• Nuclear Engineering and Technology
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• v.55 no.11
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• pp.3940-3955
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• 2023

A new method of numerical simulating prediction and decontamination effect evaluation for abrasive jet decontamination to radioactively contaminated metal is proposed. Based on the Computational Fluid Dynamics and Discrete Element Model (CFD-DEM) coupled simulation model, the motion patterns and distribution of abrasives can be predicted, and the decontamination effect can be evaluated by image processing and recognition technology. The impact of three key parameters (impact distance, inlet pressure, abrasive mass flow rate) on the decontamination effect is revealed. Moreover, here are experiments of reliability verification to decontamination effect and numerical simulation methods that has been conducted. The results show that: ⁶⁰Co and other homogeneous solid solution radioactive pollutants can be removed by abrasive jet, and the average removal rate of Co exceeds 80%. It is reliable for the proposed numerical simulation and evaluation method because of the well goodness of fit between predicted value and actual values: The predicted values and actual values of the abrasive distribution diameter are Ф57 and Ф55; the total coverage rate is 26.42% and 23.50%; the average impact velocity is 81.73 m/s and 78.00 m/s. Further analysis shows that the impact distance has a significant impact on the distribution of abrasive particles on the target surface, the coverage rate of the core area increases at first, and then decreases with the increase of the impact distance of the nozzle, which reach a maximum of 14.44% at 300 mm. It is recommended to set the impact distance around 300 mm, because at this time the core area coverage of the abrasive is the largest and the impact velocity is stable at the highest speed of 81.94 m/s. The impact of the nozzle inlet pressure on the decontamination effect mainly affects the impact kinetic energy of the abrasive and has little impact on the distribution. The greater the inlet pressure, the greater the impact kinetic energy, and the stronger the decontamination ability of the abrasive. But in return, the energy consumption is higher, too. For the decontamination of radioactively contaminated metals, it is recommended to set the inlet pressure of the nozzle at around 0.6 MPa. Because most of the Co elements can be removed under this pressure. Increasing the mass and flow of abrasives appropriately can enhance the decontamination effectiveness. The total mass of abrasives per unit decontamination area is suggested to be 50 g because the core area coverage rate of the abrasive is relatively large under this condition; and the nozzle wear extent is acceptable.

• Nuclear Engineering and Technology
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• v.55 no.6
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• pp.2335-2347
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• 2023

As medical facilities are usually built at urban areas, special concrete aggregates and evaluation methods are needed to optimize the design of concrete walls by balancing density, thickness, material composition, cost, and other factors. Carbon treatment rooms require a high radiation shielding requirement, as the neutron yield from carbon therapy is much higher than the neutron yield of protons. In this case study, the maximum carbon energy is 430 MeV/u and the maximum current is 0.27 nA from a hybrid particle therapy system. Hospital or facility construction should consider this requirement to design a special heavy concrete. In this work, magnetite is adopted as the major aggregate. Density is determined mainly by the major aggregate content of magnetite, and a heavy concrete test block was constructed for structural tests. The compressive strength is 35.7 MPa. The density ranges from 3.65 g/cm³ to 4.14 g/cm³, and the iron mass content ranges from 53.78% to 60.38% from the 12 cored sample measurements. It was found that there is a linear relationship between density and iron content, and mixing impurities should be the major reason leading to the nonuniform element and density distribution. The effect of this nonuniformity on radiation shielding properties for a carbon treatment room is investigated by three groups of Monte Carlo simulations. Higher density dominates to reduce shielding thickness. However, a higher content of high-Z elements will weaken the shielding strength, especially at a lower dose rate threshold and vice versa. The weakened side effect of a high iron content on the shielding property is obvious at 2.5 µSv=h. Therefore, we should not blindly pursue high Z content in engineering. If the thickness is constrained to 2 m, then the density can be reduced to 3.3 g/cm³, which will save cost by reducing the magnetite composition with 50.44% iron content. If a higher density of 3.9 g/cm³ with 57.65% iron content is selected for construction, then the thickness of the wall can be reduced to 174.2 cm, which will save space for equipment installation.

• Journal of Society of Preventive Korean Medicine
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• v.8 no.2
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• pp.141-156
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• 2004

Objectives : JianTeng-Yuan(交藤圓) is said to be a prescription for preservation of health in ${\ulcorner}$HuaTuo ZhongZangJing(華陀 中藏經)${\lrcorner}$. It is known to have the effect of Bu-Shen(補腎: strengthening kidney) and Yi-Shou(益壽: prolonging the span of one's life). This study investigates whether JTY is effective on inhibition of oxidation stress. Methods : Sprague-Dawley Rats(12-week-old, weight $300{\pm}20g$) were divided into 3 groups. Normal group(n=8) was injected PBS(1ml/body, s.c) at the back neck's skin. Control group(n=8) was injected D-galactose(50mg/kg, 1ml PBS/body, s.c) to induce pathological animals. JTY group was injected the same treatment for the Control group, and fed containing JTY(10%). The whole groups were treated 1 time per day for 6 weeks. After rats were sacrificed and anti-oxidant enzyme(SOD, CAT, G-px) activity, GSH quantity of RBC and tissue(heart, liver and kidney), plasma Vit-C quantity were examined. Besides, the MDA levels of liver and kidney, lipofuscin of heart and endurance of erythrocyte membrane were measured. Results : In the JTY group, RBC's SOD activity decline was halted by 21% of the normal level, compared to the control group ; G-px activity(unit/g of Hb) increased significantly, compared to the normal group ; and the level of Vit-C in plasma increased by 16%. Heart's SOD activity was kept at the same level as that of the normal group ; and CAT activity decline was halted by 26%. Kidney's CAT and G-px activities were kept at the same level as that shown in the normal group, implying the existence of halting effect. Liver also showed a slight halting effect against the decline of anti-oxidant ability, but the effect was not significant(a=0.05). A comparison between the levels of peroxide in SD rats showed that the level of TBARS in plasma increased significantly in the control group and that it was normal in the JTY group. The livers in the JTY group, compared to those in the control group, showed 36% halting effect of the normal level while their kidney's indicated the level significantly lower than the normal level. Heart's lipofuscin increased significantly in the control group, but was alike in both the JTY and the normal groups. Endurance of erythrocyte membrane(%) decreased significantly in the control group while it was kept at the similar level in both the JTY and the normal groups, indicating the halting effect. Conclusions : This study suggests that JTY is effective to defend oxidation stress caused by D-galactose in the animals. It showed that the anti-oxidant ability was maintained and strengthened. On the other hand, it reduced the level of peroxide in animals. In sum, JTY appeared to have the equilibrium normal physiological function in SD rat.

• Journal of the Korean Institute of Landscape Architecture
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• v.49 no.3
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• pp.40-52
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• 2021

Various peoples lived in Changbai Mountain in each era, and the peoples of each period regarded Changbai Mountain as part of their own religious culture. Existing studies on the culture of Changbai Mountain are conducted only based on the events of a specific period, but how the sacredness of Changbai Mountain has changed from time to time, how it is related to the religious culture of the people of each period, and how sacred the areas and spaces have changed. There has been no research to that extent. The purpose of this study is to examine and analyze the meaning of Changbai Mountain's sacredness that has changed from time to time. In order to examine the change of the sanctity of Changbai Mountain through synchronicity, the study focused on the hierophany occurring between the religious culture of the peoples of each period and the space of Changbai Mountain. Specifically, the activities to protect the sacred objects and sacred spaces revealed by the hierophany were considered, and the change of the sanctity of Changbai Mountain was interpreted with the derived results. The summary of the results of this study is as follows. The sacred activities of Changbai Mountain have changed from time to time. During the pre-Qing dynasty, civilians performed incarnation rites, holy god rites, mountain god ceremonies, and willow god rites for livelihood and survival, and the king of the Jin dynasty offered rituals to the Changbai Mountain gods as rituals such as Four Mountains(Yuezhen). During the Qing Dynasty, the emperor built Wangji Temple and sent a government official to make a ritual to the Changbai Mountain god as the best ritual to symbolize the country. In modern times, Bagua Temple was built on the top of Changbai Mountain and sacrifices were made to the Changbai Mountain gods, and the nature of Changbai Mountain. Humans living in Changbai Mountain area were judged through the tricks of the Bagua Mountain. In addition, during this period, civilians performed ritual activities centering on the god Shanshenlaobatou, who personified life and production. In summary, the sacred activities of Changbai Mountain were shamanistic rituals based on animistic ideology in the pre-Qing dynasty, the best imperial rites for honoring the sacred as an imperial sanctuary in the Qing dynasty, and the Taoist ideology of migrants in the modern period. It had been transformed into a ceremonial activity. And the meaning of Changbai Mountain, viewed as a sacred activity, was elevated from the mountain of livelihood in the pre-Qing dynasty to the mountain of the nation in the Qing dynasty, and then changed to the mountain of modern production.