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Abstract : The Power and Limitations of Synchrotron X-rays in Agro-Environmental Research
( Dean L Hesterberg ) 한국환경농학회 2012 한국환경농학회 워크샵자료 Vol.2012 No.2
High-intensity synchrotron x-rays provide some of the most advanced analytical tools for studying soils. Nevertheless, the extreme complexity of soils across all spatial scales - from landscapes to molecules - challenges our ability to use these advanced measurements in management decisions that optimize crop nutrition while protecting the environment. This presentation will introduce the technique of synchrotron x-ray absorption spectroscopy, and discuss its advantages for analyzing chemical species of trace elements (and nutrients) in soils, and its limitations for such complex systems. Synchrotron x-ray absorption spectroscopy provides chemical-speciation information about average oxidation states and average local molecular coordination environments of individual soil elements, even at part-per-million concentrations. However, in such complex matrices, the specificity of the technique is lost because of the large number of possible (and measured) chemical species present. Technological advances have provided spatially resolving x-ray microprobes that can be applied at smaller and smaller (submicron) spatial scales, which is advantageous for identifying a subset of chemical species within heterogeneous subunits of soils (microsites). A new concept of soil chemistry - the reactive microsite model - proposes that chemical speciation and chemical microenvironments must be understood to predict reactivity. Future developments of chemical-specific analytical tools with high spatial resolution provide opportunities for experimentally assessing real-time transformations of environmental contaminants within soil matrices.
Dean Price,Andrew Maile,Joshua Peterson-Droogh,Derreck Blight 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.3
Large-scale reactor simulation often requires the use of Monte Carlo calculation techniques to estimateimportant reactor parameters. One drawback of these Monte Carlo calculation techniques is they inevitablyresult in some uncertainty in calculated quantities. The present study includes parametric uncertaintyquantification (UQ) and sensitivity analysis (SA) on the Advanced Test Reactor Critical (ATRC)facility housed at Idaho National Laboratory (INL) and addresses some complications due to Monte Carlouncertainty when performing these analyses. This approach for UQ/SA includes consideration of MonteCarlo code uncertainty in computed sensitivities, consideration of uncertainty from directly measuredparameters and a comparison of results obtained from brute-force Monte Carlo UQ versus UQ obtainedfrom a surrogate model. These methodologies are applied to the uncertainty and sensitivity of keff for twosets of uncertain parameters involving fuel plate geometry and fuel plate composition. Results indicate that the less computationally-expensive method for uncertainty quantification involvinga linear surrogate model provides accurate estimations for keff uncertainty and the Monte Carlo uncertaintyin calculated keff values can have a large effect on computed linear model parameters for parameterswith low influence on keff.
University Students` Perceptions and Experience in a Physical Activity English Teaching Module
Dean Myers(딘 마이어스),Im, Hyun-Ju(임현주) 한국체육과학회 2015 한국체육과학회지 Vol.24 No.3
현대사회에서의 교육의 중심은 창조적 시대에 부합하는 글로벌인재를 양성하는 것을 목표로 하고 있으며 스포츠나 신체활동을 영어로 가르칠 수 있는 능력이 요구된다. 따라서 본 연구의 목적은 신체활동 교수를 위한 영어 티칭 모듈을 활용하여 대학생들의 경험과 인식을 해석적으로 탐색하는데 있다. 본 연구는 사례연구이며 현상학적 연구로 설계되었다. 본 연구의 참여자는 비확률표집 중 하나인 유목적 표집을 이용하여 연구자와 라포가 형성되어 있는 학생 중 11명을 선정하였다. 심층면담, 참여관찰과 관련문서 수집을 통해 자료를 수집하였고 수집된 자료는 귀납적 범주분석과 사례기록 분석을 통해 분석하였다. 연구의 진실성을 높이기 위하여 다각도 검증법, 구성원 검토, 전문가 협의과정을 거쳤으며, 연구의 윤리성과 중립성을 고려하였다. 연구결과 연구 참여자의 경험과 인식은 1)효과적인 학습경험, 2)원어민 교수자와 학생관계 3)영어에 대한 중압감으로 범주화되었다.
Performing linear regression with responses calculated using Monte Carlo transport codes
Dean Price,Brendan Kochunas 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.5
In many of the complex systems modeled in the field of nuclear engineering, it is often useful to uselinear regression-based analyses to analyze relationships between model parameters and responses ofinterests. In cases where the response of interest is calculated by a simulation which uses Monte Carlomethods, there will be some uncertainty in the responses. Further, the reduction of this uncertaintyincreases the time necessary to run each calculation. This paper presents some discussion on how theMonte Carlo error in the response of interest influences the error in computed linear regression coefficients. A mathematical justification is given that shows that when performing linear regression inthese scenarios, the error in regression coefficients can be largely independent of the Monte Carlo errorin each individual calculation. This condition is only true if the total number of calculations are scaled tohave a constant total time, or amount of work, for all calculations. An application with a simple pin cellmodel is used to demonstrate these observations in a practical problem.