• Smart Structures and Systems
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• v.6 no.1
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• pp.29-38
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• 2010

An ElectroMagnetic Actuator (EMA) is designed and assessed numerically and experimentally. The EMA has the advantage to be without contact with the structure so it could be applied to light and small mechanism. Nevertheless, the open-loop instability and the nonlinear dynamic behavior with respect to the excitation frequency could limit its application field. The EMA is designed and dimensioned as a function of the experimental structure to be controlled. An inverse model of the EMA is proposed in order to implement a linear action block for the used frequency range. The control strategy is a fuzzy controller with displacements and velocities as inputs. A fuzzy controller of Takagi-Sugeno type is used. The air gap is estimated by using a modal approximation of the displacements issued from all measurements. Several configurations of control are assessed by using numerical simulations. The block diagram used for numerical simulations is implemented under Dspace$^{(R)}$ environment. The implemented controller was tested experimentally in the context of impact perturbations. The results obtained show the effectiveness of the developed procedures and the robustness of the implemented control.

• Journal of Elementary Mathematics Education in Korea
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• v.12 no.1
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• pp.79-100
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• 2008

Freudenthal has advocated the reinvention method. In that method, the pupils start with a meaningful context, not ready-made concepts, and invent informative method through which he could arrive at the formative concepts progressively. In many face the reinvention method is contrary to the traditional method. In traditional method, which was named as 'concretization method' by Freudenthal, the pupils start with ready-made concepts, and applicate this concepts to various instances through which he could arrive at the understanding progressively. Through analysis, it turns out that Korea's seventh elementary mathematics textbook is based on concretization method. In this thesis, first of all, I will reconstruct probability unit of seventh elementary textbook according to Freudenthal's reinvention method. Next, I will perform teaching experiment which is ruled by new lesson design. Lastly, I analysed the effects of teaching experiment. Through this study, I obtained the following results and suggestions. First, the reinvention method is effective on the teaching of probability concept and algorithm. Second, in comparison with current textbook strand, my strand which made probability concept go ahead and combinatorics concept let behind is not deficiency. Third, tree diagram is effective matrix which contribute to formalization of combinatorics calculation. Lastly, except for fraction, diverse representation of probability, for example percentage or informal ratio expression must be introduced in teaching process.

• Journal of the Korean Institute of Landscape Architecture
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• v.33 no.1 s.108
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• pp.93-108
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• 2005

Fresh Kills is the largest landfill in the world located in the west side of Staten Island, New York. The landfill served as a storage area for New York City's trash for more than 50 years. After years of civilian and political pressure, state and local legislation decided its closure of landfill operation in Fresh Kills in March 2001. Soon after, Department of City Planning announced a Fresh Kills international design com-petition: 'Landfill to Landscape'. The winning entry was promised to be outline for the redevelopment of the 2,200 acre site which the size of three times Central Park. Forty-eight teams representing more than 200 offices from around world submitted proposals, from which six finalists that mostly led by landscape architects were selected. In December 2001, a jury of architects, landscape architects and city officials unanimously selected Field Operations as the winner. The plan, named Lifescape, visualizes the gradual 20-year transformation of the whole Staten Island into a 'natural lifestyle island' recognizing that Staten Island is home to coastal wetlands that shelter one of the most diverse ecosystems in the New York metropolitan area. It suggested that an ecologically reconstituted Fresh Kills could become the center of integrated parks and greenways system on the island otherwise fragmented. The project will be one of the largest and most ambitious undertakings in the metropolis in years developing a complex web of habitats and parklands on top of mountain of trash. This study tries to achieve two goals: One is to provide general explanations on the project, Lifescape, breaking down to its background, geographical context, design concepts and phased development plan. Another is to introduce the unique and innovative design approaches by Field Operations that are different from a conventional landscape architectural attitude. Since this project was well published through many magazines and newspapers, main focus will be upon aspects that differentiate this project from usual landscape projects. Conceptually Lifescape brought provocative notions on nature/culture relationship and the role of urban park as an active agency rather than just a green rest area. Also this project introduced pioneering graphics like plan collage, diagrammatic plan, phasing diagram and photo montage as vehicles conveying information, imagination and provocation. Witnessing the influence of the project gradually in the field of academic and practice in the States, this study is intended to become a constructive reference to similar landscape projects dealing with large and complex urban context in conjunction with restructure of contemporary city.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.11
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• pp.5458-5464
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• 2012

In LTE-Advanced that different networks coexist, it is considered that it is actually difficult to provide service continuity with a procedural and static control method applied to the existing voice service. This research suggests a resource management framework to support the service continuity effectively based on QoS support. In other words, as context information of mobile terminal and base station changes, set-up of related functions such as ISHO, cell selection, source allocation, load control, and QoS mapping is adapted; each function fits into the change, exchanges the process of reorganization, and interacts; these actions go toward to satisfy service continuity. For this aim, the sequence diagram between the function modules for supporting four kind of ISHO is described and then a scenario for ISHO is considered.

• Proceedings of the Korean Society of Computational and Applied Mathematics Conference
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• 2003.09a
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• pp.1-1
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• 2003

In this talk, a reduced-order modeling methodology based on centroidal Voronoi tessellations (CVT's)is introduced. CVT's are special Voronoi tessellations for which the generators of the Voronoi diagram are also the centers of mass (means) of the corresponding Voronoi cells. The discrete data sets, CVT's are closely related to the h-means clustering techniques. Even with the use of good mesh generators, discretization schemes, and solution algorithms, the computational simulation of complex, turbulent, or chaotic systems still remains a formidable endeavor. For example, typical finite element codes may require many thousands of degrees of freedom for the accurate simulation of fluid flows. The situation is even worse for optimization problems for which multiple solutions of the complex state system are usually required or in feedback control problems for which real-time solutions of the complex state system are needed. There hava been many studies devoted to the development, testing, and use of reduced-order models for complex systems such as unsteady fluid flows. The types of reduced-ordered models that we study are those attempt to determine accurate approximate solutions of a complex system using very few degrees of freedom. To do so, such models have to use basis functions that are in some way intimately connected to the problem being approximated. Once a very low-dimensional reduced basis has been determined, one can employ it to solve the complex system by applying, e.g., a Galerkin method. In general, reduced bases are globally supported so that the discrete systems are dense; however, if the reduced basis is of very low dimension, one does not care about the lack of sparsity in the discrete system. A discussion of reduced-ordering modeling for complex systems such as fluid flows is given to provide a context for the application of reduced-order bases. Then, detailed descriptions of CVT-based reduced-order bases and how they can be constructed of complex systems are given. Subsequently, some concrete incompressible flow examples are used to illustrate the construction and use of CVT-based reduced-order bases. The CVT-based reduced-order modeling methodology is shown to be effective for these examples and is also shown to be inexpensive to apply compared to other reduced-order methods.

• Journal of Educational Research in Mathematics
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• v.16 no.2
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• pp.115-138
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• 2006

The purpose of this paper is to investigate students' constructing similarities in the understanding the problem phase and the devising a plan phase of problem solving. the relation between similarities that students construct and how students construct similarities is researched through case study. Based on the results from the research, authors reached a conclusion as following. All of two students constructed surface similarities in the beginning of the problem solving process and responded to the context of the problem information sensitively. Specially student who constructed the similarities and the difference in terms of a specific dimension by using diagram for herself could translate the equation which used to solve the base problem or the experienced problem into the equation of the target problem solution. However student who understood globally the target problem being based on the surface similarity could not translate the equation that she used to solve the base problem into the equation of target problem solution.

• The Journal of the Korea Contents Association
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• v.19 no.9
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• pp.376-387
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• 2019

The role of local decentralization and balanced regional development becomes important due to the concentration of population due to urbanization, and the development of tourism contents in local governments is actively being attempted. However, this is largely due to quantitative growth, and it does not offer tourist content that offers a different experience while utilizing regional characteristics. This means that it is important to develop programs and contents that emphasize the identity of the region by cultivating local characteristics and build a different image. However, most of the small regions where characteristic resources are difficult to find have a problem that it is difficult to develop different programs and contents due to relatively few development opportunities and financial constraints. In this study, it was considered that it is effective to analyze characteristic features of the region and utilize the possessed assets as much as possible. Therefore, we propose a service design process that effectively supports ecotourism, one of the regional revitalization plan using local eco - assets. In the process, Venn Diagram Position and Context Map methodology was developed and verified through Sutonggol Observation Path.

• Journal of the Korea Society of Computer and Information
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• v.28 no.1
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• pp.111-119
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• 2023

This study aimed to analyze the changes in news articles related to 'Elderly Living Alone' by comparing Big Data-based news articles related to 'Elderly Living Alone' reported before and after the outbreak of COVID-19. For this, 2018 to 2019 were selected before the outbreak of COVID-19, and 2020 to 2021 were selected after the outbreak, and news articles related to 'Elderly Living Alone' were collected and analyzed using BIGKinds. The main results are as follows. First, the number of related articles decreased after the outbreak of COVID-19 compared to before. Second, there was no significant difference in the analysis of related words. Third, in the relationship diagram analysis, 'Executives' before the outbreak of COVID-19 and 'Corona 19' after that showed the most weight. This study is expected to be used as basic data in preparing improvement plans for national policies and systems in the context of the spread of infectious diseases in relation to 'Elderly Living Alone'.

• The Journal of Korean Philosophical History
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• no.35
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• pp.275-308
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• 2012

This article aims to investigate the studies of Yi Xue Qi Meng(易學啓蒙) performed by the researchers of Neo-Confucianism in Ki Ho region in later Chosun period. Philologically speaking, these studies were mainly performed by Han Won Jin and his colleagues. While the study of Yi Hwang(李滉)'s Qi Meng Zhuan Yi(啓蒙傳疑) performed by the researchers of Toegye(退溪) School lasts from the end of the sixteenth century to the nineteen's century, the Ki Ho(畿湖) scholars' study of Yi Xue Qi Meng are centered in the eighteenth century and hardly any significant work on this text is found before and after this century. In order to single out the distinctive features of Ki Ho School of Neo-Confucianism, this article examines three subjects the Ki Ho scholars delved into: (i) their theory of Tai Ji(太極), (ii) their theory of He-Tu(河圖) and the formation of eight trigrams, and (iii) the so-called Wu Wei Xiang De Shuo(五位相得說) discussed in one of the sections in Yi Xue Qi Meng titled the Source of He-Tu and Luo Shu[本圖書]. The Ki Ho scholars are remarkable in interpreting Tai Ji in Yi Xue Qi Meng in the context of the theory of Li-Qi and the theory of human nature. There are differences in opinion among the Ki-Ho scholars with regard to the relation between He-Tu and the formation of eight trigrams. Eventually, they withhold Zhu Xi(朱熹) and Hu Fang Ping(胡方平)'s attempt to synthesize He-Tu, the rectangular diagram of Fu Xi(伏羲)'s eight trigrams, and the circular diagram of Fu Xi's eight trigrams into one single principle. Han Won Jin tries to explain the relation between He-tu and the formation of eight trigrams in terms of the relation between He-Tu and the circular diagram, and his attempt is widely supported by his colleagues. This theory runs counter to traditional model of explaining truth. My conjecture is that such academic trend is further developed by the defenders of Practical Learning such as Hong Dae Yong(洪大容), who vigorously reject traditional system of truth and science, and that it partly explains why the study of Yi Xue Qi Meng ceases in the nineteenth century.

• Journal of Science Education
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• v.38 no.1
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• pp.182-195
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• 2014

Ray drawing in geometrical optics is an effective method for visible imagery of light. In this study, we developed peer instruction materials for in-service teachers' training concepts on the refraction of light including drawing rays. And then we applied these programs to 29 pre-service teachers and 21 in-service primary teachers and evaluated the degree of conceptual change in correct points from the pretest and the post one. As a result of pretesting, in spite of experiences for learning this topic in elementary and secondary education courses, most participants in the study did not well understand the path of refracted light before instructions. However, the result of post testing after the application of peer instruction materials shows that they have practiced ray drawing, which is helping visible imagery. Accordingly, in learning geometrical optics, we suggest that peer instruction with ray drawing activity for teachers' training program would be effective. We also suggest that similar approaches would be applied to other context.