• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.05c
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• pp.43-46
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• 2001

Polymers are widely used as insulating materials at various part of power industry. However, electrical properties of these polymers are easily degraded with their working environments, especially radiation areas. In this research, radiation degradation of low density polyethylene (LDPE) used as cable insulation was evaluated with thermoluminescence characteristics. LDPE was irradiated with gamma ray up to 1000 kGy at a dose rate of 5 kGy/hr in the presence of air at room temperature. Each of the irradiated samples were carried out thermoluminescence analysis as a function of temperature. Interrelationships between thermoluminescence and dielectric characteristics and volume resistivity are investigated as well. The results of thermoluminescence analysis showed that those would be significant factors for evaluation of radiation degradation.

• Korean Journal of Microbiology
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• v.27 no.3
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• pp.297-303
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• 1989

Attempts to isolate the naturally occurring ultra-violet resistant bacteria from environmental sources were made. The isolates, designated No.29, 100, and 107, among numbers of bacterial isolates revealed a remarkable resistance to UV ray, whose degree of resistance in dose/response kinetics was comparable to that of an endospore-former, Bacillus subtilis. In a range of 100-300 $Jm^{-2}$/min of UV irradiation, the isolates exhibited 500-1000 fold resistance compated with E. coli. The isolated appeared to possiss cell-bound pigment of organge or crimson-red. The isolate 29 is spherical in pairs or tetrads, whereas the isolates 100 and 107 are rod. All are Gram-gositive bacteria and seemed to be non-endospore-bearer. A number of biochemical studies pursued on the isolates suggested that they are quite different to each other. Electron microscopic examination and the physiological characters of the isolate 29 suggested that this UV resistant spherical bacterium might be one species of Deinococcus, probably Deinococus radiophilus. Since there is no documents on UV resistant, Gram-positive, non-sporeformer bacillus so far, the isolates 100 and 107 might be turned out as new kinds of UV resistant bacteria occurring in nature by further investigation.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.20 no.1
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• pp.139-148
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• 1990

The purpose of this study was to investigate the effects of irradiation on the rat submandibular gland which composed of the epithelial growth factors. The experimental animals were the Sprague Dawley strain rats, which were the rats as the non-irradiated control group and the rats as the experimental group which were divided into groups as the experimental duration of 1 hour, 3 hours, 6 hours, 12 hours, 1 day, 3 days, 1 week, 2 weeks, 4 weeks. The experimental animals were singly irradiated at a dose of 8 Gray gamma ray to their head and neck region by the Co-60 teletherapy unit and sacrificed after each experimental duration. The specimens were stained with H-E and Azan stain and examined light microscopically. The results of this study were obtained as follows. 1. The all of mucous and serous acini in submandibular gland showed similar pattern of changes in structure according to the lapse of time. 2. The acinic cells started to change after 1 hour, and repaired after 12hours with mitosis and proliferation of the cells between acini. The changes were marked after 1day, and repaired gradually in course of time. 3. The duct were dilatated irregularly, and the outline of the eosinophilic stained ductal cells changed indistinctly.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.10
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• pp.73-77
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• 1971

The experiment was carried out to investigate post-irradiation storage effect which was related to temperature(i.e. at 2$^{\circ}C$, 17$^{\circ}C$ and 4$0^{\circ}C$) on wheat seeds; Weibull's Svenno, treated with gamma-ray and fast neutron. Results obtained showed that the seedling height in both radiation sources was decreased with prolongation of storage period, especially when the seeds were treated with high dosage and stored at high temperature(4$0^{\circ}C$). The results of this trial, however, showed that storage effect was influenced by irradiation dose, temperature and storage time.

• Nuclear Engineering and Technology
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• v.50 no.8
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• pp.1298-1305
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• 2018

The use of System-on-Chip (SoC) solutions in the design of on-board data handling systems is an important step towards further miniaturization in space. However, the Total Ionizing Dose (TID) and Single Event Effects (SEE) characterization of these complex devices present new challenges that are either not fully addressed by current testing guidelines or may result in expensive, cumbersome test configurations. In this paper we report the test setups, procedures and results for TID testing of a SoC microcontroller both using standard $^{60}Co$ and low-energy protons beams. This paper specifically points out the differences in the test methodology and in the challenges between TID testing with proton beam and with the conventional gamma ray irradiation. New test setup and procedures are proposed which are capable of emulating typical mission conditions (clock, bias, software, reprogramming, etc.) while keeping the test setup as simple as possible at the same time.

• 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.

• Applied Chemistry for Engineering
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• v.10 no.6
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• pp.838-842
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• 1999

In order to reclaim the effluent discharged from sewage treatment facilities application of an irradiation technique was investigated in this study for industrial water reuse. Samples were filtered using a sand filter to remove particles. Co-60 was used as an irradiation source and the irradiation dose was varied from 0.1 kGy to 15 kGy. The major source of colour in secondary treatment effluent was humic substances, which could be easily removed by irradiation with a dose 5 kGy. Bacteria could be also disinfected even at low doses. It was possible to get high quality water for industrial water reuse. But the effluent still contained a small amount of organic compounds. Further treatment, of residual organic compounds will be necessry if the higher quality water is required.

• Applied Chemistry for Engineering
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• v.10 no.3
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• pp.477-485
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• 1999

The grafting of 2,3-epoxypropylmethacrylate (GMA) onto polypropylene fabric was carried out by the $\gamma$-ray preirradiation grafting technique. Subsequently, the GMA-grafted polypropylene fabric was reacted with iminodiacetic acid (IDA) in different mixed solvents to prepare the fibrous metal adsorbent. The grafting extent was found to be dependent on the reaction time, temperature, preirradiation dose and dose rate. The effects of various mixed solvents on the IDA amination onto GMA-grafted polypropylene fabric were investigated. Compared with other mixed solvents, the extent of amination was highest in the dimethylsulfoxide (DMSO)/water, but the reaction did not occur in the water. The adsorption characteristics of various metal ions by the prepared adsorbent were examined when it was immersed in the 100 ppm metal ion solution. The amount of adsorption followed the order:$Pb^{2+}>Co^{2+}>Fe^{2+}$.

• Korean Journal of Veterinary Research
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• v.31 no.3
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• pp.329-335
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• 1991

The filter elution technique was used to assay $^{60}Co$ $\gamma$ ray-induced DNA strand breaks(SB) in EL4 mouse leukemia cell and mouse spleen lymphocyte. The lymphocytes were stimulated with lipopolysaccharide (LPS, $20{\mu}g/ml$) to label $[^3H]$ thymidine. EL4 cells and lymphocytes in suspension were exposed at $0^{\circ}C$ to 0Gy, 1Gy, 5Gy, 10Gy or l5Gy for DNA single strand breaks(SSB) assay and 0Gy, 25Gy, 50Gy, 75Gy or 100Gy for DNA double strand breaks(DSB) assay of $^{60}Co$ radiation and elution procedure was performed at pH12.1 and 9.6. The number of DNA strand breaks increased with increasing doses of r rays. The strand scission factor(SSF) was estimated in each experiment (eluted volume 21ml). The slope of SSB EL4 cells was $0.01301{\pm}0.00096Gy^{-1}$ (n=5), the slope of SSB for lymphocytes was $0.01097{\pm}0.00091Gy^{-1}$ (n=5) and the slope of DSB for lymphocytes was $0.001707{\pm}0.0000573Gy^{-1}$ (n=5). Thus EL4 cells were more sensitive to induction of DNA SSB by ionizing radiation than lymphocytes (p<0.005). The ratio of slope of dose-response relationship (SSF versus dose) of lymphocytes DNA SSB as compared with the slope of DNA DSB was 6.4.

• Applied Biological Chemistry
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• v.31 no.2
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• pp.147-153
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• 1988

An assessment of the nutritional aspects on irradiated garlic bulbs, stored for 10 months at low$(3{\pm}1^{\circ}C,\;75{\sim}85%\;R.H.)$ and room$(12{\pm}5^{\circ}C,\;75{\sim}85%\;R.H.)$, was performed by means of investigations on the changes in some chemical composition. Ionizing energy treatment at 0.1kGy gamma-ray brought about no significant changes in the moisture content of stored garlic, but it contributed to the reduction of the changes in total available carbohydrate content of stored garlic. After 8 months of storage, the content of free sugars was significantly higher in nonirradiated garlic than in irradiated garlic, especially in low temperature storage. The 0.1kGy irradiation at the sprout-inhibition dose had no apparent effect on the content of ascorbic acid in stored garlic, and sulfurcontaining amino acids appeared to be little affected by the irradiation at 0.1kGy, even though there were some sensitive amino acids like glutamic and aspartic acids.