• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.2
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• pp.107-119
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• 2021

The cross-flow turbine is one of the most famous and widely used hydraulic power systems for a long time. The cross-flow turbine is especially popular in many countries and remote regions where off-grided because of its many benefits such as low cost, high efficiency at low head, simple structure, and easy maintenance. However, most modern turbines, including the cross-flow turbine, are unsuitable for the ultra-low head situation, known as less than 3m water head or zero head with over 0.5m/s flow velocity. In this study, we demonstrated a 20kW class inverted-type cross-flow turbine's performance. First, we reevaluated our previous studies and introduced how to design the inverted-type cross-flow turbine. Secondly, we fabricated the 20kW class inverted-type cross-flow turbine for the performance test. And then, we designed a testbed and installed the turbine system in the demonstration facility. In the end, we compare the demonstration with its previous CFD results. The comparing result shows that both CFD and real model fitted on guide vane angle at 10 degrees. At the demonstration, we achieved 42% turbine efficiency at runner speed 125 RPM.

• Journal of Korean Elementary Science Education
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• v.43 no.1
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• pp.64-80
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• 2024

This study aims to investigate the characteristics of verbal interaction in science class demonstrations conducted by elementary school pre-service teachers. Specifically, the study intends to examine the use of elements of verbal interaction and the progression of these interactions. Additionally, the study intends to analyze the perception of pre-service teachers about effective questioning and feedback and to determine the correlation between the proportions of the types of questioning and feedback positively perceived by the pre-service teachers and of the types of questioning and feedback used during class demonstration. Toward this end, the study analyzed the science class demonstration videos and class evaluation sheets submitted by 38 fourth-year students at the S University of Education. The results are as follows. First, pre-service elementary school teachers generally use close-ended questions during science class demonstrations. Moreover, they predicted that students would primarily provide the correct responses and would not engage in extended interaction by providing immediate feedback for the responses of the majority of the students. Second, pre-service elementary school teachers perceived the utilization of close-ended questions and immediate feedback in science class demonstrations more favorably than they did that of open-ended questions and delayed feedback. The study observed a weak positive correlation between the positive perception of specific types of questions and feedback and the use of such types in class demonstration. The results demonstrated that pre-service elementary school pre-service teachers tend to engage in fragmented verbal interactions during science class demonstrations. They primarily use close-ended questions and immediate feedback. This tendency is seemingly related to their perception of questions and feedback. Therefore, education institutions for training pre-service teachers need to provide opportunities for reflecting on verbal interactions, which tend to involve close-ended questions and immediate feedback. Lastly, assessing the perception of pre-service teachers of questions and feedback is also necessary.

• Journal of the Korean Society of Earth Science Education
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• v.4 no.3
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• pp.231-241
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• 2011

The purpose of this study lies in finding out a betterment of ongoing experimental training program in science for the secondary science teachers to increase their training ability more effectively. For this, from 2010 July to September, a preliminary study on secondary science experiment training, questionnaire on the satisfaction of 128 secondary teachers in U metropolitan city with the training program were carried out which were contributive to the preparation of a better plan for the training program to be helpful for the teachers at schools. Following are the study results. First, the class theme should be selected by the teachers who participate in the experiment for the year to raise their training ability for experiment class. Second, the direct activity of the teachers' joining in experiment training for the development of experiment training module, and the demonstration with the developed module-used experiment class need to be included to the program Third, the assessment for the demonstration of experiment attitude, the development process of experiment training module, would be more advisable compared with that for written examination for the teachers joined in the experiment training to concentrate more on the experimental activities and to get richer experiment experience As this study results show, the theme selection, class method and assessment method involved in ongoing experiment training need for betterment for the science teachers to apply it at schools and this improved experiment training program proposed by this study is suitable for that under a condition it has to be modified and supplemented to the distinct features of every city and province.

• The Journal of the Korea Contents Association
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• v.7 no.9
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• pp.240-247
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• 2007

The purpose of this study was to analyze the learning effects of video demonstration in a multitude of video screens in a science class. To examine this, an experiment from the first year science textbook was chosen, which looked at the relationship between electrical voltage and electrical current. Three experimental groups were used for the purpose of this study: 1/ a control group which used experimental still photos during a traditional class. 2/ experimental group A which used videos in a single screen, and 3/ experimental group B which used a multitude of video screens to demonstrate their effects. Post test learning effects was then carried out on each group related to the units. The results showed an improvement in grade for all groups. Experimental group B showed the most significant result, followed by the experimental group A. The control group showed the least significant grade improvement. In conclusion, the study revealed that the utilization of video demonstration in a science class is very useful and can be adapted in different forms in class. To enhance the effects of the learning method in conveying efficient meaning, versatile methods should be used to stimulate and heighten students' interests by mixing still photographs and video demonstration with various screen composition with the help of information technology.

• Journal of Engineering Education Research
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• v.15 no.3
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• pp.3-11
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• 2012

This paper discusses the effect that classroom demonstrations have on students' conceptual understanding in concepts in introductory physics. We used the same conceptual survey to probe the students' understanding on certain concepts before and after taking the course. We introduce Hake's , which is used to evaluate the effect of various kind of teaching methods, suggested by physics education research groups, on conceptual understanding of students who took the class. The effect of physics class using demonstration turned to be better than the traditional lecture, higher for students who graduated from science schools with higher prior knowledge and demonstration experience. Authors suggest to use to probe concepts which need more attention.

• Journal of the Korean Society of Earth Science Education
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• v.10 no.2
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• pp.199-213
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• 2017

The purpose of this study was to find out what pre-service teachers' views of as a good science class in evaluating class demonstrations. The study was conducted on 32 students in the second year of college who are attending teacher training schools located in central region, Korea. 32 pre-service teachers demonstrated the class with a group of 2 students, and a total of 16 lessons were demonstrated. They also evaluated the class by participating in 15 lessons except ones own class. Therefore all the collected evaluation papers were 480 sheets. This study analyze this evaluation paper and find out the good science class that earth science pre-service teachers think. As a result, the pre-service teachers' views of good science class analyzed by 3 categories. The three categories were 'Highly Engaged Instruction', 'Well-structured class design', and 'Qualitatively superior class materials'. In other words, the pre-service teachers' views that well-structured class design and active interaction were the requirements of good science class. This study confirmed that pre-service teachers can draw images of good science class through experience of class demonstration and class evaluation.

• Journal of Korean Elementary Science Education
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• v.41 no.4
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• pp.754-770
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• 2022

For teachers, noticing refers to paying attention to something, indicating they interpret it and how they are willing to react to it in the context of their own instruction. Analysis of noticing features enables us to understand the overall characteristics of the teacher's lesson design, practice, and reflection, which are core agents in the educational design and implementation. This can also be taken to be the basis of education design for competency reinforcement for teachers. Therefore, in this study, the characteristics of noticing shown in teachers' reflections after class design and demonstration were identified. For this purpose, the self-reflection journals of 106 elementary pre-service teachers enrolled in the College of Education in Gangwon-do were analyzed. In particular, the journals were gathered that were written after the demonstration dealing with the change of gas volume by temperature in science class. After designing a noticing analysis frame consisting of the five dimensions 'agent', 'stage', 'topic', 'focus', and 'stance', the frequency and ratio of noticing by each dimension's components were derived. The frequency and ratio of noticing for the dimension of 'focus' were analyzed for the dimensions of 'stage' and 'topic'. The results of the study were as follows. For the dimension of 'agent', the frequency of teacher and student was the highest, and for the dimension of 'stage', inquiry activity was the highest. For the 'topic' dimension, class design according to the teaching strategy appeared most frequently, and in the 'focus' dimension, the cases that did not specify the goal of the class and the competencies to be achieved by the students appeared most frequently. In the 'stance' dimension, description showed the highest frequency. From the analysis of how the 'focus' changes according to the 'stage' and 'topic', it was found that a characteristic focus appeared for each component of the dimension. From these results, the implications of the noticing characteristics of pre-service teachers for the design and implementation of teacher education were discussed.

• Journal of The Korean Association For Science Education
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• v.43 no.2
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• pp.87-98
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• 2023

In this study, we investigated the change in science core competency perception of high school students and the reason for change when science inquiry classes were conducted using eight 'skills' of the 2015 revised science curriculum. Fifteen first-year high school students in Jeollanam-do participated in the science inquiry class of this study, and the class was conducted for 20 hours (5 hours a day for four days). The inquiry activities used in the class consisted of four activity stages (research problems, research methods, research results, and conclusions) and each stage was constructed to include at least one 'skill (Problem Recognition, Model Development and Use, Inquiry Design and Performance, Data Collection, Analysis and Interpretation, Mathematical Thinking and Computer Application, Conclusion and Evaluation, Evidence-based Discussion and Demonstration, and Communication)'. As a result of the study, students' perception of the five science core competencies increased statistically significantly at the significance level of 0.01 through inquiry classes and more than 93% of students recognized that their science core competencies improved through the classes. However, since the class of this study was conducted for a small number of students, it is difficult to generalize the effect of the class, and so it is necessary to conduct a quantitative study for many students.

• 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.

• 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.