries. We tested the software by using GammaPro1410 detector developed by NuCare Medical Systems. The results showed that NIM performed 200K counts per seconds and the most isotopes tested were correctly recognized within 1% error range when only a single unknown isotope was used for detection test. The software is expected to be used for radiation monitoring in various applications such as hospitals, power plants, and research facilities etc.

• Journal of the Korean Society of Radiology
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• v.4 no.2
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• pp.21-25
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• 2010

Recently, various semiconductor compounds as radiation detection material have been researched for a diagnostic x-ray detector application. In this paper, we have fabricated the CdS detecton sensor that has good photosensitivity and high x-ray absorption efficiency among other semiconductor compounds, and evaluated the application feasibility by investigating the detection properties about energy range of diagnostic x-ray generator. We have fabricated the line voltage selector(LCV) for a signal acquisition and quantities of CdS sensor, and designed the voltage detection circuit and rectifying circuit. Also, we have used a relative relation algorithm according to x-ray exposure condition, and fabricated the interface board with DAC controller. Performance evaluation was investigated by data processing using ANOVA program from voltage profile characteristics according to resistive change obtained by a tube voltage, tube current, and exposure time that is a exposure condition of x-ray generator. From experimental results, an error rates were reduced according to increasing of a tube voltage and tube current, and a good properties of 6%(at 90 kVp) and 0.4%(at 320 mA) ere showed. and coefficient of determination was 0.98 with relative relation of 1:1. The error rate according to x-ray exposure time showed exponential reduction because of delayed response velocity of CdS material, and the error rate has 2.3% at 320 msec. Finally, the error rate according to x-ray dose is below 10%, and a high relative relation was showed with coefficient of determination of 0.9898.

• The Journal of Engineering Geology
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• v.27 no.1
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• pp.51-58
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• 2017

The purpose of this study was to quantitatively evaluate the state of rocks in load steps by using the low-frequency ultrasonic flaw detection method. The initial Vp-velocities measured with a CND tester were in the order of Z-axis < X-axis < Y-axis, with 1687.5 m/s along the X-axis, 1690.7 m/s along the Y-axis, 1548.3 m/s along the Z-axis, and an average of 1642.2 m/s. The overall average of the Q vlaues, measured with a Silver Schmidt hammer, was 62.6, which corresponds to a uniaxial compressive strength of ~105 MPa. The Vp-velocity, measured with a low-frequency ultrasonic flaw detector at load steps of 50%, 60%, 70%, and 80%, typically decreases in the order of X-axis < Y-axis < Z-axis with increasing load steps. This oder contrasts with that of the initial Vp-velocities. As the load step increases the factors that reduce the Vp-velocity in the X-axis direction are more influential than those in the Y-axis or Z-axis directions. This indicates that the initial state of rocks can vary and is dependent on the stress state.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.5
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• pp.282-287
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• 2017

The purpose of this study was predicted the effects of mixing and diffusion due to the operation of the apparatus before the development of the mixed diffusion device for the decontamination absorbent to minimize the influence of contaminant inflow due to radiation accident. The tracer used for the flow characteristics was $^{68}Ga$, $^{99m}Tc$, which is a radioactive isotope, and 2 inch NaI radiation detector was used to detect it. The impeller of the decontamination mixed diffusion system applied to this study was made into three types and the mixing diffusion effect was compared. As a result of analyzing the flow characteristics of the radio-isotope with decontamination mixed diffusion device, mixing, diffusion and flow pattern were obtained. The radial mixing type impeller was able to diffuse to the water surface by the upflow flow, and the fin structure was adjusted for finding optimal conditions. The model 3 type consists of a fin guiding part and an auxiliary fin so that the diffusion speed is higher than that of other types of impellers. It also showed a short time to reach complete mixing.

• Journal of Astronomy and Space Sciences
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• v.21 no.4
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• pp.481-492
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• 2004

We report the successful fabrication and I-V curve superconductivity test results of the Nb/Al-based superconducting tunnel junctions. STJs with side-lengths of 20, 40, 60 and $80{\mu}m$ were fabricated by deposition of polycrystalline Nb/Al/AlOx/Al/Nb 5-layer thin films incorporated on a 3-inch Si wafer. STJ was designed by $Tanner^{TM}$ L-Edit 8.3 program, and fabricated in SQUID fabrication facility, KRISS. S-layer STJ thin-films were fabricated using UV photolithography, DC magnetron sputtering, Reactive ion etching, and CVD(Chemical Vapor Deposition) techniques. Superconducting state test for STJ was succeeded in 4K with liquid helium cooling system. Their performance indicators such ie energy gap, normal resistance, normal resistivity, dynamic resistance, dynamic resistivity, and quality factor were measured from I-V curve. Fabricated Nb/Al STJ shows $11\%$ higher FWHM energy resolution than genuine Nb STJ.

• Geophysics and Geophysical Exploration
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• v.18 no.3
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• pp.154-161
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• 2015

For efficiently designing neutron induced gamma spectroscopy sonde, Monte Carlo simulation is employed to understand a dominant location of thermal neutron and classify the formation elements from the energy peak of capture gamma spectrum. A pulsed neutron generator emitting 14 MeV neutron particles was used as a source, and flux of thermal neutron was calculated from the twelve detectors arranged at each 10 cm intervals from the source. Design for reducing borehole effects using shielding materials was also applied to numerical sonde model. Moreover, principal elements and quantities of numerical earth models were verified through the energy spectrum analysis of capture gamma detected from a gamma detector. These results can help to enhance the signal-to-noise ratio, and determine an optimal placement of capture gamma detectors of neutron induced gamma spectroscopy sonde.

• Transactions of the Korean hydrogen and new energy society
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• v.26 no.1
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• pp.21-27
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• 2015

Hydrogen production from commercial diesel fuels is an attactive option for energy generation purpose due to the low cost and good availability of diesel fuels. However, in order to utilize commercial diesel fuels, the sulfur contents must be removed down to approximately 0.1 ppm level to protect the fuel cell catalysts from poisoning. Commercial catalysts $CoMo/Al_2O_3$ and $NiMo/Al_2O_3$ were tested for HDS (Hydrodesulfurization) of model diesel and commercial diesel. The experimental conditions were $250-400^{\circ}C$ and LHSV (Liquid Hourly Space Velocity) $0.27-2.12hr^{-1}$. $NiMo/Al_2O_3$ was found to be more effective than $CoMo/Al_2O_3$ in removing sulfur from model diesel. Based on the experimental results of model diesel, commercial diesel fuel purchased from a local petrol station was tested for HDS using $NiMo/Al_2O_3$. The GC-SCD (Gas Chromatography Sulfur Chemiluminescence Detector) results showed that the DMDBT (Dimethyldibenzothiophene) derivatives were fully removed from the commercial diesel fuel proving that HDS with $NiMo/Al_2O_3$ is technically feasible for industrial applications.

• Analytical Science and Technology
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• v.23 no.5
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• pp.465-476
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• 2010

In this study, a number of volatile organic compounds (VOCs) including benzene, toluene, p-xylene, styrene, and methyl ethyl ketone were analyzed from samples collected in ambient air and under the field conditions. These samples were analyzed independently by two different set-ups for VOC analyses, i.e., between [1] gas chromatography/flame ionization detector with tube sampling - (F-T system) and [2] gas chromatography/mass spectrometer with bag sampling (M-B system). The analytical results derived by both systems showed fairly similar patterns in relative sense but with moderately large differences in absolute sense. The results of M-B system were high relative to F-T system with the F-T/M-B ratio below 1. If the relative biases of the two measurement techniques are derived in terms of percent difference (PD) in concentration values, the results were generally above 35% on average. A student t-test was applied to investigate the statistical significance of those differences between the systems. The results of both analytical systems were different at 95% confidence level for toluene, p-xylene, styrene, and methyl ethyl ketone (P < 0.043). However, F-T and M-B systems showed strong correlations for toluene and p-xylene. The observed bias is explained in large part by such factors as the differences in standard phases used for each system and the chemical loss inside the bag sampler.