• Structural Engineering and Mechanics
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• v.46 no.1
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• pp.39-51
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• 2013

An extremum method is presented to predict the wrinkling characteristics of the inflated cone in bending. The wrinkling factor is firstly defined so as to obtain the wrinkling condition. The initial wrinkling location is then determined by searching the maximum of the wrinkling factor. The critical wrinkling load is finally obtained by determining the ratio of the wrinkling moment versus the initial wrinkling location. The extremum method is proposed based on the assumption of membrane material of beam wall, and it is extended to consider beam wall with thin-shell material in the end. The nondimensional analyses show that the initial wrinkling location is closely related to the taper ratio. When the taper ratio is higher than the critical value, the initial wrinkles will be initiated at a different location. The nondimensional critical wrinkling load nonlinearly increases as the taper ratio increases firstly, and then linearly increases after the critical taper ratio. The critical taper ratio reflects the highest load-carrying efficiency of the inflated cone in bending, and it can be regarded as a measure to optimize the geometry of the inflated cone. The comparative analysis shows fairly good agreement between analytical and numerical results. Over the whole range of the comparison, the mean differences are lower than 3%. This gives confidence to use extremum method for bending-wrinkling analysis of inflated conical cantilever beam.

• Journal of Korean Home Economics Education Association
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• v.33 no.2
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• pp.57-80
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• 2021

The purpose of this research is to develop a Home Economics education curriculum that can promote citizenship through critical literacy. To this end, the 'housing' area in the 2015 revised curriculum of home economics and textbooks were analyzed from a critical literacy perspective. Using Laster(1986)'s critical science curriculum development course and "A Teacher's guideFamily, Food and Society"(Staaland & Storm, 1996), a 'Citizenship raising curriculum of home economics education in the housing area.' was developed. The results of this research are as follows. First, when the the curriculum was examined, the teaching objectives of the overall subject, or the achievement criteria, learning elements, and evluative methods of the housing area consisted of practical problem solving curriculum that can include critical literacy content. In addition, as a result of analyzing the text of the three textbooks' housing areas, it was found that most of them were described as adapting to and coping with the current culture, and few problems or social issues were mentioned that could lead to critical literacy. Second, the housing area curriculum for critical literacy learning was developed, with a total of 13 plan of 7 modules including continuous interests, valued ends, learning contents, and 26 learning materials including reading materials, and video materials. Based on the findings, the next curriculum and textbook should address social issues related to critical literacy and various classes of housing, and teachers' communities and training should be operated to support teachers who can be examplary for practical reasoning and critical thinking.

• Journal of the Korean Ceramic Society
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• v.43 no.2 s.285
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• pp.98-105
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• 2006

YBCO film was synthesized by using a new approach to the TFA-MOD method. In the fabrication process, $Y_2Ba_1Cu_1O_x\;and\;Ba_3Cu_5O_8$ powders were used as precursors (the so called '211 process'), instead of Y-, Ba-, and Cu-based acetates, and dissolved in trifluoroacetic acid followed by calcining and firing heat treatment. Consequently, we successfully fabricated YBCO film and evaluated the phase formation, texture evolution, and critical properties as a function of the calcining and firing temperature and humidity, in order to explore its possible application in coated conductor fabrication. The films were calcined at $430-460^{\circ}C$ and then fired at $750-800^{\circ}C\;in\;a\;0-20\%$ humidified $Ar-O_2$ atmosphere. We observed that $BaF_2$ phase was effectively reduced and that a sharp and strong biaxial texture formed under humidified atmosphere leading to increased critical properties. In addition, we found that the microstructure varied significantly with the firing temperature: the grain grew further, the film became denser, and the degree of texture and phase purity varied as the firing temperature increased. For the film fired at $775^{\circ}C$ after calcining at $460^{\circ}C$, the critical current was obtained to be 39 A/cm-width (corresponding critical current density is $2.0\;MA/cm^2$ which was probably attributed to such factors as the enhanced phase purity and out-of-plane texture, the moderate film density and grain size, and crack-free surface.

• 한국초전도학회:학술대회논문집
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• 2008.08a
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• pp.69-69
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• 2008

• Korean Journal of Materials Research
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• v.26 no.7
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• pp.370-375
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• 2016

Tensile tests and creep tests were carried out at high temperatures on an Al-$Al_4C_3$ alloy prepared by mechanical alloying technique. The material contains about 2.0% carbon and 0.9% oxygen in mass percent, and the volume fractions of $Al_4C_3$ and $Al_2O_3$ particles are estimated at 7.4 and 1.4%, respectively, from the chemical composition. Minimum creep rate decreased steeply near two critical stresses, ${\sigma}_{cl}$ (the lower critical stress) and ${\sigma}_{cu}$ (the upper critical stress), with decreasing applied stress at temperatures below 723 K. Instantaneous plastic strain was observed in creep tests above a critical stress, ${\sigma}_{ci}$, at each test temperature. ${\sigma}_{cu}$ and ${\sigma}_{ci}$ were fairly close to the 0.2% proof stress obtained by tensile tests at each test temperature. It is thought that ${\sigma}_{cl}$ and ${\sigma}_{cu}$ correspond to the microscopic yield stress and the macroscopic yield stress, respectively. The lower critical stress corresponds to the local yield stress needed for dislocations to move in the soft region within subgrains. The creep strain in the low stress range below 723 K arises mainly from the local deformation of the soft region. The upper critical stress is equivalent to the macroscopic yield stress necessary for dislocations within subgrains or in subboundaries; this stress can extensively move beyond subboundaries under a stress above the critical point to yield a macroscopic deformation. At higher temperatures above 773 K, the influence of the diffusional creep increases and the stress exponent of the creep rate decreases.

• 한국초전도학회:학술대회논문집
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• v.12
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• pp.76-76
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• 2002

• 한국초전도학회:학술대회논문집
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• v.12
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• pp.77-77
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• 2002

• Journal of the Korea Fashion and Costume Design Association
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• v.22 no.2
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• pp.87-103
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• 2020

This study investigates critical fashion and discusses its critical messages, as it challenges the existing system of the fashion industry. This study reviews the literature on critical art and critical design and analyzes exhibition catalogs, magazines, and websites related to critical fashion practices. Thereupon, this study assumes the two distinctive messages of critical fashion design: materiality and experience, and the redefinition of the ideal body. First, materiality and experience pursues a change in perceptions of clothing materials by way of deconstructing clothes and exposing the process of production. This type of critical fashion breaks away from the traditional sartorial conventions and articulates new structures and experiences through dematerialization. Second, the redefinition of the ideal human body attempts to subvert the stereotypes of ideal beauty and introduce a variety of beauty in the human body. This type of critical design reconstructs the human body through transformation, expansion, and deconstruction and is often liberated from the dichotomy of gender norms.

• Progress in Superconductivity
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• v.4 no.2
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• pp.162-167
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• 2003

The critical current value of Bi-2223/Ag tape can be influenced by various factors. In particular, it was known that properties of precursor powders could affect the formation of Bi -2223 and grain growth rate of the same. Since, moistures and organic matters can easily contaminate the precursor powders of Bi-2223 tapes and degrade properties of superconductors, the precursor powders should be kept in optimal conditions to minimize contamination. In this study, the effect of moisture and organic matters has been investigated. A Bi-2223/Ag tape contaminated with a large amount of moisture and organic matter has been characterized by low critical current values and bubbling. It has been found that as the quantity of moisture increases, the Bi-2223 phases are formed at lower temperature and the amount of non-superconducting phase increases.

• Progress in Superconductivity
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• v.1 no.1
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• pp.56-60
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• 1999

Ultra fine MgO particles added BSCCO tapes were fabricated by tape casting using Doctor Blade Method and enclosed by silver foil for different starting compositions (that is, 2223 major, 2212 major). In order to obtain optimum microstructure, thermomechanical treatment was done. Microstructure and phase were analyzed by XRD, SEM and DTA. The critical current density was measured under magnetic field at 77K. The tapes fabricated from the precursor powder with BSCCO-2223 phase (>90%) result in a microstructure with a larger grain size and higher transport critical current density value under magnetic field at given thermomechanical treatment conditions.