• Journal of Plant Biotechnology
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• v.30 no.2
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• pp.201-206
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• 2003

Differential responses of red pepper plant and cultured cells to enhanced ${\gamma}$-ray($^{60}$ Co) and ultraviolet(UV) stress were investigated. In seed treatment, 1 Gy of ${\gamma}$-ray increased seedling dry weight up to 19.1%, but 50 Gy treatment markedly ingibited seed germination and subsequent growth of seedling. UV treatment to seed did not change the germination ability of seeds and the growth of seedlings regardless of duration of UV treatment until 24 hrs. In case of UV treatment to seedlings, plant injury was seriously progressed even after the seedlings were returned to no UV condition, and eventually all the leaves showed chlorosis by the stress. However, progress of plant injury by ${\gamma}$-ray stress slower than that caused by UV stress, and even at the high dose of ${\gamma}$-ray 50 Gy, did not caused the cholrosis of stressed plant leaf. Amount of electrolytes leakage from plant leaf by UV treatment for 24hrs was increased up to 28.8 folds in comparison with untreated control, whereas that of 50 Gy of ${\gamma}$-ray was increased only 1.2 folds. UV stress induced the production of capsidiol, antimicrobial phytoalexin, by activation of gene expression involved in capsidiol biosynthesis, such as sesquiterpene cyclase and cyclase and cytochrome P450 hydroxylase in the leaf and cultured cell, but ${\gamma}$-ray stress induced neither the production of capsidiol nor expression of the genes.

• Polymer(Korea)
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• v.30 no.1
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• pp.10-13
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• 2006

The effects of antioxidants and thermal treatment on the radiation resistance of the gamma-ray irradiated polypropylene (PP) were studied. The PP was blended with various antioxidants and was fabricated into a sheet. The PP sheet was irradiated with gamma-ray to a dosage of 25kGy in the nitrogen atmosphere. The differences in both color and mechanical strength were investigated for the gamma-ray irradiated PP depending on the kind and the content of antioxidant. The residual amount of free radical and the variation of oxidation index were investigated for the gramma-ray irradiated PP with thermal treatment after irradiation. The PP having phosphite antioxidant showed little difference in color after gamma-ray irradiation compared with the PP having phenolic or mine antioxidant. Sufficient amount of free radical could be removed from the gamma-ray irradiated PP by the thermal treatment at $130\;^{\circ}C$ for 30 min. Thermally treated PP showed lower oxidation index than the PP without thermal treatment.

• Nuclear Engineering and Technology
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• v.6 no.4
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• pp.239-247
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• 1974

A human phantom of polyethylene has been designed and sculptured for studying the effective radiation safety control. The phantom has the approximate size of the Korean adult and was sliced into thirty-five transverse slabs, 2.5 cm thick, The relative dose at the specified position was determined from the exposure that a TLD badge worn on the surface of the phantom body received from external ${\gamma}$-ray. The variation of the exposure as a function of depth in the phantom was measured for uncollimated ${\gamma}$-ray using TLD rods, and also isodose curves were obtained for the anatomical cross-section of the critical organs of the body. To simulate radiation exposure condition in the nuclear facility, measurements were made for given angles of incident ${\gamma}$-ray. The front to back attenuation factor for human phantom of thickness 20 cm was 0.439 for Cs$^{137}$ ${\gamma}$-ray which is in reasonable agreement with the published data.

• Journal of Institute of Control, Robotics and Systems
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• v.17 no.12
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• pp.1203-1209
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• 2011

In this paper, the degradation evaluation method of VLC (Visible Light Communication) wireless module after high dose rate gamma-ray irradiation using the thermal infrared camera is proposed. First, the heating characteristics of the active devices embedded in the VLC wireless module during the condition of normal operation is monitored by thermal infrared camera. By the image processing technique, the trends of the intensity of the heat emitted by the active devices are calculated and stored. The feature of the blob area including the area of the active devices in the thermal infrared image is extracted and stored. The feature used in this paper is the mean value of the gray levels in the blob area. The same VLC module has been gamma irradiated at the dose rate of about 4.0 kGy/h during 72 hours up to a total dose of 288 kGy. And then, the heating characteristics of the active devices embedded in the VLC wireless module after high dose gamma ray irradiation is observed by thermal infrared camera. The high dose gamma-ray induced degradation of the active devices embedded in the VLC module was evaluated by comparing the mean value of the blob area to the one of the same blob area of the VLC module before the gamma ray irradiation.

• Journal of the Korean Society of Radiology
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• v.12 no.2
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• pp.133-138
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• 2018

The measurement of gamma-ray spectrum of $^{nat}W(p,xn)$ reaction with natural tungsten were performed by using a high energy proton generated from a 100-MeV proton linear accelerator of the Korea Multi-purpose Accelerator Complex (KOMAC). Gamma rays generated by various nuclides generated through the nuclide were measured using a gamma-ray spectroscopy system composed of HPGe detector. A gamma-ray standard source was used for energy calibration and efficiency measurement of the detector. Analysis of the gamma rays observed in the measured spectra showed that the radionuclides produced were $^{167}Re$, $^{178}Re$, $^{179}Re$, $^{180}Re$, $^{181}Re$, $^{182}Re$, $^{184}Re$, $^{172}Ta$, $^{174}Ta$, $^{178}Ta$, $^{182}Ta$, $^{184}Ta$, $^{175}W$, $^{176}W$, $^{177}W$ and $^{179}W$. Nuclides were generated. The results of this study will be applied to nuclear fusion, astrophysics, and nuclear medicine applications in the future.

• Journal of Radiation Protection and Research
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• v.16 no.2
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• pp.1-6
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• 1991

The $HgI_2$ single crystal which can be used for the ${\gamma}-ray$ detector at room temperature was grown by Temperature Oscillation Method. The low temperature photoluminescence, specific resistivity and trap concentration of $HgI_2$ single crystal were investigated. Three main luminescence bands were observed at 2.30eV, 2.20eV and 2.00eV at 20K, related to the excitons, I-vacancies and impurities, respectively. The specific resistivity and trap concentration of $HgI_2$ single crystal were $10^{11}{\Omega}\;cm\;and\;1.8{\times}10^{14}/cm^3$ at room temperature, respectively. Also the radiation detecting system was deviced by $HgI_2$ ${\gamma}-ray$ detector, one chip microprocessor, LCD module and personal computer. The prepared $HgI_2$ ${\gamma}-ray$ detector showed a good linearity of ${\gamma}-radiation$ dose for standard ${\gamma}-ray$.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2004.06a
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• pp.433-433
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• 2004

Neutron induced prompt gamma-ray spectroscopy (NIPS) system measures the prompt gamma-ray, emitting by the interaction of a neutron with various materials. This system will be of great benefit to scientists worldwide, since it provides the non-destructive measurement of many elements in either solid or liquid wastes. A NIPS facility has been developed in Nuclear Chemistry Research Division, at Korea Atomic Energy Research Institute (KAERI) with the aim of analyzing the major component elements in both aqueous and solid samples.(omitted)

• The Korean Journal of Zoology
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• v.18 no.1
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• pp.41-49
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• 1975

Dose response and time dependence of DNA repair synthesis were investigated to determine the possible relationship between DNA repair synthesis and chromosome exchanges in $\\gamma$-ray irradiated BHK-21 and KB cell lines. DNA repair synthesis induced by $\\gamma$-ray was dose dependent up to 5kR, then leveling off occurred until 50 kR was reached. Time dependence of DNA repair synthesis was continued for up to 1$\\sim$2 hours after irradiation although the initial dose responses were cell line specific. Chromosome exchanges induced by $\\gamma$-ray showed different radiosensitivities in these cell lines and did not show a correlation with the DNA repair synthesis.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.2
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• pp.60.2-60.2
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• 2016

We present recent results of very long baseline interferometry (VLBI) observations of gamma-ray bright active galactic nuclei (AGNs) using Korean VLBI Network (KVN) at 22, 43, 86, and 129~GHz bands, which are part of a KVN key science program; Interferometric Monitoring of Gamma-ray Bright AGNs (iMOGABA). We selected a total of 34 radio-loud AGNs of which 30 sources are gamma-ray bright AGNs, including 24 sources monitored by the Fermi Gamma-ray Space Telescope using the Large Area Telescope on board. The selected sources consist of 24 quasars, 7 BL Lacs, and 3 radio galaxies. In this talk, we summarize recent results of the iMOGABA, including results of single-epoch multi-frequency VLBI observations of the target sources, conducted during a 24-hr session on 2013 November 19 and 20. All observed sources were detected and imaged at all frequency bands with or without a frequency phase transfer technique which enabled to detect and image 12 faint sources at 129 GHz, except for 0218+357 which was detected for only one baseline at all frequency bands.

• 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.