• Journal of Electrical Engineering and Technology
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• v.13 no.1
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• pp.250-255
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• 2018

This paper presents a method for minimizing standby power consumption in wireless power transfer (WPT) system via magnetic resonance coupling (MRC) that operates at 6.78 MHz. The proposed circuit controls the required capacitance according to operational condition in order to reduce standby power consumption. Based on an impedance characteristic of the class-E power amplifier, operational principles of the proposed circuit are analyzed. Moreover, to verify the effectiveness of the proposed class-E power amplifier, an 8 W prototype for WPT system is implemented. The measured input power of the proposed class-E power amplifier at standby condition is reduced from 5.81 W to 3.53 W.

• Journal of Engineering Education Research
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• v.23 no.5
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• pp.16-25
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• 2020

This article aims to analyze the experience of designing and operating a class model linking undergraduate and graduate students in engineering education and suggest its development direction. To achieve these objectives, the undergraduate-graduate linked class model was applied to community problem-solving education and a case was analyzed. It also specifically presented the process of how we design the class model and what the actual operational performances and improvements are. This study found that undergraduate and graduate students could build integrated and horizontal cooperative relationships in their classes through undergraduate-graduate linked education and, particularly, graduate students could gain meaningful educational experiences. However, it was difficult to obtain tangible performances through the team activities of these students within a semester. In order for engineering colleges to operate undergraduate-graduate linked education, it would be necessary to provide a longer and more systematic educational environment and better curriculum. The study tried to seek specific tasks and ways to improve them.

• Journal of Engineering Education Research
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• v.22 no.3
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• pp.68-77
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• 2019

This study dealt with a case study on the application of flipped learning to solid mechanics in college of engineering and analyzed the results of Pre-class survey, In-class activities, and Post-class survey to examine the effects of flipped learning. Total sample size of the analysis was 32 students who applied for solid mechanics in mechanical engineering department, consisting of 23 students in sophomore, five in junior and four in senior. The class was operated in three stages: Pre-class, In-class, and Post-class. The response of the students was observed at each stage of the class. According to the results, flipped learning was effective in learning knowledge of major subjects in engineering, and students actively participated in class activities and conducted smooth discussions with team members. Flipped learning has also improved students' class concentration and academic ability. Most of the students have expressed their intention to take classes or actively recommend other students when the classes are held. Effective classes will require systematic discussion guidance because flipped learning is closely related to discussion activities.

• Korean Journal of Community Nutrition
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• v.10 no.6
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• pp.952-962
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• 2005

To explore the relationship between economic status and food and nutrient intake patterns, the 2001 National Health and Nutrition Survey result was analyzed. Dietary intake data of 6,978 Korean adults of 20 years and older who participated in the 2001 National Health and Nutrition Survey were used along with their demographic data. Economic status of the subjects was classified into the following 4 groups based on the self-reported average monthly income of household with reference to the minimum monthly living expenses (MLE) in 2001 : low < $100\%$ MLE $\leq$ middle < $200\%$ MLE $\leq$ high < $300\%$ MLE $\leq$ higher, Individuals in the higher income class had significantly higher mean intake for most of the nutrients including energy, protein, carbohydrate, fat, calcium, thiamin, riboflavin, niacin and vitamin C, and a higher percentage of energy intake from fat. In addition, they consumed more animal foods including meats, eggs, fish/shellfish, milk/dairy products and fats. On the other hand, the mean intakes of individuals in the lower economic class for calcium, vitamin A, and riboflavin were lower than $75\%$ of RDAs. And, there was a predominant difference in contribution of fat to total energy intake among the groups of different economic status. These results showed that household income is an important factor influencing the food and nutrient intake patterns of the Korean adult population. Although individuals at different age classes may respond differently to a change in economic status, developing and implementing nutrition policy and intervention programs for those nutritionally vulnerable groups should consider the economic status as an important factor to customize and differentiate the content of the Program. (Korean J Community Nutrition 10(6) : $952\∼962$, 2005)

• Journal of Aerospace System Engineering
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• v.11 no.4
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• pp.48-53
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• 2017

Liquid rocket engines (LREs) are very complex systems that include combustion chambers, turbopumps, gas generators, ducts and tubes, valves and etc. Most components of the LREs require higher than or equal to level 6 IT (ISO Tolerance). The components along with pipe line and/or tubing must dispose not to interfere each other. In addition, effectiveness of maintenance and service after assembling should be considered when the allocation of the components are determined. Especially at the stage of the development, tolerance accumulations or unpredictable errors may result in misalignment and/or mismatches at interfaces of the parts. Namely, it is the engine assembling process that many inherent risks are realized and crises or incidents occur. Therefore, a rapid reaction system should be prepared. In this research, 7 tonf class liquid rocket assembling process was studied and actual building steps were introduced.

• Journal of Korean Home Economics Education Association
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• v.30 no.2
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• pp.137-147
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• 2018

The purpose of this study was to develop and examine the effects of flipped learning in ancient Mesopotamian costume history. The flipped learning class was designed to three steps(pre-class, in-class, after-class). Pre-class: Students learned the socio-cultural background of Mesopotamia by watching videos online and Mesopotamian costume with PPT. In-class: Students were evaluated for their prior learning through the quiz. After the quiz, the instructor had a supplementary mini-lecture. Then the advanced learning was progressed with the team project(Mesopotamian costume analysis) by online Louvre Museum. Students made a team presentation and the instructor provided feedback. After-class: The effectiveness of flipped learning was measured based on the students' self-reflective journals and class awareness surveys. As the results, students actively participated in flipped learning and the class was rated appropriate. Students were satisfied with the overall quality of the flipped learning class. The Effect of Flip Learning Classes in reflective journals were shown as 'related flipped learning style,' 'related online Louvre museum project,' 'understanding of cooperative learning,' and 'contents of the class'. In conclusion, the flipped learning applied to Mesopotamian costume history was positive as a learner-centered education.

• Journal of Practical Engineering Education
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• v.14 no.3
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• pp.499-504
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• 2022

Artificial intelligence is expanding its reach throughout our society, and education is no exception to its scope of application. In line with this trend, we conducted a computer programming class for teachers in graduate school. The final purpose of this class is to develop the programming skills of teachers who teach students to code artificial intelligence programs. This paper studies how the logical thinking and mental consistency of teachers, who are learners, are related to programming aptitude and describes education environmental factors of the class. It was confirmed that logical thinking and mental consistency were proportional to the programming score. This proportional relationship is expected to apply to students learning programming languages. When team formation is required in programming classes, it is expected that better learning effects will be achieved if students with excellent logical thinking and mental consistency are included in each team.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.23 no.3
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• pp.215-221
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• 2023

If the C++ programming class, an object-oriented language capable of modeling similar to the real world, is developed as a curriculum that introduces the flipped learning model, students' active problem-solving skills can be cultivated. In this subject development case, it is significant that the flipped learning technique was applied to the programming class and was effective in improving students' active problem-solving skills. First, the lectures in the 4th session were divided into Pre-Class, In-Class, and Post-Class, and the class was conducted in a way that suggested class goals suitable for the subject and formed a team to discuss. At the end of the lecture, a follow-up survey was conducted to check whether the learners learned effectively.

• Journal of Food Hygiene and Safety
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• v.28 no.1
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• pp.50-55
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• 2013

Since 1 June 2012, it is prohibited to sell oilfish as a food material but there are still many illegal cases of selling oilfish as if it is tuna or grilled Patagonian toothfish. So it is absolutely crucial to construct the system to distinguish the real food material from oilfish. There are two sorts of oil fish called Ruvettus pretiosus and Lepidocybirium flavobrunneum involved in Percifomes order and Gempylidae class. 16S DNA gene region in mitochondria was selected to design the specific primers. For design species-specific primer, the theoretical experiment were performed for the sequences of R. pretiosus, L. flavobrunneum, Thunnus thynnus, Thunnus albacores, Makaira mitsukurii and Xiphias gladius, registered at the Gene bank from the National Centre for Biotechnology Information, using BioEdit 7.0.9.0. program. Through the analysis of the result from experiments, it was possible to design the 4 kinds of primers to distinguish R. pretiosus and L. flavobrunneum. As a comparison group, 3 kinds of tuna and 4 kinds of billfishes were selected and experimental verification was performed. As a result, for R. pretiosus and L. flavobrunneum, R.P-16S-006-F/R.P-16S-008-R and L.F-16S-004-F/L.F-16S-006-R primers were selected eventually and PCR condition was established. In addition, 178bp and 238bp of PCR products were confirmed from the established condition and non-specific band was not amplified among similar species. Therefore, the species-specific primers developed in this study would be very useful and used in various ways such as internet shopping mall and illegal distributions with fast and scientific results.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.1
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• pp.61-68
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• 2010

In this work, a reduced size 20W quasi class-E Power Amplifier(PA) with defected ground structure load-network is presented for WCDMA base station application. Harmonic impedances required for the class E operation are satisfied by applying the dumbbell and the asymmetric spiral DGS. Open impedance for 2nd harmonic frequency which has the highest power and nearly short impedances for other higher order harmonics are provided by the proposed DGS load-network. The maximum Power Added Efficiency(PAE) of 70.2 % at the output power of 43.1 dBm with the saturated power gain of 12.7 dB is achieved by the proposed quasi class-E PA, which is comparable to the performance of the reference class-E PA. Total size of the proposed class-E PA is only $50{\times}50\;mm^2$ and much smaller than the conventional class-E PA that is loaded with a number of open stubs.