• Korean Journal of Environmental Biology
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• v.29 no.1
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• pp.61-67
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• 2011

N-acetyl-L-cysteine (NAC) having a thiol, a precursor for glutathione (GSH), is known as one of the antioxidants. NAC used as a radioprotector against ionizing radiation (IR)-induced injury and damage. The aim of this study was to evaluate the radioprotective effects of NAC against IR-induced cell damage in Saccharomyces cerevisiae and the antioxidative effect of NAC on transcriptional level of yeast antioxidant enzyme genes such as superoxide dismutase (SOD) and catalase. In the present study, yeast cells were pretreated with various concentrations of NAC and/or irradiated with various doses of gamma rays. The cell viability was measured by counting the cell forming unit (CFU). The quantitative real-time PCR was performed for analysis of gene expression of SOD and catalase. The viability of irradiated cells was not improved by pretreatment with NAC. Ionizing radiation with 100 Gy highly induced the gene expression of antioxidant enzymes. In the irradiated group with NAC pretreatment, the gene expression of SOD and catalase was gradually reduced with the increased concentrations of NAC. These results indicate that NAC can act as a useful antioxidant to scavenge reactive oxygen species in vivo, but does not protect cells against IR-induced cell death in S. cerevisiae.

• Journal of Radiation Protection and Research
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• v.25 no.1
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• pp.37-43
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• 2000

Protective effect of medicinal plant extracts against oxidative stress were screened in this study. Methanol extracts from 48 medicinal plants, which were reported to have antioxidative or anti-inflammtory effect were prepared and screened for their protective activity against chemically-Induced and radiation-induced oxidative stress by using MTT assay. Thirty three samples showed protective activity against chemically-induced oxidative stress in various extent Among those samples, extract of Glycyrrhiza uralensis revealed the strongest activity (25.9% at $100{\mu}g/m{\ell}$) with relatively lower cytotoxicity. Seven other samples showed higher than 20% protection at $100{\mg}g/m{\ell}$. These samples were tested for protection activity against radiation-induced oxidative stress. Methanol extract of Alpina officinarum show the highest activity (17.8% at $20{\mu}g/m{\ell}$). Five fractions were prepared from the each 10 methanol extracts which showed high protective activity against oxidative stress. Among those fraction samples butanol fractions of Areca catechu var. dulcissima and Spirodela polyrrhiza showed the highest protective activities (78.8% and 77.2%, respectively, at $20{\mu}g/m{\ell}$).

• Journal of Radiation Protection and Research
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• v.36 no.4
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• pp.200-208
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• 2011

The neutron fluence measurement and evaluation technology is very important for material irradiation test. The most essential technology in this study is the neutron irradiation evaluation method using a fluence monitor. The fluence monitors were fabricated with metal wires of the purity ${\geq}$ 99.9%, whose dimensions were 0.1mm diameter, about 3 mm length, and around 150-200 ${\mu}g$ mass range. Three wire samples (Fe, Ni, Ti) were prepared for one irradiation aluminum capsule. Five capsules were irradiated in the OR5 hole of the HANARO reactor at 30 MW power for about 25 days. After irradiation tests, radiation activities were measured with the high purity germanium (HPGe) detector. The reaction rates were calculated by using the measured radiation activity data, and then neutron fluence were obtained from the reaction rates and the weighted neutron cross section with calculated neutron spectrum at the fluence monitor position.

• Journal of Radiation Protection and Research
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• v.35 no.1
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• pp.21-25
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• 2010

Burnup of spent fuel should be determined accurately for the safety control of spent fuel. Especially, it is necessary to measure the burnup profile along the nuclear fuel axis. In the present work, an ionization chamber was designed and fabricated to measure the gamma ray profile inside the guide tube of spent fuel. The ionization chamber was composed of three parts; induction part, gas-inlet part, and sensor part. The sensor part had two electrodes; cathode and anode. A guide electrode was considered in the ionization chamber design to make the ionization chamber to be inserted easily into the guide tube. Pure gas (argon and xenon) was inserted into the ionization chamber, and the leakage current and saturation curve were measured to determine the operation characteristics of the ionization chamber. The gamma ray radiation was also measured in relatively high dose environment. The gamma ray profile of the spent fuel will be measured with the ionization chamber.

• Journal of Radiation Protection and Research
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• v.34 no.3
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• pp.107-114
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• 2009

A Compton camera, which is based on Compton kinematics, is a very promising gamma-ray imaging device in that it could overcome the limitations of the conventional gamma-ray imaging devices. In the present study, the image quality of a rotating Compton camera was evaluated by using 4-D Monte Carlo simulation technique and the applicability to nuclear industrial applications was examined. It was found that Compton images were significantly improved when the Compton camera rotates around a gamma-ray source. It was also found that the 3-D imaging capability of a Compton camera could enable us to accurately determine the 3-D location of radioactive contamination in a concrete wall for decommissioning purpose of nuclear facilities. The 4-D Monte Carlo simulation technique, which was applied to the Compton camera fields for the first time, could be also used to model the time-dependent geometry for various applications.

• Applied Biological Chemistry
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• v.30 no.2
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• pp.126-132
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• 1987

The usual sterilization methods such as fumigation and autoclaving of laboratory rodent diet was compared with a new irradiation treatment in the point of sterilization effect and physico-chemical quality. Under the treatments of $10{\sim}20\;kGy$ ${\gamma}-irradiation$ and autoclaving at $121^{\circ}C$ for 20 min, total microorganisms were eliminated but ethylene oxide fumigation was insufficient to destory them. Total amino acid content was reduced about 5% in 20 kGy radiation treatment compared with control, while in the ethylene oxide fumigation and the autoclaving, the reducing rate was markedly great as 15% and 20%, respectively. Total sugar and mineral contents were not significantly different among treatment among treatment groups. TBA values were increased in all treatments. The pH of irradiated group war stable in comparison with that of ethylene oxide. In the treatments of ethylene oxide and especially autoclaving, overall appearance was decreased to a great extent as a result of decreasing lightness and increasing redness.

• Korean Journal of Agricultural Science
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• v.34 no.1
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• pp.67-75
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• 2007

The effect of irradiation on the quality characteristics of pale-soft-exudative (PSE) pork was studied. The pork loin with severe PSE appearance was selected by meat grader,irradiated at 0 and 4.5 kGy, and meat quality characteristics including pH, color, lipid oxidation development, microbial and sensory quality were analyzed during 2 weeks of storage at $4^{\circ}C$. The pH values of non-irradiated and 4.5 kGy-irradiated PSE raw pork loin was not different. Hunter color $a^*$-value, which represents redness of meat surface showed significant increase (P<0.05) in irradiated PSE pork loin. This higher Hunter color $a^*$-value maintained during 2 weeks of storage. By 4.5 kGy of irradiation, approximately 2 log reduction of total aerobic bacterial counts was achieved during 2 weeks of storage when compared with non-irradiated control. Sensory panelists prefer the color of irradiated PSE meat than that of non-irradiated control because of redness. From the results, it is possible to use an irradiation technology to improve not only microbiological safety but also the color of meat which has severe defect such as PSE.

• Journal of the Korean Magnetics Society
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• v.11 no.1
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• pp.21-25
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• 2001

$\alpha$-Fe$_2$O$_3$ thin films were prepared on Si substrate by a pulsed laser deposition system and characterized by X-ray and Mossbauer spectroscopy. The appropriate conditions of pulsation was the power of 5.128 W/cm2 at on oxygen pressure of 0.1 Torr at a substrate temperature of 30$0^{\circ}C$. After that the film was heated at 80$0^{\circ}C$ for 1 day. The particles shape deposited on the film was ellipsoidal and the average length and width were 200~300 nm, 70~150 am respectively. The crystal structure was conformed to be of corundums symmetry with the hexagonal unit cell having a lattice constant of u = 5.03$\pm$0.05 $\AA$, c = 13.735$\pm$0.05 $\AA$. The average angles between the atomic spin and the magnetic hyperfine field of Fe ion were 38$^{\circ}$and 48$^{\circ}$ at above and blow the Morin transition temperature respectively. The Morin transition was found to occur at the temperature ranges from 200 K to room temperature and atomic spin direction was assumed to change from 48$^{\circ}$ to 80$^{\circ}$in respect to the c-axis.

• Korean Journal of Veterinary Research
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• v.45 no.2
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• pp.139-149
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• 2005

In order to study about the lobule and layer formation and cell migration of the mouse cerebellum from at the birth to 15th day effected by 2.5, 5 and 10 Gy r-raddiation at the 19th pregnancy. The routine tissue preparation and staining procedure, Immunohistochemical staining method by the several antibody and western brotting method were utilized from the birth to the15th day. The results were as followings. 1. The body and cerebellum weights were more slowly increase of the the 2.5 Gy, 5 Gy and 10 Gy irradiation group compare to the control group, and the health condition of the 2.5 Gy group was a little bad. but the 10 Gy group was more severe and begun to die from the 12th day after birth. 2. The thickness, proliferation and migration of the 2.5, 5 and 10 Gy irradiated external granular cells from the maginal zone to the medullary area forming the molecular layer from the 6th day to the 15th day after birth were thinner, weaker and more slower according to the radiated dosages than the control group in the cresyl violet staining. 3. The proliteration, migration and lobulation of the 5 Gy radiated groups from the first day to the 15th day after birth were more weak, incomplete and irregular shape in the immunostaining with Dab, Cdk5, P35, calbindin and Zebrin antibody. 4. In the western blotting analysis using the Reelin, Dab, Cdk5 and P35 antibody. The Bands were in the 60 KD, 80 KD, 33 KD and 35 KD, and there were no differences between the control and irradiated groups in the molecular band except the Reelin. 5. As a results, the proliferation and migration of the outer granular and purkinje cells, and lobulation of the cerebellum by the several dosaege of the ${\gamma}$-ray radiation were proportionally incomplete according to dosage.

• Korean Journal of Food Science and Technology
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• v.33 no.6
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• pp.693-699
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• 2001

ChlorophyII destruction by irradiation in linoleic acid in methanol system was studied. ChlorophyII b standard (3 ppm) was added into methanol solution containing 1% of linoleic acid, and the sample was irradiated up to 20 kGy with or without nitrogen gas-bubbling. The content of chlorophyII b was analyzed by HPLC, and Hunter color value and UV-visible spectra were analyzed during 6 hr of photooxidation. The content of chlorophyll was reduced by irradiation and completely destroyed at 2.517 kGy. The model system with nitrogen gas-bubbling did not develop the lipid oxidation after irradiation or photooxidation at 20 kGy UV-visible spectra showed decreasing values of optical density by increase of irradiation doses, supporting the destruction of chlorophyII b. The results indicate that irradiation technology can be applied to reduce or eliminate the residual chlorophyII and to prolong the shelf-life of oil products.