• Journal of the Korean Society of Safety
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• v.9 no.1
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• pp.48-55
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• 1994

In this paper, It is studied that the variation of the dielectric absorption of the specimen according to the change with $^{60}$ Co-${\gamma}$ ray irradiation dose of the influence of temperature and applied voltage. In order to investigate the effect of irradiated oriented polypropylene film, we have observed dielectric properties within the temporature range of 30~130 ($^{\circ}C$) and voltage range of 100~250 (V). As for the dependency of temperature by tan $\delta$, the $\alpha$ peak which appears at high temperature increases accordingly to the increment of irradiation dose which is contributed by the crystal region and moves towards the high temperature. The $\beta$ peak which appears the orientation by dipoles and molecular motions in the amorphous region at low temperature. For the dependency of voltage by tan $\delta$ at low temperature, the peak of the tan $\delta$ shifts accordingly to the increment of irradiation dose towards the high temperature region.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.11a
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• pp.565-568
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• 2002

The value of charge current, discharge current, $\varepsilon_r$' $\varepsilon_r"$, residual voltage was measured inorder to investigate electric properties in Ethylene Prophylene Rubber for is irradiated $CO^{60}\gamma$ ray 0-38.1 Mrad. The value of charge current and the discharging current of the EPR is influenced by $CO^{60}-{\gamma}$-irradiation dose The charging current and the discharging current of EPR increase, depending on the ratio of degradation. As the irradiation dose is increased, the peak of residual voltage moves to the slorter time. The properties specific electric constant due to time variation was appeared dispersion by plentiful $CO^{60}-{\gamma}$-irradiation dose. The increase of peak in $\varepsilon_r"$ is attrib uted to the irratiation dose almost proportionally.

• Journal of Radiation Protection and Research
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• v.11 no.2
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• pp.123-129
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• 1986

Using Cs-137 and Co-60 gamma-ray irradiation systems, the buildup factors for 2.9 cm thick lead absorber and the air scattering factors are determined for different beam solid angles from$2.4{\pi}{\times}10^{-3}sr\;to\;17.3{\pi}{\times}10^{-3}sr$. The corresponding buildup factors are turned out to be the values from 1.054 to 1.194 and the scattering factors to be the values from 1 to 1.064, respectively. To verify our results, calculated values using these factors and experimental values are compared. The differences between them are not more than 3. 3%.

• Journal of the Korean Society of Safety
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• v.15 no.4
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• pp.78-87
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• 2000

The $\gamma$-ray irradiation and aging effects on electrical characteristics of $^{60}Co$ $\gamma$-ray irradiated ethylene-propylene-diene-terpolymer(EPDM) contained with 1 to 3phr phenolic and quinolinic antioxidants as antirads were investigated. The marked effects of type and amounts of the antioxidant on the volume resistivity and AC breakdown strength of the $\gamma$-ray irradiated EPDM are different. A phenolic antioxidant(IR 1010) contribute to improving the electrical insulation properties on the EPDM better than quinolinic antioxidant(Kumanox RD) during irradiation. In aging the irradiated EPDM specimens contained antioxidants at room temperature in air, it was shown a improvement of insulation properties due to radical scavenging and crosslinking of EPDM aged until 360 days.

• Korean Journal of Veterinary Research
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• v.45 no.4
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• pp.457-464
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• 2005

The irradiation of radioactive ${\gamma}-ray$ induces apoptosis of radiosensitive organs for homeostasis. In this study, we investigated the repair mechanisms for homeostasis in the small intestine after cell damage by $^{60}Co\;{\gamma}-ray$ irradiation. The apoptosis was most frequently observed in the crypt cells of the small intestine after four and six hours by radioactive ${\gamma}-ray$ irradiation, and the frequency of apoptosis was proportional to the amount of irradiation. Also, the number of apoptotic cells was coincident with expression pattern of p53. Interestingly, PCNA (proliferating cell nuclear antigen) which is engaged in DNA replication and repair was expressed in apoptotic cells of small intestinal crypts. Also, it was observed that cell-cycle regulator p21 which is known to induce cell-cycle arrest is co-expressed in the same apoptotic cells of irradiated small intestinal crypt cells. These findings suggest that the co-expression of PCNA and p21 proteins, which may lead to resistance to DNA damage through cell-cycle arrest is closely associated with repair of damaged gastrointestinal cells after ${\gamma}-ray$ irradiation.

• Journal of Radiation Protection and Research
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• v.7 no.1
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• pp.11-16
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• 1982

Cysteamine(Mercaptoethyiamine, MEA), S,2-Aminoethylisothiouronium Bromide. HBr (AET), and S-(2-Aminoethyl) Dihydrogen Phosphorothioate (WR-638) were prepared and radioprotective effects of these chemicals and their combinations against $^{60}Co$ ${\gamma}-ray$ radiation were studied ,in irradiated ICR mice. Intraperitonially administered chemicals or their combinations resulted drug deaths in cases of MEA, AET, and their combinations, whereas there were a slight or no drug death in cases of WR-638 and the combination of AET with WR-638. All tested chemicals and their combinations yielded radioprotective effects against $^{60}Co$ $\gamma-ray$ radiation. An additive radioprotection effect was observed in case of the combination of AET with WR-638.

• Korean Journal of Veterinary Research
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• v.34 no.4
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• pp.665-678
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• 1994

This study was undertaken to investigate histological changes according to the radiosensitivity in the spermatogenic cells in Korean native pheasants. During spermatogenetic period, testes wete collected from male adult Korean native pheasant and they were used as experimental and control birds. The experimental group was divided into a single-dose whole body irradiation group(400, 600, 800 and 1000 rads) and a split-dose whole body irradiation groups(400/2, 600/2, 800/2 and 1000/2 rads). A Henseky's $^{60}Co$ ${\gamma}$-radiotherapy machine was used for this experiment and the dose rate of $^{60}Co$ ${\gamma}$-ray was 104 rads/min. The experimental birds were sacrificed at 24 and 72 hrs after irradiation and the control pheasants were sacrificed at the same time. General histological changes of seminiferous epithelial cells were observed by hematoxylin-eosin stain with light microscope. The results obtained are summarized as follows ; 1. In the single-dose and the split-dose irradiation groups, the average diameter of the seminiferous tubule was decreased compared with control group. 2. Seminiferous epithelial cells were more severely damaged after 72 hrs than after 24 hrs of single-dose irradiation of 400, 600 and 800 rads but the difference of cell injury was almost not observable with the elapsed time in the group of the single-dose irradiation of 1000 rads. 3. The damage of spermatogenic cells were more severe after 24 hrs than after 72 hrs of the split-dose irradiation of 400 rads but the split-dose irradiation of 600, 800 and 1000 rads were more severe after 72 hrs than after 24 hrs.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.4
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• pp.1401-1405
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• 2012

Aim: To investigate the protective effect of purified fraction 1 polysaccharide extracted from Rheum tanguticum RTP1 on irradiation-induced immune damage in mice. Methods: Kunming mice were randomly divided into five groups: normal group (NC), irradiation control group (IC), RTP1 low dose (200 mg/kg), middle dose (400 mg/kg) and high dose (800 mg/kg) groups. RTP1 was adminstered by the gastric route for 14 d, mice in the NC and IC groups being given by 0.9% sodium chloride solution in the same way. The mice in all groups except NC group were irradiated with 2.0 Gy $^{60}Co{\gamma}$-ray on the fourteenth day. Immune indives of non-specific immune function, cellular immunity and humoral immunity were assessed at the 24th hour after radiation. Results: Compared with the IC group, the spleen index, thymus index, rate of carbon clearance, phagocytic function of macrophages, lymphocyte proliferation, hemolysin value of blood serum and NK activity were increased markedly (P < 0.05 or P < 0.05). Conclusion: RTP1 has an obvious protective effects on damage in ${\gamma}$-ray radiated mice.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.05a
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• pp.732-735
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• 2013

In this study, we are measured gamma-ray induced loss on single-mode (SM) fibers from a total of four different manufactures. The $Co^{60}$ gamma-ray source was used in this test. The gamma-ray is irradiated for 2 hours at the dose rate of 0.6 kGy/hr, 1.2 kGy/hr, 2.4 kGy/hr. In test results, We clearly confirm the dose rate effect in different fiber types and evaluate the radiation sensitivity by the change of the radiation-induced loss.

• Journal of environmental and Sanitary engineering
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• v.13 no.2
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• pp.106-114
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• 1998

This study was carried out for the purpose of industrial reuse of effluent released from activated sludge unit by $\gamma $-ray irradiation technique. The dissolved organic carbon in the effluent of an activated sludge unit is mostly refractory or inert material which are difficult to be degraded by micro organism. The effluent generated from activated sludge unit was irradiated with Co$^{60}$ $\gamma $-ray under condition of air bubbling. The effects of irradiation on the pH, COD, TOC, color, molecular weight distribution were investigated by membrane filtration and u.v.-spectrum analysis. With increasing dose, the TOC was decreased smoothly. The COD was increased at lower dose, while the COD was decreased at higher dose. The TOC and COD, however, were decreased smoothly when TiO$_{2}$ was added to the solution. It was thought that the differential decreasing trend of COD and TOC in according to the absence or presence of TiO$_{2}$ was due to the molecular weight distribution shifted from group of higher molecular weight to group of lower one which are more easy to be decomposed. The removal efficiency of color was 71.5% and it was increased to 85.7% when TiO$_{2}$ was added to the solution. The $\gamma $-ray irradiation was effective on the production of chlorine.