• 한국연소학회:학술대회논문집
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• 2012.04a
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• pp.337-339
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• 2012

This study investigates the combustion and heat transfer characteristics of a 100MWe pulverized coal boiler retrofitted for demonstration of oxy-coal combustion. By computational fluid dynamics (CFD), the flame temperature and wall heat flux were compared for air-fuel and oxy-fuel combustion with different $O_2$ concentration in the oxidizers. It was found that the oxy-fuel combustion requires an $O_2$ concentration higher than 27 vol.% for the boiler to achieve the similar value of wall heat flux with air-fuel combustion.

• KIEAE Journal
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• v.4 no.4
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• pp.45-52
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• 2004

Simulation of daylighting by computer program is a method to avoid unnecessary efforts in manufacture of its testing models, to reduce its measuring tolerances and be able to provide variations of various weather conditions as well. Many simulation programs on daylighting have been released freely or commercialized for selling, however, a demonstration of their availability and validity as a tool for evaluating daylighting performance is required since each one has its own characteristics. The objectives of this study lie in suggesting an application method of evaluation tools and demonstration of limits and characteristics so as to more easily determine the daylightingperformance in the very initial stages of planning for an arbitrary office space in which windows with daylight access are built. We produced scale model of the general light inducing type side lighting with lightshelfand ceiling, and the luminance (at 78 measuring points) and illuminance (at 84 measuring points) were measured in a clear sky. And a comparison of the measured values and the calculated values from a computer simulation using the Lightscape program was performed.

• Journal of Electrical Engineering and Technology
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• v.7 no.1
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• pp.103-108
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• 2012

The present study describes the considerations on the long-term reliability of the on-line partial discharge (PD) ceramic sensor for thermal power generators. Voltage acceleration aging tests were carried out under continuous and impulsive thermal aging at more than $100^{\circ}C$, considering the practical service environment. Experimental results show that the sensors have a life that could last for more than 100 years, excellent dielectric characteristics, and insulation strength. In addition, the ceramic on-line PD sensors were installed in a thermal power generator in Korea for demonstration. The results of the PD calibration and test voltage application prove that the on-line ceramic sensors have satisfactory performances for on-line PD measurement.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2003.11a
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• pp.365-367
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• 2003

Total six units of 3㎾ photovoltaic system and data acquisition system (DAS) are constructed for analyzing performance of PV system at field demonstration test center of Gwang-Ju in Korea. As climatic and irradiation conditions are varied. operation characteristics of the PV system are collected and analyzed in data-acquisition system furthermore, not only performance test of each PV system component such as PV module and power conditioning system but also performance of total PV system e.g. system efficiency power and loss factor at the site are reviewed.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.3
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• pp.249-257
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• 2013

This study newly presents a synthetic phase tuning technique to suppress the unwanted torsional mode while enhancing the desired torsional mode in a pipe. Specifically, we aim at the enhancement of the first torsional mode and the suppression of the undesired, second torsional mode. Earlier efforts were to enhance the desired wave mode only in the hope that the enhancement results in the suppression of the unwanted wave mode. Unlike these efforts, the suggested technique makes the complete cancellation of the unwanted wave mode but it is shown to enhance the desired first mode for torsional wave problems. In the present study, the synthetic phase tuning is developed for the cancellation of the unwanted wave mode, meaning that the number of necessary experimental equipments is reduced. Simulation and experiment were carried out to check the effectiveness of the proposed method. As an application of the suggested technique, we investigated the reflection and mode conversion characteristics of the first torsional mode according to the step thickness variation in a stepped pipe.

• Korean journal of communication and information
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• v.54
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• pp.32-57
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• 2011

This study examined how the Korean courts have made a balance between rights of school teachers' expression and the public interests derived from regulating their rights for expression in related cases. Under the Korean laws such as National Public Service Law and the Law on Assembly and Demonstration, school teachers are considered as civil servants and basically not allowed to assemble to demonstrate for their own interests. The analysis revealed that in 24 cases from a total of 31 teacher-related court cases, teachers were found guilty in violation of related laws. In deciding whether the teachers' participation on anti-government assembly was guilty or not, the courts put an emphasis on public purpose of their expression, the degree to which their expressions affect the society, and specific contents of their expression. Conclusively, it was found out that in applying the related law, Korean courts tend to overweigh the public interests, rather than the teachers' right to express.

• Journal of Korean Society for Quality Management
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• v.49 no.3
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• pp.341-358
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• 2021

Purpose: After product development, a Reliability Demonstration Test(RDT) is performed to confirm that the target life has been achieved. In the RDT, there are cases where the test equipment cannot accommodate all samples. Therefore, this study considers a test method to most economically demonstrate the target life of the product at a certain confidence level when the sample size is larger than the capacity of the test equipment. Methods: If the sample size is larger than the capacity of the test equipment, test equipments may be added or the test time of individual samples may be increased. So the test method is designed to cover this situation with limited capacity. A zero-failure test method is applied as a test method to RDT. To minimize the cost, the test cost is defined and the cost function is obtained. Finally, we obtain the optimal test plan. Results: A zero-failure test method is designed when the sample size is larger than the capacity of the test equipment, and the expected total cost is derived. In addition, the process of calculating the appropriate sample size, test time, and number of test equipment is illustrated through an example, and the effects of model parameters to the optimal solutions are investigated numerically. Conclusion: In this paper, we study a zero-failure RDT with test equipment that has limited capacity. The expected total cost is derived and the optimal sample size, test time, and number of test equipment are determined to minimize the expected total cost. We also studied numerical examples and for further studies, we can relax some restrictions in the test model and optimize the test method.

• The Journal of the Korea Contents Association
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• v.19 no.3
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• pp.466-474
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• 2019

The purpose of this study was to investigate the enhancing creative competency and changes in academic challenge for the pre-service teachers. For this purpose, 94 pre-service teachers participated in project learning through the preparation of the convergence instruction and the class demonstration during one semester. The pre and post questionnaire survey was conducted the measurement of creative leader competence and K-NSSE for academic challenge. Analysis of data was performed using the IBM SPSS 18.0 program for the corresponding sample t test. The creative competency included 'higher mental thinking', 'problem solving', 'curiosity', 'sensitivity' 'task commitment', 'the pursuit of social value', and 'co-operations and considerations'. This results was significant(p< .05). Academic challenge, high-order learning domain and learning strategies domain were significant(p< .05). Based on this, in order to generalize the convergence education and convergence lesson, it is necessary to design various convergence lessons and practice study to make a plan and practice it. In addition, the implications for the necessity of correcting and supplementing the effects after repeated convergence lessons were discussed.

• Journal of the Architectural Institute of Korea Planning & Design
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• v.36 no.3
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• pp.49-58
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• 2020

Based on Merrill's instructional theory, this study pursued to develop a demonstration-based architectural design class operation model for the 3^rd year undergraduate students taking a Spring semester design studio class. The model was designed and used particularly to improve architectural thinking abilities of under-motivated learners. Learning effects of the model were examined based on the preliminary data obtained for 3 consecutive years, 2017 through 2019. A total of 52 students were participated in the class and observed by the instructor. Once developed, the model has been continually updated and improved based on results of each class operation. Five types of demo. were used in the model. First, direct contacts of the instructor with under-motivated learners were turned out to be the most preferred demo(demo. 4), while watching and listening of the demo(demo.3) between the instructor and motivated learners taking place in class was ranked at the second place. Belief of under-motivated learners on the instructor as a professional should be highly valued for improving their architectural thinking abilities. Second, motivated peers' direct help for under-motivated ones was placed in the third rank. Social attitudes of under-motivated learners towards accepting motivated ones' helps were determined the particular demo's appropriateness. Third, a set of guidelines for operating the model in undergraduate design studio classes were developed and suggested.

• Journal of The Korean Association For Science Education
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• v.18 no.4
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• pp.473-483
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• 1998

A learner's cognitive conflict with his /her existing conception is regarded to be one of the most important factors for a conceptual change. In this study, the effects of the conflict situation types on inducing students' cognitive conflicts in Newton's law were examined. The thirty-four students of 10th grade were selected from a rural high school based on the result of pre-test. The two different types of conflict situations among many possible types were used in this study. One type was using logical conflict situation and the other was demonstrating real conflict situation. The levels of cognitive conflict were measured by 4-point Likert scale by three interviewers. As the results, the demonstration method was more effective than the logical argument method. In case of the logical argument method, rather than showing scientific conceptions, suggesting another misconception was more effective to the students who have misconception. However, logical argument method was not effective to those who have scientfic conceptions. To the students who have unscientific conceptions, the demonstration method was very effective for inducing cognitive conflict. From the results of this study, demonstration method of teaching seems to be very effective for inducing students' cognitive conflict and overcoming their misconceptions on scientific concept.