• 제목/요약/키워드: Self diffusion

검색결과 387건 처리시간 0.028초

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

  • 김도영;이준신;김형준
    • 한국재료학회:학술대회논문집
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    • 한국재료학회 2009년도 추계학술발표대회
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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
    • 한국고분자학회:학술대회논문집
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    • 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
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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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Self-Aligning 기술과 반응성 이온 식각 기술로 제작된 Nb 조셉슨 접합 어레이의 특성 (Fabrication of All-Nb Josephson Junction Array Using the Self-Aligning and Reactive ion Etching Technique)

  • Hong, Hyun-Kwon;Kim, Kyu-Tea;Park, Se-Il;Lee, Kie-Young
    • Progress in Superconductivity
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    • 제3권1호
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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.
    • 아태비즈니스연구
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    • 제5권2호
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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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    • 제15권7호
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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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    • 제27권5호
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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.

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

  • 김경진;박중윤
    • 한국추진공학회지
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    • 제21권3호
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    • pp.10-17
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    • 2017
  • 빠른 반응성 및 자체전파특성을 가지는 보론/티타늄 나노 다층박막구조를 대상으로 박막층 수평방향으로의 이종금속간 화학반응 및 화염 전파현상 해석 모델링을 수립하였다. 이종금속간 화학반응은 Arrhenius 반응식을 가정하여 모델링하였으며, 열 및 화학종 확산, 발열 화학반응에 따른 화염 자체전파 현상에 대하여 2차원적 전산해석을 수행하였다. 보론 및 티타늄 박막층의 두께 및 두께비 등 나노구조 형상의 영향을 비롯하여 접촉층 예혼합 정도가 화염 자체전파속도에 미치는 영향을 분석하였다.

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

  • 김환건
    • 반도체디스플레이기술학회지
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    • 제13권4호
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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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    • 제2권2호
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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.

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

  • 이상근
    • 경영정보학연구
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    • 제7권2호
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    • pp.61-84
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    • 2005
  • 정보통신기술의 수용에 대한 많은 선행연구들은 기술수용이 유용성(usefulness), 사용의 용이성(ease of use) 그리고 기술에 대한 자긍심(self-efficacy) 같은 혁신적 요인에 의해 영향을 받는다고 하였다. 그러나, 이러한 선행연구들은 사회적 규범(subjective norms), 구전효과(word-of-mouth) 그리고 광고(advertising)와 같은 모방적 요인에 대해서는 간과해 왔다. 특히 수요대폭발(critical mass)을 불러일으키는 모방적 요인과 혁신적 요인의 상호간 인과관계에 대한 연구는 그다지 활발하지 않았다. 그래서 본 연구는 모바일 기술의 수용에 있어 모방적 요인의 역할에 대해 초점을 맞추었다. 이 연구의 목적은 복합적 관점에서 초기 모바일 기술 수용에 대한 의도에 영향을 미치는 요인들간의 인과관계를 실증적으로 검증하였다. 그 결과, 대량광고, 구전효과와 사회적 규범과 같은 모방적 요인이 모바일 수용의도에 직/간접적으로 영향을 미치고 있다는 것을 밝혔다. 본 연구는 기술 전파에 따른 시장변화에 있어 정보통신 장비공급업체에게 효과적으로 대응할 수 있는 전략수립에 도움을 주리라 믿는다.