• Journal of Elementary Mathematics Education in Korea
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• v.20 no.3
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• pp.479-498
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• 2016

Time is important in children's lives since their preschool years. However, previous studies indicate that many children struggle with the acquisition of time concepts. Also teachers do not know how to help them. This study aims to investigate elementary school students' understanding about time and induce its educational implications. To do this, about 130 children from first to fifth grades were tested for their ability to recognize(read and record) the analogue and digital times and to solve elapsed-time problems. The results showed that even first graders were able to read and record the minute times on digital clocks. And second graders were able to read and record the minute times on analogue clocks. Therefore, the ability to recognize analogue times was mastered by second grade. In case of the elapsed-time problems, there was statistically significant difference according to school years or types of problems. Students were successful in solving simple problems. However, the problems that include regrouping hour and minute remained difficult even for the older children. Based on these results, we made a few suggestions for teaching practice about time.

• Journal of Korean Society of Steel Construction
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• v.21 no.3
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• pp.267-275
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• 2009

This paper presents the behavior of column-removed double-span beams in welded steel moment frames and proposes a simplified nonlinear dynamic analysis method for the preliminary evaluation of progressive collapse potential. The nonlinear finite element analysis and the associated analytical study showed that the column gravity load and the beam span-to-depth ratio govern the maximum dynamic deformation demand of the double-span beams. Based on these results, the concept of a collapse spectrum, which describes the relationship between the gravity load parameter and the maximum chord rotation of the double-span beams, was newly proposed. A procedure for the application of the collapse spectrum to multi-story welded steel moment frames was then suggested. The inelastic dynamic finite element analysis results showed that the proposed method gives satisfactory prediction of the nonlinear progressive collapse behavior of welded steel moment frames.

• Journal for History of Mathematics
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• v.19 no.4
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• pp.31-62
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• 2006

In this article, the theoretical basis of applying mathematical his tory in lessons is inquired in various educational aspects. It also covers the psychological genetic principle, mainly concerning the childish development and states that it has to be compatible with the historico-genetic principle, which is suggested mainly concerning the development of data. In addition, it evolves the arguments about the meaning of mathematical history in math lessons based on the mentioned aspects besides that in ordinary math lessons. Next, the link between the apply of mathematical history and education for gifted children is examined. Last, cases of mathematic history applied to mathematic education is suggested mainly concerning the understanding of differential concepts.

• Journal of the military operations research society of Korea
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• v.33 no.2
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• pp.61-73
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• 2007

We examined technological forecasting of extended TFDEA(Technological Forecasting with Data Envelopment Analysis) and thereby apply the extended method to the technological forecasting problem of main battle tank. The TFDEA has the possibility of using comparatively inefficient DMUs(Decision Making Units) because it is based on DEA(Data Envelopment Analysis), which usually leads to multiple efficient DMUs. Therefore, TFDEA may result in incorrect technological forecasting. Instead of using the simple DEA, we incorporated the concept of Super-efficiency, Cross-efficiency, and CCCA(Constrained Canonical Correlation Analysis) into the TFDEA respectively, and applied each method to the case study of main battle tank using verifiable practical data sets. The comparative analysis shows that the use of CCCA with TFDEA results in very comparable prediction accuracies with respect to MAE(Mean Absolute Error), MSE(Mean Squared Error), and RMSE(Root Mean Squared Error) than using the concept of Super-efficiency and Cross-efficiency.

• Journal of the Korean association of regional geographers
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• v.19 no.3
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• pp.436-445
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• 2013

This study, by focusing on the concept of accessibility to the central city, analyses its importance for understanding baward regions and aims to investigate a new spatial strategy for developing backward regions in Korea. The study investigates the EU accessibility case study and formulates the methodological framework for the analysis, which is applied to the case of Jeonnam-do and Gyeongbuk-do in order to evaluate the backwardness of the regions in terms of the accessibility to the central city. Finally, this paper discusses a new spatial strategy for developing backward regions based on the concept of the accessibility to the central city, which includes the creative expansion of rural public services and promoting efficient delivery system, improving public and private service provision through the accessibility to the central city and securing long-term development potential through investing in regional human capital.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2003.11a
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• pp.549-555
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• 2003

For the safe management of radwaste repository, data of the site and environment have to be collected and managed systematically. Particularly, for the radwaste repository, which has to be institutionally controlled for a long period after closure, data will be collected and maintained through the monitoring programme. To meet this requirement, a new programme called "Site Information and Total Environmental data management System (SITES)" is being developed. In this study, as the first stage of GIS(Geographic Information System) development that will be embedded in SITES, the scope and function of GIS are issued. Methodology for the Selection and management of thematic maps is studied as well.d as well.

• Science of Emotion and Sensibility
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• v.1 no.1
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• pp.3-11
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• 1998

In an urgent situation of interdisciplinary research and method, we feel eagerly the necessity of discussing the philosophical background of ´the science of emotion and sensibility´. If human cognitive faculties lie in split dualism of sensibility and reason, it is difficult to find out the whole image of just recognition, Therfore, it is so important that we should pursue the interrelational context between reason and sensibility through the rationalization of sensibility and the sensibilization of reason. Both reason and sensibility constitute the immanant system of knowledge, The science of sensitive cognition has lower cognitive faculty in contrast to the science of logic, but commonsense plays a rloe to expand the world knowledge which the logical cognition can not fully accomplish. it is dur task to expand the problem of sensibility from the level of humanities on the ground of the communal to the scientific objecticity, which is based on the observation of natural appearances.

• Journal for History of Mathematics
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• v.24 no.3
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• pp.37-58
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• 2011

The development of recent Mathematical Logic is mostly originated in Hilbert's Proof Theory. The purpose of the plan so called Hilbert's Program lies in the formalization of mathematics by formal axiomatic method, rescuing classical mathematics by means of verifying completeness and consistency of the formal system and solidifying the foundations of mathematics. In 1931, the completeness encounters crisis by the existence of undecidable proposition through the 1st Theorem of G?del, and the establishment of consistency faces a risk of invalidation by the 2nd Theorem. However, relative of partial realization of Hilbert's Program still exists as a fruitful research program. We have tried to bring into relief through Curry-Howard Correspondence the fact that Hilbert's program serves as source of power for the growth of mathematical constructivism today. That proof in natural deduction is in truth equivalent to computer program has allowed the formalization of mathematics to be seen in new light. In other words, Hilbert's program conforms best to the concept of algorithm, the central idea in computer science.

• Journal of the Korean Society of Hazard Mitigation
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• v.9 no.2
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• pp.31-37
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• 2009

Most damages of civil infrastructures under natural disasters are frequently occurred at surrounding areas of the river or the road. Every year, Recovery for these disaster damages are performed by the government. Recently, the government decide to change current recovery plan system because current recovery plan which doesn't consider future disaster impacts at a site has been proved to be ineffective. Accordingly, new permanency recovery plan system is needed and its corresponding ideas are presented in this research considering more detailed disaster damage classifications and cause assessments. The proposed permanency recovery plan would also provide more systematic and diverse recovery response strategies including both two concepts, for example Preparedness considered by risk assessment and management, and Mitigation investigated by hazard impact analyses.

• Journal of the Korean Geotechnical Society
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• v.27 no.12
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• pp.117-126
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• 2011

Based on thermodynamics, the mathematical framework governing the hydro-mechanical behavior of partially saturated soil is derived by using balance equations, and the numerical analysis through implementation of various effective stress definitions is performed. Effective stress on partially saturated soil describes the soil strength which is presented by the relationship between water content and soil suction. For the estimation of hydro-mechanical behavior on partially saturated soil, effective stress parameter ${\chi}$ defined from various literatures is especially analyzed to understand the conditions of constitutive equations regarding residual saturation and displacement of soil. As a result, effective stress parameter ${\chi}$ has an influence on the variation of matric suction in soil with an external load and seepage. However it was found that the effect of each parameter ${\chi}$ varies with residual degree of saturation, and that of each parameter ${\chi}$ decreased with decrease in displacement of soil caused by an external load.