• Title/Summary/Keyword: Structural modification

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The effects of oxygen partial pressure on $SrTiO_3$ films with $RuO_2$ bottom electrode ($SrTiO_3/RuO_2$ 박막 형성시 플라즈마 가스 주입비의 영향)

  • 박치선;김상훈;마재평
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.8 no.2
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    • pp.286-291
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    • 1998
  • $SrTiO_3$[ST] thin films were fabricated on $RuO_2$bottom electrodes by RF magnetron sputtering with various $Ar/O_2$ratio in sputtering gas. As the content of oxygen increases, the leakage current of ST films measured at $10^5$ V/cm decreases from $2.0{\times}10^{-6}A/{\textrm}{cm}^2(Ar/O_2=10/0)$ to $3.8{\times}10^{-7}A/{\textrm}cm^2(Ar/O_2=5/5)$, and the dielectric constant of ST films increases from $70(Ar/O_2=10/0)$ to $190(Ar/O_2=5/5)$. The improvement of electrical properties of ST films is mainly due to the structural modification of ST films such as better crystallinity, smooth surface morphology with the increase of oxygen content in the sputtering gas.

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Modification of Schottky Barrier Properties of Ti/p-type InP Schottky Diode by Polyaniline (PANI) Organic Interlayer

  • Reddy, P.R. Sekhar;Janardhanam, V.;Jyothi, I.;Yuk, Shim-Hoon;Reddy, V. Rajagopal;Jeong, Jae-Chan;Lee, Sung-Nam;Choi, Chel-Jong
    • JSTS:Journal of Semiconductor Technology and Science
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    • v.16 no.5
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    • pp.664-674
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    • 2016
  • The electrical properties of Ti/p-type InP Schottky diodes with and without polyaniline (PANI) interlayer was investigated using current-voltage (I-V) and capacitance-voltage (C-V) measurements. The barrier height of Ti/p-type InP Schottky diode with PANI interlayer was higher than that of the conventional Ti/p-type InP Schottky diode, implying that the organic interlayer influenced the space-charge region of the Ti/p-type InP Schottky junction. At higher voltages, the current transport was dominated by the trap free space-charge-limited current and trap-filled space-charge-limited current in Ti/p-type InP Schottky diode without and with PANI interlayer, respectively. The domination of trap filled space-charge-limited current in Ti/p-type InP Schottky diode with PANI interlayer could be associated with the traps originated from structural defects prevailing in organic PANI interlayer.

Directed Evolution of Beta-galactosidase from Escherichia coli into Beta-glucuronidase

  • Xiong, Ai-Sheng;Peng, Ri-He;Zhuang, Jing;Liu, Jin-Ge;Xu, Fang;Cai, Bin;Guo, Zhao-Kui;Qiao, Yu-Shan;Chen, Jian-Min;Zhang, Zhen;Yao, Quan-Hong
    • BMB Reports
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    • v.40 no.3
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    • pp.419-425
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    • 2007
  • In vitro directed evolution through DNA shuffling is a powerful molecular tool for creation of new biological phenotypes. E. coli $\beta$-galactosidase and $\beta$-glucuronidase are widely used, and their biological function, catalytic mechanism, and molecular structures are well characterized. We applied an in vitro directed evolution strategy through DNA shuffling and obtained five mutants named YG6764, YG6768, YG6769, YG6770 and YG6771 after two rounds of DNA shuffling and screening, which exhibited more $\beta$-glucuronidase activity than wild-type $\beta$-galactosidase. These variants had mutations at fourteen nucleic acid sites, resulting in changes in ten amino acids: S193N, T266A, Q267R, V411A, D448G, G466A, L527I, M543I, Q626R and Q951R. We expressed and purified those mutant proteins. Compared to the wild-type protein, five mutant proteins exhibited high $\beta$-glucuronidase activity. The comparison of molecular models of the mutated and wildtype enzymes revealed the relationship between protein function and structural modification.

A Study on the Factors Affecting the Acceptance Intention for Mobile Ads. (모바일 광고의 수용의도에 영향을 미치는 요인에 관한 연구)

  • Yoo, Sang-Jin;Tang, Hung-Lian;Kim, Hyo-Jung
    • Information Systems Review
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    • v.9 no.1
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    • pp.1-21
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    • 2007
  • This research investigates the determinants of consumer's acceptance for the mobile Ads. Based on TAM(Technology Acceptance Model) and Flow theory, our research adopts some factors for a theoretical model such as entertainment, information, irritation, credibility, flow experience, attitudes and acceptance intention. For examining an implied relationships by this research model, a field study using survey methodology for data collection was conducted. This data was analyzed based on using AMOS, the structural equation modeling and a second generation multi variant technique, and has gained distinct advantages over other technique. After some model modification according to model generating strategy approach, this study shows that entertainment, irritation, credibility and flow experience have significant effects on the attitudes. And also, this attitudes have acceptance intention in mobile Ads. In conclusion, implications are discussed along with limitations and further research direction.

Pushover Analysis of a 5-Story RC OMRF Considering Inelastic Shear Behavior of Beam-Column Joint (보-기둥 접합부 비탄성 전단거동을 고려한 5층 철근콘크리트 보통모멘트골조의 푸쉬오버해석)

  • Kang, Suk-Bong;Kim, Tae-Yong
    • Journal of the Korea Concrete Institute
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    • v.24 no.5
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    • pp.517-524
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    • 2012
  • In this study, the effects of the inelastic shear behavior of beam-column joint and the vertical distribution of lateral load are evaluated considering higher modes on the response of RC OMRF using the pushover analysis. A structure used for the analysis was a 5-story structure located at site class SB and seismic design category C, which was designed in accordance with KBC2009. Bending moment-curvature relationship for beam and column was identified using fiber model. Also, bending moment-rotation relationship for beam-column joint was calculated using simple and unified joint shear behavior model and moment equilibrium relationship for the joint. The results of pushover analysis showed that, although the rigid beam-column joint overestimated the stiffness and strength of the structure, the inelastic shear behavior of beam-column joint could be neglected in the process of structural design since the average response modification factor satisfied the criteria of KBC2009 for RC OMRF independent to inelastic behavior of joint.

SnO2-Coated 3D Etched Cu Foam for Lithium-ion Battery Anode

  • Um, Ji Hyun;Kim, Hyunwoo;Cho, Yong-Hun;Yoon, Won-Sub
    • Journal of Electrochemical Science and Technology
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    • v.11 no.1
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    • pp.92-98
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    • 2020
  • SnO2-based high-capacity anode materials are attractive candidate for the next-generation high-performance lithium-ion batteries since the theoretical capacity of SnO2 can be ideally extended from 781 to 1494 mAh g-1. Here 3D etched Cu foam is applied as a current collector for electron path and simultaneously a substrate for the SnO2 coating, for developing an integrated electrode structure. We fabricate the 3D etched Cu foam through an auto-catalytic electroless plating method, and then coat the SnO2 onto the self-supporting substrate through a simple sol-gel method. The catalytic dissolution of Cu metal makes secondary pores of both several micrometers and several tens of micrometers at the surface of Cu foam strut, besides main channel-like interconnected pores. Especially, the additional surface pores on etched Cu foam are intended for penetrating the individual strut of Cu foam, and thereby increasing the surface area for SnO2 coating by using even the internal of Cu foam. The increased areal capacity with high structural integrity upon cycling is demonstrated in the SnO2-coated 3D etched Cu foam. This study not only prepares the etched Cu foam using the spontaneous chemical reactions but also demonstrates the potential for electroless plating method about surface modification on various metal substrates.

The Structural Path Model of Adolescents′ Internet Addiction and Expected Self-Control (청소년의 인터넷 중독현상과 자기통제기대의 구조적 경로모형에 관한 연구)

  • 박재성
    • Korean Journal of Health Education and Promotion
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    • v.21 no.3
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    • pp.1-17
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    • 2004
  • The purpose of this study is to evaluate the roles of expected self-control and expected self-control results in explaining adolescents' Internet addiction. In the study model, expectations of self-control and self-control results directly determine Internet addiction and Internet use time meditates the impacts of expectations of self-control and self-control results on Internet addiction. The study subjects are 1,080 middle and high school students in Busan. Stratified cluster sampling is applied by school type and school year. The response rate is 96%(l,037cases). This study develops the scales of expected self-control and expected self-control results. The scales of Internet addiction are devised by using the concept of functional dependency such as salience, withdrawal symptoms, mood modification, tolerance, relapse, and conflict. For verifying the study model, path analysis and multiple regression models are applied for identifying path significants and evaluating confounding effects of control variables, respectively. Moreover, multi partial F-test is performed for selecting the best regression model. Expected self-control is a significant determinant of Internet addiction and Internet use time that also significantly explains Internet addiction. The total effect of expected self-control towards Internet addiction is -.95. The total effect is comprised with the direct effect (-.71) and the indirect effect(-.24). In this result, the direct effect refers a curative effect since expected self-control directly reduces the level of Internet addiction, and the indirect effect refers a preventive effect because self-control can reduce time of Internet use that is a direct determinant of Internet addiction. In the test of the confounding effects of control variables, there are no confounding effects in the models of multiple regression. It implies a robustness of the study model as regards control variables. In conclusion, improving adolescents' expected self-control can control Internet addiction level. This finding implies that a health promotion program for improving expected self-control can be a cost effective method compared to other approaches.

Seismic response of active or semi active control for irregular buildings based on eigenvalues modification

  • Pnevmatikos, Nikos G.;Hatzigeorgiou, George D.
    • Earthquakes and Structures
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    • v.6 no.6
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    • pp.647-664
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    • 2014
  • A reduction of the response of irregular structures subjected to earthquake excitation by control devices equipped by suitable control algorithm is proposed in this paper. The control algorithm, which is used, is the pole placement one. A requirement of successful application of pole placement algorithm is a definition-selection of suitable poles (eigen-values) of controlled irregular structures. Based on these poles, the required action is calculated and applied to the irregular structure by means of control devices. The selection of poles of controlled irregular structure, is a critical issue for the success of the algorithm. The calculation of suitable poles of controlled irregular structure is proposed herein by the following procedure: a fictitious symmetrical structure is considered from the irregular structure, adding vertical elements, such as columns or shear walls, at any location where is necessary. Then, the eigen-values of symmetrical structure are calculated, and are forced to be the poles of irregular controlled structure. Based on these poles and additional damping, the new poles of the controlled irregular structure are calculated. By pole placement algorithm, the feedback matrix is obtained. Using this feedback matrix, control forces are calculated at any time during the earthquake, and are applied to the irregular structure by the control devices. This procedure results in making the controlled irregular structure to behave like a symmetrical one. This control strategy can be applied to one storey or to multi-storey irregular buildings. Furthermore, the numerical results were shown that with small amount of control force, a sufficient reduction of the response of irregular buildings is achieved.

Abnormal Work Function Modification at the Interface between Organic Molecule and Solid Surfaces

  • Kim, Ji-Hoon;Seo, Jae-Won;Kang, Hye-Seung;Kim, Jeong-Kyu;Kim, Jeong-Won;Lee, Han-Gil;Kwon, Young-Kyung;Park, Yong-Sup
    • Proceedings of the Korean Vacuum Society Conference
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    • 2010.08a
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    • pp.63-63
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    • 2010
  • Using both experimental and theoretical approaches, we have investigated the adsorption properties of an organic molecule (HATCN), which is used in OLEDs as an efficient hole injection layer, on metal and inert surfaces. We have also studied the structural and electronic properties of such interfaces and the dependences on deposition thickness. We have observed different trends in work function changes with different surfaces. Our photoelectron spectroscopic measurements have revealed an abnormal phenomenon in HATCN on a metal (Cu) surface: the work function decreases at lower coverage (~monolayer) of HATCN on a metal (Cu) surface, but it increases back and becomes higher than that of a bare Cu surface at higher coverage. It has, on the contrary, been observed that the work function of graphene surface just increases as the HATCN coverage increases. Our first-principles density functional calculations has not only verified our experimental observations, but also disclosed the underlying mechanism of such abnormal and different work function behaviors. We have found that the change in work function results from mutual polarization induced by the geometrical deformation and the bond dipole formed at the interface due to the charge redistribution. At low coverage of HAT-CN on Cu substrate, the former reduces the work function significantly by pulling down the vacuum level, while the latter tends to push up the vacuum level resulting in the work function increase.

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Stabilization of HRP Using Hsp90 in Water-miscible Organic Solvent (Hsp90을 이용한 유기용매에서의 과산화효소 안정화 연구)

  • Chung, Ja Hee;Choi, Yoo Seong;Song, Seung Hoon;Yoo, Young Je
    • Korean Chemical Engineering Research
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    • v.44 no.1
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    • pp.92-96
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    • 2006
  • Enzymes in organic media afford many advantages such as chiral synthesis and resolution, modification of fats and oils and production of biodegradable polymers. However, the nature of solvents influences the activity and stability of enzymes, and the presence of organic solvents always constitute a risk of enzyme inactivation. Heat-shock protein Hsp90, one of the molecular chaperone, was applied for understanding of enzyme inactivation and for increasing of enzyme stability in water-miscible organic solvent. Hsp90 showed stabilization effect on HRP in the 30% of DMSO, in the 30% and 50% of dioxane. Hsp90 also showed reactivation effect on the inactivated HRP by water-miscible organic solvent such as dioxane and DMSO. In addition, structural analysis using fluorescence spectrophotometry and circular dichroism showed that exposure of HRP in water-miscible organic solvent caused appreciable conformational changes and enzyme inactivation, and the unfolded HRP by water-miscible organic solvent was refolded by Hsp90.