• Journal of the Korean Society of Propulsion Engineers
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• v.16 no.6
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• pp.56-61
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• 2012

Fuel-side cold-flow tests were performed on the technology demonstration model of a 75 ton-class liquid rocket engine combustion chamber for the first stage of the Korea space launch vehicle II. Pressure drop in the cooling channels of the combustion chamber was measured by changing fuel mass flow rate through a pressure regulating system. Pressure drop in each segment of the chamber could be obtained and a lot of pressure drop was caused by high flow velocity in the nozzle throat segment. The accuracy of a hydraulic analysis method for calculating a pressure loss in cooling channels could be verified by applying it to the cold-flow test conditions.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.6
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• pp.1-11
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• 2021

As the aging of large domestic SOC facilities accelerates, facility maintenance is also changing from safety evaluation based on the current condition to performance-oriented preventive and preemptive maintenance based on the prediction of the level of future obsolescence. In particular, in the case of bridges, class 1 and 2 bridges are systematically managed along with many studies, but for small and medium-sized class 3 bridges there is no collection and utilization of historical data presenting performance degradation during their service life. Therefore, in this study, 3D model-based demonstration DB system was designed and developed to intuitively check the damage change rate at the damage location by registering the maintenance history by life cycle for each member's exterior damage in the 3D bridge object and to enable API-based comprehensive performance evaluation.

• Korean Journal of Optics and Photonics
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• v.24 no.5
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• pp.245-250
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• 2013

The Wiener-Khinchin theorem, which means that the autocorrelation function of a signal corresponds to the power spectrum of the signal, is very important in signal processing, spectroscopy and telecommunications engineering. However, because of needs for some relatively expensive equipments such as a correlator and the signal processing system, its demonstration in most undergraduate class is not easy so far. Recently, digital oscilloscopes whose functions can be replaced foresaid equipments are marketed with development of digital engineering. In this paper, a simple demonstration of the theorem is given by a digital storage oscilloscope and a personal computer with its theoretical background. The reason that deals again with this theorem which has been introduced in 1930 is that it has been not well informed yet to us and theoretical background of the demonstration is directly introduced from its driving process. Through deriving process of the theorem, some extended physical meanings of the impedance, power, power factor, Wiener spectrum, linear system response and, furthermore, basic idea of the Planck's quantization in the black body theory reveal themselves naturally. Hence it can be referred to lectures in general physics, modern physics, spectroscopy and material characterization experiment.

• Journal of the Korean Society of Combustion
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• v.15 no.2
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• pp.1-11
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• 2010

Power generation systems based on the oxy-coal combustion with carbon dioxide capture and storage (CCS) capability are being proposed and discussed lately. Although a large number of lab scale studies for oxy-coal power plant have been made, studies of pilot scale or commercial scale power plant are not enough. Only a few demonstration projects for oxy-coal power plant are publicized recently. The proposed systems are evolving and various alternatives are to be comparatively evaluated. This paper presents a proposed approach for performance evaluation of a commercial 100 MWe class power plant, which is currently being considered for 'retrofitting' for the demonstration of the concept. The system is configurated based on design and operating conditions with proper assumptions. System components to be included in the discussion are listed. Evaluation criteria in terms of performance are summarized based on the system heat and mass balance and simple performance parameters, such as the fuel to power efficiency and brief introduction of the second law analysis. Also, gas composition is identified for additional analysis to impurities in the system including the purity of oxygen and unwanted gaseous components of nitrogen, argon and oxygen in air separation unit and $CO_2$ processing unit.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.63 no.3
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• pp.169-177
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• 2014

Operation and control system has been installed and tested to use energy storage system(ESS) for frequency regulation at 4MW class of ESS demonstration facility installed at Jeju island, Korea in 2013. Simulation tests were performed by programing language C# for power system of Jeju island to develop control algorithm. Site simulation tests were performed in control system itself without connecting power system and energy storage system. Control algorithm was coded, modified and tested to load to controller and communication system and human-machine interface were developed and tested in the process of simulation tests. After similar results to that of simulation tests by programing language were obtained, power system and energy storage system demonstration facility were connected to control system by communication system. Energy storage system for frequency regulation was tested for actual frequency and simulation frequency. The site tests showed the similar results to that of simulation tests and the control systems is possible to be operated for frequency regulation. Faster response of energy storage system for frequency regulation, less costs and less capacity of energy storage systems which cover for frequency regulation of power plants. It is expected that more studies for time-reduction and time-delay elements can make less capacity of energy storage system cover more role of frequency regulation of power plants.

• 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 Fisheries and Marine Sciences Education
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• v.27 no.4
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• pp.1147-1159
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• 2015

The purpose of this study was to verify the analysis of level of importance and satisfaction in recognitions of elementary school students on useful classes among school sport clubs using Importance-Performance analysis. In order to achieve this objective, samples were taken by using convenience sampling method among non-probability sampling methods, and 384 data were used as the final valid samples for this study except 16 data with missing items or insincere responses. The results of frequency analysis, exploratory factor analysis, independent samples t-test, IPA analysis by using SPSS 20.0 were as follows. First, Iquadrant included education contents of enhance ability to ingenuity, teaching method of provides option, teaching method of encourage participation activity, education contents of the aspect of fun, evaluation of motor function and emotion, education contents of explains key contents easily, and education contents of understanding overall context. II quadrant included education environment of good sport facility, class environment of fair opportunity for activity, class atmosphere of arouses interest, and class atmosphere of autonomous and voluntary. III quadrant included diverse teaching method and instructor's demonstration, class atmosphere of systematic learning, evaluation of fairness, objectivity, and credibility, and an atmosphere that can exercise. IV quadrant included education contents of enable acquisition of knowledge and degree of improvement into consideration, and class atmosphere of trust and respect between instructor and student.

• Journal of Korean Home Economics Education Association
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• v.30 no.4
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• pp.127-139
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• 2018

The purpose of this study was to develop and examine the effect of flipped learning in hand sewing practice. The flipped learning class was designed to three steps(pre-class, in-class, after-class). Pre-class: Students learned kinds of hand sewing by watching video and ppt. In-class: Students were evaluated for their prior learning through the quiz. After the quiz, instructor had a brief hand sewing demonstration. Then basic hand sewing practice was progressed. After that advanced project(making things using more than 3 kinds of hand sewing methods) was progressed. After-class: Students were evaluated each other through project exhibition. The effectiveness of flipped learning was measured based on the students' self-reflective journals and class awareness surveys. As the results, students were actively participated in flipped learning and satisfied with the overall quality of the flipped learning class. They said that videos, project & feedback were helpful in understanding hand sewing. Flipped learning applied to hand sewing practice showed more positive learning effect than the general practice class.

• Journal of the Korean Society of Earth Science Education
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• v.10 no.1
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• pp.38-49
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• 2017

The purpose of this study was to find out how pre-service teachers who have gone through training have thought about teaching practice. Specifically, I analyzed the relationship between college curriculum and teaching practice, and what they had felt in teaching practice. The study included 20 third grade students in teacher's college. The results of this study were as follows: First, it was found that the content knowledge and the pedagogical knowledge of the subjects taught at the university were helpful for the teaching practice. Second, they were thought that teaching practice would be helpful just to watch the class. And pre-service teachers felt that class demonstration was a necessary part of becoming a teacher. Third, pre-service teachers said that it is necessary to have a lecture in the university that can have opportunity for class demonstration for teaching practice. And also they wanted to open a lecture to learn various teaching techniques and the newest teaching methods. Fourth, pre-service teachers said that it is important to form relationships with students in order to complete the lessons through the teaching practice. And they said that they felt that the education scene was more powerful and harder than they thought. In addition, they said that through this exercise, it became a moment to feel the importance of thorough preparation and experience. In this way, teaching practice is an essential process for pre-service teachers to become teachers and it can be seen that they have many influences. Based on these results, it is necessary to review and revise the curriculum of the training colleges in relation to the teaching practice.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.243-247
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• 2005

This paper describes an on-going national R&D program for the development of a gas turbine/fuel cell hybrid power generation system and related R&D activities. The final goal of this program is to develop a 200kW-c1ass gas turbine/fuel cell hybrid power generation system and achieve high efficiency over $60\%$ (AC/LHV). In the first phase of the development, a sub-scaled 60kW-class hybrid system based on the 50kW-class microturbine and the 5kW SOFC will be developed for the purpose of concept proof of the hybrid system. Core components such as the microturbine and the SOFC system are being developed and parallel preparation for system integration is being carried out. Before the core components are assembled in the final system. operating characteristics of a hybrid system are investigated from a simulated system where a turbocharger (microturbine simulator) and a modified fuel cell burner test facility (fuel cell simulator) are employed. The 60kW demonstration unit will be built up and operated to provide the valuable information for the preparation of the final full scale 200kW hybrid system.