• Nuclear Engineering and Technology
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• v.53 no.9
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• pp.3051-3057
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• 2021

The concrete is considered as an important radiation shielding material employed widely in nuclear reactors, particle accelerators, laboratory hot cells and other different radiation sources. The present research is dedicated to the shielding properties study of the ordinary concrete reinforced with different weight fractions of lead oxide micro/nano particles. Lead oxide particles were fabricated by chemical synthesis method and their properties including the average size, morphological structure, functional groups and thermal properties were characterized by XRD, FESEM-EDS, FTIR and TGA analysis. The gamma ray mass attenuation coefficient of concrete composites has been calculated and measured by means of the Monte Carlo simulation and experimental methods. The simulation process was based on the use of MCNP Monte Carlo code where the mass attenuation coefficient (μ/ρ) has been calculated as a function of different particle sizes and filler weight fractions. The simulation results showed that the employment of the lead oxide filler particles enhances the mass attenuation coefficient of the ordinary concrete, drastically. On the other hand, there are approximately no differences between micro and nano sized particles. The mass attenuation coefficient was increased by increasing the weight fraction of nanoparticles. However, a semi-saturation effect was observed at concentrations more than 10 wt%. The experimental process was based on the fabrication of concrete slabs filled by different weight fractions of nano lead oxide particles. The mass attenuation coefficients of these slabs were determined at different gamma ray energies using ²²Na, ¹³⁷Cs and ⁶⁰Co sources and NaI (Tl) scintillation detector. The experimental results showed that the HVL parameter of the ordinary concrete reinforced with 5 wt% of nano PbO particles was reduced by 64% at 511 keV and 48% at 1332 keV. Reasonable agreement was obtained between simulation and experimental results and showed that the employment of nano PbO particles is more efficient at low gamma energies up to 1Mev. The proposed concrete is less toxic and could be prepared in block form instead of toxic lead blocks.

• Journal of Radiation Protection and Research
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• v.24 no.3
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• pp.123-129
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• 1999

Tomato (Lycopericum esculentum $M_{ILL}$ cv. Seokwang and cv. Housemomotaro) seeds were irradiated with the doses of $1{\sim}20$ Gy from $^{60}Co$ $\gamma$-ray source to investigate the effect of the low dose $\gamma$-ray radiation on the early growth and resistance to subsequent high dose of radiation. Germination rate of seeds irradiated with low dose $\gamma$-ray was enhanced in Seokwang cultivar but not in Housemomotaro cultivar. Seedling height increased in 4 Gy and 8 Gy irradiation group of both cultivars. Plant height of Seokwang cultivar was depressed in low dose irradiation group but fresh weight was increased in 2 Gy and 4 Gy irradiation group. In Housemomotaro cultivar, plant height increased in 12 Gy and 20 Gy irradiation group and fresh weight increased in 4 Gy and 20 Gy irradiation group. Growth inhibition of tomato plants by high dose radiation was noticeably reduced by pre-irradiation of low dose radiation. Resistance to subsequent high dose of radiation was enhanced in 2 Gy and 8 Gy Irradiation group of Seokwang cultivar and in 2 Gy and 12 Gy irradiation group of Housemomotaro cultivar.

• Journal of Radiation Protection and Research
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• v.26 no.3
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• pp.215-224
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• 2001

In order to comply with revised national regulationson radiological protection and to implement recent nuclear data and dose conversion factors, KOPEC developed a new point kernel gamma and beta ray shielding analysis computer program. This new code, named VisualShield, adopted mass attenuation coefficient and buildup factors from recent ANSI/ANS standards and flux-to-dose conversion factors from the International Commission on Radiological Protection (ICRP) Publication 74 for estimation of effective/equivalent dose recommended in ICRP 60. VisualShieid utilizes graphical user interfaces and 3-D visualization of the geometric configuration for preparing input data sets and analyzing results, which leads users to error free processing with visual effects. Code validation and data analysis were performed by comparing the results of various calculations to the data outputs of previous programs such as MCNP 4B, ISOSHLD-II, QAD-CGGP, etc.

• Nuclear Engineering and Technology
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• v.55 no.9
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• pp.3383-3387
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• 2023

A new dyed polyvinyl alcohol (PVA) film dosimeter based on 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MMT) tetrazolium dye is proposed in this study for measuring high gamma radiation dose. Gamma cell irradiator that contains Co-60 gamma-ray source was used to expose the novel MMT-PVA films to different doses up to 25 kGy. The changed in optical property of irradiated and unirradiated films were characterized by UV-Vis spectrophotometer. The results show that the dose sensitive and the linear range of irradiated films were increased considerably with increase of MMT concentration from 1 to 5 mM. The dose response of dyed PVA film changed substantially with changing relative humidity (12-74%) as well as irradiation temperature (10-40 ℃). The absorbance of the unirradiated films does not change up to 10 days in dark while a significant increase in their absorbance was reported for similar films under fluorescent light. The irradiated dosimeters that kept in dark showed a perfect stability for 54 days. It was found that no obvious impact of dose rate on the irradiated MMT-PVA film dosimeters.

• Journal of the Korean Institute of Telematics and Electronics
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• v.27 no.4
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• pp.604-611
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• 1990

One of the confronting problems in using optical fibers under radiation environments is producing of color centers in optical materials due to nuclear radiation. These centers increase transmission loss by absorbing propagating light. In this study, the radiation effects on optical fiber are studied theoretically. Also, optical attenuation induced by \ulcorner-ray irradiation from Co**60 for single mode and multimode optical fibers is measured at the optical wavelength of 0.85\ulcorner and 1.3\ulcorner, and the results are analyzed. Gammaray is irradiated for 5hours at the rate of 300rads/min, which is corresponding to 90 krads of integrated dose. In case of multimode optical fibers, the induced loss at 0.85\ulcorner wavelength has been twice higher than that at 1.3\ulcorner. The loss in multimode fibers has been significantly larger by 7-20 times than that in single mode fibers, dependently on fiber materials at 1.3\ulcorner.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.11
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• pp.1205-1211
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• 2004

This study has investigated radiation degradation of chloroprene rubber in the presence of some fire retardant. Ammonium polyphosphate, aluminium trihydroxide, magnesium hydroxide, calcium carbonate and antimony trioxide were selected as flame retardant. Samples were irradiated using a Co$^{60}$ ${\gamma}$ -ray and ray up to 2000 kGy at a dose rate of 5 kGy/hr in the presence of air atmosphere at room temperature. After irradiation, samples were assessed fire retardancy with electrical properties and mechanical properties. Some considerations concerning the effects of the fire retardants added to chloroprene rubber on the radiation and thermal stability of chloroprene rubber are presented. From fire retardancy with electrical and mechanical property measurements, it was found that addition of magnesium hydroxide resulted in maximum fire retardant effect.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07a
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• pp.473-476
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• 2004

This study has investigated radiation degradation of low density polyethylene(LDPE). Samples were irradiated using a $Co^{60}\;\gamma-ray$ and ray up to 800 kGy at a dose rate of 5 kGy/hr in the presence of air atmosphere at room temperature. After irradiation, free radical measurement of LDPE has established by electron spin resonance(ESR). Then, each sample was stored for 2 weeks. ESR measurement showed that free radical concentration(FRC) was increased with radiation dose and changed from alkyl, allyl radical to peroxy radical with time.

• Journal of the Korean Society of Radiology
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• v.9 no.4
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• pp.187-195
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• 2015

The active transport characteristics of anions of cell membrane model which irradiated by $^{60}Co\;{\gamma}-ray$ was investigated. The cell membrane model used in this experiment was a sulfonated copolymerized membrane of poly(1-methyl-4-vinylpyridiniumiodide-co-divinylbenzene : MeVP-DVBI). First, the initial flux of $OH^-$ and $Cl^-$, $Na^+$ of membrane which was not irradiated was decreased with increase of thickness of membrane $80-200{\mu}m$, increased with increase of NaOH concentration 0-0.5mol/L and MeVP-DVBI concentration 20-80% was increased with initial flux of $OH^-$ and $Cl^-$, decreased with initial flux of $Na^+$. Second, the initial flux of membrane which was irradiated was less than that. And the driving force of pH of irradiated membrane was significantly increased more than membrane which was not irradiated. The initial flux of the $OH^-$ ion was decreased with increase of $H^+$ ion concentration. As selective transport of $OH^-$ and $Cl^-$ of cell membrane model were abnormal, cell damages were appeared at cell.

• Nuclear Engineering and Technology
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• v.2 no.3
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• pp.149-161
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• 1970

This paper describes a detailed investigational performance on the gamma radiation shield effect of heavy concretes that were manufactured by the use of mineral ores produced domestically and which may be possibly applied for the biological shield design. Ten different kinds of mineral ores were collected for use as the aggregates, physical test and chemical analysis for them were carried out to select the aggregate with a better property. Through the experimental investigation on the shielding effect of various concretes with different combination of concrete components such as water-cement and fine-coarse aggregate ratios, it was possible to derive some criteria for the best condition being capable of obtaining the concretes with high density and good uniformity. Data on the shielding-effectiveness of the different concretes were obtained by performing collimated beam experiment using 60Co gamma-ray. Analyzing the shielding-efficiency, shielding-concrete specific gravity and biological shield cost, the optimum condition of yielding the best economic shielding design, with low cost and good spatial distribution to some extent was determined.

• Journal of the Korean Society of Radiology
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• v.7 no.5
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• pp.333-338
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• 2013

Generally, it's known fact that intensity of radioactivity satisfies inverse-square law. However, the law was dissatisfied with practical experiment because of limited shape of scintillation detector. Especially, in the case of near distance between the surface of detector and the radioactive source, the difference grows larger. In the present study, reason of this difference was confirmed by experiment with $2^{{\prime}{\prime}}{\times}2^{{\prime}{\prime}}{\phi}$ NaI(Tl) scintillation detector and $^{60}Co$(1.174 MeV, 1.333 MeV)and $^{137}Cs$(0.662 MeV) gamma ray sources. From the experiment, the correction coefficient was obtained with gamma ray detection efficiency and geometrical volume. In the result of the present study, the efficiency difference of the detector was corrected with the coefficient. In the present result, we obtained that the inverse-square law experiment have to consider the efficiency and geometrical value of the detector.