• Journal of Food Hygiene and Safety
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• v.7 no.1
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• pp.7-14
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• 1992

Flavor-related components were analyzed for dried oak mushrooms (Lentinus edodes) when subjected to ethylene oxide and gamma energy. Volatile flavor components identified by GC and GC-MS were composed primarily of l-oden-3-ol (72.8%), 3-octanone (11.5%) and dimethyl disulfide (6.7%). Most of volatile components were shown labile to the standard cycle of ethylene oxide and 5 kGy-gamma energy, while insignificant changes were observed in the contents of free sugars (mannitol, arabitol, trehalose) and free amino acids. Instrumental analysis have shown, however, that the deterimental effects on flavor-related components were more apparent in EO-fumigated groups than in gamma-irradiated ones, even though the organo-leptic test revealed no significant differences between treated samples and the corresponding control.

• Journal of Radiation Protection and Research
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• v.34 no.4
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• pp.170-175
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• 2009

For the emergency radiation monitoring using gamma spectrometry, we should sufficiently survey the background spectra as environmental samples with systematic nuclide identification method. In this study, we obtained the gamma ray energy spectrum using a HPGe gamma spectrometry system from an air sample. And we identified nuclide of the gamma ray energy peaks in the spectrum using two methods -1) Half life calculation and 2) survey for cascade coincidence summing peaks using nuclear data. As the results, we produced the nuclide identification results for the air sample.

• Proceedings of the Korean Society for Food Science of Animal Resources Conference
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• 2005.10a
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• pp.302-305
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• 2005

본 연구는 에너지 위기에 따른 고유가 시대에 에너지 소비가 많은 열처리에 의한 시유 생산을 영양적으로나 미생물학적으로 안전하게 대체할 수 있는 방법으로 감마선 조사처리에 대하여 검토하였다. 1, 2, 3, 5, 10 kGy의 감마선 조사시 당일에는 일반세균과 대장균군이 모두 검출되지 않았으나, 냉장상태에서 일주일후에는 1과 2 kGy 조사구에서 일반세균이 검출되었다. 반면 LTLT, HTST, 및 UHT 처리시에도 당일에는 일반세균이 검출되지 않았으나 일주일 후에는 LTLT 처리와 HTST 처리유에서 $10^6$ CFU/mL이상 검출된 반면 UHT 처리유에서는 일반세균이 검출되지 않아, 우유에서 미생물적으로 UHT 처리 정도의 살균효과를 거두기 위해서는 3 kGy 이상의 감마선 조사 처리가 요구되었다.

• Journal of Radiation Protection and Research
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• v.38 no.4
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• pp.237-241
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• 2013

The gamma energy distributions at the major working places during refueling outage of Korean PWR nuclear power plants were measured. In order to estimate the dose reduction effect of a lead vest, Monte Carlo calculation method was used. For the simulations, the MIRD-V phantom with a lead vest was formed and exposed to the measured radiation field. The average measured gamma energy is lower than that of standard which is generally applied to radiation protection procedures. For the efficient use of a lead vest and achievement of radiation protection purpose, it is necessary to estimate the energy distribution of radiation field at working places.

• Journal of the Korean Magnetics Society
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• v.17 no.2
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• pp.103-107
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• 2007

When the gamma-ray source, $^{133}Cs$, embedded in a solid is placed at the center of a gold cylinder, the width of 81 keV level is shown to become narrower. This result implies a prolongation of the lifetime of that energy level. With a 0.5-mm-thick, 5-cm-long, 2-mm-diameter platinum cylinder, we obtain a width narrower by 6.1 % at 4.2 K.

• Geophysics and Geophysical Exploration
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• v.18 no.3
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• pp.154-161
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• 2015

For efficiently designing neutron induced gamma spectroscopy sonde, Monte Carlo simulation is employed to understand a dominant location of thermal neutron and classify the formation elements from the energy peak of capture gamma spectrum. A pulsed neutron generator emitting 14 MeV neutron particles was used as a source, and flux of thermal neutron was calculated from the twelve detectors arranged at each 10 cm intervals from the source. Design for reducing borehole effects using shielding materials was also applied to numerical sonde model. Moreover, principal elements and quantities of numerical earth models were verified through the energy spectrum analysis of capture gamma detected from a gamma detector. These results can help to enhance the signal-to-noise ratio, and determine an optimal placement of capture gamma detectors of neutron induced gamma spectroscopy sonde.

• Journal of Radiation Protection and Research
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• v.39 no.2
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• pp.81-88
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• 2014

Recently, a new imaging method, gamma vertex imaging (GVI), was proposed for the verification of in-vivo proton dose distribution. In GVI, the vertices of prompt gammas generated by proton induced nuclear interaction were determined by tracking the Compton-recoiled electrons. The GVI system is composed of a beryllium electron converter for converting gamma to electron, two double-sided silicon strip detectors (DSSDs) for the electron tracking, and a scintillation detector for the energy determination of the electron. In the present study, the modules of a charge sensitive preamplifier (CSP) and a shaping amplifier for the analog signal processing of DSSD were developed and the performances were evaluated by comparing the energy resolutions with those of the commercial products. Based on the results, it was confirmed that the energy resolution of the developed CSP module was a little lower than that of the CR-113 (Cremat, Inc., MA), and the resolution of the shaping amplifier was similar to that of the CR-200 (Cremat, Inc., MA). The value of $V_{rms}$ representing the magnitude of noise of the developed system was estimated as 6.48 keV and it was confirmed that the trajectory of the electron can be measured by the developed system considering the minimum energy deposition ( > ~51 keV) of Compton-recoiled electron in 145-${\mu}m$-thick DSSD.

• Journal of the Korean Society of Radiology
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• v.6 no.5
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• pp.403-408
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• 2012

Prompt gamma ray from the natural Indium sample was measured by using an assembly of BGO($Bi_4Ge_3O_{12}$) scintillation detectors in the neutron energy region from 1 to 300 eV. The assembly was composed of pieces of BGO. The spectrometer was composed geometrically as total energy absorption detector. 46-MeV electron linear accelerator which is located at Research Reactor Institute, Kyoto University used for neutron sources from photonuclear reaction. The measurement of the neutron capture resonances was performed to below neutron energy 1 keV, because of strong X-ray effect from photonuclear reaction in Ta target and short distance from the target to an assembly of detector. The distance of neutron flight path is $12.7{\pm}0.02m$. The large neutron capture resonances were measured from 1 to 400 eV. The energy in the capture resonance was compared with the evaluated values. The large resonances were seen in the present measurement. General agreement can be seen between the present measurement and the previous evaluated data in relevant energy region. In the present study, we measured the continues resonance structure above 1 keV neutron energy region. 91.49 eV new neutron capture resonance was found in present measurement.

• Journal of Radiation Protection and Research
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• v.22 no.3
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• pp.219-226
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• 1997

Ultralow background gamma-ray measurement system was installed to measure and analyze gamma-rays emitted from environmental and swipe samples. The background reduction techniques applied on this system are the passive shielding to surround the HPGe detector, an active external anticosmic shield to shield cosmic-rays and the nitrogen gas supply to minimize the introduction of ubiquitous radon decay nuclei. The performance test result showed that the system background at energies between 50 keV and 2 MeV is reduced about $10^{-2}$ order and the MDA is so low as to be suitable for the environmental sample analysis. But it is appeared that the neutron produced by cosmic-ray increases the background at low energy region.

• Journal of the Korean Society of Food Science and Nutrition
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• v.33 no.5
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• pp.894-898
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• 2004

This study was carried out to determine the optimum irradiation dose for infant foods with improved energy-density and extend shelf-life using gamma irradiation. Rice and rice porridge were irradiated at 0, 2.5, 5, 7.5, 10, 15 and 20 kGy, and rheological characteristics and total plate count of porridge were evaluated for 6 weeks. Rice and rice porridge at 2.5 kGy dose reduced the viscosity with 22% and 98%, respectively. The result of total aerobic bacteria of non-irradiated rice porridge was 6 log CFU/g and that of 2.5 kGy irradiated rice porridge on 2 weeks storage was 3 log CFU/g, while that of 7.5 kGy irradiated sample was not detected even at the end of storage. Irradiation on rice-based porridge was proper to enhance the total solid in inverse proportion to considering viscosity and extend shelf-life. Gamma irradiation was effective technology in enhancing calorie value of porridge due to reduction of viscosity.