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Sensitivity and uncertainty analysis for ULOF of PGSFR using PAPIRUS
Kang, Sarah,Choi, ChiWoong,Ha, Kwi-Seok,Heo, Jaeseok Elsevier 2017 Annals of nuclear energy Vol.110 No.-
<P><B>Abstract</B></P> <P>In this research, sensitivity and uncertainty analyses for 23 parameters were performed for unprotected loss of flow (ULOF) for the prototype Gen-IV sodium-cooled fast reactor (PGSFR) by using the parallel computing platform integrated for uncertainty and sensitivity analysis (PAPIRUS). Based on the development of the phenomena and model identification and ranking table (PIRT), the relative importance of the parameters was confirmed through the sensitivity analysis. The objective of the global uncertainty analysis is to evaluate all safety parameters of the system in the combined phase space formed by the parameters and dependent variables. The uncertainty propagation was performed by mapping the uncertainty bands of the model parameters through the MARS-LMR to determine the distributions for the fuel centerline, cladding, and coolant temperatures. The results show that the uncertainty bands of the temperatures are below the melting point.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Sensitivity analysis for the ULOF of the PGSFR was performed using PAPIRUS. </LI> <LI> Uncertainty propagation was performed by mapping uncertainty bands of parameters. </LI> <LI> Distributions for fuel centerline, cladding and coolant temperatures were determined. </LI> </UL> </P>
Seasonal Dependence of the Effect of Arctic Greening on Tropical Precipitation
Kang, Sarah M.,Kim, Baek-Min,Frierson, Dargan M. W.,Jeong, Su-Jong,Seo Jeongbin,Chae, Yoojeong American Meteorological Society 2015 Journal of climate Vol.28 No.15
<P> This paper examines the seasonal dependence of the effect of Arctic greening on tropical precipitation. In CAM3/CLM3 coupled to a mixed layer ocean, shrub and grasslands poleward of 60°N are replaced with boreal forests. With darker Arctic vegetation, the absorption of solar energy increases, but primarily in boreal spring and summer since little insolation reaches the Arctic in boreal winter. The net energy input into the northern extratropics is partly balanced by southward atmospheric energy transport across the equator by an anomalous Hadley circulation, resulting in a northward shift of the tropical precipitation. In contrast, in boreal fall, the slight increase in insolation over the Arctic is more than offset by increased outgoing longwave radiation and reduced surface turbulent fluxes in midlatitudes, from the warmer atmosphere. As a result, the Northern Hemisphere atmosphere loses energy, which is compensated by a northward cross-equatorial atmospheric energy transport, leading to a southward shift of the tropical precipitation in boreal fall. Thus, although Arctic vegetation is changed throughout the year, its effect on tropical precipitation exhibits substantial seasonal variations. </P>
Kang, Sarah,Park, Seong Dae,Kim, In Guk,Bang, In Cheol Atomic Energy Society of Japan 2016 Journal of nuclear science and technology Vol.53 No.3
<P>To confirm the feasibility of the gallium-water IVR-ERVCS (in-vessel retention-external reactor vessel cooling system), this paper focuses on the numerical simulation of severe accidents in APR 1400 using MARS-LMR (multidimensional analysis of reactor safety-liquid metal reactor). To analyze the gallium-cooled systems, the properties of liquid gallium were added to the MARS-LMR code used in our previous work. In this system, the generated decay heat is transferred to liquid gallium through the reactor pressure vessel and then removed from the water pool as a heat sink. The numerical analyses results show that the temperature range of the liquid gallium is much lower than its boiling point and confirm the natural convection. Sensitivity studies were also performed by changing several parameters such as the initial temperature of gallium and water pool inventory and their results indicated that the working time of the gallium-water IVR-ERVCS depends on the inventory of the water pool. Because liquid gallium in this system does not have a phase change, unlike water, the gallium-water IVR-ERVCS can provide stable and reliable cooling capability. To solve the limitation due to critical heat flux in IVR-ERVCS and to ensure the sufficient thermal margin, it is confirmed that the gallium-water IVR-ERVCS can be a successful severe accident mitigation strategy in nuclear power plants.</P>
PDR-type ABC transporter mediates cellular uptake of the phytohormone abscisic acid
Kang, Joohyun,Hwang, Jae-Ung,Lee, Miyoung,Kim, Yu-Young,Assmann, Sarah M.,Martinoia, Enrico,Lee, Youngsook Proceedings of the National Academy of Sciences 2010 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF Vol.107 No.5
<P>Abscisic acid (ABA) is a ubiquitous phytohormone involved in many developmental processes and stress responses of plants. ABA moves within the plant, and intracellular receptors for ABA have been recently identified; however, no ABA transporter has been described to date. Here, we report the identification of the ATP-binding cassette (ABC) transporter Arabidopsis thaliana Pleiotropic drug resistance transporter PDR12 (AtPDR12)/ABCG40 as a plasma membrane ABA uptake transporter. Uptake of ABA into yeast and BY2 cells expressing AtABCG40 was increased, whereas ABA uptake into protoplasts of <I>atabcg40</I> plants was decreased compared with control cells. In response to exogenous ABA, the up-regulation of ABA responsive genes was strongly delayed in <I>atabcg40</I> plants, indicating that ABCG40 is necessary for timely responses to ABA. Stomata of loss-of-function <I>atabcg40</I> mutants closed more slowly in response to ABA, resulting in reduced drought tolerance. Our results integrate ABA-dependent signaling and transport processes and open another avenue for the engineering of drought-tolerant plants.</P>
( Sarah Chung ),( Jin Young Jeong ),( Yoon Kyung Chang ),( Dae Eun Choi ),( Ki Ryang Na ),( Beom Jin Lim ),( Kang Wook Lee ) 대한내과학회 2016 The Korean Journal of Internal Medicine Vol.31 No.2
Background/Aims: There has been controversy about the role of Toll-like receptor 2 (TLR2) in renal injury following ureteric obstruction. Although inhibition of the renin angiotensin system (RAS) reduces TLR2 expression in mice, the exact relationship between TLR2 and RAS is not known. The aim of this study was to determine whether the RAS modulates TLR2. Methods: We used 8-week-old male wild type (WT) and TLR2-knockout (KO) mice on a C57Bl/6 background. Unilateral ureteral obstruction (UUO) was induced by complete ligation of the left ureter. Angiotensin (Ang) II (1,000 ng/kg/ min) and the direct renin inhibitor aliskiren (25 mg/kg/day) were administrated to mice using an osmotic minipump. Molecular and histologic evaluations were performed. Results: Ang II infusion increased mRNA expression of TLR2 in WT mouse kidneys (p < 0.05). The expression of renin mRNA in TLR2-KO UUO kidneys was significantly higher than that in WT UUO kidneys (p < 0.05). There were no differences in tissue injury score or mRNA expression of monocyte chemotactic protein 1 (MCP-1), osteopontin (OPN), or transforming growth factor (TGF-β) between TLR2-KO UUO and WT UUO kidneys. However, aliskiren decreased the tissue injury score and mRNA expression of TLR2, MCP-1, OPN, and TGF-β in WT UUO kidneys (p < 0.05). Aliskiren-treated TLR2-KO UUO kidneys showed less kidney injury than aliskiren-treated WT UUO kidneys. Conclusions: TLR2 deletion induced activation of the RAS in UUO kidneys. Moreover, inhibition of both RAS and TLR2 had an additive ameliorative effect on UUO injury of the kidney.