• Title/Summary/Keyword: self-diffusion

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Self-textured Al-doped ZnO transparent conducting oxide for p-i-n a-Si:H thin film solar cell

  • Kim, Do-Yeong;Lee, Jun-Sin;Kim, Hyeong-Jun
    • Proceedings of the Materials Research Society of Korea Conference
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    • 2009.11a
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    • pp.50.1-50.1
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    • 2009
  • Transparent conductive oxides (TCOs) play an important role in thin-film solar cells in terms of low cost and performance improvement. Al-doped ZnO (AZO) is a very promising material for thin-film solar cellfabrication because of the wide availability of its constituent raw materials and its low cost. In this study, AZO films were prepared by low pressurechemical vapor deposition (LPCVD) using trimethylaluminum (TMA), diethylzinc(DEZ), and water vapor. In order to improve the absorbance of light, atypical surface texturing method is wet etching of front electrode using chemical solution. Alternatively, LPCVD can create a rough surface during deposition. This "self-texturing" is a very useful technique, which can eliminate additional chemical texturing process. The introduction of a TMA doping source has a strong influence on resistivity and the diffusion of light in a wide wavelength range.The haze factor of AZO up to a value of 43 % at 600 nm was achieved without an additional surface texturing process by simple TMA doping. The use of AZO TCO resulted in energy conversion efficiencies of 7.7 % when it was applied to thep-i-n a-Si:H thin film solar cell, which was comparable to commercially available fluorine doped tin oxide ($SnO_2$:F).

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Effect of Oscillatory Shear on the Interfacial Morphology of a Reactive Bilayer Polymer System

  • Kim, Hwang-Yong;Lee, Dong-Hyun;Kim, Jin-Kon
    • Proceedings of the Polymer Society of Korea Conference
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    • 2006.10a
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    • pp.350-350
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    • 2006
  • We investigated, via atomic force microscopy and transmission electron microscopy, the effect of shear force on the interfacial morphology of a reactive bilayer polymer system composed of PS-mCOOH and PMMAGMA. It has been observed that in the absence of oscillatory shearing the roughness of the interface increased with reaction period, while at large values of ${\gamma}_{0}\;and\;{\omega}$ it became less than that observed in the absence of oscillatory shearing. This observation may be attributable to the possibility that oscillatory shearing might have hindered the diffusion of polymer chains, which are located away from the interface, to the interface of the layers. However, the effect of ${\gamma}_{0}\;and\;{\omega}$ on the roughness of the interface of (PS-mCOOH)/(PMMA-GMA) bilayer is found to be quite different.

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Fabrication of All-Nb Josephson Junction Array Using the Self-Aligning and Reactive ion Etching Technique (Self-Aligning 기술과 반응성 이온 식각 기술로 제작된 Nb 조셉슨 접합 어레이의 특성)

  • Hong, Hyun-Kwon;Kim, Kyu-Tea;Park, Se-Il;Lee, Kie-Young
    • Progress in Superconductivity
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    • v.3 no.1
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    • pp.49-55
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    • 2001
  • Josephson junction arrays were fabricated by DC magnetron sputtering, self-aligning and reactive ion etching technique. The Al native oxide, formed by thermal oxidation, was used as the tunneling barrier of Nb/$Al-A1_2$$O_3$Nb trilayer. The arrays have 2,000 Josephson junctions with the area of $14\mu\textrm{m}$ $\times$ $46\mu\textrm{m}$. The gap voltages were in the range of 2.5 ~2.6 mV and the spread of critical current was $\pm$11~14%. When operated at 70~94 ㎓, the arrays generated zero-crossing steps up to 2.1~2.4 V. To improve transmission of microwave power and prevent diffusion of oxygen into Nb ground-plane while depositing $SiO_2$dielectric, we applied a plasma nitridation process to the Nb ground-plane. The microwave power was well propagated in Josephson junction arrays with nitridation. The difference in microwave transmission 7an be interpreted by the surface impedance change depending on nitridation.

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Factors affecting adoption of Internet Banking: A case study from India

  • Malhotra, Pooja;Kassim, Normalini Md;Ramayah, T.
    • Asia-Pacific Journal of Business
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    • v.5 no.2
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    • pp.13-24
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    • 2014
  • The objective of this research is to find out the factors affecting adoption of Internet banking in India. The data is based upon a survey of 150 bank customers using a convenience sampling technique with the aid of a structured self-administered questionnaire. The research model was analyzed using Partial Least Squares (PLS) analysis. The recommended procedures have been tested which is measurement model and structural model. Perceived Usefulness, Perceived Ease of Use, Perceived Risk, Image, Results Demonstrability, Perceived Behavioral Control and Subjective Norm were influence intention to use Internet banking. However, Perceived Ease of Use, Perceived Credibility and Computer Self Efficacy were not influence intention to use Internet banking. The findings of this study are expected to be of great use to the bank marketers. An understanding of the factors identified in this study allows bank managers to direct efforts and resources in the most effective and efficient way to increase bank business in the long run and encourage their bank customer's to adopt Internet banking. Moreover, this paper contributes to the empirical literature of diffusion of financial innovations, particularly Internet banking in a developing country, such as India.

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Preparation and Characterization of Nanoparticles Using Poly(N-isopropylacrylamide)-$Poly({\varepsilon}-caprolactone)$ and Poly(ethylene glycol)-$Poly({\varepsilon}-caprolactone)$ Block Copolymers with Thermosensitive Function

  • Choi, Chang-Yong;Jang, Mi-Kyeong;Nah, Jae-Woon
    • Macromolecular Research
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    • v.15 no.7
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    • pp.623-632
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    • 2007
  • Thermosensitive nanoparticles were prepared via the self-assembly of two different $poly({\varepsilon}-caprolactone)$-based block copolymers of poly(N-isopropylacrylamide)-b-$poly({\varepsilon}-caprolactone)$ (PNPCL) and poly(ethylene glycol)-b-$poly({\varepsilon}-caprolactone)$ (PEGCL). The self-aggregation and thermosensitive behaviors of the mixed nanoparticles were investigated using $^1H-NMR$, turbidimetry, differential scanning microcalorimetry (micro-DSC), dynamic light scattering (DLS), and fluorescence spectroscopy. The copolymer mixtures (mixed nanoparticles, M1-M5, with different PNPCL content) formed nano-sized self-aggregates in an aqueous environment via the intra- and/or intermolecular association of hydrophobic PCL chains. The microscopic investigation of the mixed nanoparticles showed that the critical aggregation concentration (cac), the partition equilibrium constants $(K_v)$ of pyrene, and the aggregation number of PCL chains per one hydrophobic microdomain varied in accordance with the compositions of the mixed nanoparticles. Furthermore, the PNPCL harboring mixed nanoparticles evidenced phase transition behavior, originated by coil to the globule transition of PNiPAAm block upon heating, thereby resulting in the turbidity change, endothermic heat exchange, and particle size reduction upon heating. The drug release tests showed that the formation of the thermosensitive hydrogel layer enhanced the sustained drug release patterns by functioning as an additional diffusion barrier.

Self-Assembled Polymeric Nanoparticles of Poly(ethylene glycol) Grafted Pullulan Acetate as a Novel Drug Carrier

  • Jung, Sun-Woong;Jeong, Young-Il;Kim, Young-Hoon;Kim, Sung-Ho
    • Archives of Pharmacal Research
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    • v.27 no.5
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    • pp.562-569
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    • 2004
  • Self-assembling nanospheres of hydrophobized pullulan have been developed. Pullulan acetate (PA), as hydrophobized pullulan, was synthesized by acetylation. Carboxymethylated poly(ethylene-glycol) (CMPEG) was introduced into pullulan acetate (PA) through a coupling reaction using N, N'-dicyclohexyl carbodiimide (DCC). A synthesized PA-PEG-PA (abbreviated as PEP) conjugate was confirmed by Fourier transform-infrared (FT-IR) spectroscopy. Since PEP conjugates have amphiphilic characteristics in aqueous solution, polymeric nanoparticles of PEP conjugates were prepared using a simple dialysis method in water. From the analysis of fluorescence excitation spectra primarily, the critical association concentration (CAC) of this conjugate was found to be 0.0063 g/L. Observations by scanning electron microscopy (SEM) showed the spherical morphologies of the PEP nanoparticles. The particle size distribution of the PEP conjugates was determined using photon correlation spectroscopy (PCS) and the intensity-average particle size was 193.3 ${\pm}$ 13.53 nm with a unimodal distribution. Clonazepam (CNZ), as a model drug, was easy to entrap into polymeric nanoparticles of the PEP conjugates. The drug release behavior was mainly diffusion controlled from the core portion.

Computational Study of Intermetallic Reaction Propagation in Nanoscale Boron/Titanium Metallic Multilayers (보론/티타늄 나노박막다층 내 이종금속간 화학반응 전파특성 해석연구)

  • Kim, Kyoungjin;Park, Joong-Youn
    • Journal of the Korean Society of Propulsion Engineers
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    • v.21 no.3
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    • pp.10-17
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    • 2017
  • The analytical modeling has been established on the self-propagation of intermetallic reaction in the spanwise direction of highly reactive boron and titanium nanoscale multilayers. Assuming that the reaction obeys Arrhenius kinetics, two-dimensional computations are carried out for heat and atomic species diffusion with exothermic reaction model in order to simulate the self-propagation of intermetallic reaction. The effects of bimetallic layer thickness and thickness ratio on the reaction propagation speed are tested and discussed in addition to the assessment of pre-mixing zone effects.

Cure Kinetics of Self-Extinguishing Epoxy Resin Systems with Charge Transfer Complex Type Latent Catalyst for Semiconductor Encapsulation (전하전이착체형 잠재성 촉매를 사용한 반도체 성형용 자소성 에폭시 수지 시스템의 경화 반응속도 연구)

  • Kim, Whan Gun
    • Journal of the Semiconductor & Display Technology
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    • v.13 no.4
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    • pp.27-32
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    • 2014
  • The cure properties of self-extinguishing epoxy resin systems with different charge transfer type latent catalysts were investigated, which are composed of YX4000H as a biphenyl epoxy resin, MEH-7800SS as a hardener, and charge transfer type latent catalysts. We designed and used five kinds of charge transfer type latent catalyst and compared to epoxy resin systems with Triphenylphosphine-Benzoquinone(TPP-BQ) as reference system. The cure kinetics of these systems were analyzed by differential scanning calorimetry with an isothermal approach, the kinetic parameters of all systems were reported in generalized kinetic equations with diffusion effects. The epoxy resin systems with Triphenylphosphine-Quinhydrone(TPP-QH), Triphenylphosphine-Benzanthrone(TPP-BT) and Triphenylphosphine-Anthrone(TPP-AT) as a charge transfer type latent catalyst showed a cure conversion rate of equal or higher rate than those with TPP-BQ. These systems with TPP-QH and Triphenylphosphine-Tetracyanoethylene(TPP-TCE) showed a critical cure reaction conversion of equal or higher conversion than those with TPP-BQ. The increases of cure conversion rates could be explained by the decrease of the activation energy of these epoxy resin systems. It can be considered that the increases of critical cure reaction conversion would be dependent on the crystallinity of the biphenyl epoxy resin systems.

LMS for Web based e-Learning on the SCORM

  • Woo, Young-Hwan;Chung, Jin-Wook;Kim, Seok-Soo;Kim, Soon-Gohn
    • Journal of information and communication convergence engineering
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    • v.2 no.2
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    • pp.80-83
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    • 2004
  • The core purpose of the system proposed in this paper is to help learners pursue proactive and self-oriented education by allowing learners to proactively configure their own content, that is, learners no longer have to be restricted by prescribed sequence of lectures. Although a variety of standardization and Learning Management System (LMS) were produced to develop and effectively manage web contents in response to active diffusion of internet application, practical changes to assist online learners are not yet to be found. In this paper, I would like to introduce a LMS that can support self-leading education by providing various types of learners at Virtual University with delicately organized educational contents for maximum efficiency. The system allows a learner to select a lecture or a chapter which has been presorted to meet his educational needs and intellectual ability. In general, most LMSs cannot meet every individual's educational needs because they structure their programs by letting learners simply choose from a list of available lectures at prescribed level or difficulty. However the Self-Leading LMS eliminates such boundaries by allowing learners to choose contents and difficulty within the limit set by their own educational competence.

An Empirical Study on Mobile Technology Adoption based on the Technology Acceptance Model and Theory of Planned Behavior (기술수용모델(TAM)과 계획된 행동이론(TPB)를 바탕으로 한 모바일 기술수용에 대한 실증적 연구)

  • Lee, Sang-Gun
    • Information Systems Review
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    • v.7 no.2
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    • pp.61-84
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    • 2005
  • Previous studies indicate that information and communication technology (ICT) adoption is affected by innovation influence such as usefulness, ease of use and self-efficacy. Most of these studies, how-ever, bypassed imitation influence such as subjective norms, word-of-mouth, and advertising, specifically, interactive innovation having critical mass in technology acceptance research. Thus, this study focuses to investigate imitation influence in individual adoption of mobile communication technology. The purpose of this study is to empirically examine the causal relationships between initial acceptance and the intention to use in terms of a holistic approach. The results of this study show that there is an imitation influence including word-of-mouth and subjective norms, from the prior adopters to potential adopters, and mass advertising through TV or news-paper commercials in the ICT diffusion process. In addition, this imitation influence also stimulates innovation influence such as perceived usefulness. Finally, this study provides a set of guidelines to mobile communication equipment manufacturers and ICT vendors in developing effective strategies for technology diffusion.