• School Mathematics
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• v.10 no.3
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• pp.357-374
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• 2008

The complex number system is supposed to introduce first chapter in the first grade of high school. When number system is expanded to complex numbers, the main aim is to understand preservation of algebraic structure with regard to the flow of curriculum and textbook. This research reviewed overall alternative articulation and treatment of textbooks from a logical viewpoint. Two research questions are developed below. First, in the structure of the current curriculum, when we consider student's 'level', how are the alternative articulation and treatment of textbooks in complex unit on a logical point of view? Second, What are more logical alternative articulation and treatment? What alternative articulation and treatment are suitable for a running goal? and what are the improvement which is definitive?

• Journal of the Korean earth science society
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• v.28 no.7
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• pp.775-788
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• 2007

This study was aimed to understand the structures of preservice secondary school teachers' alternative conceptions on radioactive isotopes in the interior of earth. The structure of their conceptions were analyzed by the suggestions of Niaz (1988) based on the Lakatosian frameworks. The survey was carried out on a group of seventeen students who were major in science education. The research method was open-ended written questionnaire. The results of this study show that students had apparent alternative conceptions. The high temperature and pressure' explanation for radioactive decay in earth's interior had most import effects on their alternative conceptions. It was also intended to survey their conceptional change by our teaching strategies of the philosophy of science in order to construct science concepts.

• School Mathematics
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• v.4 no.2
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• pp.193-204
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• 2002

Performance assessment has been introduced to school education as an alternative measure of the former educational assessment which put much emphasis on the result rather than the process of learning, memorization than pursuit of knowledge, and passive than active study. As for the subject of mathematics, the change of the assessment came to replace multiple choice tests with descriptive- and statement-type tests. This means animprovement on the testing system, focusing on the process of finding out the answer. The main focus, however, is still on the intellectual domain without paying due attention to the emotional domain of mathematics education. The previous studies on the assessment of emotional domain In mathematics have shown that there are stumbling blocks in the application of the assessment, such as the disputes on the reliability, objectivity, and fairness as well as the complicated procedure of applying the results to school records. The lack of the development and supply of the appropriate assessment tools have also been pointed out. Therefore, this study has been carried out with the intention of establishing an applicable standard of assessment on the emotional domain of high school matematics. As a result, detailed standards of performance assessment, which adopt oral examination, discussion, observation, and report have been developed. The problems which are likely to emerge In the course of the application of the newly developed assessment are under study as a continuing research project.

• 대한공업교육학회지
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• v.30 no.1
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• pp.1-18
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• 2005

The purpose of this study was to development a model of problem solving instruction for improving practical skill-competence in technical high school. For the study, various literature researches were reviewed intensively about problem solving process, laboratory instruction's approaches and learning principals. The problem solving instruction process was composed with identifying problems, generating alternative solutions, investigation and research, choosing a solution, acting on a plan, modeling of problem solving, testing and evaluating, redesigning and improving. The skills schema combines a four domain of skilled activity, that is, cognitive skills, psychomotor skills, reactive skills and interactive skills. The problem solving instruction was composed with five major learning systems-emotional, social, cognitive, physical, and reflective-that can be used extensively as generic lesson plashing. The teacher serves as a coach or guide for student learning. As a facilitator, the teacher challenges, questions, and stimulates the students in their thinking, problem solving and self-directed study. In this process, students represent problem with think aloud, assume responsibility for their learning and move from teacher-centered to student-centered education.

• Current Optics and Photonics
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• v.4 no.1
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• pp.16-22
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• 2020

In high resolution imaging devices, smaller aperture in the color filter causes cross talk which provides incorrect information. Plasmonic color filters (PCFs) have been reported as an alternative of the conventional color resist based-color filter (CRCF) and many studies on PCFs demonstrated the filtering function by PCFs with a sub-micron size. In this work, we investigated the cross talk performance of PCFs compared to CRCFs. The effect of cross talk over distance from the filter were measured for each filter. Despite poorer spectral filtering characteristics, PCFs were more robust against cross talk than CRCFs. Also, the further away from the filter, the more cross talk appeared. As a result, PCFs showed less cross talk than CRCFs at about 82% of the results measured at a distance of 2~10 ㎛. This study will help to make practical use of PCFs in high-resolution imaging applications.

• Journal of Educational Research in Mathematics
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• v.11 no.2
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• pp.403-419
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• 2001

The axiomatic geometry unit of the space figure in Mathematics II in the expository book of high school math curriculum (published by Ministry of Education, June 20, 1995) suggests some teaching points to bear in mind, so as not to make use of the system of axiom. However, it doesn't take the axiom about the space geometry as a starting point of argument, and so many textbooks can be found, in which intuitively true propositions are proved acceptable by the logical ambiguous statements. Thus, this study analyzes the contents of axiomatic geometry in high school math II textbooks and draws their problems. As an alternative improvement, 3 kinds of axiom on the space geometry and some important propositions, which are basic to proofs of proposition, will be presented here in this paper.

• The Korean Journal of Pain
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• v.27 no.2
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• pp.139-144
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• 2014

Background: To manage intractable cancer pain, an alternative to systemic analgesics is neuraxial analgesia. In long-term treatment, intrathecal administration could provide a more satisfactory pain relief with lower doses of analgesics and fewer side-effects than that of epidural administration. However, implantable drug delivery systems using intrathecal pumps in Korea are very expensive. Considering cost-effectiveness, we performed epidural analgesia as an alternative to intrathecal analgesia. Methods: We retrospectively investigated the efficacy, side effects, and complications of epidural morphine and local anesthetic administration through epidural catheters connected to a subcutaneous injection port in 29 Korean terminal cancer patients. Patient demographic data, the duration of epidural administration, preoperative numerical pain rating scales (NRS), side effects and complications related to the epidural catheterization and the drugs, and the numerical pain rating scales on the 1st, 3rd, 7th and 30th postoperative days were determined from the medical records. Results: The average score for the numerical pain rating scales for the 29 patients decreased from $7{\pm}1.0$ at baseline to $3.6{\pm}1.4$ on postoperative day 1 (P < 0.001). A similar decrease in pain intensity was maintained for 30 days (P < 0.001). Nausea and vomiting were the most frequently reported side effects of the epidural analgesia and two patients (6.9%) experienced paresthesia. Conclusions: Epidural morphine and local anesthetic infusion with a subcutaneous pump seems to have an acceptable risk-benefit ratio and allows a high degree of autonomy to patients with cancer pain.

• The KSFM Journal of Fluid Machinery
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• v.18 no.6
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• pp.19-26
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• 2015

The present paper presented and applied an exergy analysis method to evaluate the magnitudes and the locations of exergy losses in the conventional desuperheating and depressurizing process of high pressure and temperature steam delivery system. In addition, for the reduction of exergy losses occurred in conventional process, the present study proposed new alternative processes in which the pressure reducing valve and the desuperheater of conventional process are substituted with steam turbine and heat exchanger, and their effects on exergy loss reduction and exergy efficiency improvement are theoretically investigated and compared. From the present analysis results, the total exergy loss caused in conventional desuperheating and depressurizing process accounted for 66.5% of exergy input and 85% of the total exergy loss was due to the mixing between steam and cold water(e.g desuperheating). However, it was shown from the present analysis results that the present alternative processes can additionally reduce exergy loss by maximum 92.7% of the total exergy loss in conventional process, and can also produce additional and useful energy, the electricity of 220.6 kWh and the heat of 54.3 MJ/hr.

• Wind and Structures
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• v.10 no.2
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• pp.99-119
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• 2007

Estimations of wind flow over terrain are often needed for applications such as pollutant dispersion, transport safety or wind farm location. Whilst field studies offer very detailed information regarding the wind potential over a small region, the cost of instrumenting a natural fetch alone is prohibitive. Wind tunnels offer one alternative although wind tunnel simulations can suffer from scale effects and high costs as well. Computational Fluid Dynamics (CFD) offers a second alternative which is increasingly seen as a viable one by wind engineers. There are two issues associated with CFD however, that of accuracy of the predictions and set-up and simulation times. This paper aims to address the two issues by demonstrating, by way of an investigation of wind potential for the Askervein Hill, that a good level of accuracy can be obtained with CFD (10% for the speed up ratio) and that it is possible to automate the simulations in order to compute a full wind rose efficiently. The paper shows how a combination of script and session files can be written to drive and automate CFD simulations based on commercial software. It proposes a general methodology for the automation of CFD applied to the computation of wind flow over a region of interest.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.6
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• pp.68-74
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• 2013

Induction-heated system is innovative system which applied IH(Induction Heating) magnetic induction heating generated from induction-heated metallic package and high-frequency power circuit technique for thermal converse technique. In this occurs not burning, so that the working environment and deterioration of products can be improved. This technique is used high frequency inverter. By using high frequency inverter high frequency in the range of kHz can be made with conventional alternative current. In this contribution IGBT module is used for high frequency inverter. In this paper are discussed analysis of characteristics according to the each frequency and produced Flat plate induction heating system using 1.5kW-class half-bridge resonant inverter. In addition, operating characteristics of the system to changes in the distance between the coil and the heater, applications of system are also discussed.