• Education of Primary School Mathematics
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• v.24 no.4
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• pp.247-264
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• 2021

The area of a trapezoid is an important concept to develop mathematical thinking and competency, but many students tend to understand the formula for the area of a trapezoid instrumentally. A clue to solving these problems could be found in Dienes' theory of learning mathematics and Watson and Mason' concept of example spaces. The purpose of this study is to obtain implications for the teaching and learning of the area of the trapezoid. This study analyzed the example spaces constructed by students in learning the area of a trapezoid based on Dienes' theory of learning mathematics. As a result of the analysis, the example spaces for each stage of math learning constructed by the students were a trapezoidal variation example spaces in the play stage, a common representation example spaces in the comparison-representation stage, and a trapezoidal area formula example spaces in the symbolization-formalization stage. The type, generation, extent, and relevance of examples constituting example spaces were analyzed, and the structure of the example spaces was presented as a map. This study also analyzed general examples, special examples, conventional examples of example spaces, and discussed how to utilize examples and example spaces in teaching and learning the area of a trapezoid. Through this study, it was found that it is appropriate to apply Dienes' theory of learning mathematics to learning the are of a trapezoid, and this study can be a model for learning the area of the trapezoid.

• The Journal of Korean Association of Computer Education
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• v.5 no.3
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• pp.27-35
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• 2002

This paper is presented a model of management and application of PC, one of the most important computer resources and software and a model for optimal speed of network to organize information budget of University. I propose strategies to promote utilization degree of existing PCs, problems and strategies to maintain PC, effective strategies to expand PC and change into new models, and strategies to utilize effectively and purchase softwares. Also, I propose an optimal model for network environment and management, which is core to establish master plan of information system. Network is divided into internal and external network and formula model is proposed to calculate optimal speed of these. And strategy is proposed to maintain security of University preserving its characteristics.

• Communications of Mathematical Education
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• v.25 no.3
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• pp.557-575
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• 2011

The purpose of this paper is to analyze the way of teaching and learning logarithm in high school mathematics and provide practical suggestions for teaching logarithms. For such purpose, it reviewed John Napier's life and his ideas, the effect of logarithms on seventeenth century science, and a logarithmic scale and its methods of calculation. With this reviews, introduction of logarithms with function concept, logarithmic calculation with common logarithms, and the formula of converting to other logarithmic bases were reviewed for finding a new perspective of teaching and learning logarithms in high school mathematics. Through such historical and pedagogical reviews, this paper presented practical suggestions and comments about the way of teaching and learning logarithms in high school mathematics.

• The Journal of Korean Association of Computer Education
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• v.11 no.5
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• pp.57-66
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• 2008

An adaptive optimization of parametric cubic convolution for image interpolation is derived in this paper. The proposed technique is based on optimizing the standard cubic convolution interpolation formula at each interpolated pixel. Conventional parametric cubic convolution methods use a fixed parameter in an image, so properties of each pixel cannot be incorporated into the interpolation. The proposed method optimizes the interpolation kernel by obtaining parameters adaptively on each pixel. A new cost function is introduced to reflect frequency properties of the original data. The proposed technique produces noticeably sharper edges than traditional techniques and exhibits an average PSNR improvement of traditional techniques.

• Journal of The Korean Association For Science Education
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• v.14 no.2
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• pp.143-158
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• 1994

This study aims to identify the characteristics of gas phase problem solving of college freshmen. Four students were participated in this study and solved the problem by using think-aloud method. The thinking processes were recorded and transferred into protocols. Problem solving stage, the ratio spended in each solving stage, solving strategy, misconceptions, and errors were identified and discussed. The relationships between students' belief system about chemistry problem solving and problem solving characteristics were also investigated. The results were as follows: 1. Students felt that chemical equation problem was easier than word problem or pictorial problem. 2. When students had declarative knowledge and procedural knowledge required by given problem, their confidence level and formula selection were not changed by redundunt information in the problem. 3. When the problem seemed to be difficult, students tended to use the Means-End or Random strategy. 4. In complicated problems, students spent longer time for problem apprehension and planning. In familiar problems, students spent rather short time for planning. 5. Students spent more time for overall problem solving process in case of using Means-End or Random strategy than using Knowledge-Development strategy.

• Journal of Nutrition and Health
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• v.28 no.4
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• pp.331-344
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• 1995

The process of breast feeding was investigated from the 36th week of pregnancy to 12 weeks postnatal, in order to analyze the factors affecting breast feeding duration and provide the basic data on an education program for successful breast feeding. The general characteristics of study group had no marked effects on the breastfeeding duration. The young and highly condition during pregnancy and the degree of morning sickness affected the practice of breastfeeding. In the study of prenatal sociobehavioral factors, intended duration affected the breastfeeding duration, and the maternal perception that breastfeeding is good for weight loss after delivery as well as infant formula milk is not as good as breast milk, led to successful breast feeding. Among the postnatal biological factors, the duration of gestation affected the breast feeding. Among the postnatal biological factors, the duration of gestation affected the breastiffeding outcome. In the case of early parturition, breastfeeding rate was low. Among the postnatal biocultural factors, time of first feed, milk volume and maternal perception of infant's sucking ability affected the bresatfeeding duration. From these result, it is suggested that an education program such as participation of nursing class to the pregnant women should be provided for successful breastfeeding.

• Human Ecology Research
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• v.51 no.4
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• pp.383-393
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• 2013

The purpose of this study is to investigate the infant feeding and weaning practices in multicultural families. We surveyed 159 married female immigrants in Jeonbuk province from April 2010 to April 2011. They are from Vietnam (49.7%), China (25.8%), Cambodia (8.8%), Japan (8.2%), and the Philippines (7.5%). The average rate of colostrum feeding of all the subjects was 91% and there were significant differences between nationalities (p<.05), family types (p<.01), and delivery methods (p<.001). 41.5% of those answered did breast feeding, while 49.1% combined breast and bottle feeding, and 9.4% did bottle feeding only. The reason for bottle feeding is either because they are unable to produce enough breast milk or because they think the formula is better than breast milk. Average period of breast feeding was 10.3 months. There were significant differences of breast feeding duration between maternal age (p<.05) and economic level (p<.001). The mean onset time of weaning was 7.8 months, and there were significant differences between nationalities (p<.05), family types (p<.05), and feeding methods (p<.05). There was no significant difference in methods of supplementary food preparation between nationalities, family types, jobs, and education levels. The mean onset time of commercial milk was 12.8 months, and there were significant differences between nationalities (p<.05), the duration of marriages (p<.05), education levels (p<.05) and feeding methods (p<.001).

• Publications of The Korean Astronomical Society
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• v.4 no.1
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• pp.16-30
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• 1989

We present recent data of absolute measurements of flux emmitted in the visible continua of some galactic Wolf-Rayet stars, carried out by means of a two-channel scanner built up cooperatively by the Observatoire de Lyon and the Laboratoire d'Astronomie Spatiale. Our measurements lead to the determination of stellar angular diameters which enable us to compute log $L_*/L_{\odot}$ and to locate the WR stars in the HR diagram: The WR stars are cooler than the zero age main sequence (ZAMS) and the WN7, WN8 types appear more luminous than other subclasses. The stellar wind terminal velocities, $V_{\infty}$, deduced from the empirical relation of the effective temperatures by Underhil1(1983) and $V_{\infty}$ adopted from the work of Willis(1982) show about 2,000km/s. We derived the rate of mass loss for the program stars from the formula, $\dot{M}={\varepsilon}(T_{eff})\;L/V_{\infty}{\cdot}c$ by using the obtained effective temperatures, luminosities and $V_{\infty}$ in this work. Their values range from $\dot{M}=1.4{\times}10^{-5}$ to $\dot{M}=5.8{\times}10^{-5}\;\dot{M}_{\odot}/yr$.

• Journal of The Korean Association For Science Education
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• v.30 no.7
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• pp.920-932
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• 2010

Many topics in science, especially, abstract concepts, relationships, properties, entities in invisible ranges, are described in mathematical representations such as formula, numbers, symbols, and graphs. Although the mathematical representation is an essential tool to better understand scientific phenomena, the mathematical element is pointed out as a reason for learning difficulty and losing interests in science. In order to further investigate the relationship between mathematics knowledge and science understanding, the current study examined 793 high school students' understanding of the pH value. As a measure of the molar concentration of hydrogen ions in the solution, the pH value is an appropriate example to explore what a student mathematical structure of logarithm is and how they interpret the proportional relationship of numbers for scientific explanation. To the end, students were asked to write their responses on a questionnaire that is composed of nine content domain questions and four affective domain questions. Data analysis of this study provides information for the relationship between student understanding of the pH value and related mathematics knowledge.

• Wind and Structures
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• v.22 no.2
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• pp.235-252
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• 2016

A wind velocity power spectrum (WVPS) with high fidelity is extremely important for accurate prediction of structural buffeting response. WVPS heavily depends on the geographical locations, local terrains and topographies. Hence, field measurement of wind characteristics may be the unique way to obtain the accurate WVPS for a specific region. In this paper, a systematic analysis and discussions of existing WVPSs were performed. Six recorded strong wind data from the structural health monitoring systems (SHMS) of Runyang Suspension Bridge (RSB) and Sutong Cable-stayed Bridge (SCB) in Jiangsu Province of China were selected for analysis. The measured and pre-processed wind velocity data was first transformed from time domain to frequency domain to obtain the measured spectrum. The spectrum for each strong wind was then fitted using the nonlinear least square method and compared with both the fitted spectrum from statistical analysis and the recommended spectrum in specifications. The modified Kaimal spectrum was proved to be the "best" choice for the coastal area of East Jiangsu Province. Finally, a suitable WVPS formula fit for the coastal area of East Jiangsu Province was presented based on the modified Kaimal spectrum. Results in this study provide a more accurate and reliable WVPS for wind-resistant design of engineering structures in the coastal area of East Jiangsu Province.