• Structural Engineering and Mechanics
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• v.70 no.1
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• pp.1-11
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• 2019

This study deals with a method based on the modified bivariate gamma function for reconstructions of dynamic behavior of delaminated composite plates subjected to impact loads. The proposed bivariate gamma function is associated with micro-genetic algorithms, which is capable of solving inverse problems to determine the stiffness reduction associated with delamination. From computing the unknown parameters, it is possible for the entire dynamic response data to develop a prediction model of the dynamic response through a regression analysis based on the measurement data. The validity of the proposed method was verified by comparing with results employing a higher-order finite element model. Parametric results revealed that the proposed method can reconstruct dynamic responses and the stiffness reduction of delaminated composite plates can be investigated for different measurements and loading locations.

• Journal of the Korean Society of Safety
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• v.5 no.2
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• pp.32-39
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• 1990

The ${\gamma}$-Fe$_2$O$_3$ compounds were oxidized in the furance after gas detecting sensor made molding as the Fe$_3$O$_4$ the synthesized Fe$_3$O$_4$, by ferrous sulfate and sodium hydroxide. Their sensities on carbon monoxide, ethyl alcohol and L. P. G. were measured at various temperatures, respectively. And then their electrical resistivities, thermal properties (D.T.A. ＆ T.G.A.), were examined about their having an effet on the gas-sensing in company with the effect of pure ${\gamma}$-Fe$_2$O$_3$ and the detecting sensor ${\gamma}$-Fe$_2$O$_3$, which reacts with $K_2$CO$_3$ in the hydrothermal coundition, and the electrical conductive mechanism was reflected simultaneously. It was observed that the electrical conductivities and response ratios showed highest value at the endothermic temperature part, 300~35$0^{\circ}C$ of D.T.A.―curve. Consequently, the response ratios and response times of the hydrothermal detecting sensor were higher than that of pure detecting sensor, the specific surface areas were the highest at the endothermic range of D.T.A.-curve. These response ratios of detecting sensor for $K_2$CO$_3$, process at hydrothermal condition on carbon monoxide appeared higher than that on ethyl alcohol and in case of L.P.G. last.

• Tuberculosis and Respiratory Diseases
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• v.47 no.3
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• pp.304-310
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• 1999

Background: IFN-$\gamma$ plays an important role in host response to intracellular organisms such as mycobacterium. Human infection with mycobacterium leads to a wide variety of outcomes, ranging from asymptomatic infection to widespread and rapidly fatal disease. Recent reports suggest that alteration of the function of IFN-$\gamma$ caused by a defective IFN-$\gamma$ receptor gene can explain different host response to mycobacterium. In this study, we investigated the role of IFN-$\gamma$ in the development of chronic refractory tuberculosis. Methods: The LPS-induced TNF-$\alpha$ production with or without IFN-$\gamma$ priming was compared by using monocytes taken from recently diagnosed tuberculosis, chronic refractory tuberculosis patients and controls. And the IFN-$\gamma$ receptor was measured by indirect fluorescent antibody technique to know whether change in the priming effect of IFN-$\gamma$ is related to IFN-$\gamma$ receptor deficiency or not. Results: The ratio of TNF-$\alpha$ produced in response to stimulation with INF-$\gamma$ and LPS to LPS alone was $13.5{\pm}7.6$ in controls, $10.8{\pm}6.4$ in recently diagnosed tuberculosis patients and $6.7{\pm}3.9$ in chronic refractory tuberculosis patients. The priming effect of IFN-$\gamma$ significantly decreased in chronic refractory tuberculosis patients compared with that in controls(p=0.002). However, IFN-$\gamma$ receptor deficiency was detected in one of chronic refractory tuberculosis patients. Conclusion: The decrease of the priming effect of IFN-$\gamma$ may play an important role in the development of chronic refractory tuberculosis, and in some patients, this may be related to the IFN-$\gamma$ receptor deficiency.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.49 no.1
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• pp.25-29
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• 2004

The responses of soybean seeds were evaluated to accelerated aging and gamma irradiation with regard to germination, seed leakage, seed leachate component and dry weight of hypocotyl and primary root of the germinating seed. Accelerated aging significantly reduced the final germination rate while gamma irradiation increased the final germination rate. Furthermore, the interactive effects occurred that the final germination rate of 5-day aged seeds increased considerably in response to 4 Gy of gamma irradiation. The extent to which the electrolyte was leaked from the seeds (conductivity) was significantly affected by accelerated aging and showed a close negative correlation with the germination rate. Gamma irradiation, however, did not significantly affect the electrical conductivity of seed leachate. The accelerated aging significantly increased the concentrations of the particular electrolytes leaked from the seeds while the gamma irradiation did not affect those concentrations. Of the electrolytes leaked from the seeds, Ca and Mg showed relatively lower concentrations while K showed greater concentrations than others. Moreover, N and P showed similar responses to aging treatment. Aging treatment significantly affected dry weight (DW) of hypocotyls and primary root. Also, gamma irradiation decreased DW of hypocotyls and primary root, particularly for 8 Gy associated with 5 days aging treatment. The data were discussed in terms of the relationships of seed vigor with aging treatment and gamma irradiation.

• Nuclear Engineering and Technology
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• v.54 no.9
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• pp.3390-3397
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• 2022

Among the different techniques available, nuclear methods, including gamma-gamma logging tools, are of special importance. Though the real environment which surrounds the drilled borehole is a complex fractured medium which the fluid can flow through the porosities, simulation studies generally use the traditional model of a homogeneous mixture of formation and the liquid. Considering a previously published study, which shows that modeling of fluid flow in fractured reservoirs and simulating the formation as an inhomogeneous fractured medium leads to different results compared with those of homogeneous mixture, here we study the effect of the presence of drilling fluid (mudcake) on the response of the detectors in both the models. To study this effect, a typical gamma-gamma logging tool was modeled by using the MCNPX Monte Carlo code. The results show that the responses of the detectors in the mixture model in the presence of various thicknesses of mudcake are sensitive to the density of the formation material. However, this effect is not notable in the inhomogeneous fractured medium. These results emphasize the importance of the model employed for simulation of the medium in gamma-gamma well-logging.

• Tuberculosis and Respiratory Diseases
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• v.57 no.1
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• pp.25-31
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• 2004

Background : IFN-${\gamma}$ is the main effector mediator of the host immune response against Mycobacterium tuberculosis. Evaluating the IFN-${\gamma}$ gene expression in response to M. tuberculosis antigens may help in elucidating the host defense mechanism against M. tuberculosis and in the development of a vaccine. Methods : The IFN-${\gamma}$ mRNA expression in the lymphocytes obtained from pleural effusions from tuberculous pleurisy patients (TB-PLC) after in vitro stimulation with whole cell M. tuberculosis(H37Rv), purified protein derivatives(PPD), man-lipoarabinamman (man-LAM), ara-LAM and Antigen 85B(Ag85B) were evaluated. The degree of IFN-${\gamma}$ mRNA expression was determined by a semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR) method. Results : M. tuberculosis induced the expression of IFN-${\gamma}$ mRNA in the TB-PLC in time and dose dependent manners. The PPD and Ag85B induced high levels of IFN-${\gamma}$ mRNA expression in the TB-PLC. However, man-LAM inhibited IFN-${\gamma}$ mRNA expression in the TB-PLC, while ara-LAM did not. Conclusion : IFN-${\gamma}$ mRNA expression in TB-PLC is stimulated by PPD and Ag85B, but inhibited by man-LAM.

• Nuclear Engineering and Technology
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• v.30 no.5
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• pp.452-461
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• 1998

The pin power distribution is determined by analyzing the rotational gamma scanning data for 36 element fuel bundle of HANARO. A fission monitor of Nb$^{95}$ is chosen by considering the criteria of the half-life, fission yield, emitting ${\gamma}$-ray energy and probability. The ${\gamma}$-ray spectra were measured in Korea Atomic Energy Research Institute(KAERI) by using a HPGe detector and by rotating the fuel bundle at steps of 10$^{\circ}$. The counting rates of Nb$^{95}$ 766 keV ${\gamma}$-rays are determined by analyzing the full absorption peak in the spectra. A 36$\times$36 response matrix is obtained from calculating the contribution of each rod at every scanning angle by assuming 2-dimensional and parallel beam approximations for the measuring geometry. In terms of the measured counting rates and the calculated response matrix, an inverse problem is set up for the unknown distribution of activity concentrations of pins. To select a suitable solving method, the performances of three direct methods and the iterative least-square method are tested by solving simulation examples. The final solution is obtained by using the iterative least-square method that shows a good stability. The influences of detection error, step size of rotation and the collimator width are discussed on the accuracy of the numerical solution. Hence an improvement in the accuracy of the solution is proposed by reducing the collimator width of the scanning arrangement.

• Journal of Radiation Industry
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• v.10 no.4
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• pp.243-248
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• 2016

Argonaute 2 (AtAGO2) is a well characterized effector protein in Arabidopsis for its functionalities associated with DNA double-strand break (DSB)-induced small RNAs (diRNAs) and for its inducible expression upon ${\gamma}$-irradiation. However, its transcriptional regulation depending on the recovery time after the irradiation and on the specific response to DSBs has been poorly understood. We analyzed the 1,313 bp promoter sequence of the AtAGO2 gene ($1.3kb_{pro}$) to characterize the transcriptional regulation of AtAGO2 at various recovery times after ${\gamma}$-irradiation. A stable transformant harboring $1.3kb_{pro}$ fused with GUS gene showed that the AtAGO2 is highly expressed in response to ${\gamma}$-irradiation, after which the expression of the gene is gradually decreased until 5 days of DNA damage recovery. We also confirm that the AtAGO2 expression patterns are similar to that of ${\gamma}$-irradiation after the treatments of radiomimetic genotoxins (bleomycin and zeocin). However, methyl methanesulfonate and mitomycin C, which are associated with the inhibition of DNA replication, do not induce the expression of the AtAGO2, suggesting that the expression of the AtAGO2 is closely related with DNA DSBs rather than DNA replication.

• Journal of Radiation Industry
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• v.7 no.2_3
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• pp.109-113
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• 2013

In a previous study, a relatively high dose of gamma radiation (1 kGy) did not fully induce typical SOS genes such as sulA, recA, recN, and din in Salmonella Typhimurium (S. Typhimurium) (Lim et al. 2008, Gene expression profiles following high-dose exposure to gamma radiation in Salmonella enterica serovar Typhimuium. J. Radiat. Ind. 3:111-119). In this study, we examined changes in the transcriptional repertoire of S. Typhimurium after a dose of 10 Gy using DNA microarrays. It was found that more than half (~65%) of the 26 up-regulated genes belong to the SOS regulon: ten genes are typical SOS genes, and seven genes are Salmonella prophage genes, which are known to be activated by LexA cleavage. Among 29 down-regulated genes, the function of five genes with the most decreased expression is associated with carbohydrate transport and energy production. This suggests that upon exposure to gamma radiation cells may cease growing by reducing the metabolic activity, and repair DNA damage using a DNA repair system such as the SOS response system. The difference in expression of the SOS genes between a high (1 kGy) and low (10 Gy) dose of radiation shows the possibility that cells may opt for one of multiple regulatory circuits in response to the specific gamma radiation dose.

• Journal of Radiation Protection and Research
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• v.49 no.2
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• pp.85-90
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• 2024

Background: This study focuses on the fabrication and characterization of quasi-hemispherical Cd_0.9Zn_0.1Te (CZT) detector for gamma-ray spectroscopy applications, aiming to contribute to advancements in radiation measurement and research. Materials and Methods: A CZT ingot was grown using the vertical Bridgman technique, followed by proper fabrication processes including wafering, polishing, chemical etching, electrode deposition, and passivation. Response properties were evaluated under various external bias voltages using gamma-ray sources such as Co-57, Ba-133, and Cs-137. Results and Discussion: The fabricated quasi-hemispherical CZT detector demonstrated sufficient response properties across a wide range of gamma-ray energies, with sufficient energy resolution and peak distinguishability. Higher external bias voltages led to improved performance in terms of energy resolution and peak shape. However, further improvements in defect properties are necessary to enhance detector performance under low bias conditions. Conclusion: This study underscores the efficacy of quasi-hemispherical CZT detector for gamma-ray spectroscopy, providing valuable insights for enhancing their capabilities in radiation research field.