• Journal of IKEEE
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• v.19 no.3
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• pp.282-287
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• 2015

In this study, an optical fiber detector was constructed by using a Ce:GAGG scintillator, optical fiber, and photomultiplier. The single crystal size of the scintillator was set to $3{\times}3{\times}20mm^3$ after simulating the counting efficiency of gamma rays in the scintillator by using the MCNPX code. The constructed detector used the standard gamma ray sources $^{137}Cs$ and $^{133}Ba$ to measure radiation and analyze the spectral characteristics of gamma rays. The resulting trend curve showed excellent linearity with an R-squared value of 0.99741, and the detector characteristics were found to vary 2% or less with distance based on comparison with the MCNPX value. Furthermore, the spectroscopic analysis of the gamma ray energy from the single-ray and mixed-ray sources showed that $^{137}Cs$ had its peak energy at 662 keV, and $^{133}Ba$ had at 356 keV. It seems that if the fiber-optics detector is used, working hours and exposure of worker can be reduced.

• Korean Journal of Microbiology
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• v.37 no.4
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• pp.305-311
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• 2001

Antifungal bacterium, Bacillus subtilis YS1 was isolated from Yusong hot spring showed broad antifungal spectrum against 12 kinds of plant pathogenic fungi and Candida albicans, animal pathogen. From the gamma($Co^{60}$) radiation sensitivity test, $D_10$ value was 2.08 kGy and it survived above 20 kGy of radiation dose. Several mutants were induced by gamma radiation. Among them, YS1-1009 mutant showed resistance against tebuconazole of herbicide, increased activity against Botryoshaeria dothidea and ligninase activity. YS67 mutant was antifungal deficient auxotrophic mutants(trp-pro-or arg-ura-). From this results, it suggested that gamma irradiation could be useful method for mutant induction.

• Journal of Radiation Industry
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• v.6 no.3
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• pp.239-244
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• 2012

This study was conducted to investigate bacterial growth, viscosity, color, and sensory properties of gamma-irradiated Tarakjuk powder, a Korean milk porridge powder, at 1, 3, 5, 7, and 10 kGy. The total aerobic bacteria in non-irradiated Tarakjuk powder was $2.56{\log}\;CFU{\cdot}g^{-1}$, whereas it was not observed within the detection limit of $2{\log}\;CFU{\cdot}g^{-1}$ in samples irradiated at more than 1 kGy. Spore-forming bacteria, however, were not observed in all samples within the detection limit of $1{\log}\;CFU{\cdot}g^{-1}$. The viscosity of rehydrated Tarakjuk after gamma irradiation significantly decreased from 16,770 cP to 4,060 cP when irradiated at 10 kGy. The redness ($a^*$ value) and yellowness ($b^*$ value) evaluated using a colorimeter were significantly increased according to the increase in irradiation dose (p<0.05), while there was no difference in color evaluation conducted by panels. The overall acceptance decreased as the irradiation dose increased, and the 5 kGy sample was 4.0 (normal) on a 7-point scale. As a result, it is considered that a gamma irradiation of 5 kGy is enough to sterilize Tarakjuk powder with a acceptable sensory quality.

• Nuclear Engineering and Technology
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• v.52 no.5
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• pp.1036-1042
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• 2020

Fast-Neutron Multiplicity Counter based on Liquid Scintillator Detector can directly measure the fast neutron multiplicity emitted by UO₂ rod. HPGe gamma spectrometer; which has superior energy resolution; is routinely used for the gamma energy spectrum measurement. Combing Fast-Neutron Multiplicity Counter and HPGe γ-spectrometer, the n/γ joint measurement system is developed. The fast neutron multiplicity and gamma energy spectrum of UO₂ rod assemblies under different conditions are measured by the n/γ joint measurement system. The induced fission rate and the ²³⁵U abundance, thereby the ²³⁵U mass; can be obtained for UO₂ rod assemblies. The ²³⁵U mass deviation of the measured value from the reference value is less than 5%. The results show that the n/γ joint measurement system is effective and applicable in the measurement of the ²³⁵U mass in samples.

• Korean Journal of Metals and Materials
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• v.50 no.9
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• pp.645-651
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• 2012

This study investigated changes in phase fraction caused by the addition of Mo, as well as the subsequent behaviour of N and its effect on the mechanical properties of welded 24Cr-N duplex stainless steel weld metals. Filler metal was produced by fixing the contents of Cr, Ni, N, and Mn while adjusting the Mo content to 1.4, 2.5, 3.5 wt%. The delta ferrite fraction increased as the Mo content increased. In contrast, the ${\gamma}$ fraction decreased and changed from a round to an acicular shape. Secondary austenite (${\gamma}^{\prime}$) was observed in all specimens in a refined form, but it decreased as the Mo content increased to the extent that it was nearly impossible to find any secondary austenite at 3.5 wt% Mo. Both tensile and yield strengths increased with the addition of Mo. In contrast, the highest value of ductility was observed at 1.41 wt% Mo. At all temperatures, impact energy absorption showed the lowest value at 3.5 wt% Mo, at which the amount of ${\delta}$-ferrite was greatest. There was no significant temperature dependence of the impact energy absorption values for any of the specimens. As the fraction of ${\gamma}$ phase decreased, the amount of N stacked in the ${\gamma}$ phase increased. Consequently, the stacking fault energy decreased, while the hardness of ${\gamma}$ increased.

• Journal of the Korean Society of Radiology
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• v.12 no.1
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• pp.1-7
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• 2018

$^{68}Ga$ was eluted from a $^{68}Ge/^{68}Ga$ radionuclide generator. $^{68}Ga$ decays into $^{68}Zn$, with a half life=67.8min. The decay is 88.9 % by ${\beta}$+ and 11.1 % by EC. The main ${\beta}$+ decay (87.7 %) is to the ground level of $^{68}Zn$ and it is a pure positron emission branch. A small fraction decays ${\beta}$+ (1.2 %) into an excited level of $^{68}Zn$, which promptly decays into the ground level with a ${\gamma}$ (1.077 Mev). This can constitute prompt gamma contamination in the PET data, if the 1.077 Mev ${\gamma}$ has a scatter interaction in the patient, and generates a lower energy ${\gamma}$ in coincidence with the positron annihilation pair. The purpose of this study was to evaluate standardized uptake value(SUV) before and after applying prompt gamma rays correction on $^{68}Ga$-DOTATOC PET/CT image. Fifty patient underwent PET/CT 1 hour after injection of the $^{68}Ga$-DOTATOC. The SUVmax and SUVmean of lesions and normal tissues (Pituitary, Lung, Liver, Spleen, Kidney, Intestine) were evaluated before and after applying prompt gamma correction on $^{68}Ga$-DOTATOC PET/CT image. Additionally, the SUVmax of each lesions and SUVmean of the soft tissues were measured on images. and target to background ratios (TBR) were calculated as quantitative indices. Among 15 patients, 25 of lesions (Pancreas, Liver, Thoracic Spine, Brain) with increased uptake on $^{68}Ga$-DOTATOC PET/CT image. SUVmax and SUVmean were increased in lesion site and normal tissue after prompt gamma rays correction. TBR was $51.51{\pm}49.28$ and $55.50{\pm}53.12$ before and after prompt gamma rays correction, respectively. (p<0.0001)

• Korean Journal of Clinical Laboratory Science
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• v.48 no.1
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• pp.22-29
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• 2016

Serum gamma-glutamyltransferase (GGT) has been widely used as a marker of alcohol intake and liver failure. Recently, the relativity between GGT and various diseases has been identified with growing interest. In this study, we examined relativity between GGT value and risk factors of coronary heart diseases among those with normal GGT value, excluding heavy drinkers. Specifically, we compared the differences based on age and gender. Data from the 2011 KNHNES were used (N=3,619). When the subjects were categorized according to quartile based on the serum GGT levels, there was 10~20, 21~27, 28~38, 39~71 IU/L in men, and 6~12, 13~16, 17~22, 23~42 IU/L in women. The mean of most variables was the highest in the $4^{th}$ quartile (Q4), however age and LDL Cholesterol were the highest in the $2^{nd}$ quartile (Q2) in men. The FRS and 10-year CHD risk was the highest in the $2^{nd}$ quartile in men, and the highest in the $4^{th}$ quartile in women. Increased GGT was correspondingly linked with age in women but age was the highest in GGT in the $2^{nd}$ quartile in men. In the 70's, the highest Q1 and Q2 was in men and the highest Q3 and Q4 in women. Although GGT value was within the normal range, increased GGT showed correlation with various risk factors. The FRS and 10-year CHD risk showed different patterns according to age and gender along with increased GGT value.

• Journal of the Institute of Convergence Signal Processing
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• v.12 no.3
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• pp.163-168
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• 2011

In this paper, we proposed non-linear gamma curve algorithm for gamma correction. The previous non-linear gamma curve algorithm is generated by the least square polynomial using the Gauss-Jordan inverse matrix. However, the previous algorithm has some weak points. When calculating coefficients using inverse matrix of higher degree, occurred truncation errors. Also, only if input sample points are existed regular interval on 10-bit scale, the least square polynomial is accurately works. To compensate weak-points, we calculated accurate coefficients of polynomial using eigenvalue and orthogonal value of mat11x from singular value decomposition (SVD) and QR decomposition of vandemond matrix. Also, we used input data part segmentation, then we performed polynomial curve fitting and merged curve fitting results. When compared the previous method and proposed method using the mean square error (MSE) and the standard deviation (STD), the proposed segmented polynomial curve fitting is highly accuracy that MSE under the least significant bit (LSB) error range is approximately $10^{-9}$ and STD is about $10^{-5}$.

• Journal of the East Asian Society of Dietary Life
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• v.18 no.6
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• pp.989-996
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• 2008

In this study we assessed the effects of gamma irradiation ($0.5{\sim}3\;kGy$) on the microbial and physico-chemical characteristics of maesil (Prunus mume) stored for 9 days at $20^{\circ}C$. Total aerobic bacteria, yeasts and molds were significantly decreased with increases in the irradiation dosage. In terms of the Hunter's color value, irradiated samples evidenced a higher b-value, but a lower a-value than the non-irradiated samples. Hardness was reduced with increment in the irradiation dose level. The contents of total sugar, hydrogen donating activity and organic acids were not affected by irradiation. The reducing sugar contents of the irradiated samples were superior to those of the non-irradiated samples. Vitamin C contents were reduced with the progression of storage periods and increases in the dosage level. These results demonstrated that gamma irradiation of 0.5 to 3 kGy affected the microbiological safety of maesil, but did not affect the physico-chemical characteristics(total sugar, hydrogen donating activity and organic acid) but the Hunter's color value, hardness, and vitamin C contents of the maesil deteriorated with gamma irradiation.

• Communications for Statistical Applications and Methods
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• v.4 no.1
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• pp.259-269
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• 1997

Bayesian inference for a record value statistics(RVS) model of nonhomogeneous Poisson process is considered. We seal with Bayesian inference for double exponential, Gamma, Rayleigh, Gumble RVS models using Gibbs sampling and Metropolis algorithm and also explore Bayesian computation and model selection.