• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.4 no.1
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• pp.23-32
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• 1997

The change in moisture content of moisture sensitive products in moisture-semipermeable packages was investigated for the purpose of predicting the shelf life of a product-package combination. A mathematical model, and a computer program based on the physiochemical properties of the product and the moisture permeability of the package was developed. The moisture content for products in moisture-semipermeable packages was determined under various environmental conditions and the results were compared with the predicted values by means of the simulation model. These experimental studies demonstrated that the prediction of the change in moisture content of packaged products over time by the simulation model is accurate, within a practical range of temperature and relative humidity values. The developed semi-empirical model is considered to have applications in industry, since it provides product shelf life information for a range of temperature and relative humidity conditions, with a limited number of experimentally obtained data points.

• Journal of the Korean Wood Science and Technology
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• v.43 no.3
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• pp.311-319
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• 2015

Near infrared (NIR) reflectance spectroscopy was employed to develop moisture content prediction model of pitch pine (Pinus rigida), red pine (Pinus densiflora), Korean pine (Pinus koraiensis), yellow poplar (Liriodendron tulipifera) wood below fiber saturation point. NIR reflectance spectra of specimens ranging from 1000 nm to 2400 nm were acquired after humidifying specimens to reach several equilibrium moisture contents. To determine the optimal moisture contents prediction model, 5 mathematical preprocessing methods (moving average (smoothing point: 3), baseline, standard normal variate (SNV), mean normalization, Savitzky-Golay $2^{nd}$ derivatives (polynomial order: 3, smoothing point: 11)) were applied to reflectance spectra of each specimen as 8 combinations. After finishing mathematical preprocessings, partial least squares (PLS) regression analysis was performed to each modified spectra. Consequently, the mathematical preprocessing methods deriving optimal moisture content prediction were 1) moving average/SNV for pitch pine and red pine, 2) moving average/SNV/Savitzky-golay $2^{nd}$ derivatives for Korean pine and yellow poplar. Every model contained three principal components.

• Korean journal of food and cookery science
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• v.26 no.5
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• pp.617-626
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• 2010

The purpose of this study was to determine the optimal mixing conditions of three different amounts of seatangle powder, sugar, and butter in germinated brown rice cookie prepared with seatangle powder. The experiment was designed according to the Central Composite Design of response surface, which showed 16 experimental points including 2 replicates for seatangle powder, sugar and butter. The mechanical and sensory properties of each test were measured, and these values were applied to the mathematical models. A canonical form and perturbation plot showed the influence of each ingredient on the final product mixture. The L value, a value and b value decreased with increasing seatangle powder content and increased with sugar content. The a value and b value increased with increasing butter content, whereas the L value decreased with increasing butter content. Hardness decreased with increasing butter content. The results of sensory evaluation showed very significant values for texture (p<0.001), taste (p<0.01), and overall quality (p<0.05). As a result, the optimum formulation by numerical and graphical methods was calculated to be seatangle powder 4.25 g, sugar 49.86 g, and butter 58.23 g.

• Journal of Educational Research in Mathematics
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• v.17 no.3
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• pp.295-308
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• 2007

The purpose of this paper was to investigate the pedagogical content knowledge of a middle school mathematics teacher manifested in his mathematics instruction by identifying the components of the pedagogical content knowledge of the teacher. For the purpose of the study, I conducted an interpretive case study by collecting qualitative data. The results showed that the pedagogical content knowledge of the teacher was characterized by: (a) knowledge of mathematics including connection among topics and various ways of solving problems; (b) knowledge of students' understanding involving students' misconceptions, common errors, difficulties, and confusions; and (c) knowledge of pedagogy consisting of his efforts to motivate his students by providing realistic applications of mathematical topics and his use of materials.

• Journal of Plant Biotechnology
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• v.2 no.3
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• pp.157-163
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• 2000

Optimization of chemicals in the large scale sea water medium and inoculum for biomass and natural colourants production in the marine cyanobacteria, Phomidium tenue BDU 46241 (phycoerythrin producer) and P.valderianum BDU 30501 (phycocyanin producer) was carried out by experiments in L8 orthogonal array. Mathematical analysis revealed the significance of these factors. The factor(s) that critically control the yield varied with the organism and the end-product further, the desirable level of these factors between the normal and a higher level tested was identified and improved media were evolved. In both cyanobacteria, higher level of $K_2$$HPO_4$, $NaNO_3$ and inoculum with normal level of ferric ammonium citrate was found to be desirable for biomass production and additionally, higher level of $MgSO_4$ for pigment production. The level of other factors varied with the organism and the end-product. Confirmation experiments showed that the clues obtained based on mathematical experimentation are valid. In P.tenue, the medium optimized for biomass production increased the yield of biomass by 495% and the medium optimized for phycoerythrin production increased the yield of biomass by 408% with 30% increase in phycoerythrin content of the biomass. Similarly in P.valderianum, the medium optimized for biomass production increased the yield of biomass by 224% and the medium optimized for phycocyanin production increased the yield of biomass by 143% with 44% increase in phycocyanin content of the biomass.

• Communications of Mathematical Education
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• v.30 no.2
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• pp.139-159
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• 2016

This study is the field of mathematics education on the assumption that they can extend outside the classroom. Recent mathematics education is increasing the importance of field experience and various activities based on real-life math education. Thus, it is necessary to consider this situation in pre-service teacher's education. The purpose of this study is to apply the 'Mathematics Field Trips Activities' in the pre-mathematics teacher education. So the specific case of 'Mathematics Field Trips Activities' was analyzed. Mathematics teachers conducted preliminary exploration activities on the historical cultural property which were effective in the following four aspects. First, cognitive effects and second, definitive effect. Third, cultural-mathematical effect. Fourth, the effect on improving math class. Finally they were summarized and divided into classes target content knowledge and teaching knowledge both sides. As a result, the 'Mathematics Field Trips Activities' were found to have significant effects on pre-service math teacher. Finally, ongoing research is needed to settle into a new teaching and learning methods.

• Journal of the Korean School Mathematics Society
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• v.21 no.2
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• pp.113-139
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• 2018

There is no doubt about the importance of teacher knowledge for good teaching. Many researches attempted to conceptualize elements and features of teacher knowledge for teaching in a quantitative way. Unlike existing researches, this article suggests an interpretation of preservice teacher knowledge in the field of geometry using the Shulman - Fischbein framework in a qualitative way. Seven female preservice teachers voluntarily participated in this research and they performed a series of written tasks that asked their subject matter knowledge (SMK) and pedagogical content knowledge (PCK). Their responses were analyzed according to mathematical algorithmic -, formal -, and intuitive - SMK and PCK. The interpretation revealed that preservice teachers had overally strong SMK, their deeply rooted SMK did not change, their SMK affected their PCK, they had appropriate PCK with regard to knowledge of student, and they tended to less focus on mathematical intuitive - PCK when they considered instructional strategies. The understanding of preservice teachers' knowledge throughout the analysis using Shulman-Fischbein framework will be able to help design teacher preparation programs.

• Communications of Mathematical Education
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• v.26 no.3
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• pp.317-338
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• 2012

This paper compared and contrasted the views of effective mathematics instruction by 223 elementary school teachers and 151 middle school mathematics teachers using a questionnaire with 4 main domains (i.e., curriculum and content, teaching and learning, classroom environment and atmosphere, and assessment) and a total of 48 sub-elements. The analysis of results showed that elementary school teachers put their priority on the curriculum and content domain, while middle school counterparts did on the teaching and learning domain. The teachers commonly agreed with instruction which fosters students' self-directed learning ability, reconstructs the curriculum tailored to students' diverse levels, and establishes appropriate interaction between the teacher and students. However, elementary school teachers agreed more than middle school teachers with regard to the 23 elements related to effective mathematics instruction. In contrast, middle school teachers agreed more than their counterparts as for only 2 elements (instruction fostering mathematical representation and instruction eliciting students' learning motivation). This paper includes suggestions and implications related to Korean teachers' perception of effective mathematics instruction.

• Education of Primary School Mathematics
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• v.19 no.1
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• pp.19-30
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• 2016

This study examined pre-service teachers' pedagogical content knowledge of fraction division in a context where they were asked to write a story problem for a symbolic expression illustrating a whole number divided by a proper fraction. Problem-posing is an important instructional strategy with the potential to create meaningful contexts for learning mathematical concepts, especially when real-world applications are intended. In this study, story problems written by 135 elementary pre-service teachers were analyzed with respect to mathematical correctness. error types, and division models. Patterns and tendencies in elementary pre-service teachers' knowledge of fraction division were identified. Implicaitons for teaching and teacher education are discussed.

• Communications of Mathematical Education
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• v.33 no.2
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• pp.123-139
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• 2019

This study analyzed how problem-posing tasks included in Korean middle school mathematics textbooks were distributed in terms of content area, task type, and context of task to investigate that the mathematics textbooks are giving students ample opportunities for problem-posing activities. The analysis of 10 mathematics textbooks for first grade in middle school according to the revised mathematics curriculum in 2015 found that the problem-posing tasks contained in the textbooks are insufficient in quantity and not evenly distributed in terms of content areas. There were also more problem-posing tasks with relatively moderate constraints than those with strong or weak constraints in terms of mathematical constraints. In addition, there were more problem-posing tasks that were not requiring students to make a new context, and more often camouflage contexts were used. Based on this, implications for improving mathematics problem-posing tasks in mathematics textbook were suggested.