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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

A comparative study of undergraduate student and professionally trained head resident effectiveness at selected universities

Yost, Michael William 19 May 2010 (has links)
The thesis of this investigation was that in light of several contemporary pressures (e.g., budget) the utilization of undergraduate student Head Residents may be a feasible alternative to the professionally trained Head Resident staffing approach that colleges and universities should consider. Three medium sized, state supported universities (Institutions A, B, and C) participated in the study. To explore the study's thesis, the effectiveness of undergraduate student Head Residents at Institution A was compared with that of professionally trained (Master's level) Head Residents at Institutions Band C. Effectiveness was measured by the frequency with which Head Residents at each participating institution were perceived by Resident Advisors (RA's) and Student Personnel Administrators (SPA's) as displaying typical Head Resident behaviors. A specially designed instrument containing fifty-eight items of a "person-management" oriented nature was used. All were mailed a copy of the instrument and asked to indicate on a Likert scale the frequency with which they perceived their Head Resident displaying each behavior. Selected SPA's at each institution were mailed two copies of the instrument, one to evaluate male Head Residents as a group and the other to evaluate female Head Residents as a group at their respective institutions. A factor analysis on the RA responses was pursued and five dimensions were identified. These were named the Empathy/Sensitivity, Programming/Activities, Disciplinary, Formal Leadership, and Facilities Management dimensions. ANOVA on mean ratings were used to answer several research questions related to comparative undergraduate student and professionally trained Head Resident effectiveness. The major findings of the study were the following: (a) Undergraduate students were perceived by RA's as being less effective than professionally trained personnel (.01) only in the frequency with which they displayed behaviors related to the Programming/Activities role; (b) Whereas undergraduate student males were perceived by their RA's as performing Disciplinary related behaviors more effectively (.01) than undergraduate student females, when compared with undergraduate student males the undergraduate student females were perceived as being more effective (.01) on the Empathy/Sensitivity and Programming/ Activities dimensions and as displaying person oriented behaviors more frequently (.01); (c) Professionally trained personnel were perceived by SPA's as more frequently displaying person oriented (.01) and management oriented (.01) behaviors than undergraduate student males; (d) SPA's perceived undergraduate student females as displaying person oriented functions more frequently (.01) than undergraduate student males. Among conclusions drawn from the study's findings was that professionally trained personnel are more balanced in effectiveness in the Head Resident role than undergraduate students. As perceived by RA's professionally trained males and females did not differ in effectiveness on the several dimensions analyzed. On the other hand, when the effectiveness of undergraduate student males and undergraduate student females were compared, the males were perceived by RA's as displaying "male type" behaviors (high on the Disciplinary dimension) more frequently and the females were perceived as displaying "female type" behaviors (high on Empathy/Sensitivity dimension) more frequently. Substantial differences ($100,000-$300,000) in annual institutional expenditure for Head Resident staff implied strongly that additional evaluation of the various approaches to Head Resident staffing is crucial. / Ed. D.
2

Elastic and inelastic responses of columns after sudden loss of bracing

Yoo, Rae Hak 06 June 2008 (has links)
A pinned column with initial deflection and an internal brace is investigated. The brace is modeled as a translational spring. Axial compressive loads are applied at the brace and the top of the column, and the equilibrium shape of the column is determined. The critical loads for the perfect column are computed analytically for several load combinations. The dynamic response of the column after sudden loss of bracing is analyzed using Galerkin’s method. With the consideration of the effects of the bracing location and the bracing stiffness, the maximum deflection of the column during motion is determined. The contribution of damping effects to the maximum deflection of the column is examined. Damping effects in the Galerkin method are compared to results from the finite element method (based on ABAQUS). The plastic dynamic analysis is carried out using ABAQUS. Both residual stresses and damping effects are considered, and the spread of plasticity during the motion is investigated. The cases studied include equal and unequal spans, and axial loads below and above the load which causes the column to collapse. / Ph. D.
3

Degradation mechanisms of barium titanate based thick film capacitors

Yoo, In Kyeong January 1986 (has links)
The electrical characteristics, including degradation, of high K (≅ 500) barium titanate based thick film capacitors were studied. It was found that a gold conductor made from Au metallo-organic paste is not compatible with the porous high K dielectric material. The leakage current of a thick film capacitor made from Ag/Pd thick film conducting paste and high K dielectric has shown ohmic and space charge limited current behavior with a 3/2 power voltage dependence. Voltage independence of thermal activation energy and time dependence of a leakage current have been observed. A healing effect by reversal of bias polarity and humidity effect on leakage current have also been studied. The 3/2 power voltage dependence can be attributed to point emission from surface indentations or clusters of Ag particles at the electrode. Two possible degradation mechanisms based either on simple vacancy movement or a reduced grain boundary potential barrier height are suggested. It has been found that an electronic conduction model based on reduced grain boundary barrier height is more reasonable than that of simple vacancy induced current model. / M.S.
4

Supercritical fluid extraction of polychlorinated biphenyls and organochlorine pesticides from mussel tissue (Mytilus edulis)

Yoo, Wesley Jinhan 28 August 2003 (has links)
The supercritical fluid extraction (SFE) of twenty one polychlorinated biphenyls (PCBs) and eight organochlorine pesticides (OCPs) from freeze dried mussel tissue is discussed, demonstrated, and compared to traditional Soxhlet extractions. The aim of this study was to determine the efficacy of SFE for the extraction of these lipophilic compounds which involved a spike study to determine the feasibility of on-line sample clean-up by an inclusion of activated alumina within the extraction vessel. These spike extractions from an inert matrix showed that the chemical integrity of the PCBs was not compromised while some OCPs of the DDT derivative were decomposed to other forms. Preliminary extractions of freeze dried mussel tissue focused on the effect of static extraction time and CO₂ density on recovery of twenty three specific congeners of PCBs. These extractions of freeze dried mussel tissue showed longer static extraction time and higher density/lower temperature would yield quantitative recoveries of PCBs. Triplicate extractions of mussel tissue at the appropriate extraction parameters produced quantitative and similar recoveries to Soxhlet. Finally, an alternative supercritical fluid (CHF₃) yielded non-quantitative recoveries for PCBs and OCPs, but the use of this fluid eliminated the need to use in situ alumina to retain co-extracted lipids from the matrix. / Master of Science
5

Electrical crosstalk in multilayer ceramic substrates

Yoo, In Kyeong 19 October 2005 (has links)
Electrical crosstalk is becoming increasingly important as size shrinks and component densities increase in hybrid circuits. This occurs especially in multilayer thick film circuits. Crosstalk studies at high frequencies apply transverse electromagnetic (TEM) or quasi-TEM mode. However, the TEM mode theory is not applicable at low frequencies and low frequency-crosstalk is still a concern for circuit designers. In this research, crosstalk equations were derived in a simpler way, which can be used for low frequency applications such as automotive electronics. Test patterns were designed in both single and multilayer substrates in order to study crosstalk parameters such as line separation, line width, ground distance, ground type, and multilayer thickness. The mutual inductance and the mutual capacitance were calculated in order to use them in predicting crosstalk for particular transmission line geometrical structures. A conventional technique was used for the mutual inductance, and a new conformal mapping technique was developed for the mutual capacitance. Frequency dependence of crosstalk was confirmed by the equations developed. There is good agreement between the experimental mutual inductance and mutual capacitance and the calculated values. Finally, crosstalk prediction ( simulated by combining crosstalk equations with calculated mutual parameters ) fits well with the measured values. / Ph. D.
6

Three essays on financial development, economic growth and income inequality / CUHK electronic theses & dissertations collection

January 2013 (has links)
The issue of economic growth and income inequality is always the hottest topic among economists. Over the past decades to the onset of the global economic crisis, a large majority of OECD countries have experienced widen income inequality. More recently, the break out of the Occupy Wall Street Movement has rapid spread and recaptured much attention. One of the most driving themes is a country’s economic growth and embarrassing income inequality; it also reflects a broad-based frustration about how the sophisticated financial development affects the overall economy. To understand the impact of financial development on economic growth and income distribution has more important implications than ever. This dissertation is an effort to study these issues with three studies. / In Study 1, a simplified version of Diamond and Dybvig (1983) model of liquid provision is embedded into a framework of overlapping-generations model. In the model, the agents are subject to idiosyncratic liquidity shocks, and have to make their own mind whether to hold the savings on hand or invest in a long-term illiquid technology and how to allocate. By comparing the autarky economy and the economy with financial intermediaries, our results suggest the existence of both benefits and costs of financial intermediaries and the net effects tend to differ with the development stage of the underlying economy. / In Study 2, the links between economic growth and income inequality are reexamined using a newly compiled panel dataset. This study mainly address three empirical questions: 1) Does inequality increase in the early stages of development and then decline when per capita income reaches a certain level? 2) Do countries with unequal income distribution experience slower economic growth than more egalitarian countries? 3) What might be the determinants of economic growth and income inequality, and whether they are simultaneously determined? Our results show that the links between economic growth and income inequality are quite complex and their determinants are not mutually exclusive. / In Study 3, the impacts of financial development on economic growth and income inequality are explored empirically. By collecting proxy variables measuring different aspects of financial development, this study tests 1) Is financial development pro-growth? In other words, does financial development always exert a positive impact on economic growth? 2) Is financial development pro-poor? By pro-poor, we mean whether financial development significantly improve income distribution by disproportionately boosting the incomes of the poor. Our results indicate that financial development is not always pro-growth, taking into account of country-specific effects, endogeneity and potential heteroskedasticity. In addition, after controlling for the overall growth, financial development is not pro-poor. It is more likely for the rich to get more benefits from both bank-based and market-based developments. / 經濟增長和收入不平等的問題始終是經濟學家中最熱門的話題。在過去的幾十年到近年全球經濟危機爆發,大多數經濟合作與發展組織(OECD)國家都經歷了收入不平等的擴大。近年來爆發的"佔領華爾街"運動在全球迅速蔓延,並成為關注的焦點。其中一個最為重要的導火索是國家的經濟增長和愈加惡化的收入不平等,同時也反映出廣大民眾對於金融業發展會如何影響整體經濟的困惑。因此,理解金融發展對經濟增長和收入分配的影響變得比以往任何時刻都更具有重要的意義。本論文通過三篇研究從不同的角度分析這一問題。 / 在研究一中,我們把一個簡化的Diamond 和Dybvig(1983)模型嵌入代際交疊模型的框架中。在這個模型中,每個人都會受到流動性的衝擊,因此必須決定是將儲蓄持有在手邊還是投資於長期的不能流動的技術中,以及如何分配。通過比較自給自足的經濟和有金融機構存在下的經濟,我們的研究結果表明,金融機構是把雙刃劍,其淨效應取決於相關經濟體的發展階段。 / 在研究二中,我們用新編譯的面板資料重新檢驗了經濟增長和收入不平等之間的聯繫。這篇研究主要回答了三個問題:1)收入不平等是否在經濟發展的早期增加,在人均收入達到一定水準後下降?2)收入不平等的國家是否比收入平等的國家經濟增長緩慢?3)經濟增長和收入不平等的決定因素是什麼,二者是否是同時決定的?我們的研究結果表明,經濟增長和收入不平等之間的聯繫相當複雜,並且其決定因素也不是相互排斥的。 / 在研究三中,我們通過實證的方法探索金融發展對經濟增長和收入不平等的影響。通過用不同變數來衡量金融發展的各個方面,這篇研究主要回答了兩個問題:1)金融發展是否促增長?換句話說,金融發展對經濟增長是否都產生了積極的影響?2)金融發展是否有利於窮人?所謂有利於窮人,我們是指金融發展能大幅提高窮人的收入,從而顯著改善收入分配。我們的研究結果顯示,在考慮了國家影響、內生性和潛在異方差等因素後,金融發展並不總是有利於經濟增長。另外,剔除整體經濟增長的影響,金融發展也並不利於窮人。相反,富人更有可能從銀行和市場為主的金融發展中得到更多的實惠。 / Yu, Yao. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references (leaves 192-207). / Abstracts also in Chinese. / Title from PDF title page (viewed on 20, December, 2016). / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only.
7

The microbial immobilization of zinc sulfate

Yoon, Sung Ok January 1983 (has links)
M. S.
8

The microbial immobilization of zinc sulfate

Yoon, Sung Ok January 1983 (has links)
M.S.
9

Tribological behavior of unfilled and carbon fiber reinforced polyether ether ketone/polyether imide composites

Yoo, Jong Hyun 30 December 2008 (has links)
The friction and wear of injection molded Poly(ether ether ketone) (PEEK) and Poly(ether imide) (PEI), PEEK/PEI blends with the weight compositions of 50/50 %, 70/30 %, and 85/15 %, with and without short carbon fibers were measured in a pin(52100 steel ball)-on-disk(polymer blend) configuration under dry friction. 50/50, 70/30, and 85/15 compositions were annealed to study the effect of crystallinity on wear test. The test variables were sliding speed and normal load. The wear mechanism of pure PEEK matrix was plowing and as the weight percentage of PEI in the blend was increased the wear mechanism changed to the generation of small particles. The wear rates of the unfilled PEEK/PEI blends were found to be a function of not only the blend composition, but also of the normal load, sliding speed and crystallinity in complex manner. However, the coefficient of friction of the unfilled blends did not seem to significantly depend on those testing parameters. When no wear debris was produced, it was below 0.15 otherwise it was ranged from 0.2 to 0.3. The 30 weight % carbon fiber reinforced (CFR) PEEK did produced wear particles but 70/30 and 100 % PEI composites showed reduced wear rates compared to those of unfilled blends. The coefficients of friction of CFR did not seem to be changed from those of the untreated blends except for 100% PEI. Presence of the incubation time before wear particles were produced indicated that the predominant wear mechanism was fatigue. An increase in friction correlated with the generation of wear particles and the formation of a wear groove. / Master of Science
10

Effect of pre-exposure thermal treatment on susceptibility of type 304 austenitic stainless steel to stress corrosion

Yoon, Kap Suk 04 May 2010 (has links)
The effect of a specific type of pre-exposure heat treatment on the susceptibility of AlSI type 304 stainless steel to stress corrosion cracking was studied in terms of time for crack nucleation and rate of crack propagation. U-bend specimens were exposed to 42 weight percent magnesium chloride aqueous solution after pre-exposure heat treatments at 140°C and 154°C. The straight-line relationship between maximum crack depth and the logarithm of exposure time expressed by the empirical equation log t = log t<sub>o</sub> + D/M was obtained. The stress corrosion constants derived from the empirical equation indicate that this type of pre-exposure heat treatment promotes crack nucleation because of the formation of less protective surface films, and retards the rate of crack propagation because of effects on internal structural changes within the alloy. / Master of Science

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