• Journal of Korean Elementary Science Education
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• v.29 no.2
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• pp.124-133
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• 2010

The study presents preliminary research on how science activities focusing on problem recognition worked and affected students' perception of their learning environment in a sixth science classroom. The science activities were based on the Science Writing Heuristic (SWH) which was suggested by Keys, Hand, Prain & Collins (1999), where problem recognition was an important part of scientific inquiry. For developing the working sheets for the modified SWH in this study, analyses of target units of 6th grade science curriculum in the aspects of problem recognition were conducted. After consecutive 6 classes with the developed working sheets for sixth graders, the student working sheets for each lesson were collected and analyzed. In order to investigate the developed units' affect on student learning, students' perceptions of their learning environment were administered before and after the applied classes. Students working sheets and questionnaires on their perceptions of learning environment indicated that students perceived that the science activities were more student-centered classes where students had active discussion and dialogue with one another giving them more chances to actively take part in the class as well as they used more properly recognized their inquiry problem.

• Journal of the Korean Society of Safety
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• v.25 no.6
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• pp.53-59
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• 2010

A fatigue damage caused by cyclic load is considered as one of the important failure mechanisms that threaten the integrity of structures and components in a nuclear power plant. In ASME code section III NB, the fatigue analysis procedure and standard S-N curves for the class 1 components are described and these criteria should be met at the design step of components. As the current ASME S-N curves are based on the very conservative assumptions such as a local stress concentration effect, immoderate transient frequencies and a constant Young's modulus, however, they can not precisely address the fatigue behavior of components. In order to find out the technical solution for these problems, a number of researches and discussion have been carried out continuously at home and abroad over the decades. In this study, detailed fatigue analyses for DVI nozzle with various mesh density of finite elements were performed to evaluate effect of stress concentration factors on the fatigue analysis procedure and the excessive conservatism of stress concentration factors are confirmed through the analysis results.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.53 no.2
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• pp.114-122
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• 2004

This paper presents a novel single-stage active-clamp type high frequency resonant inverter. The proposed topology is integrated full-bridge boost rectifier as power factor corrector and active-clamp type high frequency resonant inverter into a single-stage. The input stage of the full-bridge boost rectifier works in discontinuous conduction mode(DCM) with constant duty cycle and variable switching frequency. So that a boost converter makes the line current follow naturally the sinusoidal line voltage waveform. By adding additional active-clamp circuit to conventional class-E high frequency resonant inverter, main switch of inverter part operates not only at Zero-Voltage-Switching mode but also reduces the switching voltage stress of main switch. Simulation results have demonstrated the feasibility of the proposed high frequency resonant inverter. Characteristics values based on characteristics estimation through circuit analysis is given as basis data in design procedure. Also, experimental results are presented to verify theoretical discussion. This proposed inverter will be able to be practically used as a power supply in the fields of induction heating applications, fluorescent lamp and DC-DC converter etc.

• Journal of Engineering Education Research
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• v.26 no.6
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• pp.40-50
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• 2023

This study is to examine the validity of assessing basic-level proficiency in physics among incoming engineering freshmen through item analysis and standard setting. For empirical analysis, we examined the physics subject taken by the freshman class of 2021 at K University, considering its significance for engineering students. In this study, we initially performed item analysis utilizing both classical test theory and item response theory. Subsequently, leveraging the item and test information, we employed a modified Angoff method and the Bookmark method for standard setting. Consequently, the difficulty level initially set during item development was found to be higher than the actual performance level exhibited by the students. This study highlights a discernible disparity between the expected university standard and the real proficiency level of incoming freshmen in terms of basic academic ability in physics. Based on these research findings, a comprehensive discussion on the fundamental academic competence of engineering students was conducted, underscoring the necessity for formulating a tailored learning approach leveraging the outcomes from the basic ability test.

• Journal of Radiation Protection and Research
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• v.46 no.4
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• pp.204-212
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• 2021

Background: Identification of radioisotopes for plastic scintillation detectors is challenging because their spectra have poor energy resolutions and lack photo peaks. To overcome this weakness, many researchers have conducted radioisotope identification studies using machine learning algorithms; however, the effect of data normalization on radioisotope identification has not been addressed yet. Furthermore, studies on machine learning-based radioisotope identifiers for plastic scintillation detectors are limited. Materials and Methods: In this study, machine learning-based radioisotope identifiers were implemented, and their performances according to data normalization methods were compared. Eight classes of radioisotopes consisting of combinations of ²²Na, ⁶⁰Co, and ¹³⁷Cs, and the background, were defined. The training set was generated by the random sampling technique based on probabilistic density functions acquired by experiments and simulations, and test set was acquired by experiments. Support vector machine (SVM), artificial neural network (ANN), and convolutional neural network (CNN) were implemented as radioisotope identifiers with six data normalization methods, and trained using the generated training set. Results and Discussion: The implemented identifiers were evaluated by test sets acquired by experiments with and without gain shifts to confirm the robustness of the identifiers against the gain shift effect. Among the three machine learning-based radioisotope identifiers, prediction accuracy followed the order SVM > ANN > CNN, while the training time followed the order SVM > ANN > CNN. Conclusion: The prediction accuracy for the combined test sets was highest with the SVM. The CNN exhibited a minimum variation in prediction accuracy for each class, even though it had the lowest prediction accuracy for the combined test sets among three identifiers. The SVM exhibited the highest prediction accuracy for the combined test sets, and its training time was the shortest among three identifiers.

• Journal of Dental Rehabilitation and Applied Science
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• v.20 no.2
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• pp.121-134
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• 2004

This article describes a clinical protocol for the conventional rehabilitation of patient diagnosed with partial anodontia. A combined dental therapy approach was used and included endodontic therapy and root capping on the maxillary central incisors, fabrication of a maxillary overdenture, and fabrication of mandibular konus overdenture supported by 3 konus abutments. Within this protocol, tooth-supported overdenture prostheses are used for 2 purposes: first, to obtain the most rigid retention and function at an established maxillary-mandibular relationship; and second, to continuously maintain function and esthetic appearance applying immediate dentures after teeth extraction. The idea behind this protocol and its associated clinical procedures is presented along with a discussion compared with implant therapy. In the case introduced, and after 7 years of observation, the therapy can be seen as a success. We increased the occlusal vertical height in this case, but it would be more appropriate to see this as recovering the occlusal vertical height that was lost. The process of increasing the occlusal vertical height, that is restoration of the face, modification of the extrinsic occlusion of the incisors, and retraction of the mandible is very difficult and important. Ultimately, class III malocclusion is fixed, adequate occlusal vertical height is gained, and the retracted posterior anodontial portion is restored by prosthodontic dentures based on the rigid support theory. The result of the therapy done on the later-achieved malocclusion with partial anodontia on the posterior portion must consider the following in order to maintain the safety of the esthetics of the tooth and face for a period of time: 1) occlusal restoration with an ideal occlusal vertical height, 2) allowance of the final occlusion induced by the functional relationship of the upper and lower jaw, 3)final occlusion functionally induced by the lip competence limit.

• The Mathematical Education
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• v.59 no.4
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• pp.313-329
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• 2020

The purpose of this study was to develop an integrated teaching model that integrates mathematics and ethics with social justice theme centric approach. To solve the research problems, the investigator conducted literature studies on the 2015 revised mathematics curriculum, 2015 revised mathematics 3rd to 6th grade textbooks, and the 2015 revised ethics curriculum.. Based on the results of analysis, the mathematics and ethics integrated model for social justice was devised by using the three axes of mathematics subject, ethics subject, and social justice. The integrated class of mathematics and ethics for social justice consists of the steps of problem recognition (ME 1), analysis (ME 2), discussion (ME 3), inquiry and practice (ME 4), and it can be implemented in a total of 27 ways. In order to confirm the effectiveness of the integrated model, two classes of sixth grade were selected as experimental and comparative classes. As a result of the study, the integrated class of mathematics and ethics can be used as a tool to improve the value perception of mathematics, However, it should be conducted with full consideration of students' mathematical tendencies in advance. Also, it can improve students' social consciousness. However, practice and experience-oriented classes are effective to overcome 'reserved agency' problem. Finally, it can improve students' perception of integrated classes and their creative thinking and critical thinking skills.

• Journal of Gifted/Talented Education
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• v.22 no.2
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• pp.291-315
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• 2012

This study try to analyze feature of model creation and model developing process for gifted students and the activity of students and teachers affected those processes in scientific model constructing class for phase change of moon. For this, I teach scientific model constructing class for science gifted students. I shoot video and record the voice for whole class and each group activity, have a face-to-face talk for selected group members, analyze the paper of activities. I reconstruct model creation and model developing process for each groups and each students, draw a influence that activity aspects of the students and role of the teacher affected modelling process based on those data. After analyzing, I find that discussion in the group contribute model creation and model developing process and developing process of each model changed according to the similarity between target model and first model. The more the students actively participate group activities, the more first model is diversified and final model is more elaborated. Also, the teacher influence model creation and developing process.

• Journal of Ethics
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• no.75
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• pp.63-98
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• 2009

The Social Conflict Index in Korea is considerably high. In the situation where both parties' interests conflict each other, Korean society has shown immature democracy, which couldn't peacefully resolve the conflict because of the lack of tolerance against the counterparty's position. In terms of upbringing educated citizens, who could democratically communicate with others and approach problems, communication skill training is very important, reducing social costs by extreme conflict. Thus, this paper studied the necessity of communication skills training and its sociopolitical implication through case studies about "Communication and Negotiation" class, which is proceeded under university liberal education. Under current university curriculums, increased liberal education programs, related with speaking, focus on cultivating logical and critical thinking in the main. Based on these thinking skills, "Communication and Negotiation" has important implication in terms of cultivating mindset which resolves conflicts and considers other's position by collaborative and emotional perspectives. In terms of cultivating practical communication skills, this "Communication and Negotiation" class requires the change of teaching skills with various training programs, under students' active participation and feedback in the class exercise for resolving problems. Ultimately, through "Communication and Negotiation" class, and as members of society, students could learn matured citizenship and sense of responsibility by respecting others' position and reasonably resolving conflicts.

• Journal of Gifted/Talented Education
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• v.19 no.1
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• pp.119-140
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• 2009

This paper examined its possibility and made its new definition by finding relevant bases in order to make a close inquiry into its Identity and direction at this point when cyber-based gifted education academy is established and operated again by its necessity And 4 models which can be used in special education for the gifted were developed making a link with special education for the gifted by collecting and re-classifying cyber educational methods developed by basic research as priority of the educational method which is considered to be the most urgent issue in practical cyber learning. It is a project-type cooperation education model, an information collection-type research education model, a community-type discussion education model, and a problem focus-type e-PBL education model. To apply developed leaching-learning models to reality, students at gifted education academy in Gyeonggi Cyber Gifted Province were imputed models in different ways respectively for 4 months. As a result of analysis and statistical data of activity level and satisfaction level of students who participated in learning activity, it appeared that high level of satisfaction and active activity level were induced compared to the previous method based on tasks. It is expected that this paper will provide the bases when each cyber-based gifted education academy plans operation plan later on, and it will provide proper methods when cyber guidance teachers plan class activities.