• 제목/요약/키워드: reaction-diffusion

검색결과 970건 처리시간 0.025초

확산모델을 이용한 다중전자 전극반응에 대한 순환전위법의 전산모델링 (Computational Modeling of Cyclic Voltammetry on Multi-electron Electrode Reaction using Diffusion Model)

  • 조하나;윤도영
    • 전기화학회지
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    • 제15권3호
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    • pp.165-171
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    • 2012
  • 본 연구에서는 전기화학계에서 중요한 다중전자의 이동이 수반되는 전극 반응에 대하여 순환전위법의 특성곡선을 모델링하여, MATLAB 프로그램으로 구현하였다. 전극주변의 전기화학 물질전달계에 대하여 반무한 확산모델의 경계조건을 설정하였고, Fick의 농도방정식은 유한차분법으로 전개하여 수치해를 구하였고, Butler-Volmer 식으로부터 계산된 농도값을 전류의 값으로 전환하였다. 본 연구에서 구현된 수치해는 기존의 실험치들과 합리적으로 설명하고 있었으며, 이를 근거로 다중전자 전기화학 반응계에서 반응메카니즘에 대한 전극반응속도 상수와 CV 주사속도 영향을 효과적으로 해석할 수 있었다.

고온자전합성과 확산 열처리를 이용한 V 이 첨가된 TiAl계 금속간화합물 복합판재의 제조 (Formation of a V-Added Ti Aluminide Multilayered Sheet by Self-Propagating High-Temperature Synthesis and Diffusion Annealing)

  • 김연욱
    • 한국재료학회지
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    • 제12권9호
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    • pp.696-700
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    • 2002
  • The Ti-aluminide intermetallic compound was formed from high purity elemental Ti and Al foils by self-propagating, high-temperature synthesis(SHS) in hot press. formation of $TiAl_3$ at the interface between Ti and Al foils was controlled by temperature, pressure, heating rate, and so on. According to the thermal analysis, it is known in this study that the heating rate is the most important factor to form the intermetallic compound by this SHS reaction. The V layer addition between Al and Ti foils increased SHS reaction temperatures. The fully dense, well-boned inter-metallic composite($TiA1/Ti_3$Al) sheets of 700 m thickness were formed by heat treatment at $1000^{\circ}C$ for 10 hours after the SHS reaction of alternatively layered 10 Ti and 9 Al foils with the V coating layer. The phases and microstructures of intermetallic composite sheets were confirmed by EPMA and XRD.

Correlation between rare earth elements in the chemical interactions of HT9 cladding

  • Lee, Eun Byul;Lee, Byoung Oon;Shim, Woo-Yong;Kim, Jun Hwan
    • Nuclear Engineering and Technology
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    • 제50권6호
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    • pp.915-922
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    • 2018
  • Metallic fuel has been considered for sodium-cooled fast reactors because it can maximize the uranium resources. It generates rare earth elements as fission products, where it is reported by aggravating the fuel-cladding chemical interaction at the operating temperature. Rare earth elements form a multicomponent alloy (Ce-Nd-Pr-La-Sm-etc.) during reactor operation, where it shows a higher reaction thickness than a single element. Experiments have been carried out by simplifying multicomponent alloys for mono or binary systems because complex alloys have difficulty in the analysis. In previous experiments, xCe-yNd was fabricated with two elements, Ce and Nd, which have a major effect on the fuel-cladding chemical interaction, and the thickness of the reaction layer reached maximum when the rare earth elements ratio was 1:1. The objective of this study is to evaluate the effect and relationship of rare earth elements on such synergistic behavior. Single and binary rare earth model alloys were prepared by selecting five rare earth elements (Ce, Nd, Pr, La, and Sm). In the single system, Nd and Pr behaviors were close to diffusion, and Ce showed a eutectic reaction. In the binary system, Ce and Sm further increased the reaction layer, and La showed a non-synergy effect.

$H_2/CO/CO_2$ 합성가스화염에서 선호확산 효과에 관한 연구 (A Study on Preferential Diffusion Effects in $H_2/CO/CO_2$ Syn-gas Flames)

  • 김태권;박정;하지수
    • Journal of Advanced Marine Engineering and Technology
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    • 제32권5호
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    • pp.737-746
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    • 2008
  • Numerical study is conducted to grasp preferential diffusion effects on flame characteristics in $H_2/CO$ syn-gas diffusion flames diluted with $CO_2$. The models of Sun et al. and David et al., which have been well known to be best-fitted for $H_2/CO$ synthetic mixture flames. are evaluated for $H_2/CO$ synthetic mixture flames diluted with $CO_2$. Comparison of flame structures with mixture-averaged species diffusion and suppression of the diffusivities of $H_2$ and H was made. The behaviors of maximum flame temperatures with those species diffusion models are not explained by scalar dissipation rate but by the nature of chemical kinetics. Importantly-contributing reaction steps to heat release rate are also compared for the three species diffusion models in $H_2/CO/CO_2$ flames with and without $CO_2$ dilution.

박막 $p^+-n$ 접합 형성을 위한 보론 확산 시뮬레이터의 제작에 관한 연구 (A study on the design of boron diffusion simulator applicable for shallow $p^+-n$ junction formation)

  • 김재영;김보라;홍신남
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2004년도 춘계학술대회 논문집 반도체 재료 센서 박막재료 전자세라믹스
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    • pp.30-33
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    • 2004
  • Shallow p+-n junctions were formed by low-energy ion implantation and dual-step annealing processes The dopant implantation was performed into the crystalline substrates using $BF_2$ ions. The annealing was performed with a rapid thermal processor and a furnace. FA+RTA annealing sequence exhibited better junction characteristics than RTA+FA thermal cycle from the viewpoint of junction depth. A new simulator is designed to model boron diffusion in silicon, which is especially useful for analyzing the annealing process subsequent to ion implantation. The model which is used in this simulator takes into account nonequilibrium diffusion, reactions of point defects, and defect-dopant pairs considering their charge states, and the dopant inactivation by introducing a boron clustering reaction. Using a resonable parameter values, the simulator covers not only the equilibrium diffusion conditions but also the nonequilibrium post-implantation diffusion. Using initial conditions and boundary conditions, coupled diffusion equation is solved successfully. The simulator reproduced experimental data successfully.

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$p^+-n$ 박막접합 형성방법과 열처리 모의 실험을 위한 시뮬레이터 개발에 관한 연구 (A Study on the Shallow $p^+-n$ Junction Formation and the Design of Diffusion Simulator for Predicting the Annealing Results)

  • 김보라;김재영;이정민;홍신남
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2005년도 하계학술대회 논문집 Vol.6
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    • pp.115-117
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    • 2005
  • In this paper, we formed the shallow junction by preamorphization and low energy ion implantation. And a simulator is designed for predicting the annealing process results. Especially, if considered the applicable to single step annealing process(RTA, FA) and dual step annealing process(RTA+FA, FA+RTA). In this simulation, the ion implantation model and the boron diffusion model are used. The Monte Carlo model is used for the ion implantation. Boron diffusion model is based on pair diffusion at nonequilibrium condition. And we considered that the BI-pairs lead the diffusion and the boron activation and clustering reaction. Using the boundary condition and initial condition, the diffusion equation is solved successfully. The simulator is made ofC language and reappear the experimental data successfully.

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CONVERGENCE PROPERTIES OF PREDATOR-PREY SYSTEMS WITH FUNCTIONAL RESPONSE

  • Shim, Seong-A
    • 호남수학학술지
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    • 제30권3호
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    • pp.411-423
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    • 2008
  • In the field of population dynamics and chemical reaction the possibility or the existence of spatially and temporally nonhomogeneous solutions is a very important problem. For last 50 years or so there have been many results on the pattern formation of chemical reaction systems studying reaction systems with or without diffusions to explain instabilities and nonhomogeneous states arising in biological situations. In this paper we study time-dependent properties of a predator-prey system with functional response and give sufficient conditions that guarantee the existence of stable limit cycles.

Plasma Assisted ALD 장비 계발과 PAALD법으로 증착 된 TaN 박막의 전기적 특성 (Development of Plasma Assisted ALD equipment and Electrical Characteristic of TaN thin film deposited PAALD method)

  • 도관우;김경민;양충모;박성근;나경일;이정희;이종현
    • 반도체디스플레이기술학회지
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    • 제4권2호
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    • pp.39-43
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    • 2005
  • In the study, in order to deposit TaN thin film for diffusion barrier and bottom electrode we made the Plasma Assisted ALD equipment and confirmed the electrical characteristics of TaN thin films grown PAALD method. Plasma Assisted ALD equipment depositing TaN thin film using PEMAT(pentakis(ethylmethlyamino) tantalum) precursor and NH3 reaction gas is shown that TaN thin film deposited high density and amorphous phase with XRD measurement. The degree of diffusion and reaction taking place in Cu/TaN (deposited using 150W PAALD)/$SiO_{2}$/Si systems with increasing annealing temperature was estimated for MOS capacitor property and the $SiO_{2}$, (600${\AA}$)/Si system surface analysis by C-V measurement and secondary ion material spectrometer (SIMS) after Cu/TaN/$SiO_{2}$ (400 ${\AA}$) layer etching. TaN thin film deposited PAALD method diffusion barrier have a good diffusion barrier property up to 500$^{\circ}C$.

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