• Coupled systems mechanics
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• v.11 no.1
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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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• v.55 no.2
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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.

• Communications of Mathematical Education
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• v.23 no.2
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• pp.327-347
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• 2009

The purpose of the present study is to investigate the effects of mathematical communication-centered teaching using peer feedbacks on students' mathematics achievement and mathematical dispositions toward mathematics, and then this study examined the characteristics of feedbacks used by students. To do this study, two sixth grade classes selected from an elementary school in Seoul participated in the current study; one class for a treatment group applying mathematical communication-centered teaching using peer feedback, and the other for a comparison group applying traditional teaching using teacher-centered communication. The results of this study showed the fact that a treatment group of mathematical communication-centered teaching applying peer feedback scored statistically higher than a comparison group applying teacher-centered communication with respect to both students' mathematical achievement and disposition. Especially, this communication-centered teaching program focused on peer feedback was more effective to middle or lower level students than higher level students. In addition, mathematical communication-centered teaching applying peer feedbacks helps students reflect their own thinking process about problem solving, and students experienced the improvement of their confidence about mathematics from opportunities to provide peers with feedbacks. Finally, the present study suggests the important role of communication in mathematics learning, particularly student-to-student feedbacks rather than teacher-to-students feedbacks. That is to say, students need to have many opportunities to represent their own mathematical thinking processes using mathematical language.

• Journal of the Korean Mathematical Society
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• v.33 no.3
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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.

• Bulletin of the Korean Mathematical Society
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• v.25 no.2
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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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• v.5 no.1
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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.

• Research in Mathematical Education
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• v.14 no.3
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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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• 2008.08a
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• pp.39.4-39.4
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• 2008

• Education of Primary School Mathematics
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• v.18 no.2
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• pp.123-139
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• 2015

The purpose of this study was to investigate the effects of the experiences of productive failures on students' mathematical problem solving abilities and mathematical dispositions. The experiment was conducted with two groups. The treatment group was applied with the productive mathematics failure program, and the comparative group was taught with traditional mathematics lessons. In this study, for quantitative analysis, the students were tested their understanding of mathematical concepts, mathematical reasoning abilities, students' various strategies and mathematical dispositions before and after using the program. For qualitative analysis, the researchers analyzed the discussion processes of the students, students's activity worksheets, and conducted interviews with selected students. The results showed the followings. First, use of productive failures showed students' enhancement in problem solving abilities. Second, the students who experienced productive failures positively affected the changes in students' mathematical dispositions. Along with the more detailed research on productive mathematical failures, the research results should be included in the development of mathematics textbooks and teaching and learning mathematics.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.12 no.4
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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".