• Journal of the East Asian Society of Dietary Life
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• v.18 no.1
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• pp.49-57
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• 2008

In order to control or kill insects and pests, control ripening, and delay spoilage, kiwifruits were irradiated with gamma rays at 0.1, 0.3, and 0.5 kGy. Vitamin C, hydrogen donating activity, sugar content, organic acid content, texture, chromaticity, and sensory qualities were examined in the fruits over 2 weeks of storage at 20$^{\circ}C$. Vitamin C content and hydrogen donating activity decreased during the storage period, but they were not reduced by the irradiation process. Total sugar and reducing sugar contents increased as the storage period increased; however, these were also unaffected by irradiation. Organic acid content significantly decreased as a result of irradiation, and all samples had decreases in organic acids over the storage period. Hardness decreased with the storage period as well as with increasing doses of irradiation. In terms of Hunter's color values, irradiation increased the $L^*-\;and\;a^*-$ values in the initial storage period, but it did not have any significant effect on these values during the 2 weeks of storage. When compared with control samples, the irradiated samples had lower color and overall acceptability scores just after irradiation (week 0). However, during the storage period, the irradiated samples had higher scores for smell, taste, texture, and overall acceptability than the control. In conclusion, based on the results, gamma irradiation up to 0.5 kGy is the recommended treatment to maintain the overall quality attributes kiwifruit.

• Analytical Science and Technology
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• v.16 no.1
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• pp.39-47
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• 2003

The measurement of radium ($^{226}Ra$) in the groundwater was established using ${\gamma}$-ray spectroscopy without sample preparation. The background interference by air borne radon daughter nuclides was reduced by $N_2$ gas flow into the counting chamber. Leakage of radon gas produced in the radioactive equilibrium with radium and its daughter nuclides was prevented by use of the air-tighted aluminium container. We investigated the effect of air layer in the counting container. Radioactivity variation due to emanation of radon into the air layer was within the counting error range 5%. When the nitrogen gas was flowed around the detector, peak counts of ${\gamma}$-rays from the daughters of airborne radon was decreased and detection limit was decreased to 0.02 Bq/L. The detection limit of detector was lower than 0.74 Bq/L, the $^{226}Ra$ Maximum Contaminant Level (MCL) in the groundwater proposed by US Environmental Protection Agency (EPA). It was confirmed that $^{226}Ra$ radioactivity in the groundwater could be determined by the ${\gamma}$-ray spectroscopy.

• Journal of radiological science and technology
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• v.45 no.6
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• pp.523-529
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• 2022

Gamma spectroscopy analysis is widely used for radioactivity analysis, and various factors are required for radioactivity calculations. Among the factors, K3 for each sample significantly influences the results. The previous methods of correcting the self-absorption effect include a computational simulation method and a method that requires making a CRM(certified reference material) identical to the sample medium. However, the above methods have limitations when used in small institutions because they require specialized program utilization skills or high manufacturing costs and large facilities. The aim of this study is to develop a method that can be easily and rapidly applied to radioactivity analysis. After filling the beaker with water, we placed the radiation source in a uniform position and used the measured value as the benchmark. Next, a correction factor was derived based on the difference in the radiation source count of the benchmark and the identically measured sample. For the radiation source, Eu-152, which emits a broad range of energy within the measurement range of gamma rays, and Cs-134 and Cs-137, which are indicator nuclides in environmental radiation analysis, were used. The sample was selected within the density range of 0.26-2.11 g/cm³, and the correction factor was derived by calculating the count difference of each sample compared to the reference value of water. This study presents a faster and more convenient method than the existing research methods for determining the self-absorption effect correction, which has become increasingly necessary.

• Journal of the Korean Society of Radiology
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• v.82 no.6
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• pp.1524-1533
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• 2021

Purpose To investigate the incidence of tuberculosis (TB) in healthcare workers (HCWs) with positive interferon-gamma release assay (IGRA) results based on chest X-ray (CXR) and CT findings and determine the role of imaging in the diagnosis of TB. Materials and Methods Among 1976 hospital personnel screened for TB using IGRA, IGRApositive subjects were retrospectively investigated. Clustered nodular and/or linear streaky opacities in the upper lung zone were considered positive on CXR. The CT findings were classified as active, indeterminate, inactive, or normal. The active or indeterminate class was considered CT-positive. Results IGRA was positive in 255 subjects (12.9%). CXR and CT were performed in 249 (99.2%) and 113 subjects (45.0%), respectively. CXR- and CT-positive findings were found in 7 of 249 (2.8%) and 9 of 113 (8.0%) patients, respectively. Among the nine CT-positive subjects, active and indeterminate TB findings were found in 6 (5.3%) and 3 (2.7%) patients, respectively. Microbiological tests, including acid-fast bacilli staining, culture, and polymerase chain reaction for TB, were negative in all nine CT-positive subjects. Empirical anti-TB medications were administered to 9 CT-positive subjects, and 3 of these nine subjects were CXR-negative for pulmonary TB.

• Journal of the Korean Recycled Construction Resources Institute
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• v.5 no.1
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• pp.45-52
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• 2017

This study evaluated the durability of nuclear power plant concrete. The main parameters were the water-to-binder ratio and admixture type. The results revealed that high-volume ground granulated blast-furnace slag(GGBS) concrete had lower initial strength, while the strength reached higher after 28 days. On the other hand, the initial strength of fly ash blended concrete was high, but the long-term strength of the robbery was low. The measured durability of GGBS blended concrete was found to be better than that of the existing concrete mix for use in the construction of nuclear power plants. Especially, the GGBS blended concrete was more durable than the fly ash blended concrete in terms of chloride attack, carbonation resistivity and freezing-thawing durability in low compressive strength. The effects of concrete compressive strength according to gamma rays were minor.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.2
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• pp.600-604
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• 2011

In this paper, the scintillation properties of $LaCl_3:Eu^{2+}$ crystal were investigated as new scintillator. This scintillation material was grown by a Czochralski method. $LaCl_3:Eu^{2+}$ was determined to have a hexagonal $P_63$/m space group with cell parameters a = b = $7.48{\AA}$, c = $4.37{\AA}$. Under 335 nm UV excitation, the crystal shows a broad emission band between 370 nm and 640 nm wavelength range, peaking at 430 nm. At room temperature, the crystal exhibits one exponential decay time component. The component of scintillation time profile of the crystal emission decays with a $2.82{\pm}0.72{\mu}s$ time constant. The energy resolution of the crystal was measured to be 8.8% (FWHM) for $^{137}Cs$ 662 keV ${\gamma}$-rays.

• Journal of Astronomy and Space Sciences
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• v.23 no.3
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• pp.167-176
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• 2006

We investigate the correlation between the peak energy and the burst duration using available long GRB data with known redshift, whose circumburst medium type has been suggested via afterglow light curve modeling. We find that the peak energy and the burst duration of the observed GRBs are correlated both in the observer frame and in the GRB rest frame. For our total sample we obtain, for instance, the Spearman rank-order correlation values ${\sim}0.75\;and\;{\sim}0.65$ with the chance probabilities $P=1.0{\times}10^{-3}\;and\;P=6.0{\times}10^{-3}$ in the observer frame and in the GRB rest frame, respectively. We note that taking the effects of the expanding universe into account reduces the value a bit. We further attempt to separate our GRB sample into the 'ISM' GRBs and the 'WIND' GRBs according to environment models inferred from the afterglow light curves and apply statistical tests, as one may expect that clues on the progenitor of GRBs can be deduced directly from prompt emission properties other than from the ambient environment surrounding GRBs. We find that two subsamples of GRBs show different correlation coefficients. That is, the Spearman rank-order correlation are ${\sim}0.65\;and\;{\sim}0.57$ for the 'ISM' GRBs and 'WIND' GRBs, respectively, after taking the effects of the expanding universe into account. It is not yet, however, statistically very much significant that the GRBS in two types of circumburst media show statistically characteristic behaviors, from which one may conclude that all the long bursts are not originated from a single progenitor population. A larger size of data is required to increase the statistical significance.

• Korean Journal of Veterinary Research
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• v.42 no.4
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• pp.451-457
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• 2002

The purpose of the present experiment was to investigate the micronuclei (MN) frequency in cytokinesis-blocked (CB) cells after various doses of gamma-rays in two species (fish and fowl) and so to contribute to the clarification of the question whether these species are suitable as a target organism in the test system. The frequencies of binucleated cells, and gamma-ray-induced MN in CB cells at several doses were measured in three donors of two species. No binucleated cell was noted in erythrocyte. The peaks of binucleated lymphocyte formation were found at a concentration of 2% phytohaemagglutinin (PHA) and $3{\mu}g/m{\ell}$ cytochalasin B (Cyt-B) in fish at 144 hours after incubation and 2% PHA and $6{\mu}g/m{\ell}$ Cyt-B in fowl at 72 hours after incubation. But the micronucleus counts failed to show any evidence of radiation damage. Measurements performed after irradiation showed a dose-related decrease in the formation of binucleated cells in each of the donors studied. Results indicated that the assays were not suitable for this due to blastization inhibition (binucleation failure) after irradiation. We concluded that the use of CB cell from fish and fowl for detecting the results of mdiation exposure was highly questionable.

• Preventive Nutrition and Food Science
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• v.9 no.3
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• pp.227-231
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• 2004

Green, black and oolong teas were irradiated by $^{60}$ Co-gamma rays (0～10 kGy) and were investigated for detection of irradiation treatment using pulsed photostimulated luminescence (PPSL) and thermoluminescence (TL) during storage. Teas irradiated at 2.5 kGy or more showed a photon count of greater than 5000 counts/60 sec while the non-irradiated yielded only 650～1000 count/60 sec. Correlation coefficients between irradiation dose and photon counts/60 sec were 0.8951, 0.7934 and 0.9007 for green, black and oolong teas, respectively. The TL glow curves for minerals isolated from the non-irradiated teas were situated at about 30$0^{\circ}C$ with a low intensity, but for irradiated samples were approximately 15$0^{\circ}C$ with a high intensity. The TL ratios (TL$_1$/TL$_2$), calculated from values after initial radiation and then after re-irradiation of the teas, were below 0.1 for the non-irradiated samples and higher than 1.44 for all irradiated samples, enhanced the reliability of the identification results for TL. The signal intensity of PPSL and TL for irradiated teas decreased with the lapse of post-irradiation storage time at room temperature but was still distinguishable from that of the non-irradiated samples even after one year.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.157-160
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• 2002

The dosage of intra-operative BNCT using near-threshold $^{7}$ Li(p,n)$^{7}$ Be direct neutrons was evaluated with the calculation method validated with the phantom experiment. The production of both neutrons by near-threshold $^{7}$ Li(p,n)$^{7}$ Be and gamma rays by $^{7}$ Li(p,p'gamma)$^{7}$ Li in a Li target was calculated using Lee's method and their transport in the phantom was calculated with MCNP-4B. As a result, the region satisfying the requirements of the protocol in intra-operative BNCT for brain tumors in Japan was acknowledged to be comparable to present BNCT, for the proton energy of 1.900 MeV for example. A boron-dose enhancer (BDE) introduced in this study to increase $^{10}$ (n,$\alpha$)$^{7}$ Li dose in a living body was effective. The void used to increase doses in deep regions was also valid with the BDE. It was found that intra-operative BNCT using near-threshold $^{7}$ Li(p,n)$^{7}$ Be direct neutrons is feasible.