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Du, H.I.,Kim, M.J.,Kim, Y.J.,Lee, D.H.,Han, B.S.,Song, S.S. North-Holland 2010 Physica. C, Superconductivity Vol.470 No.20
The YBCO thin-film wire has a high index value and a fast phase transition speed when a fault current is applied to it. Its critical properties are also superior to those of the existing Bi-Sr-Ca-O wire. Moreover, it can choose its stabilizing layers and control the magnitude of the resistance it generates in with the specific-resistance of the stabilizing layers. Thus, many researchers are studying the application of the Y-Ba-Cu-O(YBCO) thin-film wire to superconducting power machines. Being particularly studied are the properties of the YBCO thin-film wire as a current-limiting element material. In this study, to evaluate the basic properties of superconducting current-limiting elements that contain insulating layers, test samples were manufactured using the YBCO thin-film wire according to the absence and presence as well as the thickness of the insulating layers. Then a fault current was applied to the test samples to examine their quenching resistance trends and operational properties according to the fault angles. Towards those ends, a current was applied to various YBCO thin-film wires with different stabilizing layers to test their properties, and the YBCO thin-film wire that exhibited superior current-limiting performance was selected. Also, a fault current was applied to the selected YBCO thin-film wire with insulating layers to test their properties. Using the test results, the resistance occurrence trends were examined at the critical temperature of 90K, the perfect quenching temperature of 250K, and the middle temperature of 180K. Also, to increase the current limiters' capacity, the element's operational properties, such as its maximum voltage, maximum current, initial limited current, and response time were observed at 90K, 180K, and 250K according to the fault angles.
HRTEM ANALYSIS OF A METAL-CERAMIC INTERFACE IN Cu-AIN SYSTEM
Du, J.,Liang, H.Y.,Yang, G.Y. 한국재료학회 1995 Fabrication and Characterization of Advanced Mater Vol.2 No.4
A metal-ceramic interface Cu-AIN in a copper implanted and annealed AIN matrix is analyzed by HRTEM techniques. The precipitation in AIN matrix after an appropriate annealing treatment yields metallic particles all exhibiting the same low energy orientation relationship with the ceramic matrix. At an early stage of the precipitation, the small coppr paritcles are constrained by the matrix and are described by a near rhombohedral disturbance. The copper precipitates were often observed in twin-related palte-like shape which is determined by low energy interfaces, especially on the meta side. In the case of the interface parallel to (11ⅰ)Cu, the contrast at the interface is associated to a quasi-low energy configuration and gave us some crystal information for geometric and structural modelizations. The atomic structure at the interface is modelled according to these informations ; experimental and simulated images ahve been qualitatively compared.
Du, W.,Li, Y.J.,Zhao, G.Y.,Yin, Y.L.,Kong, X.F. Asian Australasian Association of Animal Productio 2009 Animal Bioscience Vol.22 No.8
Two experiments were carried out to study the effects of dietary energy level on nutrient digestion, nitrogen (N) utilization, growth performance, insulin-like growth factor-I (IGF-I), and insulin-like growth factor binding protein-3 (IGFBP-3) in plasma, liver and longissimus dorsi muscle in growing-finishing pigs. In experiment 1 (Exp 1), 15 castrated male pigs (Duroc${\times}$Landrace${\times}$Large White) (Body weight, BW, 55.6${\pm}$1.8 kg) were divided into three groups and fed rations containing 13.33, 14.87 and 17.35 MJ digestible energy (DE)/kg as treatments I, II and III, respectively, using soybean oil as an energy source. The experiment lasted 8 days and faecal and urinary samples were collected during the last 3 days. The results showed that the digestibility of dry matter (DM), energy and N was increased from treatments I to III (p<0.01). N-retention and N-retention rate were not influenced by dietary DE level (p>0.05). In experiment 2 (Exp 2), 36 female pigs (Duroc${\times}$Landrace${\times}$Large White) (BW 41.5${\pm}$3.8 kg) were divided into three groups. The pigs were fed with the same three rations used in Exp 1 for 60 days. At the end of Exp 2, eight pigs were selected from each group for blood sampling and 4 pigs for slaughter trial. The results indicated that average daily feed intake (ADFI) and N-intake were significantly decreased (p<0.01), and DE intake (p<0.01) and average daily gain (ADG) (p<0.05) were increased. IGF-I and IGFBP-3 in plasma were increased (p<0.05). No significant differences in IGF-I and IGFBP-3 in liver and longissimus dorsi muscle were found between different treatments. It was concluded that higher dietary DE level improved nutrient digestibility, ADG and feed/gain ratio when soybean oil was used as an energy source in the ration of growing-finishing pigs. No significant differences were found in Nretention and IGF-I and IGFBP-3 in liver and longissimus dorsi muscle between different treatments.
Du, J.,Chen, H.,Yang, H.,Sang, R.,Qian, Y.,Li, Y.,Zhu, G.,Mao, Y.,He, W.,Kang, D.J. Elsevier 2013 Microporous and mesoporous materials Vol.182 No.-
A porous Nd-doped TiO<SUB>2</SUB> monolith was successfully synthesized with polystyrene spheres as a template using a sol-gel method followed by calcination at high temperature. The porous Nd-doped TiO<SUB>2</SUB> monolith was characterized by X-ray diffractometry, scanning electron microscopy and Brunauer-Emmett-Teller measurements. Nd doping can increase the TiO<SUB>2</SUB> surface area by hindering the growth of large TiO<SUB>2</SUB> particles, and suppressing the recombination of photo-produced hole/electron (h<SUP>+</SUP>/e<SUP>-</SUP>) pairs. Moreover, its porous structure can provide a large surface area, facilitating enhanced adsorption and fast transfer of pollutants. To evaluate the photocatalytic activity of the porous Nd-doped TiO<SUB>2</SUB> monolith, the photo-degradation for methyl orange was investigated under UV-Vis irradiation. The porous 0.5% Nd-doped TiO<SUB>2</SUB> monolith showed better behavior than the other as-prepared samples and Degussa P25 due to its narrow band gap, high efficiency for h<SUP>+</SUP>/e<SUP>-</SUP> pair separation, and large surface area. The synergistic combination of Nd doping and the porous structure is a promising material design strategy for use in the degradation of organic pollutants.
Effect of surface modification layer thickness on the gas sensitivity of SnO2 films
Y.H. Xiong,L. Wang,X.Y. Wei,G.R. Qin,C.H. Mao,J. Du 한양대학교 세라믹연구소 2006 Journal of Ceramic Processing Research Vol.7 No.4
Nickel was used as a surface modification material to enhance the gas-sensing properties of SnO2 films. The thickness of the Ni modification layer was controlled by the sputtering time. The surface morphology and surface chemical composition of the surface modification layers of different thicknesses were analyzed by Field Emission Scanning Electron Microscopy (FESEM) and X-ray Photoelectron Spectroscopy (XPS), respectively. The gas sensitivity to clean air with a low hydrogen concentration of 1000 ppm of the modified tin dioxide thin films was investigated at temperatures from 20oC to 100oC. The results show that the thickness of the modification layer plays an important role in the enhancement of the gas-sensing properties and surface electric properties of SnO2 films. A Ni modification layer with a thickness of 50 nm on the surface of a SnO2 film can improve the hydrogen gas sensitivity of a SnO2 film up to 112%, and reduce the response time to 80s. Nickel was used as a surface modification material to enhance the gas-sensing properties of SnO2 films. The thickness of the Ni modification layer was controlled by the sputtering time. The surface morphology and surface chemical composition of the surface modification layers of different thicknesses were analyzed by Field Emission Scanning Electron Microscopy (FESEM) and X-ray Photoelectron Spectroscopy (XPS), respectively. The gas sensitivity to clean air with a low hydrogen concentration of 1000 ppm of the modified tin dioxide thin films was investigated at temperatures from 20oC to 100oC. The results show that the thickness of the modification layer plays an important role in the enhancement of the gas-sensing properties and surface electric properties of SnO2 films. A Ni modification layer with a thickness of 50 nm on the surface of a SnO2 film can improve the hydrogen gas sensitivity of a SnO2 film up to 112%, and reduce the response time to 80s.
Kim, Du Y.,Han, Seung H.,Kim, Hyoungkwan,Park, Heedae Elsevier 2009 expert systems with applications Vol.36 No.2
<P><B>Abstract</B></P> <P>Early understanding of project conditions is crucial so as to proactively respond to the variable situations of a project. Particularly, international construction projects are affected by more complex and dynamic factors than domestic projects; frequently being exposed to serious external uncertainties such as political, economical, social, and cultural risks, as well as internal risks from within the project itself. This study develops a structural equation model (SEM) to predict the project success of uncertain international construction projects. Through a comparative analysis of SEM with a multiple regression analysis and artificial neural network, SEM shows a more accurate prediction of performance because of its intrinsic ability to consider various risk variables in a systematic and realistic way. In addition, the use of SEM allows for visually depicting the paths of how those complicated variables are interrelated so as to promote the clear understanding of the complex system and its underpinned causes that critically affect the project success.</P>