• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.10a
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• pp.644-647
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• 2001

The investigations were discussed on the radiation effects of the electrical properties to the p-type MOS capacitors, which were irradiated by cobalt-60 gamma ray sources. The characteristics of capacitance-bias voltage(C-V) and of dielectric dissipation tarter-bias voltage(D-V) on the capacitors were measured at 1 [MHz] frequency. The microscopic behaviors of spate charges in oxide and silicon-silicon dioxide(Si- $SiO_2$) interface were investigated from the experimental data. The C-V characteristics are statical and convenient for the evaluation of the steady state behavior of carriers and interface states characteristics. While, the distribution and magnitude of space charges in oxide can be found out accurately on the $V_{dp}$ in D-V curves. The density of interface states can be deduced with ease from the magnitude of D-peak at depletion state. Thus, it is also concluded that the D-V curves are more useful and easier than conventional C-V curves for analysis of the microscopic and dynamic behavior of carriers in oxide and Si- $SiO_2$interface.

• Nuclear Engineering and Technology
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• v.54 no.12
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• pp.4514-4521
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• 2022

In this study, the effects of heat and radiation on the degradation behaviour of fluoroelastomer under simulated normal operation and a severe accident environment were investigated using sequential testing of gamma irradiation and thermal degradation. Tensile properties and Shore A hardness were measured, and thermogravimetric analysis was used to evaluate the degradation behaviour of fluoroelastomer. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy were used to characterize the structural changes of the fluoroelastomer. Heat and radiation generated in nuclear power plant break and deform the chemical bonds, and fluoroelastomer exposed to these environments have decreased C-H and functional groups that contain oxygen and double bonds such as C-O, C=O and C=C were generated. These functional groups were formed by auto oxidation by reacting free radicals generated from the cleaved bond with oxygen in the atmosphere. In this auto oxidation reaction, crosslinks were generated where bonded to each other, and the mobility of molecules was decreased, and as a result, the fluoroelastomer was hardened. This hardening behaviour occurred more significantly in the severe accident environment than in the normal operation condition, and it was found that thermal stability decreased with the generation of unstable structures by crosslinking.

• Journal of the Korean Society of Food Science and Nutrition
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• v.12 no.2
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• pp.116-121
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• 1983

A study was conducted to evaluate the effect of $^{60}CO-{\gamma}$ irradiation on the preservation on Satauma mandarin in Cheju Island. Four varieties (S. m. early, S. m. Komezawa, S. m. Hayashi and S. m. Aoshima) were irradiated using 10,000Ci, $^{60}CO-{\gamma}$ ray with dosages of 0, 50, 100 and 150Krad. During 92 days of storage the effects of irradiation on mandarin porperties were as follows: At the end of storage period the accumulated fruit rotting percentage were S. m. Komezawa($T_2$);74.32%, S. m. early($T_1$);69.67%, S. m. Aoshima($T_4$);64.33% and S. m. Hayashi ($T_3$);61.79%. The rottings steadily increased from the early stage of storage and rapid spoilage continued after 59 days of irradiation. A high corelation existed between fruit rotting and varieties ($T_3$;Y=0.78x-15.30, $T_4$;Y=0.79x-12.29, $T_1$;Y=0.93x-9.01 and $T_2$;Y=0.79x-13.49) High dosages(100 and 150 Krad)improved fruit preservation during the mid storage stage. However 76 days after high dose irradiation there was no significant difference a rotting between irradiated fruit and the control. Irradiation decreased acidity of fruit during storage (p<0.01). The mean acidities of examined varieties were $T_1$;1.01%, $T_3$;1.01%, $T_4$;0.84% and $T_2$;0.77%. A significant differences were observed in acidity between varieties and dosages(P<0.01) With one exception in all treatments. the increase in free and total sugar content was not statestically significant. The exception was the 50 Krad treatment where the total sugar content decreased. $T_1$ and $T_4$ showed slightly higher value of than Brix $T_2$ and $T_3$, and were significantly(P<0.01) decreased by higher dosage. The ascorbic acid content in all treatments decreased with length of storage and also decreased significantly with a higher dosage.

• 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.

• Radiation Oncology Journal
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• v.17 no.1
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• pp.65-69
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• 1999

Purpose : It has been well established that the response of cells and tissues to low LET radiations (X- or gamma-ray) can be enhanced by combining with hyperthermia. However, there has been relatively little work of hyperthermia on the possible modification of either cellular or tissue responses to other types of radiation. So, we investigated the combined effect of fast neutron irradiation and hyperthermia according to the sequence and time interval of the two. Materials and Methods : In MKN-45 cells, a human stomach cancer ceil line, suwiving fractions were measured according to the sequential treatment of 0, 4, 2, 0 hour-intewal for fast neutron irradiation (1.5 Gy) combined with hyperthermia (41 $^{\circ}C$ for 30 min or 43$^{\circ}C$ for 30 min). Results : D$_{0}$ and n of MKN-45 for neutron were 0.8 Gy and 2.5, respectively. The surviving fraction by 1.5 Gy of neutron was 0.36$\pm$0.34. Interacting powers were mostly ranged between 1 and 2, but they were 3.0 and 2.7, respectively for hyperthermia (41 $^{\circ}C$ for 30 min) fellowed by neutron irradiation 6 and 4 hours later. Conclusion : The combined effect of fast neutron (1.5 Gy) and hyperthermia (41 $^{\circ}C$ or 43$^{\circ}C$ for 30min) is largely independently additive. Preceding mild hyperthermia (41 $^{\circ}C$ for 30 min) 4 or 6 hours before neutron may cause decreased sensitivity to subsequent neutron irradiation.

• Journal of radiological science and technology
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• v.11 no.1
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• pp.71-77
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• 1988

To improve the storage method for kimchi, optimal ripening kimchi was irradiated with doses of 1, 3, 5kGy Co-60gamma radiation, followed by the microbiological, physicochemical and senosory evaluations during storage at $5^{\circ}C$. 1. Total aerobic count increased in the beginning of storage and then decreased slowly as the number of total lactobacilli (anaerobe) increased. The above, total aerobic and lactobacilli were reduced by 1 to 3 log cycles with irradiation and at the 90th day after storage the number of total lactobacilli remained $1.30{\times}10^{8}$ per ml in 3 kGy irradiated group. Irradiation treatment at 3 kGy sterilized coliforms and molds contaminating the sample as the level of $2.0{\times}10^{4}$ per ml and $5.4{\times}10^{2}$ per ml respectively and no apparent growth was observed in both control and 1 kGy irradiated groups after 20 days of storage. The population of yeast, $3.5{\times}10^{3}$ per ml initially, increased steadily during kimchi storage and at 90 days of storage the number was shown to be $5.6{\times}10^{4}$ per ml and $6.5{\times}10^{2}$ per ml in control and 3 kGy irradiated groups, respectively. 2. In the physicochemical changes during kimchi storage, pH, acidity and volatile acid of non-irradiated control at the 45th day after storage were 4.0, 0.7% and 0.066%, while those of 3 kGy irradiated group were 4.2, 0.59 and 0.06% at the 90th day of storage, respectively. The reducing sugar content of all stored samples changed inversely total acidity content, indicating irradiation delayed the changes of them. The amount of ascorbic acid decreased gradually with the storage time and irradiation dose increase. Textural parameters of 3 kGy irradiated group were superior to those of other groups at the latter stage of storage. 3. Sensory evaluations showed that 3 kGy irradiation was the optimum dose level to extend the shelf-life of kimchi more than two months as compared to control.

• Journal of the Korean Society of Radiology
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• v.4 no.1
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• pp.31-35
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• 2010

Recently, the incidents of direct or indirect radiation exposure due to increase of use of radiation or radioisotope are on the increase in medical and industrial circles. If cells are irradiated, free radicals are created through biological process, and cells are directly or indirectly damaged. This research intends to explore into the effect of saponin at the level of cell (in vitro) and entity (in vivo), using red ginseng extract "saponin", as radioprotective agent. In the experiment implemented at the level of cell (in vitro), degree of cell activity was measures by adding mouse mesenchymal stem cells "C3H/10T1/2 cells" into red ginseng extract "saponin(0, 0.05, 0.2, and 0.4 g/L)", and then the optimal concentration of saponin influencing cells was calculated, in 24, 48, 72, and 96 hours after gamma irradiation at the optimal concentration of saponin, each cell survival rate was observed through XTT assay. The best time period of cultivation for the optimal activity of C3H/10T1/2 cells was as 48 hours, and the degree of optimal activity was shown at 0.05 g/L. In 48 hours after irradiation of 5 Gy to C3H/10T1/2 cells at 0.05 g/L, the degree of activity of cells increased by 10%. In the experiment implemented at the level of entity (in vivo), red ginseng extract "saponin" at a dose of 100 mg/kg/day was injected into the abdominal cavity of six-week immature mouse for two weeks. Right after the last abdominal injection, total body irradiation of gamma rays was carried out at a dose of 5 Gy and 10 Gy. And after irradiation, the blood sample was taken, and then the number of red corpuscles was counted. In result, the decrement of experimental group treated with red ginseng extract "saponin" was 2.3 times larger than that of control group. In view of the results so far achieved, it was revealed that red ginseng extract "saponin" has a radiation exposure protection effect in the experiment implemented at the level of cell (in vitro). In case of animal experiment, the decrement of number of red corpuscles decreased. Finally, it is necessary to carry out more various researches continuously.

• Journal of Ginseng Research
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• v.35 no.3
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• pp.283-293
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• 2011

With the purpose of improving ginsenoside content in adventitious root cultures of Korean wild ginseng (Panax ginseng Meyer), the roots were treated with different dosages of ${\gamma}$-ray (5, 10, 25, 50, 75, 100, and 200 Gy). The growth of adventitious roots was inhibited at over 100 Gy. The irradiated adventitious roots showed significant variation in the morphological parameters and crude saponin content at 50 to100 Gy. Therefore, four mutant cell lines out of the propagation of 35 cell lines treated with 50 Gy and 100 Gy were selected on the basis of phenotypic morphology and crude saponin contents relative to the wild type control. The contents of 7 major ginsenosides ($Rg_1$, Re, $Rb_1$, $Rb_2$, Rc, Rf, and Rd) were determined for cell lines 1 and 3 from 100 Gy and lines 2 and 4 from 50 Gy treatments. Cell line 2 showed more secondary roots, longer length and superior growth rate than the root controls in flasks and bioreactors. Cell line 1 showed larger average diameter and the growth rate in the bioreactor was comparable with that of the control but greater in the flask cultured roots. Cell lines 1 and 2, especially the former, showed much more ginsenoside contents than the control in flasks and bioreactors. Therefore, we chose cell line 1 for further study of ginsenoside contents. The crude saponin content of line 1 in flask and bioreactor cultures increased by 1.4 and 1.8-fold, respectively, compared to the control. Total contents of 7 ginsenoside types ($Rg_1$, Re, $Rb_1$, $Rb_2$, Rc, Rf, and Rd) increased by 1.8 and 2.3-fold, respectively compared to the control. Crude saponin and ginsenoside contents in the bioreactor culture increased by about 1.4-fold compared to that the flask culture.

• Food Science and Preservation
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• v.16 no.3
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• pp.371-375
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• 2009

Electron spin resonance (ESR) spectroscopy was used to detect radiation-induced signals from irradiated spices and ESR parameters were analyzed to define specific signals. Four powdered spices (red pepper, garlic, onion, and black pepper) were irradiated with 0, 1, 5, or 10 kGy at room temperature using a [60Co] gamma-ray irradiator prior to ESR analysis. Radiation-induced triplet signals, including those from the cellulose radical, which are center signals ($g_2=2.00673$) within the range of 3.0455 mT, were observed in all irradiated spice samples. The parameters g-value, center field, and signal range of hyperfine triplet ESR signals were constant in all irradiated samples, being specific for cellulose radicals and thereby distinguishing these signals from those of nonirradiated control samples. High positive correlation coefficients ($R^2=0.8452-0.9854$) were obtained between irradiation doses and corresponding ESR signal intensities. Thus, reliable detection of irradiated dried spices by measurement of ESR cellulose signals was confirmed by parameter analysis for the cellulose radical.

• Journal of The Korean Society of Grassland and Forage Science
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• v.18 no.4
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• pp.351-354
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• 1998

Centipedegrass (Eremochloa ophiuroides) is a popular lawn grass in the southeastern USA. It has a naturally light green color and grows well on a wide range of soil types. Studies show limited morphological variation present in centipedegrass germplasm. To obtain the high morphological variation, plants were established from the irradiated seed at 10 Kr, allowed to interpollinate and harvested bulk seed, and then irradiated again for the next cycles. Morphological characteristics were measured in the 5 genetic varition lines (TC201 : cv. Common and non irradiated, TC202 : 4th cycles, TC241 : 6th cycles, TC306 : 8th cycles, and TC318 : 5th cycles) induced by recurrent gamma radiation. The ranges of variation of recurrently radiated centipedegrass lines < TC202, TC241 and TC306 except TC318(TifBlair) > for the stolons per plant, total stolon length per plant, longest stolon length, leaf length and width at top-most exposed internode were wider than those of non-irradiated line (TC201). Recurrent gamma radiation was very effective to enlarge the ranges of variation of morphological characteristics in reproductive organ like stolons of centipedegrass. The effect of quantity of gamma ray irradiation cycles on the means and ranges of variation in the morphological characteristics of centipedegrass was not regularly tended.