• Journal of Sensor Science and Technology
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• v.10 no.1
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• pp.42-51
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• 2001

In this study, the effects of embedded optical fibers on the static properties under tensile load and dynamic properties under fatigue load of composite laminates were investigated by experimental tests and finite element analysis. Based on the results, it can be concluded that the embedded optical fiber sensors do not have significant effects on the structural integrity of the smart composite structures except when the sensors are embedded perpendicular to the adjacent reinforcing fibers under fatigue loading. An intensity-based optical fiber sensor was embedded in the crossply composite laminates to monitor the fatigue damage by detecting the stiffness changes of the laminates. The result of this experiment has shown that the intensity-based optical fiber sensor has large potential to monitor the fatigue damage of composite structures by detecting the stiffness changes of the structures with simple and inexpensive instruments and without complex post-processing of measured signals. In addition, the optical fiber sensor showed good resistance to fatigue loading and wide sensing ranges of stiffness.

• Composites Research
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• v.32 no.1
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• pp.45-49
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• 2019

Fiber reinforced composites fabricated by the resin film infusion (RFI) process, which is one of the outof-autoclave process, have the advantage of significantly reducing the processing cost in large structures while having excellent mechanical properties and uniform impregnation of the resin. In this study, we applied RFI carbon fiber composites to unmanned aerial vehicle structures to improve structural safety and achieve weight reduction. The tensile test results showed that the strength was 46% higher than that of generic T300 grade plain weave carbon fiber composites. As a result of the layup design and finite element analysis of the composite wing structure using the above material properties, the wing tip deflection is decreased by 31%, the structural safety factor is increased by 28% and the weight of the entire structure can be reduced by more than 10% compared to the reference model using glass fiber composite material.

• Journal of the Korea Convergence Society
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• v.12 no.1
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• pp.163-170
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• 2021

Smart-textronics technology which enables functional textiles has recently been applied in various fields such as smart clothes, smart home and smart health care, and a variety of smart-textronics products have been developed. In this context, the smart-textronics product development process is proposed based on the systematic participatory design method in this paper. The proposed method consists of two phases: in-depth interviews and analyzing. In the phase of in-depth interviews, participants are asked to create journey maps that include activities, pain points and emotional status and to generate solution ideas with sketches and simple prototypes. In the analyzing phase, design researchers investigate the participants' journey maps, and create personas by identifying critical characteristics with the behavior pattern analysis. Then, each persona's needs are linked with value elements of the E3 value framework. Finally, pre-survey was conducted to identify smart-textronics market and a smart sofa design is proceeded as the case study to show the applicability of the proposed method.

• Membrane Journal
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• v.31 no.6
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• pp.393-403
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• 2021

Enzymes are important class of catalyst for biotransformation. Stability and reusability of enzymes during the catalysis process is a key issue. Activity of enzyme can be enhanced by its immobilization on a suitable substrate by creation of specific microenvironment. A variety of membranes has been used as substrate due to the biocompatibility and simpler method to tune hydrophilicity/hydrophobicity property of the membrane surface. In this review, polymer membranes including cellulose, polyacrylonitrile (PAN), polydimethylsiloxane (PDMS), polyvinylidene fluoride (PVDF), polyethersulfone (PES) are introduced and discussed in detail. Biodegradation of organic contaminants by immobilized enzyme is an environmental friendly process to reduce the contamination of environment in pharmaceutical company and textile industries. The controlled hydrolysis of oil can be performed in enzyme immobilized membrane bioreactor (EMBR), resulting in reducing carbon emission and reduced environmental pollution. Bioethanol and biodiesel are considered alternative fossil fuels that can be prepared in EMBR.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.34 no.6
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• pp.363-370
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• 2021

In this paper, we presented an optimized crack and flexural strength analysis of a glass-fiber reinforced polymer (GFRP) rebar, used as reinforcements for in-site railway concrete slabs. The insulation performance of a GFRP rebar has the advantage of avoiding the loss of signal current in an audio frequency (AF) track circuit. A full-scale experiment, and three-dimensional finite element simulation results were compared to validate our approaches. Parametric numerical results revealed that the diameters and arrangements of the GFRP rebar had a significant effect on the flexural strength and crack control performances of the concrete track slabs. The results of this study could serve as a benchmark for future guidelines in designing more efficient, and economical concrete slabs using the GFRP rebar.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.5
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• pp.309-316
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• 2022

This paper presents nonlinear numerical analysis results which were compared with the tested tensile strengths of CFRP(Carbon Fiber Reinforced Plastic) laminates with 14 different stacking sequences. The composite laminate coupons were cured under an autoclave pressure using resin-impregnated unidirectional tapes. The nonlinearity of the matrix was considered for the analysis, which was obtained from lamina tests. The Hashin failure criteria and progressive failure analysis were used for the nonlinear finite element analysis. The comparison results show that the current approach is acceptable to predict the tensile strengths of the CFRP laminate coupons with various stacking sequences and no damage. However, it is not acceptable to predict the tensile strengths of the laminate specimens with a center hole.

• Fashion & Textile Research Journal
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• v.23 no.2
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• pp.159-173
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• 2021

This study attempted to investigate the perspective of the skirts of male and female students by analyzing the differences in image evaluation according to the constituent elements (type, length, and wearing method) of men's skirt designs in modern fashion. The study included 109 male and female college students from Generation Z residing or whose life center was in Gwangju Metropolitan City, to evaluate 12 images depicting types of men's skirts. First, the constituent image evaluation factors according to the constituent design elements of men's skirts were analyzed. Second, the differences in each constituent image evaluation factor based on the constituent design elements of men's skirt designs were analyzed. Third, the gender-based differences in image evaluation by men and women concerning the constituent design elements of men's skirt designs were analyzed. The analysis included relatively more women than men. The results of the image recognition dimension included the following categories: "attractive image," "evaluable image," "gender image," and "personality image." In modern fashion, skirts are used to express the diverse personalities of men's fashion. Thus, they are used beyond the stereotype of women's clothing, toward expanding and diversifying the image of men's clothing through mixing and creating a dichotomous image of men and women. It can be used as a design that suggests a gender-fluid image.

• Journal of the Korea Convergence Society
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• v.12 no.4
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• pp.87-94
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• 2021

While the shielding substances of radiation shields in medical institutions are beginning to be replaced by environmentally friendly materials, radiation protection according to the shielding properties of environmentally friendly substances is becoming an important factor rather than the existing lead shielding properties. Tungsten and barium sulfate are representative shielding materials similar to lead, and are made in sheets or fiber form with eco-friendly materials. Ytterbium is an impermeable material used as a fluorine compound in the dental radiation field. This study aims to evaluate the shielding performance in the x-ray shielding area by comparing the shielding properties of ytterbium by energy band and that of existing eco-friendly materials. When three types of shielding sheets were fabricated and tested under the same process conditions, the shielding performance of the medical radiation area was about 5 % difference from tungsten. Furthermore, shielding performance was superior to barium sulfate. In the cross-sectional structure of the shielding sheet, there was a disadvantage that the arrangement of particles was not uniform. Ytterbium oxide showed sufficient potential as a medical radiation shielding material, and it is thought that it can improve the shielding performance by controlling the particle arrangement structure and particle size.

• Journal of Aerospace System Engineering
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• v.16 no.6
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• pp.8-17
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• 2022

This paper presents a novel geometric modeling technique to predict the mechanical properties of an aircraft wing's skin-stringer integrated panel. Due to mechanical and adhesive fastening, this panel is vulnerable to stress concentration and debonding, so we designed it to integrate the skin and stringer using three-dimensional woven composites. Geometric modeling was conducted by measuring the geometric parameters of the specimen and defining the pattern of the yarns as functions. We used a weighted average model with iso-strain and iso-stress assumptions to predict the mechanical properties of the panel parts. We then compared the results of a finite element analysis with a compression test to verify the accuracy of our model. Our proposed technique proved to be more efficient than the traditional experimental method for predicting the mechanical properties of skin-stringer integrated panels.

• Journal of the Korea Fashion and Costume Design Association
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• v.24 no.1
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• pp.59-69
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• 2022

Vyshyvanka, the embroidered folk costume shirt of Ukraine, originated during the early reign of the Slavs, and currently, it is also called Ukrainian embroidery. In cases of Vyshyvanka embroidery expressed in apparel elements, it is necessary to research formative characteristics for expanding the visual aspect through the diversification of techniques, but also the aspect of the psychological meaning to Ukrainians. This study aims to consider Vyshyvanka as a unique embroidery technique, and also analyze the formative characteristics expressed in apparel elements. The study of Vyshyvanka embroidery expressed in apparel elements can present meaning to understanding the Ukrainian fashion. The image materials for the analysis of Vyshyvanka design, included work photos contained in literary materials and foreign online visual materials. The results of formatively analyzing the Vyshyvanka embroidery expressed in apparel are as follows. First, the Vyshyvanka embroidery expressed in apparel elements held an incantatory meaning, protecting wearers from getting easily invaded by evil spirits. Second, the Vyshyvanka patterns utilized symbolism that implied the incantatory meaning. Third, a single color was used for the embroidery. Lastly, materials like cotton, that are easy to embroider, were mostly used. The formative characteristics of Vyshyvanka embroidery expressed in apparel elements implied the community spirit, nature worship, and folk beliefs. As an attempt to understand the Ukrainian fashion, this study is significant in the aspect of expanding, widely utilizing, and expanding the range of understanding of Ukrainian fashion. Therefore, there should be more active researches on Ukrainian fashion, so Vyshyvanka can be more widely used as a design element.