• Communications of Mathematical Education
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• v.38 no.2
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• pp.121-144
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• 2024

This study analyzes how the academic achievement of students in Korea changes as they transition from 4th grade of elementary school to 2nd grade of middle school, considering that the 4th graders in the previous TIMSS cycle become 2nd graders in the next cycle. In particular, this study selects and compares the eight main countries in the TIMSS math evaluation (Korea, Singapore, Taiwan, Japan, USA, UK, Australia, and Russia) to analyze the trend of change in academic achievement of Korean students according to school grade transition. The trend of change in academic achievement of students was analyzed not only overall but also by content area (number, geometry and measurement, data representation (data and probability/data and probability), gender, and regional scale. The analysis focused on the average score and the proportion of students by achievement level. The results of the study are as follows. First, there was no significant change in the average score of Korean students' academic achievement as the school grade transitioned, but the achievement gap widened in terms of the proportion by achievement level. Second, there were differences in students' academic achievement by content area according to school grade transition, and the pattern differed depending on the evaluation cycle. Third, there was a significant gap in students' math academic achievement depending on gender and regional scale of school location. This study reveals that the achievement gap among students in our country widens as they transition between school levels. The gap is found to vary in terms of achievement level, math content area, student gender, and school location. To alleviate these disparities, more substantial research and support are proposed in addition to policy implementation by the government or provincial offices of education.

• Korean Journal of Food Science and Technology
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• v.24 no.5
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• pp.408-413
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• 1992

This study was conducted to determine the effect of the homogenizing grade of sample on absorbance of near infrared reflectance spectrophotometer with which chemical compositions of food were rapidly and effectively analyzed. By the mathematical treatment of absorbance values standard error of prediction was reduced as follows. 1. The absorbance values of various samples ground for the same periods of time were calibrated before or after treatment with first or second derivative in an attempt to accurately predict the components of samples ground for the different periods of time. The standard error of prediction for moisture content were 1.478%, 0.658% and 0.580%, respectively, those for fat content 0.949%, 0.637% and 0.527%, respectively, and those for protein content 0.514%, 0.493% and 0.394%, respectively. Calibration of absorbance values after second derivative treatment showed the highest accuracy in predicting sample components. 2. The absorbance values of various samples ground for the different periods of time were calibrated before or after treatment with first or second derivative in order to accurately predict the components of samples ground for the different periods of time. The standard error of prediction for moisture content were 1.026%, 0.589% and 0.568%, respectively, and those for protein content 0.860%, 0.557% and 0.399%, respectively. The standard error of prediction were lower in the order of calibrations before and after first and second derivative treatments. As a result, calibration of absorbance values after second derivative treatment showed higher accuracy regardless of grinding time of samples.

• Journal of Elementary Mathematics Education in Korea
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• v.21 no.1
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• pp.215-241
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• 2017

This study analyzed teachers' Pedagogical Content Knowledge (PCK) regarding the pedagogical aspect of the instruction of ratio and rate in order to look into teachers' problems during the process of teaching ratio and rate. This study aims to clarify problems in teachers' PCK and promote the consideration of the materialization of an effective and practical class in teaching ratio and rate by identifying the improvements based on problems indicated in PCK. We subdivided teachers' PCK into four areas: mathematical content knowledge, teaching method and evaluation knowledge, understanding knowledge about students' learning, and class situation knowledge. The conclusion of this study based on analysis of the results is as follows. First, in the 'mathematical content knowledge' aspect of PCK, teachers need to understand the concept of ratio from the perspective of multiplicative comparison of two quantities, and the concept of rate based on understanding of two quantities that are related proportionally. Also, teachers need to introduce ratio and rate by providing students with real-life context, differentiate ratios from fractions, and teach the usefulness of percentage in real life. Second, in the 'teaching method and evaluation knowledge' aspect of PCK, teachers need to establish teaching goals about the students' comprehension of the concept of ratio and rate and need to operate performance evaluation of the students' understanding of ratio and rate. Also, teachers need to improve their teaching methods such as discovery learning, research study and activity oriented methods. Third, in the 'understanding knowledge about students' learning' aspect of PCK, teachers need to diversify their teaching methods for correcting errors by suggesting activities to explore students' own errors rather than using explanation oriented correction. Also, teachers need to reflect students' affective aspects in mathematics class. Fourth, in the 'class situation knowledge' aspect of PCK, teachers need to supplement textbook activities with independent consciousness and need to diversify the form of class groups according to the character of the activities.

• Journal of Astronomy and Space Sciences
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• v.27 no.4
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• pp.359-366
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• 2010

In this study, we developed a global ionosphere model based on measurements from a worldwide network of global positioning system (GPS). The total number of the international GPS reference stations for development of ionospheric model is about 100 and the spherical harmonic expansion approach as a mathematical method was used. In order to produce the ionospheric total electron content (TEC) based on grid form, we defined spatial resolution of 2.0 degree and 5.0 degree in latitude and longitude, respectively. Two-dimensional TEC maps were constructed within the interval of one hour, and have a high temporal resolution compared to global ionosphere maps which are produced by several analysis centers. As a result, we could detect the sudden increase of TEC by processing GPS observables on 29 October, 2003 when the massive solar flare took place.

• Journal of the Korean Society of Tobacco Science
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• v.15 no.1
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• pp.90-97
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• 1993

1. Average moisture content of tobacco in BIB silo was about 19: 1% until 4hours conditioned time, and then moisture variation of tobacco after 2hr conditioned was very small. 2. Application of mathematical model for ordering system. 1) The constant K in the exponential equation varies inversely with both relative humidity and equilibrium moisture. 2) Time needed to order blending tobacco leaves with standard moisture from bulking and blending silo was 4 hours. 3) Reconstituted tobacco sheet had higher moisture absorption ratio than Oriental and Burley tobacco. 4) For minimize of conditioning time in BIB silo, the values of K and Mo given in this study can be used in equation(1) to calculate moisture absorption ratio and optimum conditioning time. 3. Average moisture content and water activity of conditioned tobacco for 4 hours in BIB silo was about 20% and 0.65. In this condition. microbial life will inhibite 4. Physical properties of conditioned tobacco in bulking and blending silo for 4hours was virtually no change.

• Geomechanics and Engineering
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• v.9 no.2
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• pp.261-273
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• 2015

In the present investigation, a series of laboratory compaction and unconfined compressive strength laboratory tests has been performed. To determine the effect of compaction energy, type of sand, and fly ash content, compaction tests have been performed with varying compaction energy ($2700kJ/m^3-300kJ/m^3$), types of sand, and fly ash content (0% to 40%) respectively. From the experimental results, it has been found that the optimum value of unconfined compressive strength obtained for a sand-fly ash mixture comprised of 65% sand and 35% fly ash. Based on the data obtained in the present investigation, a linear mathematical model has been developed to predict the OMC of sand-fly ash mixture.

• Journal of the Korea Convergence Society
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• v.5 no.3
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• pp.45-51
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• 2014

Computer science and computing technologies are applied into mathematical, science, medical, engineering and educational applications. The models are used to solve the issues in all the domains. Educational systems are used top down, bottom up, Gap Analysis model in the educational learning system. Educational learning process integrated with Lerner, content and the methodology. The Learners and content are same in the educational system or similar courses but the teaching methodologies are differing one with another. The determinations of teaching methodologies are based on the factors related to that particular model or subject. The learning model influencing determinations are made by the surveys, analysis and observation of data to maximize the learning outcome. This paper attempted to evaluate the SNE learners cognitive using NASA Scaling.

• Communications of Mathematical Education
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• v.30 no.3
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• pp.353-374
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• 2016

Communication is one of 6 core competencies suggested newly in mathematics curriculum revised in 2015 in Korea. Also, it's importance has been emphasized through NCTM and CCSSI. By the subject of Mathematics in Context(MiC) textbook, this study planned to explore the communication elements according to the types of communication such as discourse, representation, operation. Namely, this study dealt with 316 questions in a total of 34 tasks relevant to function content in the MiC textbook, and this study explored the communication elements on the questions of each task. To accomplish this, this study first of all was to reconstruct and establish an analytic framework, on the basis of 'D.R.O.C type' of communication developed by Kim & Pang in 2010. In addition, based on the achievement standards of function domain in mathematics curriculum revised in 2015 in Korea, this study basically compared with the function content included in MiC textbook and Korean mathematics curriculum document. Also, it tried to explore the distribution of communication elements according to the types of communication.

• Journal of the Korean School Mathematics Society
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• v.20 no.3
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• pp.211-237
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• 2017

Depending on the type of textbook, the word and mathematical notation expression used in high school mathematics textbooks varied and there were also some differences on the mathematical definition and the content description methods. Not only the composition of textbooks but also various expressing ways of textbooks have significant impacts on teaching and learning of teacher and student. The diversity of expression had pros and cons like both sides of a coin. There is a positive aspect that we can pursue pedagogical diversity. Simultaneously there is a negative aspect that the possibility of acting as a learning burden exists in the viewpoint of the student and the equality of evaluation may be undermined. In this study, Preferentially we focused on analyzing the actual situation rather than judging what is more appropriate about the diversity of words and notation expressions used in mathematics textbooks which is based on the current curriculum. For this purpose, we analyzed 56 kinds of mathematics textbooks based on the 2009 revised mathematics curriculum, and presented four aspects(terms expressing, notations expression, mathematical definition, content description method) with examples about differences of the various expressions used in textbooks including 'terms and notations'.

• Communications of Mathematical Education
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• v.26 no.1
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• pp.71-84
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• 2012

The purpose of this study is to analyze some Korean elementary pre-service teachers' Mathematical Knowledge for Teaching(MKT) and compare the results with those obtained by Kwon, Nam, & Kim(2009), so that we can provide some suggestions to improve education of elementary mathematics subject at Korean teachers colleges. For this purpose, we selected the MKT items on number and operations which were adapted for Korean in-service teachers by Kwon et al. The survey consisting of those items was administered to 88 Korean elementary pre-service teachers at teachers college, J University. The results are the following: First, the respondents, elementary pre-service teachers, showed that they already had a sufficient amount of Content Knowledge(CK) on number and operations, but that their level of Knowledge of Content and Students(KCS) was insufficient. This means we need to strengthen our students' KCS in education of elementary mathematics subject at our teachers colleges. Second, there was a strong correlation, in both CK and KCS, of item difficulty felt by the respondents with that by the Kwon et al's in-service teachers. Third, although the respondents valued the MKT items more than the above-mentioned elementary in-service teachers, about 70% of them said the items were never learned at their college. Furthermore, they had different opinions on some of the items from their counterparts'. The suggestions we get here are we need to first consider the results in improving education of elementary mathematics subject at our teachers colleges and second develop MKT items suitable for the situation of Korean schools and curriculums in order to obtain exact estimations of Korean elementary pre-service teachers' MKT.