• Journal for History of Mathematics
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• v.19 no.4
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• pp.63-80
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• 2006

Along with natural and algebraic languages, schema is a fundamental component of mathematical language. The principal purpose of this present study is to focus on this point in detail. Schema was already in use during Pythagoras' lifetime for making geometrical inferences. It was no different in the case of Oriental mathematics, where traces have been found from time to time in ancient Chinese documents. In schma an idea is transformed into something conceptual through the use of perceptive images. It's heuristic value lies in that it facilitates problem solution by appealing directly to intuition. Furthermore, introducing schema is very effective from an educational point of view. However we should keep in mind that proof is not replaceable by it. In this study, various schemata will be presented from a diachronic point of view, We will show with emaples from the theory of categories, Feynman's diagram, and argand's plane, that schema is an indispensable tool for constructing new knowledge.

• The Journal of Society for e-Business Studies
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• v.8 no.4
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• pp.129-149
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• 2003

Explosive growth of mobile devices over the past years has greatly increased commercial interests in mobile commerce, but mobile commerce has not yet seen enough increase on demand side as anticipated. Despite the slow start, mobile commerce has a lot of potential from users' perspective. In order to make this potential a reality, businesses must focus on the values from their customers' perspective, not technical competencies. This research employed Keeney's(1992) value focused thinking approach and explore values of mobile commerce from actual users' viewpoint. In depth interviews were conducted with seventy Practical users of mobile commerce. Through an extensive focus group sessions, 748 statements obtained from actual users were classified into 18 categories of means objectives and 12 categories of fundamental objectives of mobile commerce. The means-ends network diagram of values seen in mobile commerce by actual users were presented and compared to typical electronic commerce diagram. Results suggest the mobile commerce needs to be handled differently from the traditional electronic commerce.

• Journal of Industrial Convergence
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• v.22 no.5
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• pp.39-48
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• 2024

Due to COVID-19, much research has been conducted on learning loss and educational gaps due to the postponement of the start of school and prolonged online distance learning, and most of the research has focused on the phenomenon of educational gaps. If a pandemic situation like this occurs in the future, fundamental policies are needed to resolve the educational gap. A fundamental solution requires not only an understanding of the educational gap phenomenon, but also the structure behind the phenomenon. Therefore, from a structuralist perspective, this study sought to model the educational gap caused by COVID-19 as a prototype of systems thinking and identify its structure. In addition, we looked at the unintended consequences resulting from policies aimed at resolving existing educational gaps. In order to respond to similar disaster situations in the future, policies for resolving the digital gap, support for basic academic skills, quality improvement for distance learning, and self-directed learning were discussed based on the structure of this study.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.6
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• pp.1071-1079
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• 2007

In this paper, a novel space vector control method for isolated multi-level inverter using 3-phase low frequency transformers is proposed. This method is based on the simplification of the space-vector diagram of a five-level inverter using calculated table into fully programming method. The execution time of the proposed method is about same as that of the method using calculated table. Also, the proposed method is easily applied to other case level inverter. We applied this method into the 3-phase IHCML inverter using common arm. It makes possible to use a single DC power source due to employing low frequency transformers. In this inverter, the number of transformers could be reduced compare with an exiting 3-phase multi-level inverter using single phase transformer. In addition, this method generates very low harmonic distortion operation with nearly fundamental switching frequency. Finally, We tested multi-level inverter to clarify electric circuit and reasonableness through Matlab simulation and experiment by using prototype inverter.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2008.11a
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• pp.658-661
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• 2008

This study aims to suggest a methodology for developing the AR-4D CAD system which can improve construction progress control process by using augmented reality(AR) technology for civil engineering project. This study reviews practical application of AR process in 4D CAB system and suggests the detailed requirements, information flow system and integrated interface function for developing AR-4D CAD system. Through these methods, this research classifies main functions of AR-4D CAD system that can visualize construction progress control data, and suggests an operation scenarios of the system.

• Korean System Dynamics Review
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• v.15 no.2
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• pp.5-25
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• 2014

The purpose of this study is to analyze the effects of nuclear power plant workers and organizational characteristics on accidents, and seek the combination of policies for reducing accidents. For this purpose, it grasped, by using System Dynamics and Causal Loop Diagram, how various factors that cause accidents in nuclear plants are interrelated, and performed simulations after building simulation models. As a result of the analysis, first, the fundamental cause of safety accidents in nuclear power plants turned out to be the time constraint on the workload. Second, it turned out that as the workload of workers increases, physical and mental stresses increase, thereby increasing accidents due to errors and violations. Third, it turned out that as the levels of educational training and compliance with regulations and procedures are enhanced, accidents are reduced. Lastly, it turned out that as the combination of policies (reliance level + working environment + educational training + compliance with regulations and procedures) is increased, accidents are reduced. Especially, it turned out that if the combination of policies is increased by 30%, more than 10 cases of accidents are reduced.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.2
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• pp.175-181
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• 2007

The objective of this study was to develop formability evaluation techniques in order to apply aluminum sandwich panel for automotive body parts. For this purpose, newly adopting formability evaluation (using limit dome height and plane strain test) was carried out in order to secure the fundamental data for the measurement of sheet metal forming and the establishment of optimum forming conditions of the aluminum sandwich panel. The results showed that there were good agreements between the old formability evaluation method and the new method which was more simplified than that of old one. From the results of these formability evaluation, the formability of sandwich panel was higher than that of aluminum alloy sheet alone which was the skin component for the sandwich panel. Also, it was found that sandwich panel could reduce the weight and could have the same flexural rigidity simultaneously when it was compared to the automotive steel sheet.

• Architectural research
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• v.16 no.2
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• pp.45-56
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• 2014

The objective of this article, positively recognizing existing researches, is to revisit some aspects regarding the Vāstupuruṣamaṇḍala with a square grid work which is a fundamental planning guideline to control the construction of a Hindu temple and a mathematical doctrine to lead ritual programs. Hence, this paper suggests some reservations as to certain details such as temple constructions. In order to lay hold on its meaning, this paper touches upon the specific matters about the Vāstupuruṣamaṇḍala in the building construction of Hindu temples, which set out to shed light on four concerns; first, it explores the formation process of the Vāstupuruṣamaṇḍala in concert with the evolution of Hindu temples over time; second, it considers differences and similarities in comparison with other texts intimately articulated with the construction of temples, and then understands the relationship between their local languages and applications to the Vāstupuruṣamaṇḍala; third, it examines the symbolic and sanctified process of the temple's construction on the Vāstupuruṣamaṇḍala grids with two- or three-dimensional computer graphics (by means of the Auto Cad and Rhino tools), invisibly situating the divinities within it and illuminating the roles of ornamentation in the structural terms of temples; fourth, it presents that there are another rules on the building construction based upon architect-priest's craftsmanship skilled as a stonemason or a carpenter in the manual processes of the temples' construction for proper measurements and truncations of stone and wood closely linked together structural stability of completed temples. In conclusion, proceeding from what has been said above, this thesis shows that the Vāstupuruṣamaṇḍala grid includes both practical and spiritual meanings to construct a Hindu temple.

• Journal of Environmental Health Sciences
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• v.34 no.2
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• pp.153-160
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• 2008

Personal noise exposure was assessed in railroad operators working in 40 operation units including the Gyeongbu line, Honam line, and Janghang line between 2004 and 2006. 8-hour TWA were assessed based on the MOL (Ministry of Labor) guideline on noise evaluation, and 17% of these measurements exceeded 85 dBA while 70% were over 80 dBA. When the ACGIH TLV is adopted, 40% of measurements were over TLV (85 dBA). The noise exposure risk of railroad operators was higher for diesel locomotive operation and longer operational distances; in addition, the risk was higher for passenger car operation compared to freight car driving. Given that in Korea, over the past 30 years diesel locomotives have provided most of the railway's motive power and that hearing protective equipment is not likely to be used by workers during operation, railroad operators are at a high risk of noise-induced hearing loss. The result of audiometric test among 568 railroad operators showed that 32.6% of those tested had a hearing threshold shift of more than 40 dB. In conclusion, this study calls for more fundamental measures including noise control countermeasures within the operation areas, development of equipment that generates less noise and adopting limitation on the operation distance for a work shift.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.5 s.236
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• pp.617-624
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• 2005

An analysis of the effects of $CO_{2}$ on fundamental combustion characteristics was performed in Oxygen enriched condition by comparing the laminar burning velocities, flame structures, fuel oxidation paths. Fictitious $CO_{2}$ was introduced to discriminate the chemical reaction effects of $CO_{2}$ from the thermal effects. PREMIX code was utilized to evaluate the laminar burning velocities. OPPDIF code was utilized to investigate the flame structure and fuel oxidation path variation. The contributions of thermal effects on laminar burning velocities are dominant at lowly oxygen-enriched condition but those of chemical reaction effects become dominant at highly oxygen-enriched condition. Chemical reaction effects caused the additional flame temperature decrease besides thermal effects and oxygen-leakage increase in non-premixed flame. Specific fuel oxidation path and CO production path is enhanced in spite of overall decrement of fuel consumption rate by chemical reaction effects of$CO_{2}$.