8,456 research outputs found
An extension of the weighted sum of gray gases non-gray gas radiation model to a two phase mixture of non-gray gas with particles
No full textA great deal of efforts has been exercised to date to accurately model the non-gray behavior of the gases. Among others, the weighted sum of gray gases model (WSGGM), which replaces the non-gray gas behavior by an equivalent finite number of gray gases, is a simplified model yielding reasonable results. However, a discussion on the weighting factors required for an estimation of radiation in a mixture of non-gray gas/gray particulate is not yet established for WSGGM, since they are dependent on the particle number density, particle size distribution: local temperature and partial pressure. Consequently, the relation between the weighting factors used in the WSGGM for a mixture of non-gray gas and gray particles with scattering in the thermal non-equilibrium has been discussed here, which has not been done before to the author's best knowledge. Weighting factors for the particles, of which temperature is different from that of the gas, were evaluated analytically for the WSGGM. The results were, then, validated for the problem of isothermal gas containing soot particulates between two parallel slab walls. For further application, the approach derived here was implemented to examine the non-gray radiative effects of the two phase mixture in an axisymmetric cylinder by changing such various parameters as the particle temperature, non-gray gas composition and particle concentration. The effects of thermal non-equilibrium in a mixture of gas and particles were also discussed in parallel with scattering effects by particles. Parametric study showed that a variation in the gas concentration yielded a noticeable change in the radiative heat transfer when the suspended particle temperature was different from the gas temperature. New contribution of this study consisted in an extension of applicability of the WSGGM non-gray model to two phase radiation. (C) 2000 Elsevier Science Ltd. All rights reserved.The authors wish to acknowledge the financial support of the Korea Research Foundation made in the program year of 1998 under the contract 1998-018-E00016
On co-authorship for author disambiguation
No full textAuthor name disambiguation deals with clustering the same-name authors into different individuals. To attack the problem, many studies have employed a variety of disambiguation features such as coauthors, titles of papers/publications, topics of articles, emails/affiliations, etc. Among these, co-authorship is the most easily accessible and influential, since inter-person acquaintances represented by co-authorship could discriminate the identities of authors more clearly than other features. This study attempts to explore the net effects of co-authorship on author clustering in bibliographic data. First, to handle the shortage of explicit coauthors listed in known citations, a web-assisted technique of acquiring implicit coauthors of the target author to be disambiguated is proposed. Then, a coauthor disambiguation hypothesis that the identity of an author can be determined by his/her coauthors is examined and confirmed through a variety of author disambiguation experiments. (C) 2008 Elsevier Ltd. All rights reserved.X1174sciescopu
The distance-regular graphs such that all of its second largest local eigenvalues are at most one
No full textIn this paper, we classify distance-regular graphs such that all of its second largest local eigenvalues are at most one. Also we discuss the consequences for the smallest eigenvalue of a distance-regular graph. These extend a result by the first author, who classified the distance-regular graphs with smallest eigenvalue -1 - b(1)/2. (C) 2011 Elsevier Inc. All rights reserved.X1154sciescopu
Hydrate phase equilibria of the carbon dioxide, methane, and water system
No full textThree-phase equilibria for the carbon dioxide + methane:+ water system were obtained by employing the isobaric temperature search method. Based on these isobaric hydrate equilibrium studies, the ternary hydrate, water-rich liquid, and vapor equilibrium lines generated-at different compositions of carbon dioxide and methane were all located between two three-phase equilibrium lines of simple hydrates formed by a single guest component. The upper quadruple points where the four phases hydrate, water-rich liquid, CO2-rich liquid, and vapor coexist were measured for the:composition range of 100-82.50 mol % carbon dioxide. Below 82.50 mol;% carbon dioxide, the upper quadruple points do not exist because none of the components in-the vapor phase, neither methane nor carbon dioxide, is able to liquefy at these conditions. In addition, two-phase equilibria of vapor and hydrate were also determined at the three different pressures 20, 26, and 35 bar. Judging from the resulting T-x diagram, the concentration of carbon dioxide ia the hydrate phase was found to be higher than 90 mol % when the corresponding equilibrium vapor-phase composition was more than 40 mol % carbon dioxide. The carbon dioxide concentration and relative selectivity over-methane in the hydrate phase appeared to increase with decreasing pressure.This work was supported by Grant 98-0502-04-01-3 from the Basic
Research program of the KOSEF and also partially by the Brain
Korea 21 Project
Comparison of medical students' perceptions of patient safety: Focusing on simulation training using a high-fidelity simulator.
No full textPatient safety education is necessary for the provision of high-quality medical services. A significant aspect of patient safety education is simulation training, which allows medical students to experience realistic clinical environments. This study aimed to verify the effectiveness of patient safety education using simulation training. We retrospectively analyzed the results of a 30-question questionnaire survey on the perceptions of patient safety before and after simulation training, which was completed by 40 medical students who participated in clinical practice between June and December 2021. A paired t-test was performed by calculating the mean and standard deviation for each item. We found that students' overall perceptions of patient safety improved after training. Specifically, after simulation training, attitudes toward patient safety were maintained at the same level as before training, while students' self-efficacy of patient safety increased. Simulation training is effective in improving students' perceptions of patient safety, and increasing students' confidence can improve their clinical performance. To maintain this effect, repeated learning is required, and theoretical classes and simulation training should be used appropriately for patient safety education in the future
Factors in turnover intention of cardiothoracic surgery residents
No full textIncreasing numbers of cardiothoracic surgery residents are resigning, without completing their training. This study analyzes how their turnover intention is related to the training environment, and individual psychological factors. Responses by 57 Korean cardiothoracic surgery residents were analyzed. Their levels of depression, anxiety, grit, and empathy, working conditions, the effect of someone’s presence to discuss their concerns with, burnout, and turnover intention were identified as the research variables. Descriptive statistical analysis, correlation analysis, and structural equation modeling were used for data analysis. Burnout has the most significant relationship with turnover intention. It has a mediating effect on the influence of depression, grit (sustained interest), and working conditions, over turnover intention. Empathy, and the presence of someone to discuss concerns with, also affect turnover intention directly. The study also confirmed that grit and work satisfaction affect turnover intention indirectly, through burnout. The study identified both individual- and systemic-level factors for an effective training environment, to reduce cardiothoracic surgery residents’ tendencies of leaving the residency program, and supporting them for greater satisfaction with their career choice. In order to resolve negative emotions such as burnout and depression, and foster empathy, a human resource development program for the residents’ psychological support must be prepared. The program director should be adequately educated to take charge of the training program, oversee the residents’ education and welfare, and perform the roles of role-model and mentor
E-portfolio utilization in medical school clinical practice: assessing satisfaction and learning advantages
No full textPurpose: This study aimed to investigate the difference in satisfaction and learning benefits between e-portfolios compared to paper portfolios during clinical practice in medical schools. Methods: Utilization of and satisfaction with e-portfolios among 40 third-year medical students in the medicine department of Ajou University School of Medicine was collected using an online survey in December 2020. The collected data were analyzed using descriptive statistics and an analysis of variance. Results: Students perceived that e-portfolios were highly beneficial for consistently documenting activities during clinical practice, when compared to paper-based portfolios (mean±standard deviation [SD]=2.60±1.22). However, the least rated aspect was that e-portfolios require less time than paper-based portfolios (mean±SD=1.80±1.14). Additionally, among the various clinical practice courses using e-portfolios, the highest satisfaction was observed with the fewest content items in the e-portfolio. Conclusion: To maximize the potential benefits of e-portfolios, improvements in implementation and usability are essential. Additionally, for effective utilization of e-portfolios in clinical practice, it is necessary to clearly define students’ required competencies and ultimate goals, and structure content accordingly
Synthesis and Structure Determination of the Hierarchical Meso-Microporous Zeolite ITQ-43
No full textThe formation of mesopores in microporous zeolites is generally performed by postsynthesis acid, basic, and steam treatments. The hierarchical pore systems thus formed allow better adsorption, diffusion, and reactivity of these materials. By combining organic and inorganic structure-directing agents and high-throughput methodologies, we were able to synthesize a zeolite with a hierarchical system of micropores and mesopores, with channel openings delimited by 28 tetrahedral atoms. Its complex crystalline structure was solved with the use of automated diffraction tomography. RI Mugnaioli, Enrico/E-6237-2011; Kolb, Ute/A-2642-2011; Jorda, Jose L./D-1334-2009; yu, jihong/C-1381-201
- …
