• Journal of The Korean Association For Science Education
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• v.18 no.4
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• pp.571-587
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• 1998

This paper reviews and analyzes the conceptions of science achievement in the United States and Korean reform documents, including those on science content standards(NSES, Porject 2061, and Korean 7th science curriculum), performance standards(New Standards, and Survey of Ecucational Achievement in Korean Elementary and Secondary Schools), and large-scale assessment framworks(1996 NAEP, TIMSS, The National Assessment of Science Inqury Abilities, The National Assessment of Science Knowledge, and The National Assessment of Affective Characteristics related to Science). The analysis of these documents indicates that there is an overall agreement on the conceptions of science achievement. The documents consistently emphasize high achievement in terms of knowledge and abilities in scientific, technological, social, and environmental perspectives. In addition, these documents define science achievement at different developmental levels and at certain depths of knowledge and abilities for all students. Despite the overall agreement, there are also noticeable variations among the documents because of different contexts and purposes. There is a difference in the balance of representations or emphases among content and process standards in the documents. The conceptions of science achievement in the Korean documents are not as comprehensive or inclusive as those in the United States documents. There is no representation of the mathematical world, the nature of science, historical perspectives, unifying concepts, or scientific communication. From these results, two conclusions are drawn. First, more coherent conceptions of science achievement are needed for common understanding among educators and the public. Second, efforts are needed for developing more comprehensive and inclusive conceptions of science achievement in Korea.

• Journal of the Korea Society for Simulation
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• v.21 no.3
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• pp.79-88
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• 2012

Recently, the study in efficient operation, maintenance, and equipment-design have been growing rapidly in military industry to meet the required missions. Through out these studies, the importance of Concurrent Spare Parts(CSP) are emphasized. The CSP, which is critical to the operation and maintenance to enhance the availability, is offered together when a equipment is delivered. Despite its significance, th responsibility for determining the range and depth of CSP are done from administrative decision rather than engineering analysis. The purpose of the paper is to optimize the number of CSP per item using simulation and multiple regression. First, the result, as the change of operational availability, was gained from changing the number of change in simulation model. Second, mathematical regression was computed from the input and output data, and the number of CSP was optimized by multiple regression and linear programming; the constraint condition is the cost for optimization. The advantage of this study is to respond with the transition of constraint condition quickly. The cost per item is consistently altered in the development state of equipment. The speed of analysis, that simulation method is continuously performed whenever constraint condition is repeatedly altered, would be down. Therefore, this study is suitable for real development environment. In the future, the study based on the above concept improves the accuracy of optimization by the technical progress of multiple regression.

• Elastomers and Composites
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• v.34 no.2
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• pp.135-146
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• 1999

The thermal degradation kinetics of SBR and tire were studied using a conventional thermogravimetric analysis in the stream nitrogen at a heating rate of 5, 10, 15, $20^{\circ}C/min$, respectively. Thermogravimetric curves and their derivatives were analyzed using various analytical methods to determine the kinetic parameters. The degradation of the SBR and tire was found to be a complex process which has multi-stages. The Friedman method gave average activation energies for the SBR and tire of 247.53kJ/mol and 230.00kJ/mol, respectively. Mean-while, the Ozawa method Eave 254.80kJ/mol and 215.76kJ/mol. It would appear that either. Friedman's differential method or Ozawa's integral method provided satisfactory mathematical approaches to determine the kinetic parameters for the degradation of the SBR and tire. Approximately 86% and 55% of oil products were obtained at a final temperature of $700^{\circ}C$ and a heating rate of $20^{\circ}C/min$ for the SBR and tire respectively.

• Journal of the Earthquake Engineering Society of Korea
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• v.15 no.2
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• pp.53-60
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• 2011

When designing building structures, dynamic serviceability is one of the most important items. Much research is being carried out on machine vibrations that affect inside residents and expensive equipment in the building structure. The vibration effect generally depends on the mass ratio, and an adequate mass ratio is determined by comparison with the serviceability limit according to the criteria. This study investigates the evaluation of vibration serviceability by using ISO 2631 to confirm the propriety of adequate mass ratios and it is verified that the application of a complicated FE model to model the real large shaking table facility with the mathematical model simulated as a SDOF system. The weighted RMS value is then compared with the comfort limit given by ISO 2631. As a result, the analysis of the numerical model is consistent with analysis of the FE model. Moreover, it is found that the adequate mass ratio of the concrete foundation and shake table, considering the self-weight of the real facility, should be less than 0.013. It is also confirm that the sample facility is satisfies the requirement of an adequate mass ratio.

• Journal of Elementary Mathematics Education in Korea
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• v.23 no.1
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• pp.19-41
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• 2019

In this study, we present an analysis framework based on the 2015 revised curriculum to analyze how mathematical contents and achievement standards for domains of numbers and computations have changed in the curriculum of elementary mathematics in Korea. Based on this, we classified the achievement standards by type and investigated their characteristics. The achievement standards for numbers and computations can be divided into the successive, the extinctive, and the additive achievement standards depending on their characteristics. The successive achievement standards are the ones that have consistently existed without being removed from the 1-st curriculum to the latest revision in 2015. The extinctive achievement standards are the ones that have been removed at some point during the revisions of nine times and do not remain in the current revision in 2015. The characteristics of the extinctive achievement standards were analyzed to be different before and after the 4-th curriculum. The additive achievement standards refer to the ones that have been newly added to the curriculum or that have been removed at a certain moment but added back in later and thus exist in the current revision in 2015. The characteristics of each type according to the changes of the achievement standards can be thought to be the results that the revision for the mathematics curriculum in Korea has been faithfully conducted. Based on the results of this study, we suggest some implications for organizing the achievement standards in the future curricular development.

• Korean Chemical Engineering Research
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• v.43 no.5
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• pp.549-559
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• 2005

Sustainable industrial development which can minimize an ecological effect by the mankind exertion is recently interested due to an environmental contamination and a resource exhaustion problem. An eco-industrial park (EIP) is a community of manufacturing and service businesses seeking enhanced environmental and economic performance through collaboration in managing environmental and resource issues, including energy, water, and materials. EIP developments which improve a production plant within an eco-friendly greenfield and design a new industrial ecosystem are accomplished recently, which can efficiently re-use the waste and resources from each company within EIP. In this review, the outside and domestic case studies of EIP and cornerstone technologies to develop the EIP, such as energy integration, waste reuse, mass flow analysis, water pinch, and life cycle assessment, are summarized.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.2
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• pp.422-429
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• 2007

Location awareness is one of the key functionalities to build an U-city. Recently, many of works of the location-aware systems are emerging to commercially apply to on-going large-scale apartment complex based on U-city. As dwellers or cars being attached with active tags are moving in the U-city complex, the active tags periodically broadcast their own identifiers and receivers fixed along the street or in building use those information to calculate location of them. There are several issues to be considered for such an environment. The first is that the number of active tags operating in the same region are large as much as tens of thousands, and the second is that the active tags should be alive without change of batteries more than a year, hence low power consumption is very important. In this paper we propose i) a new architecture for location-aware system considering such issues, ii) technical issues to implement it using active tags, and iii) a mathematical analytic model to investigate overall performance and verify it by comparing with actual experimental results. Through the analysis we can show the theoretical boundary of the lowest packet loss rate and the maximum number of tags with acceptable performance for the systems based on active tags. The results can be applied to practical design of location-based systems of U-City projects.

• Education of Primary School Mathematics
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• v.22 no.3
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• pp.181-203
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• 2019

Even though the properties of operations in multiplication serve a fundamental basis of conceptual understanding the multiplication with whole numbers for elementary students, there has been lack of research in this field. Given this, the purpose of this study was to analyze instructional methods related to the properties of operations in multiplication (i.e., commutative property of multiplication, associative property of multiplication, distributive property of multiplication over addition) in a series of mathematics textbooks of Korea, Japan, and the US. The overall analysis was conducted in the following two aspects: (a) when and how to deal with the properties of multiplication in three instructional context (i.e., introduction, application, generalization), and (b) what models use to represent the properties of multiplication. The results of this showed that overall similarities in introducing the properties of multiplication .in (one digit) ${\times}$ (one digit) as well as emphasizing the divers representation. However, subtle but meaningful differences were analyzed in applying and generalizing the properties of multiplication. Based on these results, this paper closes with some implications on how to teach the properties of operations in multiplication properties in elementary mathematics.

• Journal of the Korean Society of Marine Environment & Safety
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• v.25 no.5
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• pp.527-534
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• 2019

Several types of mathematical analysis methods are used for port waterway risk assessment based on marine traffic volume. In Korea, a marine traffic congestion model that standardizes the size of the vessels passing through the port waterway is applied to evaluate the risk of the waterway. For example, when marine traffic congestion is high, risk situations such as collisions are likely to occur. However, a scientific review is required to determine if there is a correlation between high density of maritime traffic and a high risk of waterway incidents. In this study, IWRAP Mk2(IALA official recommendation evaluation model) and a marine traffic congestion model were used to analyze the correlation between port waterway risk and marine traffic congestion in the same area. As a result, the linear function of R2 was calculated as 0.943 and it was determined to be significant. The Pearson correlation coefficient was calculated as 0.971, indicating a strong positive correlation. It was confirmed that the port waterway risk and the marine traffic congestion have a strong correlation due to the influence of the common input variables of each model. It is expected that these results will be used in the development of advanced models for the prediction of port waterway risk assessment.

• Journal of the Korean School Mathematics Society
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• v.22 no.1
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• pp.1-21
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• 2019

Mathematics is one of the subjects in which learners seriously experience under-achievements in school education. Middle school level mathematics especially plays such a role as a bridge between elementary level informal mathematics and high school level formal mathematics that learners' under-achievements in the middle school level mathematics may yield more serious under-achievements later. Therefore it is crucial to prevent learners' later under-achievements that we analyze the status of under achievements including analysing various under-achievers' errors in the middle school level mathematics. From this point of view, we analysed errors of mathematics under-achievers in understanding the concept of the square root of positive numbers and related calculations in this paper. As the results of our research, we found some unexpected errors of 'some mathematics under-achievers regarding the mathematical symbol ${\surd}$ of square root as a parenthesis ( ), and others interpret $x=-2{\pm}{\sqrt{10}}$ as x=-2 or ${\pm}{\sqrt{10}}$.' that suggest the necessity of more various and in-depth discussions and researches of analysis on learners' errors and misconceptions in all areas of school mathematics.