• Journal of Educational Research in Mathematics
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• v.23 no.4
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• pp.449-466
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• 2013

Mathematical discussion has been highlighted so that what students do actually guides their learning of mathematics and mathematical practice. However, the work of leading mathematical discussions has not yet been specified in such a way that it can be adequately studied and taught to teachers. This study analyzes a teacher's lessons that show full engagement in leading discussions, and examines the work of leading mathematical discussions in elementary classrooms. It identifies and illustrates the central tasks of leading mathematical discussions with single case questions with five steps. This article argues several key issues in leading mathematical discussions: helping students engage in struggling with important mathematical ideas, treating mathematical connections in an explicit and public way to have coherent and structured discussions, and parsing the work of teaching at a grain size that is usable in educating teachers.

• Journal of the Korean Society of Propulsion Engineers
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• v.20 no.6
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• pp.38-45
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• 2016

A study was conducted on the effect of leading edge location for the performance characteristics of a centrifugal compressor impeller. Five impellers with different leading edge location were selected for numerical analysis. The impeller with leading edge located 10% away from the inlet about meridional distance from entrance to exit showed the best total pressure ratio and efficiency. Also, this case showed relatively uniform flow distribution because of a weak intensity of the separation region at impeller exit. The impeller with leading edge located far from this location showed lowest total pressure ratio and efficiency. Performance of compressor also decreased due to non-uniform flow distribution at impeller exit.

• Journal of the Ergonomics Society of Korea
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• v.32 no.3
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• pp.253-258
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• 2013

Objective: This study investigates user performance and user perceptions of dynamic Chinese text displays (Leading display and RSVP display) when users search for target information. Background: Today, information searching with dynamic displays is widely used in TV programs, on Internet advertisements, for traffic information systems, and more. Method: A human factors experiment was conducted to compare both displays. Eighteen subjects participated in evaluating two simulated interfaces for the leading display and the RSVP display. Results: The results show that the leading display was better in terms of search time and certain subjective measurements (Easiness, frustration, anxiety). The latter results are consistent with the conclusions of other research efforts showing that dynamic displays are more effective and efficient when reading information. Conclusion: The leading display is more useful for Chinese users in terms of both information searching and information reading. Application: This study helps design dynamic displays written in Chinese texts.

• Journal of Wind Energy
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• v.14 no.3
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• pp.43-53
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• 2023

To improve AEP, wind turbine blade lengths are increasing every year. As the length of blades increases, the blade tip speed also increases. Because of the increased tip speed, the impact energy between the leading edge and raindrops also increases. The increased impact energy is the primary factor contributing to erosion of the blade's leading edge. Blade leading edge erosion reduces aerodynamic performance, increases repair costs, and causes downtime. Therefore, numerous studies are being conducted on protective solutions and RET systems to prevent and delay erosion of the blade's leading edge. However, few institutions in Korea research protective solutions and RET systems. In this study, we aim to develop a laboratory-scale RET system. The developed RET system was based on the ASTM G73-10 standard. As a result of the RET, it was confirmed that the erosion tendency was similar to that of overseas institutions. In addition, the effectiveness of the RET system was verified by a maximum erosion rate of 0.0023 for an epoxy-based protective solution.

• International Commerce and Information Review
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• v.9 no.2
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• pp.3-18
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• 2007

Now the one of problems of digital culture contents industry in korean region is to focus only on small company in the related industry. So a plan for overcoming this is a cultivation of leading company in this industry. Thus, in this paper, we tried to make an importance level between the related industries including this leading company by the AHP analysis. For achieving the objective of this paper, first of all, this study yielded the relative importance between the industries as the quantitative values. As the result of this analysis, the important factor in this leading company is 'creation' factor and this paper proposed the basic results for cultivating the leading companies for the future time.

• Current Optics and Photonics
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• v.3 no.2
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• pp.154-163
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• 2019

In this study, we developed an optical sighting system capable of shooting at a long-distance target by operating a digital gyro mirror composed of a gyro sensor and an FSM. The optical sighting system consists of a reticle part, a digital gyro mirror (FSM), a parallax correction lens, a reticle-ray reflection mirror, and a partial reflection window. In order to obtain the optimal volume and to calculate the leading angle range according to the driving angle of the FSM, a calculation program using Euler rotation angles and a three-dimensional reflection matrix was developed. With this program we have confirmed that the horizontal leading angle of the developed optical sighting system can be implemented under about ${\pm}8^{\circ}$ for the maximum horizontal driving angle (${\beta}={\pm}12.5^{\circ}$) of the current FSM. Also, if the ${\beta}$ horizontal driving angle of the FSM is under about ${\pm}15.5^{\circ}$, it can be confirmed that the horizontal direction leading angle can be under ${\pm}10.0^{\circ}$. If diagonal leading angles are allowed, we confirmed that we can achieve a diagonal leading angle of ${\pm}10.0^{\circ}$ with a vertical driving angle ${\alpha}$ of ${\pm}7.1^{\circ}$ and horizontal driving angle ${\beta}$ of ${\pm}12.5^{\circ}$.

• The Korean Journal of Physiology and Pharmacology
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• v.14 no.6
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• pp.413-417
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• 2010

To understand the function of edges in perception of moving objects, we defined four questions to answer. Is the focus point in visual motion detection of a moving object: (1) the body or the edge of the object, (2) the leading edge or trailing edge of the object, (3) different in scotopic, mesopic and photopic luminance levels, or (4) different for colored objects? We measured the Optomotor Response (OMR) and Edge Triggering Response (ETR) of goldfish. We used a square and sine wave patterns with black and red stripes and a square wave pattern with black and grey stripes to generate OMR's and ETR's in the goldfish. When we used black and red stripes, the black leading edges stimulated an ETR under scotopic conditions, red leading edges stimulated an ETR under photopic conditions, and both black and red leading edges stimulated an ETR under mesopic luminance levels. For black and gray stripes, only black leading edges stimulated an ETR in all three light illumination levels. We observed less OMR and ETR results using the sine wave pattern compared to using the square wave pattern. From these results, we deduced that the goldfish tend to prefer tracking the leading edge of the pattern. The goldfish can also detect the color of the moving pattern under photopic luminance conditions. We decided that ETR is an intriguing factor in OMR, and is suitable as a method of behavioral measurement in visual system research.

• Korean Journal of Construction Engineering and Management
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• v.13 no.2
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• pp.25-36
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• 2012

As the international construction market is rapidly expanding, Korean contractors have the need for having new leading businesses for their sustainable growth and high performance. Thus, this research tried to explore new leading businesses with two questions: 'What can be the new leading businesses?' and 'How can Korean contractors implement new leading businesses?' To this end, based on Porter's five forces framework and the resource-based view (RBV), we first derive three evaluation criteria (possibility of market entry, possibility of profit earning, and possibility of value-added earning). Next, we developed a framework for business evaluation which considers external market condition, internal competitiveness, and spin-off effects toward domestic market. Based on the framework, we defined green-energy plant, environmental plant, desalination plant, nuclear power plant, new urban development, and high-rise building as new leading business. Then, we selected green energy plant, environmental plant, and new urban development for the purpose of prior occupation of the market, consolidation of the competitiveness, and expansion of the ripple effect, respectively. Finally, we deduced market entry strategies for each business by investigating experts' opinions.

• Korean Journal of Agricultural Science
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• v.39 no.1
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• pp.143-149
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• 2012

It is necessary to construct the supply system which is stable and quality assured for professional performance of agro-food export. The purpose of this study is to present the basic information about the improvement directions on the Leading Group of Agro-food Export. The result of analysis is presented by the achievement of business objective, farm-organization and large scale-up, marketing achievement, and the fidelity of group operations etc.

• Journal of Ship and Ocean Technology
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• v.3 no.2
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• pp.1-16
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• 1999

The incompressible Reynolds-Averaged Navier-Stokes(RANS) equations are solved using the standard $\textsc{k}-\varepsilon$ turbulence model and a finite volume method(FVM)with an O-type grid system. The computed results for its performance test are in good agreement with the published experimental data. The present method is applied to the study on the leading edge radius of a hydrofoil section Calculated results suggest that the leading edge radius has some effects on cavitation performances of a 2-D foil. A natural leading edge radius for the NACA66 section is determined from this study.