• The Transactions of the Korean Institute of Power Electronics
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• v.4 no.5
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• pp.449-454
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• 1999

A new scheme of the automotive High Intensity Discharge (HlD) lamp ballast systems is proposed. The p proposed scheme consists of the high frequency IX DC converter and the low frequency DC-AC inverter, like t that the conventional HID ballast system. However, this system separates the input voltage of the ignitor from t the dc link voltage, which results in the use of lower voltage rating power devices for the HID lamp ballast s system, comparlu with convention띠 system. As a result, proposed system has a lower cost and higher e efficiency. This paper presents th$\varepsilon$ design and anlaysis of the propoSlU ballast and some 앉아、nmental results.

• Journal of The Korean Association For Science Education
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• v.23 no.3
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• pp.239-245
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• 2003

The primary purpose of the study was to determine the appropriateness o the inquiry processes and its activities as described in Science 8's which were written according to the 7th National Science Curriculum. It was found that the basic processes were well reflected on the textbooks analyzed for the research. However, only a few integrated processes and the inquiry activities could be read on the same textbooks. Furthermore, a large majority of the inquiry processes and activities were not agreed with what the tasks and titles say. Especially, the none of as many as 216 experiments were not coincided with their titles' intentions. Also suggested in the paper were the implications of the results for inquiry-based science education in the Korean middle schools.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.7
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• pp.748-756
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• 2007

In SIR filter, fringing capacitances and discontinuities yield a distorted frequency response from those expected by design formulas, especially in higher frequencies. In this paper, a procedure is presented in order to compensate for fringing capacitances and step impedance discontinuities by EM simulation for a 5th order SIR filter. This method propose the procedure of tuning the coupling and the length of individual resonator by EM simulation. For the filter composed by the tuned resonators, no further tuning is required. The procedure is experimentally justified by comparing the measured data of the fabricated filter with the simulation results.

• KSBB Journal
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• v.32 no.2
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• pp.160-167
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• 2017

Coating of individual cells with organic or inorganic materials has drawn a great deal of attention, because it provides the cells with physicochemical durability, which would contribute to the development of bioreactors, biosensor, and lab-on-a-chip, as well as to the fundamental studies in single cell-based biology. Although many strategies have been developed for coating of microbial cells, limited methods are available to coat mammalian cells because most mammalian cells do not have a robust membrane or exoskeleton. Instead, they are enclosed in a lipid bilayer, which is fluidic and vulnerable to changes in its environments. It is more difficult to treat mammalian cells in vitro than microbial cells because the surfaces of mammalian cells are not protected or reinforced by a tough coat. In this work, we report a cytocompatible and degradable nanocoat for mammalian cells. Three types of mammalian cells (HeLa cells, NIH 3T3 fibroblasts, and Jurkat T cells) were individually coated within metal-polyphenol. To maintain the viability of the mammalian cells, we performed the whole processes under strictly physiological culture conditions, and carefully selected nontoxic materials.

• Journal for History of Mathematics
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• v.20 no.4
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• pp.153-174
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• 2007

The concept of Function is not just a single concept but an integrated concept that includes various mathematic topics such as arithmetics, geometry and so on. Therefore, the concept of function is the basic principal underlying mathematics. Moreover, we should think of function as conceptual expedient for understanding the phenomena in the variously changing real world. Therefore in this article, I would like to consider the concept of an integrated function through historical investigation. Especially, from the middle ages to the 19th century, representation which related to the function has been evolved, and therefore, I will consider function as an integrated concept through changing the concept of function.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.10
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• pp.16-24
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• 2009

Independent-gate-mode double-gate(IGM-DG) MOSFET overcomes the limitation of 3-terminal device structure, and enables to operate with different voltages for front-gate and back-gate. Therefore, circuit designs becomes not only simple, but also area-efficient due to the controllability of the 4th terminal provided by IGM-DG MOSFETs. In this paper, an RF receiver utilizing IGM-DG MOSFETs is presented and also, the circuit performance is verified by the HSPICE simulations. Besides, the circuit analysis and optimization are performed for various IGM-DG characteristics.

• Journal of Science Education
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• v.34 no.2
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• pp.421-431
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• 2010

The purpose of this study was to identify instructional components supporting students' interest and creativity in American middle school science classrooms. Two 7th grade classrooms were selected, and observed for 11 class periods each. Results showed that hands-on and small group activities were the most effective ways to increase students' interest. The teachers' instructional approaches, such as individualized paced teaching, sufficient peer teaching, permissive atmosphere, various media, and purpose-focused summary game were found to influence students' interest. To enhance students' creativity, increasing interest, making hypothesis, and trying to various experimental method with sufficient time were identified as effective components.

• Journal of the Korean Society of Earth Science Education
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• v.2 no.1
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• pp.41-47
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• 2009

This study examined the difference for the ability of self-directed learning and information literacy(the ability to use information) between small group-cooperative instruction of ICT practical environment and explanatory instruction using ICT of general classroom in middle school science education. The 138 students(7th grade) participated in this study were classified in two group, experimental group(68) and controlled group(70). Experimental small group consisted of 5-6 students who had different levels and the ability of each the group was equal. The teaching of experimental group was made in the science lab which was equipped with computers to connect super high-speed Internet. The teaching of control group was made in general classroom. Under these two environment, this study was executed during 10 weeks. As the result, Small group-cooperative learning using ICT was more effective in diminishing the gap of information literacy in middle school students. And in the ability of self-directed learning, the small group learning using ICT was also more effective than general classroom instruction.

• Korean Journal of Head & Neck Oncology
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• v.15 no.2
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• pp.243-245
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• 1999

Solitary fibrous tumors are commonly arise in the pleura and less commonly in extrapleural sites. In head and neck area, solitary fibrous tumors can occur in nose, paranasal sinus, soft palate, epiglottis, thyroid, parotid and submandibular gland. To our knowledge, this is the 5th case of solitary fibrous tumor arising from the parotid gland in English literature. We report a case of solitary fibrous tumor occurred in the superficial lobe of right parotid gland which was successfully treated by superficial parotidectomy with preservation of the facial nerve.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.05a
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• pp.91-95
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• 2006

In whole world consciousness of environment maintenance have increased very quickly for the end of the 20th century. To use and disuse toxic substances have been controled at the field of industry. Also the field of lighting source belong to environmental control. And in the future the control will be strong. In radiational mechanism of fluorescence lamp mechanism is the worst environmental problem. In radiational mechanism of fluorescence lamp mercury is the worst environmental problem root. In the mercury free lighting source system the Xe gas lamp is one type. And the Ne:Xe mixing gas lamp improvements firing voltage of Xe gas lamp. Purpose and subject of this study are understand, efficiency, ideal of Ne:Xe plasma which mercury free lamp. Before ICP was designed, basic parameters of plasma, which are electron temperature and electron density, were measured and calculated by Langmuir probe data. Property of electron temperature and electron density were confirmed by changing ratio of Ne:Xe.