• Nuclear Engineering and Technology
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• v.53 no.11
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• pp.3764-3771
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• 2021

Based on the convolutional neural network (CNN), a novel technique is investigated for lost gamma source detection in a room. The CNN is trained with the result of a GEANT4 simulation containing a gamma source inside a meshed room. The dataset for the training process is the deposited energy in the meshes of different n-step paths. The neural network is optimized with parameters such as the number of input data and path length. Based on the proposed method, the place of the gamma source can be recognized with reasonable accuracy without human intervention. The results show that only by 5 measurements of the energy deposited in a 5-step path, (5 sequential points 50 cm apart within 1600 meshes), the gamma source location can be estimated with 94% accuracy. Also, the method is tested for the room geometry containing the interior walls. The results show 90% accuracy with the energy deposition measurement in the meshes of a 5-step path.

• Nuclear Engineering and Technology
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• v.52 no.7
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• pp.1524-1531
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• 2020

The aim of this work is to develop a Geiger-Muller (GM) detector system for robot to look for a radioactive source in case of a nuclear emergency or in a high radiation environment. In order to find a radiation source easily, a detector system, including 3 detectors, was designed to search γ-ray radiation sources autonomously. First, based on GEANT4 simulation, radiation dose rates in 3 Geiger-Muller (GM) counters were simulated at different source-detector distances, distances between detectors and angles. Various sensitivity analyses were performed experimentally to verify the simulated designed detector system. A mono-energetic ¹³⁷Cs γ-ray source with energy 662 keV and activity of 1.11 GBq was used for the observation. The simulated results were compared with the experimental dose rate values and good agreements were obtained for various cases. Only based on the dose rates in three detectors, the radiation source with a specific source activity and angle was localized in the different location. A method was adopted with the measured dose rates and differences of distances to find the actual location of the lost γ-ray source. The corresponding angles of deviation and detection limits were calculated to determine the sensitivity and abilities of our designed detector system. The proposed system can be used to locate radiation sources in low and high radiation environments.

• Journal of Life Science
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• v.18 no.8
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• pp.1066-1071
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• 2008

Schizandra fruit (Schizandra chinensis fructus) were dried by three processes, $50^{\circ}C$ (50HAD), $70^{\circ}C$ hot air (70HAD) and freeze drying process (FRD). Terpenoid were collected by SDE(Simultaneous Steam Distillation-Extraction) and followed by GC-MSD analysis. Also colour profile of each dried samples were measured by Hunter colorimeter. From fresh schizandra fruit, were detected 15 kinds of monoterpene, 28 kinds of sesquiterpene and 7 kinds of terpene alcohol. Myrcene(56.97 ${\mu}g/g$) and ${\gamma}$-terpinene(58.49 ${\mu}g/g$) were the major monoterpenes, ${\beta}$-elemene(120.16 ${\mu}g/g$), ${\alpha}$-bergamotene (103.45 ${\mu}g/g$), ${\gamma}$-selinene (75.97 ${\mu}g/g$), ${\beta}$-cubebene(66.69 ${\mu}g/g$), aristolene (51.25 ${\mu}g/g$) and ${\alpha}$-ylangene(28.06 ${\mu}g/g$) were the sesquiterpenes, and T-muurolol (96.45 ${\mu}g/g$) and terpinen-4-ol(46.02 ${\mu}g/g$) were the terpene alcohols. The dried samples lost more than half of terpenoid content of fresh schizandra fruit during early stage of drying process, and then the level of terpenoid content was not significantly changed. The content of sesquiterpenes appeared to increase until 6 day of FRD. The amount of residual terpene alcohols contained in schizandra fruit dried by FRD was more than those remained after drying by other processes, and schizandra fruit dried by 70HAD exhibited the least residual terpene alcohols. Brightness parameter $L^{\ast}$ decreased with the rise in the level of drying temperature, to which redness parameter $a^{\ast}$ and yellowness $b^{\ast}$ appeared to be similar.