• Journal of Advanced Navigation Technology
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• v.20 no.5
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• pp.482-489
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• 2016

Detection of gamma ray can be available using optical fiber scintillator under radiation environment. It monitors the transfer energies of these ions by photodiodes and then convertes into currents. The module which converts those currents into voltages and processes signals is named fine current module TIA, and it is essentially important to convert currents into voltages with high linearity. We have studied and developed the TIA, improving converting linearity and minimizing noises and off-set voltages. Also, we have made efforts to develop precise and accurate current module in compliance with concerned requirements. First of all, we established developing theory, developed related circuits, and then made the current module. And, we confirmed its stability and linearity to be more excellent than any other equipment proposed by other references. We tested the developed fine current modules in the real radiation environment under authorized supervising, confirmed them to meet related requirements.

• Journal of Radiation Protection and Research
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• v.41 no.2
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• pp.87-91
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• 2016

Background: A hand-held detector for an emergency response was developed for nuclide identification and to estimate the information of the ambient dose rate in the scene of an accident as well as the radioactivity of the contaminants. Materials and Methods: To achieve this, the most suitable sensor was first selected as a cadmium zinc telluride (CZT) semiconductor and the signal processing unit from a sensor and the signal discrimination and storage unit were successfully manufactured on a printed circuit board. Results and Discussion: The performance of the developed signal processing unit was then evaluated to have an energy resolution of about 14 keV at 662 keV. The system control unit was also designed to operate the CZT detector, monitor the detector, battery, and interface status, and check and transmit the measured results of the ambient dose rate and radioactivity. In addition, a collimator, which can control the inner radius, and the airborne dust sampler, which consists of an air filter and charcoal filter, were developed and mounted to the developed CZT detector for the quick and efficient response of a nuclear accident. Conclusion: The hand-held CZT detector was developed to make the in-situ gamma-ray spectrometry and its performance was checked to have a good energy resolution. In addition, the collimator and the airborne dust sampler were developed and mounted to the developed CZT detector for a quick and efficient response to a nuclear accident.

• Korean Journal of Food Science and Technology
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• v.4 no.4
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• pp.300-308
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• 1972

For the purpose of utilizing agricultural waste products for animal feeds, chemical analysis of some important agricultural wastes in Korea and enzymatic hydrolysis of rice hull were undertaken and summarized as follows: 1) Rice hull and straws of rice, barley and wheat were analyzed for their proximate principles and carbohydrate composition. 2) A strain of Aspergillus niger was selected as having the highest productivity of rice hull decomposing activity among many species of molds. The optimum conditions for the culture on washed wheat bran were. 3 days of culture period, 55% moisture content and neutral pH and one hour was proper for the extraction of enzymes. 3) The extent of hydrolysis of xylan and rice hull by a crude enzyme preparation from this strain was 63% and 7%, respectively, and the optimum pH for its activity was 4.0 and 4.5, respectively. 4) Enzymatic hydrolysis of rice hull was generally suppressed by gamma-ray irradiation ($0.5{\sim}5\;Mrad$, in dry state), but the effect was less by irradiation in wet state.

• Nuclear Engineering and Technology
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• v.56 no.9
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• pp.3545-3552
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• 2024

Polymers have become widely used substrate materials for shielding neutron rays because of their high hydrogen content and easy processing procedures. Rare-earth materials are also being gradually adopted as neutron absorbers because of their considerable thermal neutron absorption cross-sections. This paper utilizes the FLUKA Monte Carlo simulation program to compare the shielding effects of various polymers and rare-earth oxides on neutron rays across different energy ranges. The study investigates the superior shielding materials for neutron radiation in each energy range. Subsequently, a series of materials are simulated by combining the preferred shielding materials for neutron rays in each energy range, exploring the influence of material composition and composite structure on the effectiveness of neutron ray shielding. It is revealed that the preferred material for shielding neutron rays changes for different energy ranges. For low-energy neutron rays, rare-earth oxides such as Sm₂O₃ and Gd₂O₃ demonstrate the most effective shielding, whereas for high-energy neutron rays, polyethylene (PE) provides the best shielding performance. Materials with different compositions show varying preferred structures when dealing with a ²⁵²Cf neutron source. However, in mitigating the secondary gamma rays generated during the neutron shielding process, stacked-type materials exhibit the most effective shielding performance.

• Journal of Radiation Protection and Research
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• v.24 no.2
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• pp.93-99
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• 1999

The alkaline single-cell gel electrophoresis (SCGE) assay, called the comet assay, has been applied to the detection of DNA damage from a number of chemical and biological factors in vivo and in vitro. The comet assay is a novel method to assess DNA single-strand breaks, alkali-labile sites in individual cells. The effect of peach kernel extracts on radiation-induced DNA damage in human blood lymphocytes was evaluated by the SCGE assay. The lymphocytes, with or without pretreatment of the extracts, were exposed to 0, 0.1, 0.3, 0.5, 1.0 and 2.0 Gy of $^{60}Co$ gamma ray. Significantly increased tail moment, which was a marker of DNA strand breaks in the comet assay, showed an excellent dose-response relationship. The treatment of the peach kernel extracts reduced the DNA damage by 30 % in irradiated groups as compared to that in non-treated control groups. The result indicates that the extracts shows radioprotective effect on lymphocyte DNA when assessed by the comet assay.

• Polymer(Korea)
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• v.38 no.1
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• pp.38-42
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• 2014

The poly[(9,9-bis((6'-(N,N,N-trimethylammonium)hexyl)-2,7-fluorene)-alt-(9,9-bis(2-(2-(2-methoxyethoxy)ethoxy)ethyl)-9-fluorene)) dibromide (WPF-6-oxy-F)] and graphene oxide (GO) was blended and irradiated with gamma ray under ambient condition. This WPF-6-oxy-F-GO composite was investigated as a hole-transporting layer (HTL) in organic solar cells (OSCs). Compared with the pristine GO, the sheet resistance ($R_{sheet}$) of irradiated WPF-6-oxy-F-GO was decreased about 2 orders of magnitude. The reason for the decrease of $R_{sheet}$ is the effect of efficient ${\pi}-{\pi}$ packing resulted from the formation of C-N bond between WPF6-oxy-F and GO. As a result, the efficiency of OSCs was dramatically enhanced ~ 6.10% by introducing irradiated WPF-6-oxy-F-GO as a HTL. WPF-6-oxy-F-GO is a sufficient candidate for HTL to facilitate the low-cost and high efficiency OSCs.

• Journal of Plant Biotechnology
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• v.34 no.1
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• pp.61-68
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• 2007

To develop rice (Oryza sativa L.) cultivars to be planted on salt-affected sites, cell lines with enhanced proline content and resistance to growth inhibition by Azetidine-2-carboxylic acid (AZCA), a proline analogue, were screened out among calli irradiated with gamma ray of 50, 70, 90, and 120 Gy. The calli had been derived from embryo culture of the cultivar Donganbyeo. Selected AZCA resistant lines that had high proline accumulation were used as sources for selection of NaCl resistant lines. To determine an optimum concentration for selection of NaCl resistant lines, Donganbyeo seeds were initially cultured on the media containing various NaCl concentrations (0 to 2.5%) for 40 days, and 1.5% NaCl concentration was determined as the optimum concentration. One hundred sixteen salt-tolerant (ST) lines were selected from bulked 20,000 seeds of the AZCA resistant $M_{3}$ seeds in the medium containing 1.5% NaCl. The putative 33 lines ($M_{4}$ generation) considered with salt-tolerance were further analyzed for salt tolerance, amino acid and ion contents, and expression patterns of the salt tolerance-related genes. Out of the 33 lines, 7 lines were confirmed to have superior salt tolerance. Based on growth comparison of the entries, the selected mutant lines exhibited greater shoot length with average 1.5 times, root length with 1.3 times, root numbers with 1.1 times, and fresh weight with 1.5 times than control. Proline contents were increased maximum 20%, 100% and 20% in the leaf, seed and callus, respectively, of the selected lines. Compared to control, amino acid contents of the mutants were 24 to 29%, 49 to 143%, 32 to 60% higher in the leaf, seed and callus, respectively. The ratio of $Na^{+}/K^{+}$ for most of the ST-lines were lower than that of control, ranging from 1.0 to 3.8 for the leaf and 11.5 to 28.5 for the root, while the control had 3.5 and 32.9 in the leaf and root, respectively. The transcription patterns for the P5CS and NHXI genes observed by RT-PCR analysis indicated that these genes were actively expressed under salt stress. The selected mutants will be useful for the development of rice cultivar resistant to salt stress.

• Journal of the Korean Society of Radiology
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• v.15 no.2
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• pp.247-255
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• 2021

The purpose of this study was to examine the radiation protection effect of protaetia brevitarsis larvae extracts known as antioxidant food. In this study 90 female rats were clssified in to 5 groups: NC Group, PBE Group, IR Group, PBE+IR Group and IR+PBE Group. In IR Group, 7 Gy of Co-60 gamma ray was irradiated to SD rat and protaetia brevitarsis larvae extracts were administered orally at 200 mg/kg once a day for 14 days. And then on the 1 day, 7 days, 21 days later after irradiation, changes in blood cell component, superoxide dismutase(SOD) activity, spleen index, histopathological evaluation of the ovary and uterus were observed. As a result, the PBE+IR Group (p<0.01, p<0.05) and IR+PBE Group (p<0.01, p<0.01) showed a significantly radiation protection than the IR Group in lymphocyte and red blood cell on the 21 days. It was also confirmed that SOD activity of PBE+IR Group (p<0.01) and IR+PBE Group (p<0.01) was significantly increased than the IR Group. In spleen index, PBE+IR Group (p<0.05) and IR+PBE Group (p<0.01) showed a significantly recovery than the IR Group. In histopathological observation, PBE+IR Group in the ovary and PBE+IR, IR+PBE Group in the uterus showed less inflammatory reactions of cystoplasm than the IR Group. Based on These results, It is judged that protaetia brevitarsis larvae Extracts have radiation protection effect against blood and reproductive. It is expected to be useful for research of radiation protection agent.

• The Journal of Korean Society for Radiation Therapy
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• v.16 no.2
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• pp.69-79
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• 2004

In the process of photon treatments, linear accelerators with energies higher than 10 MV produce neutrons through the (${\gamma}$, n) interactions with the composite materials of the linac head md these materials further produce the induced radiations. We investigate the possible risks from these induced radiations especially in the wedge filters to the radiation workers. Wedge filters are used to modify the isodose profiles in the radiation treatment using the linear accelerator and always be handled by the radiation workers. For the background radiation, we measured the radiation in both the waiting room and the outside of the building for two hospitals, S and H. The results of S hospital were $0.11\;{\mu}Sv/hr$ and $0.10\;{\mu}Sv/hr$ for waiting room and outside respectively, and in the case of H hospital, they were $0.12\;{\mu}Sv/hr$ and $0.11\;{\mu}Sv/hr$. Using a survey meter, we measured the radiation from wedge filters inserted in 10 MV and 15 MV Siemens linear accelerators. The time series measurements were done in ${\sim}1$ minutes after exposure of 5 Gy of monitor units for the field size of $25{\times}25cm^2$. The starting value of 10 MV machine was about $3.26\;{\mu}Sv/hr$, which was three times higher than that of 10 MV. The measured radiation was from $^{28}Al$ and $^{53}Fe$ with a half life of 3.5 min. If the treatment patients are $20{\sim}50$ per day and the number of process of wedge filter change per patient is one or two, the annual dose equivalent is $0.08{\sim}0.4\;mSv$ for 10 MV, and $0.27{\sim}1.36\;mSv$ for 15 MV, which are in the range of dose equivalent limits of radiation workers.

• Journal of the Korean Society of Food Science and Nutrition
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• v.35 no.5
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• pp.588-593
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• 2006

This study was intended to observe possibility of which radiation technique can be used for oligopeptide production from pigskin collagen to reduce environmental pollution in processing and simplify the processing steps. Raw pigskin was ground using chopper, and then defatted in acetone cooled at $-20^{\circ}C$ freezer. Defatted dried pigskin was irradiated at 20, 40, 60, 100, 150, 200, 250, and 300 kGy using Co-60 gamma rays irradiator. With irradiation doses, the amount of soluble proteins increased, and the viscosity and turbidity of soluble proteins decreased, which could be clue of that irradiation degrade high molecular proteins directly. pH of soluble proteins from defatted pigskin increased in the sample above 150 kGy, and low molecular weight components (below 24 kDa) in SDS-PAGE increased. From gel permeation chromatography of the hydrolysates of pigskin irradiated at 300 kGy showed the major peak of 9,000, 8,200, 860, and 170 Da.