• Coupled systems mechanics
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• 제11권1호
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• pp.79-91
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• 2022

Models for water treatment processes include simulation, i.e., modelling of water quality, flow hydraulics, process controls and design. Water treatment processes are inherently dynamic because of the large variations in the influent water flow rate, concentration and composition. Moreover, these variations are to a large extent not possible to control. Mathematical models and computer simulations are essential to describe, predict and control the complicated interactions of the water treatment processes. An accurate description of such systems can therefore result in highly complex models, which may not be very useful from a practical, operational point of view. The main objective is to combine knowledge of the process dynamics with mathematical methods for processes estimation and identification. Good modelling practice is way to obtain this objective and to improve water treatment processes(its understanding, design, control and performance- efficiency). By synthesize of existing knowledge and experience on good modelling practices and principles the aim is to help address the critical strategic gaps and weaknessesin water treatment models application.

• Human Ecology Research
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• 제55권2호
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• pp.193-204
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• 2017

This study examines the effect of 5-year-old children's mathematical problem solving ability and their self-esteem based on the Havruta method using math storybooks. The subjects of this study were 40 5-year-old students attending a kindergarten in the Incheon area: 20 students comprised the treatment group and 20 students comprised the control group. An instrument originally created by Ward (1993) but adapted by Hwang (1997) and later modified by Ryu (2003) was used to test the children's mathematical problem solving abilities. A modified version (Kim, 1997) of an instrument developed by Harter and Pike (1984) was used to measure children's self-esteem. Test results were analyzed using SPSS ver. 18.0 for Windows. The findings are as follows. First, the treatment group that had Havruta classes utilizing math story books was found to improve significantly more than the control group in their mathematical problem solving ability. Havruta classes had positive effects on children's mathematical problem solving abilities. Second, there was no significant difference found between the two groups in terms of self-esteem when the children's self-esteem was compared after Havruta classes that utilize math storybooks. It may not be possible to see immediate changes in children's self-esteem because positive parent and teacher feedback had the strongest influence on 5-year-old children's self-esteem, as opposed to self-learning. The results of this study provide meaningful basic data for Havruta classes that focus on questions and discussions through math story books to increase children's mathematical problem solving abilities in the child education field.

• 한국수학교육학회지시리즈E:수학교육논문집
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• 제23권2호
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• pp.327-347
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• 2009

이 연구는 동료 피드백을 활용한 수학적 의사소통 수업이 학생들의 수학 학업 성취도 및 수학적 성향에 미치는 효과를 알아보고 또한 이 과정에서 나타난 피드백의 특성에 대해 분석하였다. 이를 위해서 서울특별시 소재의 초등학교 6학년 학생을 대상으로 동료 피드백 중심의 실험반과 전통적인 교사 주도의 피드백을 적용한 비교반을 대상으로 실험을 실시하였다. 그 결과 동료 피드백을 활용한 수학적 의사소통 수업을 적용한 반이 전통적인 교사 피드백 중심의 반에 비해 수학 학업 성취도 및 수학적 성향 측면에서 모두 높게 나타났다. 특히 상위 집단보다는 중 하위 집단에게 동료 피드백 중심의 의사소통 수업이 더욱 효과적인 것으로 드러났다. 그리고 동료 피드백 중심의 의사소통 수업을 통해 학생들은 문제해결에 대한 자신의 사고 과정을 점검해 볼 수 있었으며, 또한 피드백 제공 경험으로부터 수학에 대한 자신감이 향상됨을 알 수 있었다. 끝으로 이 연구는 수학 학습에서 수학적 의사소통의 중요성을 강조하고, 또한 교사 주도의 의사소통 보다는 다양한 학생들이 자신의 수학적 사고 과정을 수학적 언어를 사용하여 표현해 볼 수 있도록 하는 기회를 제공할 필요가 있음을 제언한다.

• 대한수학회지
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• 제33권3호
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• pp.587-599
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• 1996

We assume throughout the paper that f(z) is a conformal function in the ipen unit disk $D = {z : $\mid$z$\mid$ < 1}$. In the rest of paper, conformal means analytic and locally univalent.

• 대한수학회보
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• 제25권2호
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• pp.247-251
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• 1988

This note gives a combinatorial treatment to the problem finding a generating set among conjugating automorphisms of a free group and to the method deciding when a conjugating endomorphism of a free group is an automorphism. Our group of pseudo-conjugating automorphisms can be thought of as a generalization of the artin's braid group.

• Biotechnology and Bioprocess Engineering:BBE
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• 제5권1호
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• pp.65-70
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• 2000

An approximated analytical solution of mathematical model for the three phase fluidized bed bioreactor (TFBBR) was proposed using the linearization technique to describe oxygen utilization rate in wastewater treatment. The validation of the model was done in comparison with the experimental results. Satisfactory agreement was obtained in the comparison of approximated analytical solution and numerical solution in the oxygen concentration profile of a TFBBR. The approximated solutions for three modes of the liquid phase flow were compared. The proposed model was able to predict the biomass concentration, dissolved oxygen concentration the height of efficient column, and the removal efficiency.

• 한국수학교육학회지시리즈D:수학교육연구
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• 제14권3호
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• pp.249-262
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• 2010

Large Midwest university faculty members proposed the Science and Technology Enhancement Program Project (STEP) to improve students' learning in the secondary mathematics classroom using modules of inquiry-based teaching. The purpose of this study was to determine the impact of the STEP Project on students' attitude toward mathematics. Hierarchical linear models (HLM) were used to evaluate the impact of the STEP Project. The sample group for the study was 130 ninth grade students enrolled in Integrated Algebra I in a large urban school district. The school was one of eight secondary schools that participated in the STEP Project. The classes in the treatment group were three of five classes ordered in terms of the highest, middle, and lowest mean GPA. The control group consisted of two other middle GPA classes. The classes had an average of 25 students. Teachers who previously had been involved in the STEP Project taught all treatment and control classes. The inquiry-based teaching activities provided by the project were confined to the treatment classes. The survey measuring students' attitudes toward mathematics were obtained for both groups of students. The inquiry-based teaching affected students' attitudes toward mathematics (p < 0.07, ES = 3.07). Especially, students who had preexisting low attitudes toward mathematics were significantly affected by treatment (p < 0.02, ES = 0.02), while the treatment positively affected African American students overall at p < 0.08 (ES = 0.58).

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 12th Asian Congress of Fluid Mechanics
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• pp.39.4-39.4
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• 2008

• 한국수학교육학회지시리즈C:초등수학교육
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• 제18권2호
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• pp.123-139
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• 2015

본 연구의 목적은 수학 수업에서 생산적 실패를 한 경험이 초등학생들의 수학적 문제해결력과 수학적 성향에 미치는 영향을 알아보는 것이다. 이를 위해 선행 연구를 바탕으로 생산적 실패를 경험할 수 있도록 수업 과정을 고안하였다. 연구대상으로 서울 은평구 Y초등학교 4학년 2개 학급을 선정하여 실험반은 생산적 실패를 활용한 수업을 진행하였으며, 비교반은 전통적인 강의식 수업을 진행하였다. 사전 사후 검사로 수학 개념이해 검사, 다양한 수학적 문제해결력 검사, 수학적 성향 검사를 실시하여 각각 t-검정하였으며, 학생들의 토의과정 및 활동지, 면담 등을 활용하여 수학적 문제해결력과 성향을 질적으로 분석하였다. 그 결과 생산적 실패를 경험한 학생들의 문제해결력과 수학적 성향에 유의미하게 개선되는 효과를 보였다. 이는 학생들이 실패를 통해 수학 개념을 스스로 구성하면서 보다 명확한 이해를 하는 과정에서 긍정적인 효과를 가져 온 것으로 보인다. 심층적인 추후 연구로 수학교과서 개발 및 수업 방법 개선에서 이를 활용해야 함을 제안하였다.

• 한국기계가공학회지
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• 제12권4호
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• pp.22-28
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• 2013

It is important to begin left ventricular assist device (LVAD) treatment at appropriate time for heart failure patients who expect cardiac recovery after the therapy. In order to predict the optimal timing of LVAD implantation, we predicted pumping efficacy of LVAD according to the severity of heart failure theoretically. We used LVAD-implanted cardiovascular system model which consist of 8 Windkessel compartments for the simulation study. The time-varying compliance theory was used to simulate ventricular pumping function in the model. The ventricular systolic dysfunction was implemented by increasing the end-systolic ventricular compliance. Using the mathematical model, we predicted cardiac responses such as left ventricular peak pressure, cardiac output, ejection fraction, and stroke work according to the severity of ventricular systolic dysfunction under the treatments of continuous and pulsatile LVAD. Left ventricular peak pressure, which indicates the ventricular loading condition, decreased maximally at the 1st level heart-failure under pulsatile LVAD therapy and 2nd level heart-failure under continuous LVAD therapy. We conclude that optimal timing for pulsatile LVAD treatment is 1st level heart-failure and for continuous LVAD treatment is 2nd level heart-failure when considering LVAD treatment as "bridge to recovery".