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Petkov, Valeri,Prasai, Binay,Shastri, Sarvjit,Park, Hyun-Uk,Kwon, Young-Uk,Skumryev, Vassil The Royal Society of Chemistry 2017 Nanoscale Vol.9 No.40
<P>Practical applications require the production and usage of metallic nanocrystals (NCs) in large ensembles. Besides, due to their cluster−bulk solid duality, metallic NCs exhibit a large degree of structural diversity. This poses the question as to what atomic-scale basis is to be used when the structure-function relationship for metallic NCs is to be quantified precisely. We address the question by studying bi-functional Fe core−Pt skin type NCs optimized for practical applications. In particular, the cluster-like Fe core and skin-like Pt surface of the NCs exhibit superparamagnetic properties and a superb catalytic activity for the oxygen reduction reaction, respectively. We determine the atomic-scale structure of the NCs by non-traditional resonant high-energy X-ray diffraction coupled to atomic pair distribution function analysis. Using the experimental structure data we explain the observed magnetic and catalytic behavior of the NCs in a quantitative manner. Thus we demonstrate that NC ensemble-averaged 3D positions of atoms obtained by advanced X-ray scattering techniques are a very proper basis for not only establishing but also quantifying the structure-function relationship for the increasingly complex metallic NCs explored for practical applications.</P>
손채훈,Young Jun Kim,Young-Mog Kim,Valery P. Pikalov 대한기계학회 2012 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.26 No.11
A scaling method to examine combustion-stability characteristics of a coaxial injector is devised based on the acoustics and combustion dynamics in a chamber. The method is required for a subscale test of stability rating with a model chamber, which is cost-effective compared with an actual full-scale test. First, scaling and similarity rules are considered for stability rating and thereby, three conditions of acoustic, hydrodynamic, and flame-condition similarities are proposed. That is, for acoustic similarity, the natural or resonant frequencies in the actual chamber should be maintained in the model chamber. And, two parameters of density ratio and velocity ratio are derived for the requirement of hydrodynamic and flame-condition similarities between the actual and the model conditions. Next, one example of an actual combustion chamber with high performance is selected and the proposed scaling method is applied to the chamber for understanding of the method. The design operating condition for a model test is presented by mass flow rates of propellants. Stability boundaries can be identified on the coordinate plane of chamber pressure and mixture ratio of fuel and oxidizer by applying the scaling method.
Lee, Eun-Young,Carson, Valerie,Jeon, Justin Y.,Spence, John C. SAGE Publications 2016 Asia-Pacific journal of public health Vol.28 No.6
<P>This study aimed to describe physical activity (PA) and sitting time, and to examine associations between sociodemographic factors, weight status, PA, and sitting time among South Korean adolescents (12-18 years). Findings are based on self-report data from 638 participants in the 2013 Korea National Health and Nutrition Examination Survey. Only 4.9% of adolescents accumulated 60 minutes of moderate-to-vigorous PA daily. Adolescents spent 532.4 +/- 9.3 mins/d sitting. After controlling for age and sex, individuals in higher income groups compared with the lowest income group, living in nonmetro Seoul compared with metro Seoul, and who were overweight compared with nonoverweight were more likely to meet PA guidelines. Participants in the highest income group compared with lowest income group, and residing in nonmetro Seoul compared with metro Seoul were more likely to be in the high sitting time group (>720 min/d) (P < .05). Increasing PA and reducing sitting should be a public health priority in South Korea.</P>
Virtualization-based Radio Access Network Evolution
Caroline Chan,Udayan Mukherjee,Valerie Young,유탁기 에스케이텔레콤 (주) 2013 Telecommunications Review Vol.23 No.5
The recent researches on telecommunication area see the potential for network functions virtualization (NFV) to reduce both capital and operational expenditures (CapEx/OpEx), as well as speed up the time to market for new services. These benefits arise because NFV helps decouple network functions from hardware so they are no longer tied to proprietary hardware, running instead on high-volume, industry-standard server platforms. At the heart of NFV is virtualization technology, which until recently has posed significant challenges to realizing the real-time performance required to support telecom workloads. This paper describes some of the issues equipment developers face in a virtualized environment and explains how they can be overcome. In particular, there is an in-depth analysis showing how a virtualized base station running on a general purpose processor-based platform can meet the 4G network requirements for latency and performance. Some test results and the corresponding observations are described for real-time processing in virtualized environment. We also present the RAN evolution vision based on virtualization technology.
Jin, Jun-O,Shastina, Valeria,Park, Joo-In,Han, Jin-Yeong,Makarieva, Tatyana,Fedorov, Sergey,Rasskazov, Valery,Stonik, Valentin,Kwak, Jong-Young Pharmaceutical Society of Japan 2009 Biological & pharmaceutical bulletin Vol.32 No.6
<P>Two-headed sphingolipids bear a certain similarity with sphingolipids in the structure and but differing from classical sphingolipids in α,ω-position of the basic groups. We analyzed the apoptotic effects of some two-headed sphingolipids including rhizochalin (Rhz) and its derivatives isolated from sponge <I>Rhizochalina incrustata</I> on human leukemia HL-60 cells. Direct addition of Rhz induced apoptosis of HL-60 cells. The aglycon of Rhz, which has no galactosyl residue, showed a stronger ability to induce apoptotic activity than Rhz. Rhz congeners with acetate derivatives only weakly induced apoptosis. The usual mitochondrial membrane permeability changes and the decrease of protein levels of procaspases-8, -9, and -3 correlated with the apoptotic activity of Rhzs. These results suggest that derivatives of two-headed sphingolipids potently induce apoptosis in mammalian cells when administered exogenously and this cell death was dependent on caspase activation pathways.</P>