• Proceedings of the Korean Society of Crop Science Conference
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• 2003.10a
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• pp.130-131
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• 2003

• Journal of Microbiology and Biotechnology
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• v.28 no.4
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• pp.527-533
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• 2018

This study compared the radioprotective effects of high-molecular-weight poly-gamma-glutamate (${\gamma}-PGA$, average molecular mass 3,000 kDa) and a reduced form of glutathione (GSH, a known radioprotector) on calf thymus DNA damage. The radiation-induced DNA damage was measured on the basis of the decreased fluorescence intensity after binding the DNA with ethidium bromide. All the experiments used $^{60}Co$ gamma radiation at 1,252 Gy, representing 50% DNA damage. When increasing the concentration of ${\gamma}-PGA$ from 0.33 to $1.65{\mu}M$, the DNA protection from radiation-induced damage also increased, with a maximum of 87% protection. Meanwhile, the maximal DNA protection when increasing the concentration of GSH was only 70%. Therefore, ${\gamma}-PGA$ exhibited significant radioprotective effects against gamma irradiation.

• Journal of Radiation Protection and Research
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• v.45 no.3
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• pp.108-116
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• 2020

Background: This foundational study on educational interventions aimed to analyze the changes in awareness, knowledge, and attitudes of young learners after they received objective information on safety management. Materials and Methods: Educational sessions on nuclear power and radiation safety were delivered to 4,934 Korean elementary, middle, and high school students in two separate sessions conducted in 2016 and 2017. The effects of these interventions were subsequently analyzed. Results and Discussion: Learner attitudes toward safety were found to be the predominant variables affecting the post-intervention risk (safety) awareness of nuclear power generation. Conclusion: The safety awareness of future generations will significantly influence policy decisions on nuclear power generation. Hence, the design of educational interventions on this subject must match variables suited to learner levels.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.2
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• pp.382-390
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• 1992

The problem of natural convection from a vertical fin is solved by coupling the thermal diffusion equation in the fin to the constitutive equations of the ambient medium involving the radiation of the medium. The analysis is accomplished by employing an integral method. The governing equations for the problem are solved by shooting method based on the Runge-Kutta Scheme at Pr= 0.7. For the range of values of the fin parameter and the radiation-conduction parameter in the analysis, the numerical results show that the radiation effects play an important role in the heat transfer and enhance the heat transfer.

• Korean Journal of Digital Imaging in Medicine
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• v.2 no.1
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• pp.92-95
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• 1996

Computed Radiography(CR) is a relatively new technology that relies on an image plate(IP) as an alternate x-ray sensor to screen/film. Standard CR cassettes do not have lead foil behind the IP to control scatter radiation. The result of this study indicate that such control is needed. In most screen/film cassettes, that lines the rear of the cassette eliminates back scatter radiation. This study was performed to Investigate on the effects of back scatter in CR images by size of exposure field, distance between the CR cassette and the wall of radiography room. 1. It showed artifacts from hinges and clips located on the back of CR cassette by back scatter radiation. 2. The greater effects of back scatter radiation in CR images was attributed to the greater size of exposure field and the longer distance between the CR cassette and the wall of radiography room.

• Journal of Radiation Industry
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• v.4 no.3
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• pp.285-288
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• 2010

Polyimide films have excellent thermal stability, reliable mechanical properties and low dielectric constant. Therefore, this material is widely used in many industrial fields such as microelectronics, flexible circuits, semiconductor products and aerospace materials. In space applications, earth-orbiting hardware operates in environments that generally include neutral particles, charged particles such as trapped protons and electrons, solar protons, and cosmic rays. Under these conditions, polyimide films were changed in the optical, electrical and mechanical properties. Therefore, in this study, we evaluated the effects of electron beam irradiation on polyimide. The O-H functional groups were created on the polyimide film surface in the results of FT-IR spectra. And it was found that the dielectric constants were changed as a function of electron beam dose.

• Radiation Oncology Journal
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• v.22 no.4
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• pp.280-287
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• 2004

Purpose: This study was carried out to determine the protective effects of vitamin C on the hepatotoxicily induced by radiation. Materials and Methods : The Spraque Dawley rats were randomly divided into 3 groups; the control group, the radiation exposed group, aud the radiation and vitamin C-treated group. SOD activity, ca-talase, malondialdehyde and liver enzymes were analyzed to assess the antioxidant effects of vitamin C. Results: The increased level of malondialdehyde and the decreased catalase activity that were induced by radiation were improved after vitamin C but there was no statistical significance among three groups. The superoxide dismutase activity of the liver was increased by vitamin C, but there were no statistically significant differences between the vitamin C-treated group and the non vitamin C-treated group. The level of liver enzymes in sera such as glutamic oxaloacetic transaminase, glutamic pyruvic transaminase, lactate dehyrogenase and alkaline phosphatase were remarkably elevated by radiation. The levels of those enzymes were decreased in the vitamin C-treated group and statistical significance was noted for the GPT level ($p<0.01$). On the electromicrographic findings, the hepatic cell destruction was considerably decreased in the vitamin C-treated group. Conclusion: Vitamin C is thought to be an effective antioxidant against the hepatotoxicity induced by radiation.

• The Korean Journal of Malacology
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• v.29 no.1
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• pp.23-32
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• 2013

The purpose of this study is to evaluate the effects of oil dispersant and ultraviolet (UV) radiation on the toxicity of crude oil. The toxicity of water-accommodated fraction (WAF) and chemically enhanced water-accommodated fraction (CEWAF) of Hebei Spirit crude oil was investigated in the embryo of the Manila clam, Ruditapes philippinarum with- and without ultraviolet radiation. The WAF and CEWAF with- and without UV radiation affected significantly the embryonic development of R. philippinarum. The EC50s of WAF without UV, WAF with UV, CEWAF without UV, and CEWAF with UV were 2.82, 0.79, 1.60, and 0.45 g/L, respectively. CEWAF was 1.6 times more toxic than WAF. UV radiation increased crude oil toxicity to 3.6 times for both WAF and CEWAF. The oil dispersant and UV radiation did not affect the acute toxicity to the embryo but retarded the period of embryonic development up to 26%. R. philippinarum proved to be a sensitive species to reflect the toxic effects of oil spill combined with oil dispersant and UV radiation. It is suggested that the chemical analyses on the WAF and CEWAF is important for the identification and quantitative explanation of the phototoxic compounds in crude oil.

• Journal of Haehwa Medicine
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• v.5 no.2
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• pp.473-484
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• 1997

This study was performed to survey the specific information about the time of onset, frequency, duration, and severity of the side effect of radiation therapy following breast cancer surgery, and identify the difference of these data according to the type of breast cancer surgery : modified radical mastectomy(MRM) vs. breast consevative operation(BCO). 38 breast cancer patients were interviewed with side effect profile about radiation therapy. Interview was done weekley from the start of radiation therapy through 6 weeks and 3 month follow-up interview was done at 3 month after completion of the treatment. The results are as follow : 1. Total score of side effect experienced by the breast cancer patients was rapidly increased at 2-3 week after intiating treatement and continousely raised maintaing high score until completion of the treatement. Some problems like cough, dyspnea and pain were more experienced after treatment. 2. Patients with modified radical mastectomy showed more total score of side effects than patients with breast conservative operation. And both patients with MRM and BCO experienced similar pattern of side effect to radiation therapy. Through these data we concluded that side effect to radiation therapy was not ended at completion of treatement. Patents will continously experiend various problems and suffer from not only acute side effects like skin problem, sore throat and swollowing difficulty but also late effect of the radiation therapy. Clinically these data can be used for oncologic nurse to provide informational interventions to prepare breast cancer patients for the radiation therapy.

• Journal of Radiation Protection and Research
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• v.36 no.3
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• pp.119-126
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• 2011

Mitochondrial DNA (mtDNA) deletion is a well-known marker for oxidative stress and aging, and contributes to harmful effects in cultured cells and animal tissues. mtDNA biogenesis genes (NRF-1, TFAM) are essential for the maintenance of mtDNA, as well as the transcription and replication of mitochondrial genomes. Considering that oxidative stress is known to affect mitochondrial biogenesis, we hypothesized that ionizing radiation (IR)-induced reactive oxygen species (ROS) causes mtDNA deletion by modulating the mitochondrial biogenesis, thereby leading to cellular senescence. Therefore, we examined the effects of IR on ROS levels, cellular senescence, mitochondrial biogenesis, and mtDNA deletion in IMR-90 human lung fibroblast cells. Young IMR-90 cells at population doubling (PD) 39 were irradiated at 4 or 8 Gy. Old cells at PD55, and H2O2-treated young cells at PD 39, were compared as a positive control. The IR increased the intracellular ROS level, senescence-associated ${\beta}$-galactosidase (SA-${\beta}$-gal) activity, and mtDNA common deletion (4977 bp), and it decreased the mRNA expression of NRF-1 and TFAM in IMR-90 cells. Similar results were also observed in old cells (PD 55) and $H_2O_2$-treated young cells. To confirm that a increase in ROS level is essential for mtDNA deletion and changes of mitochondrial biogenesis in irradiated cells, the effects of N-acetylcysteine (NAC) were examined. In irradiated and $H_2O_2$-treated cells, 5 mM NAC significantly attenuated the increases of ROS, mtDNA deletion, and SA-${\beta}$-gal activity, and recovered from decreased expressions of NRF-1 and TFAM mRNA. These results suggest that ROS is a key cause of IR-induced mtDNA deletion, and the suppression of the mitochondrial biogenesis gene may mediate this process.