• Carbon letters
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• v.9 no.3
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• pp.218-231
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• 2008

Carbon fibers are a new breed of high-strength materials which have been described as a fiber containing at least 90% carbon obtained by the controlled pyrolysis of appropriate fibers. Carbon fiber composites are ideally suited to applications where strength, stiffness, lower weight, and outstanding fatigue characteristics are critical requirements. They also can be used in the occasion where high temperature, chemical inertness and high damping are important. In recent decades, carbon fibers have found wide applications in commercial and civilian aircraft, recreational, industrial, and transportation markets. Therefore, understanding the basic structure, synthesis and physicochemical properties of carbon fibers is very important to apply them as a precursor of above applications. This review paper discuss the general information and manufacture technique of carbon fibers used for improving the performance of composite materials in various industries for the present.

• Journal of the Korean Mathematical Society
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• v.58 no.3
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• pp.723-740
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• 2021

Design and maintenance of large span roof structures require an analysis of their static and dynamic behavior depending on the physical parameters defining the structures. Therefore, it is highly desirable to estimate the parameters from observations of the system. In this paper we study the parameter estimation problem for damped shallow arches. We discuss both symmetric and non-symmetric shapes and loads, and provide theoretical and numerical studies of the model behavior. Our study of the behavior of such structures shows that it is greatly affected by the existence of critical parameters. A small change in such parameters causes a significant change in the model behavior. The presence of the critical parameters makes it challenging to obtain good estimation. We overcome this difficulty by presenting the Parameter Estimation Algorithm that identifies the unknown parameters sequentially. It is shown numerically that the algorithm achieves a successful parameter estimation for models defined by arbitrary parameters, including the critical ones.

• Journal of the Korean Mathematical Society
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• v.59 no.5
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• pp.869-890
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• 2022

We develop a rigorous mathematical framework for studying dynamic behavior of cracked beams and shallow arches. The governing equations are derived from the first principles, and stated in terms of the subdifferentials of the bending and the axial potential energies. The existence and the uniqueness of the solutions is established under various conditions. The corresponding mathematical tools dealing with vector-valued functions are comprehensively developed. The motion of beams and arches is studied under the assumptions of the weak and strong damping. The presence of cracks forces weaker regularity results for the arch motion, as compared to the beam case.

• Nonlinear Functional Analysis and Applications
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• v.27 no.2
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• pp.405-432
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• 2022

Cracks in beams and shallow arches are modeled by massless rotational springs. First, we introduce a specially designed linear operator that "absorbs" the boundary conditions at the cracks. Then the equations of motion are derived from the first principles using the Extended Hamilton's Principle, accounting for non-conservative forces. The variational formulation of the equations is stated in terms of the subdifferentials of the bending and axial potential energies. The equations are given in their abstract (weak), as well as in classical forms.

• Journal of Practical Engineering Education
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• v.13 no.2
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• pp.233-242
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• 2021

In this paper, as a liberal arts course for non-majors, we proposed a supervised learning artificial neural network parameter optimization method and a basic education method for activation function to design a basic artificial neural network subject curriculum. For this, a method of finding a parameter optimization solution in a spreadsheet without programming was applied. Through this training method, you can focus on the basic principles of artificial neural network operation and implementation. And, it is possible to increase the interest and educational effect of non-majors through the visualized data of the spreadsheet. The proposed contents consisted of artificial neurons with sigmoid and ReLU activation functions, supervised learning data generation, supervised learning artificial neural network configuration and parameter optimization, supervised learning artificial neural network implementation and performance analysis using spreadsheets, and education satisfaction analysis. In this paper, considering the optimization of negative parameters for the sigmoid neural network and the ReLU neuron artificial neural network, we propose a training method for the four performance analysis results on the parameter optimization of the artificial neural network, and conduct a training satisfaction analysis.

• Journal of The Korean Association For Science Education
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• v.33 no.4
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• pp.708-717
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• 2013

The new paradigm of the 21st Century science education explores a wide range of possibilities that can foster students' interest toward science and creative convergence thinking. In this study, through the analysis of programs that were developed in 'STEAM leader school' and 'STEAM teacher association for research' supported by the 'Ministry of Education, Science, and Technology,' we analyzed the linking frequency with each of STEAM education's fields and teachers' perception for the convergence strategy of technology and engineering. The results of this study show that linking frequency of technology and engineering is lower than the field of arts and mathematics in elementary school, but higher in middle and high school. 'Introduction technology contents in lives' in technology and 'crafts activity' in engineering are the most used teaching and learning strategy in STEAM education. But, although 'crafts activity' is engineering's major way of learning, many teachers understand and use it as a technological teaching learning strategy. It is important to understand that each of STEAM education's field has a unique nature and educational implications, for the effective settlement of STEAM education, we need to consider teaching and learning strategy in various way.

• International Journal of Advanced Culture Technology
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• v.6 no.3
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• pp.1-11
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• 2018

The purpose of this study is to develop and analyze the meaning and contents of the "H-STEAM teaching & learning model" which combines Science, Technology, Engineering, Arts & Mathematics (STEAM) with the elements of Humanities. We developed this model based on the key competencies linked with career path for middle school students in Korea, with the recognition of two issues. First, the existing Korean STEAM education lacks the elements of humanities, thus failing to achieve an authentic convergence education. Second, it is necessary to develop a program that might correspond to the Free Semester Program that was first introduced in 2013, and implemented at full scale in 2016 for middle school students in Korea. The advantages of H-STEAM are as follows: First, H-STEAM enables students to flexibly think while traversing the physical world and the symbolic world in the process of dealing with the daily problems. Second, it combines advanced technology with human sensibility and imagination, and enables students to derive creative outcomes that stimulate their minds. Third, it makes students feel and realize a point of contact between the subject that students learn, and jobs of the real world.

• Journal of Gifted/Talented Education
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• v.25 no.3
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• pp.401-420
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• 2015

The purpose of this study was to perform a comparative analysis of the research trends in STEAM education in gifted education and suggest educational implications to improve the current STEAM education for the gifted. The results were as follows. First, STEAM education has been increasing in the past couple of years and gifted and talented education took up relatively high proportion of it. This demonstrates that gifted education closely related to creative and versatile individuals plays a leading role in STEAM education. Second, researches on STEAM education and STEAM education for the gifted targeted elementary school students the most. Third, researches on the development of STEAM program for the gifted have been mainly addressing science-oriented convergence programs. Among them, programs including all the five combined factors(Science, Technology, Engineering, Arts and Mathematics) were the most common. In terms of learning types, a criterion-referenced teaching-learning model has been developing and there were diverse learning types which applied teaching-learning models tailored to characteristics of a gifted child. The researches related to STEAM programs'application effects on creativity were most dominant.

• Journal of Broadcast Engineering
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• v.27 no.6
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• pp.848-859
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• 2022

This paper presents a novel 360-degree video streaming system for large-scale immersive displays and its ongoing implementation. Recent VR systems aim to provide a service for a single viewer on HMD. However, the proposed 360-degree video streaming system enables multiple viewers to explore immersive contents on a large-scale immersive display. The proposed 360-degree video streaming system is being developed in 3 research phases, with the final goal of providing 6DoF. Currently, the phase 1: implementation of the 3DoF 360-degree video streaming system prototype is finished. The implemented prototype employs subpicture-based viewport-dependent streaming technique, and it achieved bit-rate saving of about 80% and decoding speed up of 543% compared to the conventional viewport-independent streaming technique. Additionally, this paper demonstrated the implemented prototype on UCSB AlloSphere, the large-scale instrument for immersive media art exhibition.

• Journal of environmental and Sanitary engineering
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• v.22 no.4
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• pp.105-117
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• 2007

The research was conducted based on the 1012 cases questionnaire for the purpose of to evaluate the change effect of university student's consciousness and behavior before and after lecture on environmental problems. And this questionnaires were performed with self-administered by the university student who made a application for liberal arts related to environmental subjects. The results were as follows. According to the analysis results the most students responded that the most serious problem of environmental pollution before the lecture on environmental education was a genetic modified organism(3.64/4.00), but the most serious problem of environmental pollution was changed to the topic of water pollution(3.96/4.00) after the lecture on environmental problem. And also according to the analysis results dributed by gender were that boy students show a higher concerning(170%) than that of girl students(150%). The most good results obtained after lecture on environmental problem were water pollution(23.0%), air pollution(11.5%), waste material pollution(10.9%), food additives (10.0%), genetic modified organism(8.0%), endocrine disrupter(7.5%), respectively. And according to the analysis results distributed by a grade were that the concerning of a low grade(freshman, sophomore)were higher than that of a high grade(junior, senior) in the topic of water pollution, air pollution, waste material pollution. But there were high level of awareness on the topic of food additives, genetic modified organism, endocrine disrupter to the all students(freshman to senior). And according to the analysis results distributed by a major field of study were that students who major in art & athletics, liberal art and etc(public health) were show a deep concerning than that of science & engineering. Finally, the environmental education during the university class were effectively contribute to increase the awareness of the seriousness of environmental pollution problem(8.2%) and also contribute to the practical life after class also increase their consciousness of environmental problem(59.8%).