• Korean Journal of Food Science and Technology
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• v.19 no.3
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• pp.273-278
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• 1987

The physicochemical properties of dried oak mushrooms were investigated to determine the comparative effects of ethylene oxide (E.O) fumigation and gamma irradiation with doses at 1 and 5 kGy. The total amino acid content was relatively stable in irradiated groups in comparison with the control. Treatments with gamma irradiation did not effect the content of reducing sugar but caused en increase in free sugars, such as mannitol, arabitol and trehalose. There were no significant differences in concentrations of minerals. The amount of water and fat soluble pigments and the rancidity of the samples stored at $25^{\circ}C$ increased with increasing the storage time and the relative humidity, and the tendency to change was more apparent in E.O. fumigated sample than gamma irradiated one.

• Journal of IKEEE
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• v.19 no.3
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• pp.282-287
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• 2015

In this study, an optical fiber detector was constructed by using a Ce:GAGG scintillator, optical fiber, and photomultiplier. The single crystal size of the scintillator was set to $3{\times}3{\times}20mm^3$ after simulating the counting efficiency of gamma rays in the scintillator by using the MCNPX code. The constructed detector used the standard gamma ray sources $^{137}Cs$ and $^{133}Ba$ to measure radiation and analyze the spectral characteristics of gamma rays. The resulting trend curve showed excellent linearity with an R-squared value of 0.99741, and the detector characteristics were found to vary 2% or less with distance based on comparison with the MCNPX value. Furthermore, the spectroscopic analysis of the gamma ray energy from the single-ray and mixed-ray sources showed that $^{137}Cs$ had its peak energy at 662 keV, and $^{133}Ba$ had at 356 keV. It seems that if the fiber-optics detector is used, working hours and exposure of worker can be reduced.

• Korean Journal of Microbiology
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• v.2 no.1
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• pp.1-11
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• 1964

Yung Nok Lee (Dept. of Biology, Korea University) : Studies on the phosphate metabolism in Chlorella, with special reference to polyphosphate. Kor. J. Microbiol., Vol.2, No.1, p1-11 (1964). 1. Uniformly $^{32}P$-labeled Chlorella cells which were irradiated with Cobalt-60 gamma-rays of about 70, 000 $\gamma$ dose, were further grown in a standard "cold" medium ("hot".rarw."cold"), and some portions of the algae were taken out at the begining of, and at intervals during the culture, and subjected to analyze the contents of $^{32}P$- and total P in various fractions of the cell materials. Results obtained were compared with those of nonirradiated normal cells. 2. Amounts of phosphate in various fractions of the nonirradiated normal Chlorella cells were measured using uniformly $^{32}P$--labeled cells. Analysis of the $^{32}P$--labeled algal cells showed that the highest value in P-content was the fraction of RNA followed by those of lipid, polyphosphate "C" polyphosphate "B", DNA, nucleotidic labile phosphate compounds, polyphosphate "A" and protein. It was observed that content of total polyphosphates in a single Chlorella cell was almost equal to RNA-P content in the cell, and the amount of RNA-P was almost equal to ten times of DNA-P content. 3. When the $^{32}P$--labeled algae which were irradiated with gamma-rays were grown in a normal "cold" medium, phosphate contents in the fraction of DNA, nucleotidic labile phosphate compounds and protein decreased markedly, while the contents of phosphate in the fractions of polyphosphate "C" and potyphosphate "B" increased in comparison with those of unirradiated normal cells. So, it was considered that the pretreatment of above mentioned dose of gamma-ray inhibited DNA and protein synthesis from polyphosphate in Chlorella cells. 4. Proceeding the culture of $^{32}P$--labeled Chlorella in a "cold" standard medium, whose synthetic activity of DNA and protein from polyphosphate was disturded by gamma-ray irradiation, the amounts of $^{32}P$-in the fraction of polyphosphate "C" increased, in contrast with those of polyphosphate "B" fraction. According to these experimental results, it was inferred that polyphosphate "B" could transform into polyphosphate "C" in normal growing Chlorella cells.sults, it was inferred that polyphosphate "B" could transform into polyphosphate "C" in normal growing Chlorella cells.ing Chlorella cells.

• Journal of Radiation Industry
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• v.4 no.3
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• pp.277-283
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• 2010

Rape (Brassica napus L.) plants are one of the major oilseed crops. The main components of rapeseed are oil (35 to 47%) and protein (15 to 32%). For the biodiesel production, the development of a new variety of rape plant with high biomass and/or oleic acid contents is required. In order to determine the optimum dose of gamma-ray irradiation, the rape seeds of cvs. Hanra (Hr), Youngsan (Ys), Tammi (Tm), and Tamra (Tr) were irradiated with a 100~4,000 Gy dose range of gamma-rays. Considering the growth factors, the optimum doses were determined to be within the range of 600~1,000 Gy for the selection of useful mutant lines. Six-hundred and eighty-eight (688) $M_2$ mutant lines were obtained from 600~1,000 Gy gamma-ray-irradiated $M_1$ plants through selfing. The growth characteristics, leaf shape, early flowering, and flower color were all investigated. The selected mutant numbers of early flowering, leaf shape, and flower color were 34, 52, and 3 from the four cultivars, respectively. These mutant lines will be used for the development of a new variety of rape plant with high biomass and oleic acid contents.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.55 no.3
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• pp.302-309
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• 2022

Low-salt fermented pollack Theragra chalcogramma roe (Myungran Jeotgal, MJ), a traditional Korean fermented seafood, was prepared using a commercially available method and irradiated using gamma rays (0-10.0 kGy) to investigate the effect of gamma irradiation (GI) on food quality. After irradiation with 2.5 kGy gamma rays, the number of viable cells in MJ was reduced by one log compared to that observed in non-irradiated MJ, and no living cells were detected after 7.5 kGy GI. Though up to 2.5 kGy GI had no effect on color quality, over 7.5 kGy GI resulted in significantly poor quality MJ surface color. Saturated fatty acid contents increased slightly in irradiated MJ, while those of polyenes and monoenes decreased slightly as the GI dose increased. Exposure of MJ to GI had no effect on the free amino acid and mineral composition. These results demonstrated that the appropriate GI dose for MJ ranged from 2.5 to 5.0 kGy, which may be recommended for industrial application.

• Journal of Electrical Engineering and Technology
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• v.9 no.6
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• pp.2065-2069
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• 2014

The DAC-7512E is a 12-bit digital to analog converter that is low power and a single package with internal buffers. The DAC-7512E takes up minimal PCB area for applications of space power electronics design. The spacecraft mass is a crucial point considering spacecraft launch into space. Therefore, we have performed a TID test for the DAC-7512E 12-bit serial input digital to analog converter to reduce the spacecraft mass by using a low-level Gamma-ray irradiator with $Co^{60}$ gamma-ray sources. The irradiation with $Co^{60}$ gamma-rays was carried out at doses from 0 krad to 100 krad to check the error status of the device in terms of current, voltage and bit error status during conversion. The DAC-7512E 12-bit serial digital to analog converter should work properly from 0 krad to 30 krad without any error.

• Nuclear Engineering and Technology
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• v.52 no.11
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• pp.2572-2580
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• 2020

Emerging gamma ray detection applications that utilize neutron-based interrogation result in the prompt emission of high-energy (>2 MeV) gamma-rays. Rapid imaging is enabled by scintillators that possess high density, high atomic number, and excellent energy resolution. In this paper, we evaluate the bright (50,000 photons/MeV) oxide scintillator, cerium-doped Gd₂Al₂Ga₃O₁₂ (GAGG(Ce)). A silicon photomultiplier (SiPM) array is coupled to a GAGG(Ce) scintillator array (12 × 12 pixels) and integrated into a coded-aperture based gamma-ray imaging system. A resistor-based symmetric charge division circuit was used reduce the multiplicity of the analog outputs from 144 to 4. The developed system exhibits 9.1%, 8.3%, and 8.0% FWHM energy resolutions at 511 keV, 662 keV, and 1173.2 keV, respectively. In addition, a pixel-identification resolution of 602 ㎛ FWHM was obtained from the GAGG(Ce) scintillator array.

• Nuclear Engineering and Technology
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• v.32 no.5
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• pp.457-464
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• 2000

In this paper, we describe the results of various calculations performed for a design of the thickness gauges that use the gamma-ray backscattering method. The radiation source is assumed to be the $_{24}$1Am(60keV gamma-ray) and the detector is a single crystal scintillator in a cylindrical form. The source is located at the center of the detector with the collimator of a cylindrical shape. First, when gamma-rays are incident on a material with a constant angle, we compute the variations of the spectrum for the photons scattered into different angular intervals. Next, we compute for an optimal size for the collimator cylinder for a fixed detector size and an optimal distance from the detector to the material. Finally, we compute the number of observed photons for different thickness of two different materials, a plastic film and an Al foil.

• Journal of Astronomy and Space Sciences
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• v.30 no.3
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• pp.133-140
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• 2013

Most of high energy cosmic rays (CRs) are thought to be produced by diffusive shock acceleration (DSA) at supernova remnants (SNRs) within the Galaxy. Fortunately, nonthermal emissions from CR protons and electrons can provide direct observational evidence for such a model and place strong constraints on the complex nonlinear plasma processes in DSA theory. In this study we calculate the energy spectra of CR protons and electrons in Type Ia SNRs, using time-dependent DSA simulations that incorporate phenomenological models for some wave-particle interactions. We demonstrate that the time-dependent evolution of the self-amplified magnetic fields, Alfv$\acute{e}$nic drift, and escape of the highest energy particles affect the energy spectra of accelerated protons and electrons, and so resulting nonthermal radiation spectrum. Especially, the spectral cutoffs in X-ray and ${\gamma}$-ray emission spectra are regulated by the evolution of the highest energy particles, which are injected at the early phase of SNRs. Thus detailed understandings of nonlinear wave-particle interactions and time-dependent DSA simulations of SNRs are crucial in testing the SNR hypothesis for the origin of Galactic cosmic rays.

• Nuclear Engineering and Technology
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• v.42 no.4
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• pp.426-433
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• 2010

The characteristic X-rays emitted from materials after gamma ray exposure was simulated and measured. A CdTe semiconductor detector and a $^{57}Co$ radiation source were used for energy spectroscopy. The types of materials could be identified by comparing the measured energy spectrum with the theoretical X-ray transition energy of the material. The sample composition was represented by the $K_{\alpha1}$-line (Siegbahn notations), which has the highest intensity among the characteristic X-rays of each atom. The difference between the theoretic prediction and the experimental result of K-line measurement was < 0.61% even if the characteristic X-rays from several materials were measured simultaneously. 2D images of the mixed materials were acquired with very high selectivity.