• 공학교육연구
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• 제24권4호
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• pp.52-60
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• 2021

This study designed and developed a class using review games as a way to enhance students' interest, class participation, and class comprehension in engineering theory classes, and explored their educational effectiveness. To this end, a review game strategy based on the Creative Training Technique was established and applied to three engineering theory subjects. The types of review games include Jin-jin-ga, Bingo, Challenge Golden Bell, Finding hidden terms, and Completing initial sentences. As a result of applying this review game strategy to the classes over the past decade, students' satisfaction and lecture evaluation scores significantly increased compared to before application, and it was confirmed that students' interest in and understanding of the class increased significantly. Furthermore, this gamification class strategy can be a way to increase students' participation in theory classes regardless of their major, and can be applied to non-face-to-face online classes.

• 공학교육연구
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• 제25권6호
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• pp.38-46
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• 2022

In order to improve students' interest, class participation and class comprehension in engineering theory classes, a class applying review games as Jinjinga, Bingo, etc. were designed and developed. Through applying them to three engineering theory subjects, the specific effects of the strategy on students' understanding, interest, participation, and academic achievement were analyzed and the usefulness of each review game strategy was analyzed. Analyzing class data over the past 11 years, there was a clear correlation between performance of the students in the review game and their actual grades, which was found to be greater than the negative effect of absence rate on the test performance or grades. This study also researched students' perceptions compared to other general subjects not applying the review games. The results of a survey of the students who took the review game class showed the usual amount of usual studying hours increased, the burden of examination or the amount of studying hours for preparing the exam was reduced, and the class interest and achievement significantly increased compared to other subjects in the same major.

• 공학교육연구
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• 제26권5호
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• pp.3-16
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• 2023

This study was to investigate the operation status and the students' perception for both theory-focused and practice-focused online class in engineering college that were implemented in responses to COVID-19. For this purpose of the study, the survey including the open-ended questions were conducted to the 147 students in college of engineering in 2021 at one of the universities located in the metropolitan area. The survey were analyzed by SPSS 26.0 and then findings were as follows. First, while the most students were satisfied with the operation of online classes that were implemented in response to COVID-19, many students were unsatisfied with the practice-focused online class. Also, there were some differences in the level of students' satisfaction for some factors of online class operation in terms of the students' background. Second, there were significant differences in some parts of students' satisfaction in terms of the background of students. specifically, males students were more satisfied with the supports of teaching assistant in online classes than female students and the junior and senior levels of students are more satisfied with the teaching strategies of online classes than freshman and sophomore year students. Third, the level of students' satisfaction was different in terms of the types of online platforms as well as the methods of communication between students and professors. Finally, even though the students in the college of engineering understand the benefits in the online classes, they indicated the limitations and difficulties for participating in practice-focused online class and demanded the improvement of the operation for the online lab classes. The further research needs to be conducted to investigate the status of operation for online lab and practice classes in college of engineering.

• Journal of information and communication convergence engineering
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• 제10권1호
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• pp.5-10
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• 2012

The cyber class has many advantages because it removes the limitations of sharing the same time and space of a class in a classroom. However, most instructors still hesitate to use it because it is more vulnerable to academic misconduct than a faceto- face class. To overcome this problem, we identified suspected cheaters out of a group of test-takers through several objective data, and verified whether or not the suspects were actually cheaters. By investigating the status of academic cheating, we also implement our assessment system with Skinner’s reinforcement theory in order to eliminate or reduce cyber misconducts.

• Journal of Advanced Marine Engineering and Technology
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• 제39권8호
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• pp.856-862
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• 2015

Tidal current energy is an important alternative energy resource among the various ocean energy resources available. The tidal currents in the South-Western sea of Korea can be utilized for the development of tidal current power generation. Tidal power generation can be beneficial for many fishing nurseries and nearby islands in the southwest region of Korea. Moreover, tidal power generation is necessary for promoting energy self-sufficient islands. As tidal currents are always available, power generation is predictable; thus, tidal power is a reliable renewable energy resource. The selection of an appropriate hydrofoil is important for designing a tidal current turbine. This study concentrates on the selection and numerical analysis of four different hydrofoils (MNU26, NACA63421, DU91_W2_250, and DU93_W_210LM). Blade element momentum theory is used for configuring the design of a 50 W class turbine rotor blade. The optimized blade geometry is used for computational fluid dynamics (CFD) analysis with hexahedral numerical grids. Among the four blades, NACA63421 blade showed the maximum power coefficient of 0.45 at a tip speed ratio of 6. CFD analysis is used to investigate the power coefficient, pressure coefficient, and streamline distribution of a 50 W class horizontal axis tidal current turbine for different hydrofoils.

• 공학교육연구
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• 제15권5호
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• pp.54-59
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• 2012

It is reported that the constructivistic learning method (CLM) enhances the understanding of the students in the learning process, especially in engineering classes. In CLM-based classes, the students can take the initiative in the learning process, which is called the student-centered model of the learning process. This is different from the traditional learning method based on the teacher-centered model, where a teacher plays the central role in the learning process of students. The authors have applied the method of CLM to one of the Engineering classes, namely production planning and inventory control (PPIC) class for undergraduate students. The PPIC class provides multimedia-based study materials and factory visits as well as regular lecture sections to cover the whole subject of inventory control theory and practice. In the review sessions, students are divided into several groups, and question-and-answer discussions were actively carried out among these groups under the support of the teacher as a facilitator. It was observed that the student engagement in the class was very active compared to the conventional lecture-based classes. As for further support of students understanding on the subject, simulation-based materials are also under study for the class. This paper presents the review of case study of CLM-based PPIC class and discusses the feasibility of simulation-based study materials for further improvement of the class.

• 대한수학회보
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• 제59권1호
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• pp.141-154
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• 2022

Let R be a commutative ring with identity. Denote by w𝒫_w the class of weak w-projective R-modules and by w𝒫_w^⊥ the right orthogonal complement of w𝒫_w. It is shown that (w𝒫_w, w𝒫_w^⊥) is a hereditary and complete cotorsion theory, and so every R-module has a special weak w-projective precover. We also give some necessary and sufficient conditions for weak w-projective modules to be w-projective. Finally it is shown that when we discuss the existence of a weak w-projective cover of a module, it is enough to consider the w-envelope of the module.

• Journal of electromagnetic engineering and science
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• 제16권3호
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• pp.143-149
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• 2016

This work presents a method used for designing a broadband class-E power amplifier that combines the two techniques of a nonlinear shunt capacitance and a low quality factor of a series resonator. The nonlinear shunt capacitance theory accurately extracts the value of class-E components. In addition, the quality factor of the series resonator was considered to obtain a wide bandwidth for the power amplifiers. The purpose of using this method was to produce a simple topology and a high efficiency, which are two outstanding features of a class-E power amplifier. The experimental results show that a design was created using from a 130 to 180 MHz frequency with a bandwidth of 32% and a peak measured power added efficiency of 84.8%. This prototype uses an MRF282SR1 MOSFET transistor at a 3-W output power level. Furthermore, a summary of the experimental results compared with other high-efficiency articles is provided to validate the advantages of this method.

• Earthquakes and Structures
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• 제26권5호
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• pp.337-348
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• 2024

This paper presents a new seismic isolation design for liquid storage tank (LST). The seismic isolation system includes: LST, flexible membrane, sand mat and rolling seismic isolation devices. Based on the mechanical equilibrium theory, the symmetric concave rolling restoring force model of the isolation device is derived. Based on the elasticity theory and restoring force model of the seismic isolation, a simplified mechanical model of LST with the new seismic isolation is established. The rationality of the seismic isolation design of LST is explored. Meanwhile, the seismic response of the new seismic isolation LST is investigated by numerical simulation. The results show that the new seismic isolation tank can effectively reduce the seismic response, especially the control of base shear and overturning moment, which greatly reduces the risk of seismic damage. The seismic reduction rate of the new seismic isolation storage tanks in Class I, II, and III sites is better than that in Class IV sites. Moreover, the seismic isolation device can effectively control the ground vibration response of storage tanks with different liquid heights. The new seismic isolation LST design provides better isolation for slender LSTs than for broad LSTs.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 추계학술대회 논문집 학회본부
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• pp.401-403
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• 1996

In this paper, a new control strategy is presented that combines sliding mode control theory with a neural network. Sliding mode control theory requires the complete knowledge of the dynamics of the controlled system. However, in practice, one often bas only a small number of state measurements. This could be a serious limitation on the practical usefulness of sliding mode control theory. A multilayer neural network is employed to solve this kind of problem. The neural network serves as a compensator without a prior knowledge about the system. The proposed control algorithm is applied to a class of uncertain nonlinear system. The robustness against parameter uncertainty, nonlinearity and external disturbances, and the effectiveness is verified by the simulation results.