• Proceedings of the KSRS Conference
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• 2004.10a
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• pp.577-580
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• 2004

To overcome with large size noise source distribution network design difficulty in interferometric radiometer system, especially for sub-Y-type array, a new on-board calibration technique using noise re-radiation is proposed in this paper. The suggested calibration technique is using noise re-radiation effect of center antenna after noise source injection from matched load. This approach is especially proper to sub-Y-type array interferometric synthetic aperture radiometer in mm-wave frequency band. Compared with noise injection network of a conventional synthetic aperture radiometer, the system mass, volume, and hardware complexity is reduced and cost-effective. Only one internal noise source, matched load, is used for injection using noise re-radiation technique a small set of sub-Y receiver channels is calibrated. Detailed calibration scenario is discussed and simulation results about noise re­radiation effect are presented.

• Journal of Radiation Protection and Research
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• v.41 no.2
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• pp.133-140
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• 2016

Backgrounds: The accident at Fukushima Daiichi Nuclear Power Plant (NPP), March 2011, caused serious radioactive contamination over wide area in east Japan. Therefore, it is important to know the effect of the accident and the status of NPP. Materials and Methods: This paper provides a review on the status of radiation dose and radioactive contamination caused by the accident on the basis of publicized information. Results and Discussion: Monitoring of radiation dose and exposure dose of residents has been conducted extensively by the governments and various organizations. The effective dose of general residents due to the accident proved to be less than a mSv both for external and internal dose. The equivalent committed dose of thyroid was evaluated to be a few mSv in mean value and less than 50 mSv even for children. Monitoring of radioactivity concentration has been carried out on food ingredients, milk and tap water, and actual meal. These studies indicated the percentage of foods above the regulation standard was over 10% in 2011 but decreasing steadily with time. The internal dose due to foods proved to be tens of ${\mu}Sv$ and much less than that due to natural $^{40}K$ even in the Fukushima area and decreasing steadily, although high level concentration is still observed in wild plants, wild mushrooms, animals and some kind of fishes. Conclusion: According to extensive studies, not only the effect of the accident but also the pathway and countermeasures against radioactive contamination have been revealed, and they are applied very effectively for restoration of environment and reconstruction of the area.

• Radiation Oncology Journal
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• v.2 no.1
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• pp.25-32
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• 1984

The pathological changes of stomach of the rat following 1,000 rad and 1,800 rad single exposure by Cobalt-60 has been made with 50 experimental rats. The dose of 1,000 rad and 1,800 rad single exposure were equivalent of biologic effect of 2,500 rad in 2 1/2 weeks and 6,000 rad in 6 weeks. Following single exposure, the groups of rat were terminated in 1, 2, 4, 8, 12 weeks intervals and the stomach were fixed to formalin solution immediatly after dissection. The pathological changes were as follows : 1. Following 1,000 rad single exposure, the stomach show only mild to moderate submucosal edema in 4,8,12 weeks group. 1 and 2 weeks group show no changes. 2. Following 1,800 rad single exposure, $32\%(8/25)$ of rats were dead by radiation effect and all other groups of stomach revealed variable pathological changes such as submucosal edema, squamous dysplasia, squamous papilloma as well as squamous cell carcinoma. 3. Optimal tolerance dose to the stomach was $4,500\~5,000$rad when irradiation given by supervoltage. The entire stomach was included within the irradiation field, the dose to the stomach should not exceed 6,000 rad. 4. In conclusion, the radiation injury to the stomach were more direct radiation effects to the gastric mucosa rather than secondary changes of radiation injured vessels.

• Radiation Oncology Journal
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• v.2 no.1
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• pp.1-9
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• 1984

To evaluate the influence of prior heat treatment on the thermal enhancement of irradiation effect after hyperthermia, an experimental study was carried out using a total of 80 mice. Hyperthermia was carried out at $43^{\circ}C$ for 40 minutes and was repeated with various intervals. A single dose of 3,000 rad was delivered on skin of mouse tail immediately after the second hyperthermia. The skin changes of the irradiated mouse tail were observed from 7th to 35th post-irradiation days, and the skin scores were analyzed. The results are as follows, 1. The radiation damage on mouse skin increased significantly when radiation was combined with hyperthermia. 2. The radiation damage after repeated hyperthermia is significantly less than that after single hyperthermia, when the interval is 1 to 6 days. 3. As a result, thermal tolerance persists from 1 through 6 days after the initial hyperthermia.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.05a
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• pp.791-794
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• 2013

Electronic systems may be cause of various serious failures due to an ionizing radiation effect when exposed to a prompt gamma-ray pulse. This transient electrical malfunction can, in some cases, results in a failure of the electronic system of which the circuits are a part. Transient radiation measurement and evaluation system is required to development for enhanced radiation-resistance against the initial nuclear radiation produced by the detonation of a nuclear weapon of semiconductor devices. In these studies, we performed the following work. In the first part of the work, we carried out a SPICE simulation applied to nuclear radiation condition for PN diode and we also investigated the photocurrent by a pulsed gamma-ray on a PN diode using a TCAD simulation.

• Journal of the Korea Institute of Military Science and Technology
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• v.17 no.2
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• pp.197-203
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• 2014

In this paper, the effect of unsteady radiation on the horizontal fin of an external fuel tank by flame of a flying flare was analysed to see the temperature increase of the fin and the thermal impact on the fin. Radiation between two surfaces was calculated using the concept of radiation resistance of surface and space including radiation, irradiation and shape factor for two flying trajectories of a flare, maximum temperature of 2200 K, emissivity of 0.95, flying velocity of 30 m/s, and thermal surface area of $0.01m^2$. The result shows that the temperature increase of the fin is 0.236 K, and the thermal effect on the fin is ignorable. And it was found that temperature is increased a little because small amount of heat energy can be radiated due to the short exposure time to the heat source.

• Journal of Ginseng Research
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• v.35 no.3
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• pp.261-271
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• 2011

Chemical radiation protection is an important strategy to protect living beings against the deleterious effects of radiation. In the present study, the radioprotective effect of hydro-alcoholic extract of Panax ginseng extract (PGR-HAE) was studied on radiation-induced deleterious alterations in Swiss albino mice. Oral administration of such extract (25 mg/kg b wt/day/animal) for 5 consecutive days, half an h. before whole-body exposure to 6 Gy gamma radiation, enhanced the 30 days survival and also inhibited the radiogenic sickness, weight loss and life shortening. PGR-HAE ameliorated radiation induced depletion in blood constituents at different necropsy intervals between 12 h to 30 d, and significantly increased the number of femoral spleen colony forming units that survived after irradiation. Furthermore, it checked depletion of glutathione and antioxidant enzymes (superoxide dismutase, catalase, and glutathione S-transferase) as well as elevation of lipid peroxidation (LPO) level in blood and liver. The significant reduction in the yield of LPO demonstrates that PGR-HAE protects the membranes against radiation-induced oxidative damage. These findings conclude that such plant extract provides significant radioprotection, and it may be potentially valuable in the prevention of injuries caused during planned and unplanned radiation exposure.

• Journal of Radiation Industry
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• v.9 no.2
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• pp.103-109
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• 2015

More recently, companies that have obtained permission to use radioactive materials or radiation device and registered radiation workers have increased by 10% and 4% respectively. The increased use of radiation could have an effect on radiation safety control. However, there is not nearly enough manpower and budget compared to the number of workers and facilities. This paper will suggest a counteroffer thought analyzing pending issues. The results of this paper indicate that there are 47 and 31.3 workers per radiation protection officer in educational and research institutes, respectively. There are 20.1 persons per RPO in hospitals, even though there are 2 RPOs appointed. Those with a special license as a radioisotope handler were ruled out as possible managers because medical doctors who have a special license for radioisotope handling normally have no experience with radiation safety. The number of staff members and budget have been insufficient for safety control at most educational and research institutes. It is necessary to build an optimized safety control system for effective Radiation Safety Control. This will reduce the risk factor of safety, and a few RPOs can be supplied for efficiency and convenience.

• Archives of Pharmacal Research
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• v.18 no.6
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• pp.410-414
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• 1995

Adaptive response induced by low dese .gamma.-ray irradiation in human cervical carcinoma cells was examined. Cells were exposured to low dose of .gamma.-ray irradiation in human cervical carcinoma cells was examined. Cells were exposured to low dose of .gamma.-ray (1-cGy) followed by high doses of r-ray irradiation (0,1,2,3,5,7 and 9Gy for chlnogenic assay or 1.5Gy for micronucleus assay) with various time intervals. Survival fractions of cells in both low dose-irradiated and unirrated groups were analyzed by clonogenic assay. Surviva fractions of low dose-irradiated in cell survival was maximum when low and high dose irradiation time interval was 4 hr. Frequencies of micronuclei which is an indicative of chromosome aberration were also enutained from survival fractions analyzed by clonogenic assay, maximum when low and high dose irradiation time interval was 4hr. Frequencies of micronuclei which is an indicative of chromosome aberration were also enumerated in both low dose-irradiated and unirradiated groups. In consiststent with the result obtained from survival fractions analyzed by clonogenic assay, maximum reduction in frquencies of micronuclei was observed when low dose radiation was given 4 hr prior to high response to subsequent high dose .gamma.-ray irradiation in human cervical carcinomal cells. Our data suggest that one of the possible mechanisms of adaptive response induced by low dose rediation is the increase in repair of DNA double strand breaks in low dose radiation-adapted cells.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.39 no.6
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• pp.42-48
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• 2002

The design, construction and performance test of a convenient multi-purpose irradiator is described. A multi-purpose irradiator using Cesium-137 has been developed for studies of low dose radiation effects in biology and for calibration of Thermo Luminescent dosimeter(TLD). During the operation, three rods of radioactive material which are 10cm in length revolve 180 degrees and irradiate biological samples, or TLD, and return to their shielded position, after the programmed time. A programmable Logic Controller(PLC) controls the sequence of operation, interlock, motor rotation and safety system. The rotation speed of biological samples can vary up to 20 RPM. A real time monitoring system was also incorporated to check and control the operation status of the irradiator. The capacity of the irradiation chamber was 4.5 liters. The isodose distribution at arbitrary vertical planes was measured by using film dosimetry. The dose-rate was 0.13 cGy/min in air and 0.11 cGy/min in water equivalent material in the case of Cesium-137. Range of activity was 2 Ci. The homogeneity of dose distribution in the chamber was ${\pm}$7%. The actual radiation level on the surface was within permissible levels. The irradiator had a maximum 0.35 mR/min radiation leakage on its surface.