• Research in Mathematical Education
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• v.6 no.2
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• pp.159-170
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• 2002

The undergraduate curriculum in differential equations has undergone important changes in favor of the visual and numerical aspects of the course primarily because of recent technological advances. Yet, research findings that have analyzed students' thinking and understanding in a reformed setting are still lacking. This paper discusses an ongoing developmental research effort to adapt the instructional design perspective of Realistic Mathematics Education (RME) to the teaching and learning of differential equations at Ewha Womans University. The RME theory based on the design heuristic using context problems and modeling was developed for primary school mathematics. However, the analysis of this study indicates that a RME design for a differential equations course can be successfully adapted to the university level.

• Journal of electromagnetic engineering and science
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• v.8 no.1
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• pp.6-11
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• 2008

Advances in low power design open the possibility to harvest energy from the environment to power electronic circuits. Electrical energy can be harvested from piezoelectric transducer. Piezoelectric materials can be used as mechanisms to transfer mechanical energy usually vibrating system into electrical energy that can be stored and used to power other devices. Micro- to milli-watts power can be generated from vibrating system. We developed definitive and analytical models to predict the power generated from a cantilever beam attached with piezoelectric transducer. Analytical models are pin-force method, enhanced pin-force method and Euler-Bernoulli method. Harmonic oscillations and random noise will be the two different forcing functions used to drive each system. It has been selected the best model for generating electric power based upon the analytical results obtained.

• Advances in nano research
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• v.1 no.3
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• pp.171-182
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• 2013

The alternating current (AC) conductivity in semiconductor crystals with an open-core screw dislocation is studied in the current work. The screw dislocation in crystalline media results in an effective potential field which affects the electronic transport properties of the system. Therefore, from a technological view point, it is interesting to investigate properties of AC conductivity at frequencies of a few terahertz. To quantify the screw-induced potential effect, we calculated the AC conductivity of dislocated crystals using the Kubo formula. The conductivity showed peaks within the terahertz frequency region, where the amplitude of the AC conductivity was large enough to be measured in experiments. The measurable conductivity peaks did not arise in dislocation-free crystals threaded by a magnetic flux tube. These results imply different conductivity mechanisms in crystals with a screw dislocation than those threaded by a magnetic flux tube, despite the apparent similarity in their electronic eigenstates.

• Proceedings of the Korean Institute of Landscape Architecture Conference
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• 2007.10b
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• pp.157-161
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• 2007

Full-scale ferro-concrete building technology came was introduced in Japan in Meiji $35{\sim}40(1902{\sim}1907)$ and heralding the beginning of urban modernization. On the roofs of these new architectural constructions, full-scale rooftop gardens were also developed. We consider that gardens established on the roofs of hotel and department stores created a new, modernized garden culture, which greatly influenced the early modern urban culture of Japan, the drama of which it conceived based on the impression in a rooftop garden is made. In this paper, we discuss the influence of Meiji-Era cultural and technological advances on rooftop gardens constructed during the Taisho $Era(1912{\sim}1926)$, as represented by the gardens of Kobe's Oriental Hotel, Tokyo's Mitsukoshi Department Store and Shimonoseki City's Akita Company. Photographic and print sources are utilized to analyze the design features and temporal changes of these pioneering rooftop gardens, as well as their influence on urban culture.

• Applied Microscopy
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• v.46 no.4
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• pp.171-175
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• 2016

A distinctive neuronal network in the brain is believed to make us unique individuals. Electron microscopy is a valuable tool for examining ultrastructural characteristics of neurons, synapses, and subcellular organelles. A recent technological breakthrough in volume electron microscopy allows large-scale circuit reconstruction of the nervous system with unprecedented detail. Serial-section electron microscopy-previously the domain of specialists-became automated with the advent of innovative systems such as the focused ion beam and serial block-face scanning electron microscopes and the automated tape-collecting ultramicrotome. Further advances in microscopic design and instrumentation are also available, which allow the reconstruction of unprecedentedly large volumes of brain tissue at high speed. The recent introduction of correlative light and electron microscopy will help to identify specific neural circuits associated with behavioral characteristics and revolutionize our understanding of how the brain works.

• Journal of the Korean Society of Safety
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• v.26 no.5
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• pp.27-32
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• 2011

Recently new technological development needs the advances in the fields of new materials. The most advanced design is not useful if new material's performance is not realized adequately for bearing the service loads and conditions. FGMs suggests the reasonable solution for the those requirements because of its wide range microstructure and the continuous constitutions. It's especially good for the heat-resisting components, piezoelectricity and aerocraft fields. However the fabrication and its experimental estimation methods have not been established because of its various freedom of material's properties. Therefore it is necessary to develope the fabrication method and estimation of strength and deformation. The experiments are conducted under a four point flexural test. According to results, this study shows that FGMs is well fabricated and the deformation and strain fields are expressed very well by digital image correlation method.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.5
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• pp.1043-1048
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• 2013

Authorities of the major industrialized countries infer that technological advances have a greater contribution to economic growth compared to traditional factors of production such as labor and capital and are actively pursuing investment in research and development. We have examined quantitatively the effect of R & D investment on exports in the IT sector in this study. Based on that results, how much of R & D investment in the IT sector should be made in order to reach trade surplus of two trillion dollars, which Korea government has aimed in 2020, is also to be analyzed.

• Proceedings of the KIEE Conference
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• 2005.10c
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• pp.223-225
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• 2005

This paper presents a novel prototype of a current source resonant inverter using insulated gate bipolar transistors for driving a streamer reactor, streamer generation technology has been recognized as one of the best methods for water treatment, disinfection, industrial wastes utilization, and so on. However, some technological difficulties related to efficient streamer production have been significant problems restricting streamer usage in the industrial plants. Introduced in this paper is a pulse density modulated high frequency inverter for a plasma generate, which is developed with the aim to improve power conversion and control characteristics of the streamer reactor by using advances in power electronic technology. The developed system implements the feedforward control-based pulse density modulation control scheme with pulse width modulation feedback control strategy to compensate temperature and other environmental influences on streamer discharge.

• Polymer Science and Technology
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• v.25 no.3
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• pp.194-200
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• 2014

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.05a
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• pp.317-320
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• 2009

At the present day, the use of containers crisscrossing seven seas and intercontinental transport has significantly increased and bringing the change on the shape of the world economy which we cannot be neglected. Additionally, with the recent technological advances in wireless sensor network (WSN) technologies, has providing an economically feasible monitoring solution to diverse application that allow us to envision the intelligent containers represent the next evolutionary development step in order to increase the efficiency, productivity, utilities, security and safe of containerized cargo shipping. This paper we present a comprehensive containerized cargo monitoring system which has adaptively embedded WSN technology into cargo logistic technology. We share the basic requirement for an autonomous logistic network that could provide optimum performance and a suite of algorithms for self-organization and bi-directional communication of a scalable large number of sensor node apply on container regardless inland and maritime transportation.