• 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.

• Nuclear Engineering and Technology
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• v.54 no.6
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• pp.2198-2203
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• 2022

As robotics become more sophisticated, there are a growing number of generic systems being used for routine tasks in nuclear environments to reduce risk to radiation workers. The nuclear sector has called for more commercial-off-the-shelf (COTS) devices and components to be used in preference to nuclear specific hardware, enabling robotic operations to become more affordable, reliable, and abundant. To ensure reliable operation in nuclear environments, particularly in high-gamma facilities, it is important to quantify the tolerance of electronic systems to ionizing radiation. To deliver their full potential to end-users, mobile robots require sophisticated autonomous behaviors and sensing, which requires significant computational power. A popular choice of computing system, used in low-cost mobile robots for nuclear environments, is the UP Core single board computer. This work presents estimates of the total ionizing dose that the UP Core running the Robot Operating System (ROS) can withstand, through gamma irradiation testing using a Co-60 source. The units were found to fail on average after 111.1 ± 5.5 Gy, due to faults in the on-board power management circuitry. Its small size and reasonable radiation tolerance make it a suitable candidate for robots in nuclear environments, with scope to use shielding to enhance operational lifetime.

• Plant Biotechnology Reports
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• v.3 no.3
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• pp.191-197
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• 2009

Four-leaf white clover is not found easily in nature due to its low appearance rate (1 in 10,000). Because people believe that it brings good luck and like to either keep it or present it to a loved one, it has commercial and ornamental value. To breed four-leaf clover, we exposed its flowers to ${\gamma}-rays$ at the pollination stage. The $M_1$ seeds produced following doses at 25-100 Gy showed an approximately 74% germination rate, with seedling survival at 46%. In the $M_1$ generation of plants irradiated within that dose range, we found an increased frequency of four leaflets. One of them, Jeju Lucky-1 (JL-1), had a frequency of about 60%. To see whether that mutation was somaclonal or genetic, we observed its $M_2$ generation and found that such a phenotype reappeared. Although our results demonstrated that the irradiation of fully mature flowers led to a higher frequency of 4-leaflets, we could not clearly explain the genetic mechanism involved. We suggest that JL-1 is valuable as a new variety, without further genetic fixation, because white clover can be propagated vegetatively by stolons.

• Korean Journal of Veterinary Research
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• v.41 no.3
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• pp.395-400
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• 2001

The present study analyze the morphological aspects of the cerebrum of mice with prenatal exposure to high and low dose (0.5, 1, 2 Gy) of $\gamma$-radiation on gestation day 12 or 16. The animal were allowed to give birth and the offspring were sacrificed at postnatal days 28 for gross and microscopic examination of cerebrum. Their body weight, brain weight, brain length, brain width, cortical thickness and area of cingulum bundle were examined. The histological and planimetric analysis were performed observing coronal sections. The gross malfomation (microcephaly) and abnormality of cortical architecture were prominent after exposure to 2 Gy on day 12 of gestation. significant dose-related reductions in body weight, brain weight, brain size were found in all irradiated groups. A significant change was found in thickness of the cerebral cortex and area of the cingulum bundle in the groups exposed to 0.5 Gy or more. There was no difference a lamina patter of six layers in cerebral cortex between the control and irradiated groups, but cell packing density increased significantly in the group exposed to 1 Gy or more. These results suggested that dose as low as 0.5 Gy could cause a morphologically reduce change in developing mouse cerebrum and exposure on day 12 of gestation to $\gamma$-irradiation is a particularly sensitive phase in causing malformation and abnormality of central nerve system.

• Korean Journal of Veterinary Research
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• v.41 no.4
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• pp.571-578
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• 2001

To evaluate if the apoptotic fragment assay could be used to estimate the dose prediction after radiation exposure, we examined apoptotic mouse crypt cells per 1,000 cells after whole body $^{60}Co$ $\gamma$-rays and 50MeV ($p{\rightarrow}Be^+$) cyclotron fast neutron irradiation in the range of 0.25 to 1 Gy, respectively. The incidence of apoptotic cell death rose steeply at very low doses up to 1 Gy, and radiation at all doses tigger rapid changes in crypt cells in stem cell region. These data suggest that apoptosis may play an important role in homeostasis of damaged radiosensitive target organ by removing damaged cells. The curve of dose-effect relationship for the data of apoptotic fragments was obtained by the linear-quadratic model $y=0.18+(9.728{\pm}0.887)D+(-4.727{\pm}1.033)D^2$ ($r^2=0.984$) after $\gamma$-rays irradiation, while $y=0.18+(5.125{\pm}0.601)D+(-2.652{\pm}0.7000)D^2$ ($r^2=0.970$) after neutrons in mice. The dose-response curves were linear-quadratic, and a significant dose-response relationship was found between the frequency of apoptotic cell and dose. These data show a trend towards increase of the numbers of apoptotic crypt cells with increasing dose. Both the time course and the radiation dose-response curve for high and low linear energy transfer (LET) radiation modalities were similar. The relative biological effectiveness (RBE) value for crypt cells was 2.072. In addition, there were significant peaks on apoptosis induction at 4 and 6h after irradiation, and the morpholoigcal findings of the irradiated groups were typical apoptotic fragments in crypt cells that were hardly observed in the control group. Thus, apoptosis in crypt cells could be a useful in vivo model for studying radio-protective drug sensitivity or screening test, microdosimetric indicator and radiation-induced target organ injury. Since the apoptotic fragment assay is simple, rapid and reproducible in the range of 0.25 to 1 Gy, it will also be a good tool for evaluating the dose response of radiation-induced organ damage in vivo and provide a potentially valuable biodosimetry for the early dose prediction after accidental exposure.

• Korean Journal of Food Science and Technology
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• v.16 no.4
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• pp.408-412
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• 1984

This study was intended to investigate the physiological effect of gamma irradiation at 50, 100 and 500 Gy on the garlic bulbs stored at low temperature of $3\;{\pm}\;1\;^{\circ}C$ and a relative humidity of 70-80%, and room temperature of $12\;{\pm}\;5\;^{\circ}C$ and a relative humidity of 75-85%, respectively for 10 months. Irradiation treatment stimulated temporary the respiration of garlic, which was greatly affected by storage conditions later. Sprouting of garlic was effectively inhibited in the all irradiated and low temperature groups until 10 months of storage, while the nonirradiated and 50 Gy groups were partially rooted around the 4th month after storage under both conditions. Weight loss and spoilage were shown to be little affected by irradiation until the nonirradiated garlic sprouted, and at the latter stage of storage period, the optimum dose of irradiation showed a significant effect on the reduction of weight loss and spoilage in stored garlic. It was also found that irradiation for sprout inhibition did not influence the firmness of garlic cloves.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.240-240
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• 2017

Quinoa (Chenopodium quinoa Willd.) is one of the ancient crops cultivated in the Andes region at an altitude of 3,500-4000m in Chile and Bolivia from 5000 BC. It contains a large amount of protein, minerals and vitamins in comparison with other crops. The cultivation area has been increasing worldwide because of its excellent resistance to various abiotic stress such as salinity, drought and low temperature. ${\gamma}$-Ray radiation of high dose is often used as a tool to induce mutations in plant breeding, but it has a deleterious effect on organisms. However, the radiation may have a positive stimulatory effect of 'hormesis' in the low dose range. This experiment was carried out to investigate the optimum dose range for creating the quinoa genetic resources and to investigate the hormesis effect at low dose on the quinoa. This experiment was performed for 120 days from November, 2016 to February, 2017 in the greenhouse of Gyeongsang National University. ${\gamma}$-Ray radiation was irradiated to seeds at 0 Gy, 50 Gy, 100 Gy, 200 Gy, 300 Gy, 400 Gy, 600 Gy, 800 Gy and 1000 Gy for 8 hours. (50 Gy) using the low level radiation facility ($Co^{60}$) of Cooperative Research Institute of Radiation Research Institute, KAERI. Fifty seeds were placed on each petri dish lined with wet filter paper and germination rate was measured at a time interval of 2 hours for 40 hrs. The length of the root length was measured one week after germination. Each treatment was carried out in 3 replicates. The growth of seedlings were investigated for 10 days after transplanting of 30 day-old seedlings. The plant height, NDVI, SPAD, Fv/Fm, and panicle weight were measured. The germination rate was highest at 50Gy and 0Gy and the rate of seeds treated with 400Gy or higher rate decreased to 25% of the seeds treated with 50Gy. The emergence rate of seedling in pot experiment was higher at the dose of 200 Gy, 300 Gy and 400 Gy than at 0 and 50Gy. However, the rate was lower at strong radiation higher than 600Gy at which $1^{st}$ leaf was not expanded fully and dead due to extreme overgrowth at 44 days after treatment (DAT). The highest value of panicle weight was observed at 50Gy (6.15g) and 100Gy (5.57g). On the other hand, the weight at high irradiated dose of 300Gy and 400Gy was decreased by about 55% compared to low dose (50 Gy). NDVI measurement also showed the highest value at 50 Gy as the growth progressed. SPAD was the highest at 400 Gy and showed positive correlation with irradiation dose except 0 Gy. Fv/Fm was high at 50 Gy up to 30 DAT and no difference between treatments was observed except for 400 Gy from 44 DAT. The plant height was the highest in 50Gy during the growing period and was higher in the order of 50Dy, 100Gy, 0Gy, 200Gy, 300Gy and 400Gy in 88 DAT. In this experiment, the optimal radiation dose for hormesis was 50Gy and 100Gy, and the optimal radiation dose for mutagenesis seems to be 400 Gy.

• Korean Journal of Veterinary Research
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• v.43 no.1
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• pp.49-55
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• 2003

This study was performed to determine the effect of Phyllostachys nigra var. henenis Strapf leaf extract on jejunal crypt survival, endogenous spleen colony formation and apoptosis in jejunal crypt cells of mice irradiated with high and low dose of gamma-radiation. Phyllostachys nigra var. henenis Strapf administration before irradiation (I.P.: 125 mg/kg of body weight, at 24 hours before irradiation) resulted in an increase of the formation of endogenous spleen colony (p<0.01). The frequency of radiation-induced apoptosis was also reduced by pretreatment of Phyllostachys nigra var. henenis Strapf (I.P.: 280 mg/kg or 28 mg/kg of body weight, at 24 hours before irradiation, p<0.01). These results indicated that Phyllostachys nigra var. henenis Strapf might be a useful radioprotector, especially since it is a relatively nontoxic natural product. Further studies are needed to characterize better the promotion nature of Phyllostachys nigra var. henenis Strapf and its components.

• Journal of Plant Biology
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• v.6 no.3
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• pp.6-14
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• 1963

YIM, Kyong Bin (Coll. of Agriulture, Seoul National University) Effect of neutron and gamma irradiation on the germination of diploid and tetraploid rye seeds. Kor. Jour. Bot. VI(3):6-14, 1964. Tetraploid rye, Secale cereale 4x, was more tolerant to fast nuetron than diploid rye. Root growth was more suppressed than was seedling height in both diploid and tetraploid rye. A stimmulative effect on the dry weight of the shoot could be observed at very low doses of irradiation. It was the fact that the lower the moisture content of the seeds, the higher the radiosensitivity. Concerning seedling height growth, the effectiveness ratio of N/X equalled about 20.0 in diploid rye and about 18.2 in tettraploid rye, when the 50% dose ratios is used for this quotient calculaiton.

• Journal of Radiation Protection and Research
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• v.37 no.3
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• pp.123-128
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• 2012

Evidence suggests that even low-dose irradiation can lead to progressive cognitive decline and memory deficits, which implicates, in part, hippocampal dysfunction in both humans and experimental animals. This study examined whether diethyldithiocarbamate (DDC) could attenuate memory impairment, using passive avoidance and object recognition test, and suppression of hippocampal neurogenesis, using the TUNEL assay and immunohistochemical detection with markers of neurogenesis (Kiel 67 (Ki-67) and doublecortin (DCX)) in adult mice treated with gamma radiation (0.5 or 2 Gy). DDC was administered intraperitonially at a dosage of 1,000 $mg{\cdot}kg^{-1}$ of body weight at 30 min. before irradiation. In passive avoidance and object recognition memory test, the mice, trained for 1 day after acute irradiation (2 Gy) showed significant memory deficits compared with the sham controls. The number of TUNEL-positive apoptotic nuclei in the dentate gyrus (DG) was increased 12 h after irradiation. In addition, the number of Ki-67- and DCX-positive cells were significantly decreased. DDC treatment prior to irradiation attenuated the memory defect, and blocked the apoptotic death. DDC may attenuate memory defect in a relatively low-dose exposure of radiation in adult mice, possibly by inhibiting a detrimental effect of irradiation on hippocampal neurogenesis.