• Nuclear Engineering and Technology
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• 제56권7호
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• pp.2748-2755
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• 2024

This paper presents two new methods for variance reduction for shielding calculation in Monte Carlo radiation transport. One method is CADIS-NEE, which combines Consistent Adjoint Driven Importance Sampling (CADIS) and next-event estimator (NEE) methods to increase the calculation efficiency of tallies at points. The other is CADIS-deterministic transport (DXTRAN), which combines CADIS and DXTRAN to obtain higher performance than using CADIS and DXTRAN separately. The combination processes are derived and implemented in the hybrid Monte-Carlo-Deterministic particle-transport code NECP-MCX. Various problems are tested to demonstrate the effectiveness of the two methods. According to the results, the two combination methods have higher efficiency than using CADIS, NEE or DXTRAN separately. In a long-distance photon-transport problem, CADIS-NEE converges faster than NEE and the figure of merit (FOM) of CADIS-NEE is 75.6 times of NEE. In a labyrinthine problem, CADIS-DXTRAN's FOM surpasses that of DXTRAN and CADIS by a factor of 45.3 and 17.7, respectively. Therefore, it is advisable to employ these two novel methods selectively in appropriate scenarios to reduce variance.

• 동의생리병리학회지
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• 제30권6호
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• pp.439-446
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• 2016

The purpose of this study was to examine the effects of Angelica gigas Nakai on ulcerative colitis. Mice were divided into 5 groups: Control group, DSS group, 5-ASA group, 50mg/kg Angelica gigas Nakai group, 100mg/kg Angelica gigas Nakai group. Four groups, excluding the control group, were fed a 5% solution of dextran sulfate sodium(DSS) in water for 7days to induce ulcerative colitis. Each water extract was administrated orally for 7 days in 5-ASA group, 50mg/kg Angelica gigas Nakai group and 100mg/kg Angelica gigas Nakai group. 5 groups were evaluated by weight, length of intestine, weight of spleen, disease activity index(DAI), amount of cytokine IL-6 production, thickness of bowel wall and degree of inflammatory cell infiltration and intestinal tissue damage. Comparing to DSS group, 100 mg/kg Angelica gigas Nakai group showed significant suppressive effect of weight loss until 4th day of experiment while 50 mg/kg Angelica gigas Nakai group showed no significant effect of suppression. Decrease of intestinal length, enlargement of spleen, intestinal tissue damage and thickening of bowel wall were significantly suppressed in both 50 mg/kg and 100mg/kg Angelica gigas Nakai group. Also disease activity and cytokine IL-6 production were inhibited significantly. Based on this result, Angelica gigas Nakai seemed to have anti-inflammatory effect and also seemed to suppress histological changes and aggravation of ulcerative colitis.