• Journal of Educational Research in Mathematics
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• v.13 no.3
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• pp.287-307
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• 2003

This study analyzed the concept of equal symbol(=) that is the most symbol used in learning of mathematics and investigated students' understanding of that. The equal symbol is endowed with the 'same', 'equal', and 'equivalent' meaning, represented by =, but students interpret the meaning of equal symbol according to the mathematical con text. Thus, we analyzed the equal symbol on the basis of the theory of conceptual fields. In the theory of conceptual fields, concept is a three-tuple of three sets of situation, operational invariants and symbolic representations, and the operational invariants are the concept-in-action and the theorems- in-action. With the analysis contents, we investigated how students read = by korean, what equals in the expression containing = or by what meaning students used =, and which they could correct the error for =. This study imply that we should consider the symbol notation agreed by mathematical society, the meaning, and the situational context that it used, when we teach the mathematics symbols.

• Journal of the Korean Society of Industry Convergence
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• v.17 no.4
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• pp.203-210
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• 2014

In this study, we present a method for correcting unbalanced sitting posture alignment to its optimal position, by designing a chair equipped with pressure sensor. With increasement in sedentary work, such as office work or study, people are now spending more time in chair. To accommodate sedentary life styles, many chairs are being designed for a comfortable sitting condition. However, without awareness and efforts for correct sitting posture, it may not be possible to achieve such condition. When the weight is not distributed evenly while sitting, it may cause various diseases such as scoliosis and a herniated disc. Being inspired by such facts, we have progressed basic researches to maintain the correct sitting posture. To demonstrate the proof-of-concept validation, we installed a series of sensors to a chair and then measured the changes in pressure distribution in various postures. The results show that this approach can be potentially helpful for understanding how fundamental problems due to unbalanced sitting posture can be corrected and maintained properly.

• The Mathematical Education
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• v.55 no.1
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• pp.21-39
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• 2016

This research examined the Korean and American $6^{th}$ grade students' mathematical problem solving ability and methods via an intuitive thinking. For this, the survey research was used. The researcher developed the questionnaire which consists of problems with intuitive and algorithmic problem solving in number and operation, figure and measurement areas. 57 Korean $6^{th}$ grade students and 60 American $6^{th}$ grade students participated. The result of the analysis showed that Korean students revealed a higher percentage than American students in correct answers. But it was higher in the rate of Korean students attempted to use the algorithm. Two countries' students revealed higher rates in that they tried to solve the problems using intuitive thinking in geometry and measurement areas. Students in both countries showed the lower percentages of correct answer in problem solving to identify the impact of counterintuitive thinking. They were affected by potential infinity concept and the character of intuition in the problem solving process regardless of the educational environments and cultures.

• Korean Journal of Optics and Photonics
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• v.30 no.1
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• pp.8-14
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• 2019

This paper presents methods to correct and evaluate the chromatic aberration occurring on the cut-off line of a headlamp without additional optical components and alignment process. To correct the chromatic aberration using a geometrical concept, the maximum differences in exit-ray angle between wavelengths are reduced by tilting the convex surface of an aspheric projection lens. To evaluate the chromatic aberration, the position and luminous intensity to be measured are suggested, and the criterion for chromatic aberration is presented through color coordinates. From the evaluation of an automotive headlamp designed using this geometrical method, it is found that the chromatic aberration of the cut-off line is significantly reduced.

• Atmosphere
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• v.30 no.4
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• pp.455-462
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• 2020

Among the weather conditions on the Korean Peninsula, Changma is a notable phenomenon. This is because substantial amount of the precipitation on the Korean Peninsula tends to happen during the Changma season. But there are times when this tendency falls into whims. That's the case when it doesn't rain or rains only little during the Changma season. The Korea Meteorological Administration (KMA) describes this phenomenon as 'Dry Changma' - meaning . However, 'Dry Changma' is often regarded as an instance of contradicto in adjecto. Since the general public believe that 'Changma' means . This confusion often leads to distrust in meteorologists. In this paper, we would like to propose a reasonable solution to this conundrum by employing the conceptual resources of contemporary philosophy. First of all, I will make explicit the meaning of 'Changma' that the public and meteorologists think of. And then a brief explanation of the concept of natural kinds will be presented and the argument will be made that Changma is a natural kind. Next, we will discuss a view on natural kind terms advanced by Saul Kripke, a renowned philosopher. We will argue that in Kripke's view, the general public's thought that 'Dry Changma' is contradicto in adjecto is not correct. This will eventually lead to the conclusion that the meteorologist usage of 'Changma' is the correct one, which is thereby to be adopted by the public.

• Journal of The Korean Association For Science Education
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• v.22 no.2
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• pp.378-386
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• 2002

In this study, the students' responses on the chemistry items of in the general science of College Scholastics Ability Test (CSAT) implemented for the past 3 years since 1999 were investigated. The number of items by content and inquiry process, the average percent correct by content and inquiry process, the distribution of items by the level of percent correct, and the items with high and/or low percent correct were analysed. There were the fewest items in 'environment' area, especially in 'ozon layer', no test item had been made. The most difficult content area was 'acid rain' in 'environment'. By inquiry process, the most number of items belonged to 'analyzing & interpreting data', and 'identifying problems & formulating hypothesis' was the most difficult process. No test item came under the level of 'very difficult', and many items under the 'easy' or 'very easy' level. Students were generally poor at solving test items demanding several concepts, and very good at simply requiring basic concept treated in lower grade. Educational implications are discussed.

• Journal of the Korean School Mathematics Society
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• v.21 no.4
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• pp.303-326
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• 2018

Fraction has difficulties in learning because of the diversity of meanings, the ways of presenting contents and teaching methods in elementary school mathematics. Therefore, the various strategies of teaching of fraction concept is proposed as an alternative. The problem of equal sharing problem is that children can experience the concept of fractions naturally in the context of everyday distribution. Even before learning formal fractions, children can solve them in various ways based on their own experiences. The purpose of this study is to investigate the degree of problem solving and problem solving strategies for children in 2nd, 4th, and 6th grades in elementary school. As a result of the research, the percentage of correct answers increased as the grade increased, but the grade levels showed a difference depending on the numbers given to the problems. Also, there were differences in the problem solving strategies according to the grade levels. Also, according to the numbers presented in the problem, the percentage of correct answers was high in items that were easy to divide, and the percentage of correct answers was low in items that were difficult to divide. When children solved the problems, they were affected by the strategies they could use immediately according to the number presented in the problem, and their learning experiences were also affected.

• KIPS Transactions on Software and Data Engineering
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• v.12 no.6
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• pp.259-266
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• 2023

It is very difficult to measure the performance of the machine learning model in the business service stage. Therefore, managing the performance of the model through the operational department is not done effectively. Academically, various studies have been conducted on the concept drift detection method to determine whether the model status is appropriate. The operational department wants to know quantitatively the performance of the operating model, but concept drift can only detect the state of the model in relation to the data, it cannot estimate the quantitative performance of the model. In this study, we propose a performance prediction model (PPM) that quantitatively estimates precision through the statistics of concept drift. The proposed model induces artificial drift in the sampling data extracted from the training data, measures the precision of the sampling data, creates a dataset of drift and precision, and learns it. Then, the difference between the actual precision and the predicted precision is compared through the test data to correct the error of the performance prediction model. The proposed PPM was applied to two models, a loan underwriting model and a credit card fraud detection model that can be used in real business. It was confirmed that the precision was effectively predicted.

• The Mathematical Education
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• v.44 no.4 s.111
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• pp.547-563
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• 2005

There have been many papers reporting that the axiomatic approach in Abstract Algebra is a big obstacle to overcome for the students who are not trained to think in an abstract way. Therefore an instructor must seek for ways to help students grasp mathematical concepts in Abstract Algebra and select the ones suitable for students. Mathematics faculty and students generally consider Abstract Algebra in general and quotient groups in particular to be one of the most troublesome undergraduate subjects. For, an individual's knowledge of the concept of group should include an understanding of various mathematical properties and constructions including groups consisting of undefined elements and a binary operation satisfying the axioms. Even if one begins with a very concrete group, the transition from the group to one of its quotient changes the nature of the elements and forces a student to deal with elements that are undefined. In fact, we also have found through running abstract algebra courses for several years that students have considerable difficulty in understanding the concept of quotient groups. Based on the above observation, we explore and analyze the nature of students' knowledge about $Z_n$ that is the set of congruence classes modulo n. Applying the genetic decomposition method, we propose a model to lead students to achieve the correct concept of $Z_n$.

• Journal of Korean Medical classics
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• v.30 no.3
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• pp.95-108
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• 2017

Objectives : The concept of hidden Yin in summer by Zhu Danxi deals with the relationship between summer heat disease and hidden yin inside of human body. This paper attempts to ponder upon the clinical issues around which the discussions regarding the topic unfolded, and upon the texts on which the doctors of the discussions based their opinions. Methods : First, Danxi's argument as discussed in $G{\acute{e}}zh{\grave{i}}y{\acute{u}}l{\grave{u}}n$ is analyzed to find out his understandings of clinical issues and his textual sources on which he based his new perspective. Moreover, the prescriptions that Danxi thought was problematic and the concept of hidden yin as it existed before the time of Danxi are reviewed, and these findings are used understand Zhangjingyue's ground of criticism against Danxi. Lastly, this paper contemplates how these opposing opinions may be helpful to the general principles of medical theories. Results & Conclusions : There was a trend before the time of Danxi of abusing drugs as prescription based on warm-heat, understanding that a human body has yin-cold during summer. However, Danxi brought forth a new concept of yin deficiency in order to correct people's misunderstanding. Despite his effort, Zhangjingyue and other doctors contemporary to Danxi emphasized on one hand that human body is placed on a state of external heat inside the cold, and on the another, criticized Danxi of failing to fully understand the principle of "Abandon the time and follow the symptoms", a principle which asserts that the cold and warm of medicine should be decided by the symptom itself and not by the season. The value of these contradicting assertions seems to hold true even to this day because it helps us understand that the principles of "Counting Season as a Treatment Factor" and "Abandon the time and follow the symptoms" could be applied with balance in conjunction with each other.