• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.12
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• pp.2310-2316
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• 2016

We studied the effect of $Co^{60}$ gamma-radiation on the fiber Bragg gratings (FBGs) by irradiation time of UV Krypton fluoride (KrF) excimer laser among grating processing parameters. The FBGs were fabricated in a different UV laser irradiation time at 30, 60, 90, and 120 seconds using the same commercial Ge-doped silica core fiber (SMF-28e). It was exposed to gamma-radiation up to a high dose of 34.3 kGy at the dose rate of 106 Gy/min, and then it was analyzed radiation effects by measuring the radiation-induced change in the temperature sensitivity coefficient and Bragg wavelength shift. According to the experimental results, We confirmed that the UV laser irradiation period for grating inscription has a highly effect on the radiation sensitivity of the FBGs. The radiation-induced Bragg wavelength shift by the change of laser irradiation conditions showed a difference more than about 50 %.

• Progress in Medical Physics
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• v.27 no.2
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• pp.98-104
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• 2016

We investigated the effect of high dose on the sensitivity of optically stimulated luminance dosimeters (OSLDs) on Co-60 gamma rays and used a commercial OLSD (Landauer, Inc., Glenwood, IL). New OSLDs were chosen arbitrarily and were irradiated with 1 Gy repeatedly. We confirmed the change in the radiation sensitivity after repeated irradiation. The OSLD sensitivity increased up to 3% after irradiating for seven times and decreased continuously after the eighth time. It dropped by approximately 0.35 Gy per irradiation. Finally, after irradiating for 30 times, the OSLD sensitivity decreased by approximately 7%. When the OSLDs were irradiated 10 times with 1 Gy after their irradiation using a high dose of 15 Gy and 30 Gy, their sensitivity decreased by 6% and 12%, respectively, compared to that before high-dose irradiation. The change in the OSLD sensitivity with a high dose could be modeled by an exponential equation. We confirmed the radiation sensitivity variation caused by a high dose, and the irradiation history of dosimeters was considered to reuse OSLDs irradiated with a high dose.

• Journal of Radiation Industry
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• v.5 no.3
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• pp.279-283
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• 2011

This study was compared microbiological safety with gamma-irradiated porcine tendon and skin, as materials for the development of xenografts to regenerate damaged tissues and protect secondary contamination. The porcine tendon and skin were gamma-irradiated after inoculation of bacteria and virus to evaluate irradiation sensitivity of microorganisms. The result showed that the porcine tendon and skin were not different on the sensitivity of microorganisms by gamma irradiation. Bacteria inoculated in the porcine tendon and skin were confirmed that E. coli was the $D_{10}$ values of $0.32{\pm}0.082$ and $0.25{\pm}0.1kGy$ on tendon and skin, and B. subtilis was $4.00{\pm}0.312$ and $3.88{\pm}0.3kGy$ on gamma irradiation, respectively. Moreover, Virus inoculated in the porcine tendon and skin was observed that poliovirus (PV) was $6.26{\pm}0.332$ and $6.88{\pm}0.3kGy$, and porcine parvovirus (PPV) was $1.75{\pm}0.131$ and $1.73{\pm}0.2kGy$ and bovine viral diarrhoea virus (BVDV) was $3.70{\pm}0.212$ and $3.81{\pm}0.2kGy$ on gamma irradiation, respectively. Virus showed higher resistance compared to bacteria on gamma irradiation, but was not detected CPE (cytopathic effect) by virus both tendon and skin at 25 kGy, a standard dose recommended from IAEA for sterilization of medical products. Therefore, These results were considered that gamma irradiation could control effectively bacteria and virus to develop safe porcine xenograft, and apply same irradiation doses to all tissues including tendon and skin of porcine.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.7
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• pp.963-968
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• 2013

Ionizing Radiation effects on MOS devices provide useful information regarding the behavior of MOS based devices and circuits in the electronic instrumentation parts and instructive data for making the high sensitive sensors. The study presents the results of the analysis on the structural characteristics of MOS capacitor for sensing the ionizing radiation effect. We performed numerical modeling of Ionizing-radiation effect on MOS capacitor and simulation using Matlab program. Also we produced MOS capacitors and obtained useful data through radiation experiment to analyse the characteristic of ionizing radiation effect on MOS capacitor. Increasing the thickness of MOS capacitor's oxide layer enhanced the sensitivity of MOS capacitor under irradiation condition, but the sensitivity of irradiated MOS capacitor is uninfluenced by the area of MOS capacitor. The high frequency capacitance of the MOS capacitor is found to be strongly affected by incident ionizing radiation.

• Nuclear Engineering and Technology
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• v.54 no.8
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• pp.2871-2876
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• 2022

The sensitivity of polymer-based capacitive relative humidity (RH) sensors after irradiation with neutrons, electrons and protons was measured. Degradation consists of the decreasing of the upper RH limit that can be measured. At the same time, low RH-level sensitivity is almost stable. After 30 krad of absorption dose, RH cut off is equal to 85% of max value, after 60 krad-40%. Degradation reduces after annealing which indicates high radiation sensitivity of the internal circuit in comparison to RH-sensing polymer film.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.44 no.3
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• pp.296-301
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• 1999

The concerns on the crop damage by ultraviolet (UV) radiations is increasing owing to the decrease of their absorbing stratospheric ozone in the tropospheric. Cultivar differences on early growth of UV radiation among five Korean rice cultivars, four japonica types and one Tongil type (indica-japonica cross hybrid), were studied. Pot-seeded rice plants were grown under four different radiation conditions, i.e., visible radiation only, visible radiation with supplemented with high or low dose of UV-B (280~320 nm in wavelength) and UV-C (less than 280 nm in wavelength). The inhibitory degree on plant height, shoot and root weight and length of leaf blade and leaf sheath were determined at 40 days after seeding. UV-C showed the most severe inhibitory effect on the degree of biomass gain and leaf growth in most cultivars examined, followed by high UV-B and low UV-B. Among the cultivars used, the Kuemobyeo was the most sensitive cultivar and had not repair or showed resistance ability to continued irradiation of UV radiation. However, Janganbyeo and Jaekeon showed different responses that the elongation of leaf blades was promoted on 2nd and 3rd leaves and inhibited on 4th and 5th leaves but this inhibitory degree was reduced on 6 th and 7th leaves. Such tendency on leaf growth means that both cultivars had low sensitivity and most resistant ability to continued irradiation of UV radiation. While Tongil showed different response to enhanced UV radiation, ie., low UV-B promoted leaf growth but the inhibitory was severely increased by continued irradiation of high UV-B and UV-C, which means that Tongil had high threshold of UV radiation for response as an inhibitory light of plant growth. The results of this study indicate that the differences on sensitivity or resistant to the effects of UV radiation were existed among Korean rice cultivars.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.1181-1182
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• 2008

The study presents the results of the analysis on the structural characteristics of MOS capacitor for sensing the ionizing radiation effect. Increasing the thickness of MOS capacitor's oxide layer enhanced the sensitivity of MOS capacitor under irradiation condition, but the sensitivity of irradiated MOS capacitor is uninfluenced by the area of MOS capacitor.

• Progress in Medical Physics
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• v.6 no.1
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• pp.49-57
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• 1995

The semiconductor detector has a high sensitive to radiation and a small volume. It has been frequently used in high energy photon and electron beamdosimetry. However, Semiconductor detector are subject to radiation damage in high energy radiation beam which reduces the sensitivity and creat a large discrepancy. In this experiments, P-type semiconductor was irradiated to 18 MeV electron beam with pre-irradiation for reducing the sensitivity for high reproducibility and investigated the dose characteristics against the dose rate variations. The sensitivity per unit dose in small dose rate showed a 35％ large different to a large dose rate with pre-irradiation dose for 0.5 KGy and 20％ for 3 KGyin this study. The silicon detector has showed a large dependency of beam direction with 13％ discrepancy and a linear sensitive as increased temperature.

• Nuclear Engineering and Technology
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• v.31 no.3
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• pp.287-293
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• 1999

To assess the effects of gamma-ray (Co-60) on radiation sensitivity and genetic similarity of the basidiospore and mycelium in oyster mushroom, Pleurotus ostreatus, the D$_{10}$ values and RAPD patterns were analysed. Three strains were isolated from basidiospores (PO-Bl, -B2, and - B3 from 2 kGy irradiation group) and five strains from mycelia (PO-Ml, -M2 from 1 key, PO-M3 from 2 kGy, and PO-M4 and -M5 from 2+1 key irradiation group). The D$_{10}$ values of basidiospore and mycelium of P. Preurotus ostreatus were 1,250 Gy and 500 Gy, respectively. The growth rates of the eight strains on the five media were various and the activities of extracellular chitinases of them were generally higher than those of the control. By the gamma-ray radiation, 22-25% of genetic similarities were changed in the basidiospore strains and 23-36% of them in the mycelium strains. From these results, it seems that the basidiospore could be more radio-resistant than the mycelium of P. ostreatus and that the genetic similarity of the mycelium of P ostrentus could be changed easier than that of the basidiospore by the gamma-ray radiation.ion.

• Journal of Radiation Industry
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• v.6 no.3
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• pp.223-229
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• 2012

In this study, we investigated the biological damage and stress responses induced by ion beam (proton beam) irradiation as a basis for the development of protective measures against space radiation. We examined the biological effects of proton beam produced by MC-50 cyclotron at KIRAMS on the cultured cells and mice. The proton beam energy used in this study was 34.9 MeV and the absorption dose rate for cells and mice were $0.509Gy\;sec^{-1}$ and $0.65Gy\;sec^{-1}$, respectively. The cell survival rates measured by plating efficiency showed the different sensitivity and dose-relationship between CHO cells and Balb/3T3 cells. HGPRT gene mutation frequency in Balb/3T3 was $15{\times}10^{-6}Gy^{-1}$, which was similar to the reported value of X-ray. When stress signaling proteins were examined in Balb/3T3 cells, $I{\kappa}B-{\alpha}$ decreased markedly whereas p53, phospho-p53, and Rb increased after proton beam irradiation, which implied that the stress signaling pathways were activated by proton beam irradiation. In addition, cellular senescence was induced in IMR-90 cells. In the experiments with C57BL/6 mouse, the immune cells (white blood cells, lymphocytes) in the peripheral blood were greatly reduced following proton beam irradiation whereas red blood cells and platelets showed relatively little change. These results can be utilized as basic data for studying the biological effects of proton beam using MC-50 cyclotron with respect to proton therapy research as well as space radiation research.