• Journal of Radiation Protection and Research
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• v.7 no.1
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• pp.34-48
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• 1982

The prime purpose of this study is to realize an index quantity, absorbed dose index, defined by the ICRU for the characterization of ambient radiation level at any location for the purpose of radiation protection. The experiment has been designed to be carried out in two phases, namely, preliminary and main experiment. In the primary study a 30cm diameter sphere of polyethylene was used, while in the main experiment that of tissue equivalent material was fabricated and used. Both experiments were performed in the gamma-ray fields of $^{137}Cs\;and\;^{60}Co$, and in a neutron beam of thermal column of the TRIGA MARK-II research reactor. In the measurement of gamma-ray absorbed dose TLD-700 $(^{7}LiF)$ chips were used, and for the neutron dose both Au activation foils and TLD chips (TLD-600 $(^{6}LiF)$ and TLD-700 for the discrimination of gamma-ray contribution) were used. Theoretical assessment of the absorbed dose in the sphere phantom has been carried out in accordance with the Ehrlich's idea that deduced on the basis of Burlin's cavity theory in the case of gamma-ray irradiation. For the analysis of neutron dose fluence-KERMA rate conversion method was used. The explanation on the dose assessment is given in detail. Results obtained were numerically and statistically analyzed and the depth dose distributions are presented in the graphic forms with normalized values. In the concluding remarks, the possibility and difficulty of realizing the index quantity, including questions and problems to be solved are mentioned.

• Proceedings of the KIEE Conference
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• 2003.11c
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• pp.793-796
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• 2003

The electronics of a mobile robot ill nuclear facilities is required to satisfied the reliability to sustain survival in its radiation environment. To know how much radiation the robot has been encountered to replace sensitive electronic parts, a dosimeter to measure total accumulated dose is necessary. Among many radiation dosimeters or detectors, semiconductor radiation sensors have advantages in terms of power requirements and their sires over conventional detectors. This paper describes the use of the radiation-induced threshold voltage change of a commercial power pMOSFET as an accumulated radiation dose monitoring mean and that of the photo-current of a commercial PIN Diode as a dose-rate measurement mean. Commercial p-type power MOSFETs and PIN Diodes were tested in a Co-60 gamma irradiation facility to see their capabilities as radiation sensors. We found an inexpensive commercial power pMOSFET that shows good linearity in their threshold voltage shift with radiation dose and a PIN diode that shows good linearity in its photo-current change with dose-rate. According to these findings, a radiation hardened hybrid electronic radiation dosimeter for nuclear robots has been developed for the first time. This small hybrid dosimeter has also an advantage in the point of view of reliability improvement by using a diversity concept.

• Journal of radiological science and technology
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• v.29 no.4
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• pp.285-291
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• 2006

During cancer therapy, gamma-ray irradiation and treatment of anti-cancer chemicals destroy the normal cells as well as cancer cells. In this study, we investigated the effect of epigallocathechin-gallate(EGCG) extracted from green tea, which is known to have anti-cancer and anti-oxident activities, in order to find out the feasible method to protect the normal cells and to kill the cancer cells efficiently. We investigated the effect of EGCG on the leukemia cell growth and cell necrosis, especially when treated along with gamma radiation. The EGCG inhibited the leukemia cell, HL-60, growth at the appropriate concentration while it exhibited no influence on the normal cell growth. More significantly, it enhanced leukemia cell necrosis when its treatment was combined with gamma irradiation. Simultaneous treatment of EGCG and gamma radiation increased leukemia cell necrosis up to 35% compared with separate treatments. These results suggest that drinking of green tea or co-treatment of EGCG during gamma irradiation therapy may result in better prognosis through enhancement of the tumor cell necrosis and protection of the normal cells.

• Korean Journal of Breeding Science
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• v.40 no.2
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• pp.113-118
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• 2008

This study was carried out to investigate the chemical composition of peanut mutants induced by gamma radiation (Co-60) at 300 Gy in seeds of the cultivar Shinnamkwang. The protein contents of twenty-eight peanut mutants ranged from 23.3% to 31.7% and were increased by from 0.5% to 8.4% in fifteen mutants lines from the 26.8% of the original variety, cv. Shinnamkwang. Lipid contents of in mutants ranged from 43.2% to 53.5%, an increase of 0.2% to 5.7% from the 47.8% of the original variety. The range of unsaturated oleic acid in 28 mutants was from 38.9% to 56.9% an increase of from 1.3% to 14.0% from the 50.6% in the original variety. Linoleic acid, the highest unsaturated fatty acid, constituted 32.6% meanly of mutants, it was 17.4% lesser than oleic acid, ranging from 25.9% to 42.0%. Palmitic acid (16:0) contents ranged from 8.6% to 11.1%, and the mutant line-9 had the highest content. The ratio of oleic to linoleic acid was 0.9 to 2.2. A negative coefficient (r=-0.98**) was obtained between oleic and linoleic acid, but for other fatty acids, no significant relation was observed. Similarly, a negative coefficient of r=-0.68**was observed between saturated and unsaturated acids. The sucrose compositions of mutants ranged from 2.6% to 6.2%.

• Journal of Radiation Industry
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• v.2 no.1
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• pp.1-7
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• 2008

Active polymer gels expand and contract in response to certain environmental stimuli, such as the application of an electric field or a change in the pH level of the surroundings. This ability to achieve large, reversible deformations with no external mechanical loading has generated much interest in the use of these gels as biomimetic actuators and artificial muscles. In this study, poly (vinyl alcohol)(PVA) grafted acrylic acid monomer (PVA-g-AAc) hydrogels were prepared by $^{60}Co$ ${\gamma}-ray$ irradiation and their properties such as degree of grafting and weight swelling in electrostimulation as an artificial muscle and actuator were investigated.

• Structural Engineering and Mechanics
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• v.87 no.5
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• pp.499-516
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• 2023

To defend against harmful gamma radiation, new types of materials for use in the construction of heavyweight concrete (HWC) are still needed to be developed. This research introduces new materials to be employed as a partial replacement for fine aggregate (FA) to manufacture high-performance heavyweight concrete (HPHWC). These materials include hematite, black sand, ilmenite, and magnetite, with substitution ratios of 50% and 100% of FA. In this research, the hardening and fresh characteristics of HPHWC were obtained. Concrete samples' Gamma-ray linear attenuation coefficient was evaluated utilizing a gamma source of Co-60 through the thicknesses of 2.5, 5, 7.5, 10, 12.5, and 15 cm. High temperatures were studied for HPHWC samples, which were exposed to up to 700℃ for two hours. Energy-dispersive x-rays and a scanning electron microscope carried out microstructure analyses. Magnetite as an FA attained the lowest compressive strength of 87.1 MPa, but the best radiation protection characteristics and the highest density of 3100 kg/m³ were achieved. After 28 days, the attenuation efficiency of concrete mixtures was increased by 6.5% when fine sand was replaced with black sand at a ratio of 50%. HPHWC, which contains hematite, black sand, ilmenite, and magnetite, is designed to reduce environmental and health dangers and be used in medicinal, military, and civil applications.

• Nuclear Engineering and Technology
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• v.53 no.5
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• pp.1483-1490
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• 2021

Many studies are undertaken into nuclear power plants (NPPs) in preparation for accidents exceeding design standards. In this paper, we analyze the applicability of various wireless communication technologies as accident countermeasures in different NPP environments. In particular, a commercial wireless communication module (WCM) is investigated by measuring leakage current and packet error rate (PER), which vary depending on the intensity of incident radiation on the module, by testing at a Co-60 gamma-ray irradiation facility. The experimental results show that the WCMs continued to operate after total doses of 940 and 1097 Gy, with PERs of 3.6% and 0.8%, when exposed to irradiation dose rates of 185 and 486 Gy/h, respectively. In short, the lower irradiation dose rate decreased the performance of WCMs more than the higher dose rate. In experiments comparing the two communication protocols of request/response and one-way, the WCMs survived up to 997 and 1177 Gy, with PERs of 2% and 0%, respectively. Since the request/response protocol uses both the transmitter and the receiver, while the one-way protocol uses only the transmitter, then the electronic system on the side of the receiver is more vulnerable to radiation effects. From our experiments, the tested module is expected to be used for design-based accidents (DBAs) of "Category A" type, and has confirmed the possibility of using wireless communication systems in NPPs.

• Journal of Radiation Industry
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• v.6 no.1
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• pp.11-15
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• 2012

This study confirmed the cytotoxicity and anti-inflammatory activities of natural herbal extracts (HE) including Eucommia ulimoides and Ulmus davidiana against human mast cell (HMC-1). HE was extracted with distilled water (at $75^{\circ}C$) and then freeze-dried for 5 days. Finally, the HE was sterilized by gamma radiation with $^{60}Co$ ${\gamma}$ source at room temperature. Cytotoxicity of the HE against HMC-1 cell was measured using cell counting kit-8 (CCK-8) assay. In addition, inflammatory cytokines such as $TNF-{\alpha}$, IL-6 and IL-8 were evaluated by ELISA kit on the HMC-1 cells with calcimycin A23187 and phorbol 12-myristate 13-acetate (PMA). The results showed that HE had no toxicity and reduced $TNF-{\alpha}$, IL-6, IL-8 response on HMC-1 cells.

• 대한방사선방어학회:학술대회논문집
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• 2009.04a
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• pp.234-235
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• 2009

• Journal of Plant Biology
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• v.1 no.2
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• pp.1-4
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• 1958

1. A vernalized Korean rye was exposed to Co60 in dose of 150r (dose rate was 7r per minute) and pollen mother cells were examined for cytological study. 2. According to the observation, it is quite clear that scraping of chromosomes soon after irradiation and surface stickiness at the period of 6 hours after irradiation were followed by structural changes at the period of 12 hours after irradiation.