• 공업화학
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• 제1권2호
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• pp.176-181
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• 1990

탄소섬유/알루미늄 복합 재료의 계면 전단 강도를 향상시키기 위하여 탄소섬유 표면을 $400-600^{\circ}C$의 온도 범위에서 황화수소 기체로 처리하였다. 처리 탄소섬유 표면의 변화를 주사 전자 현미경과 X-선 광전자 스펙트럼에 의해 관찰하고 분석하여 표면 처리 탄소섬유의 표면에 황 화합물이 존재하는 것을 확인하고, 표면처리 탄소섬유의 탄소 및 탄소의 함량 변화를 조사하였다. 탄소섬유 표면의 황화수소 기체 처리의 최적 온도는 $550^{\circ}C$였고, 처리 탄소섬유 표면의 황 화합물은 disulfide, $(S)_n$ 및 thiophene의 형태를 이루고 있었다. 처리 탄소섬유는 처리 온도 $400-600^{\circ}C$의 범위에서 5% 정도의 인장 강도 저하를 나타냈다.

• 한국의류산업학회지
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• 제14권1호
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• pp.122-129
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• 2012

To develop a waterproof breathable material, we fabricated three kinds of nanofiber web laminates using a massproduced electrospun nanofiber web with different substrates and layer structures. The waterproofness and breathability of nanofiber web laminates were evaluated after repeated launderings and compared with those of conventional waterproof breathable fabrics currently in use, including densely woven fabric, microporous membrane laminated fabric, and coated fabric. The durability of nanofiber web laminates, including adhesion strength, abrasion resistance, tensile strength, and tearing strength, was also assessed and compared with those of conventional waterproof breathable fabrics. The water vapor transmission of nanofiber web laminates increased slightly after repeated launderings, whereas the air permeability somewhat decreased after launderings but still maintained an acceptable level of air permeability. Laundering reduced the resistance to water penetration of nanofiber web laminates, which implies that laminating techniques or substrate materials that could support waterproofness of the laminated structure should be explored. The adhesion strength, abrasion resistance, tensile strength, and tearing strength of nanofiber web laminates were in a range comparable to conventional waterproof breathable materials.

• 복식문화연구
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• 제22권2호
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• pp.326-338
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• 2014

This study is to examine the satisfaction of protective clothing for riot policewomen. The protective clothing that riot policewomen currently wear are not suitable for them because they are structurally designed for men. A survey was conducted about satisfaction of protective clothing for 190 riot policewomen who work in Seoul and Gyeonggi province. This study focused on functionality and comfort of the protective clothing. It examined overall condition of protective clothing and policewomen's satisfaction in terms of safety, activity, fitness, comfort, convenience and design. The first three aspects were examine to measure its functionality and the last three to measure its comfort. Most results show under 3 out of 5 point in terms of functions and comfort level. In conclusion, it is strongly recommended that new design which fits better to women according to their body structures and sizes as well as new fabric materials that permeability better are needed.

• Structural Engineering and Mechanics
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• 제33권4호
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• pp.429-446
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• 2009

Three-scale homogenization procedure is proposed in this paper to provide estimates of the effective thermal conductivities of porous carbon-carbon textile composites. On each scale - the level of fiber tow (micro-scale), the level of yarns (meso-scale) and the level of laminate (macro-scale) - a two step homogenization procedure based on the Mori-Tanaka averaging scheme is adopted. This involves evaluation of the effective properties first in the absence of pores. In the next step, an ellipsoidal pore is introduced into a new, generally orthotropic, matrix to make provision for the presence of crimp voids and transverse and delamination cracks resulting from the thermal transformation of a polymeric precursor into the carbon matrix. Other sources of imperfections also attributed to the manufacturing processes, including non-uniform texture of the reinforcements, are taken into consideration through the histograms of inclination angles measured along the fiber tow path together with a particular shape of the equivalent ellipsoidal inclusion proposed already in Sko ek (1998). The analysis shows that a reasonable agreement of the numerical predictions with experimental measurements can be achieved.

• Earthquakes and Structures
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• 제19권6호
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• pp.411-425
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• 2020

Unreinforced masonry (URM) walls present low shear strength and are prone to brittle failure when subjected to inplane seismic overloads. This paper discusses the shear strengthening of URM walls with Textile Reinforced Mortar (TRM) jackets. The available literature is thoroughly reviewed and an extended database is developed including available brick, concrete and stone URM walls retrofitted and subjected to shear tests to assess their strength. Further, the experimental results of the database are compared against the available shear strength design models from ACI 549.4R-13, CNR DT 215 2018, CNR DT 200 R1/2013, Eurocode 6 and Eurocode 8 guidelines as well as Triantafillou and Antonopoulos 2000, Triantafillou 1998, Triantafillou 2016. The performance of the available models is investigated and the prediction average absolute error (AAE) is as high as 40%. A new model is proposed that takes into account the additional contribution of the reinforcing mortar layer of the TRM jacket that is usually neglected. Further, the approach identifies the plethora of different block materials, joint mortars and TRM mortars and grids and introduces rational calibration of their variable contributions on the shear strength. The proposed model provides more accurate shear strength predictions than the existing models for all different types of the URM substrates, with a low AAE equal to 22.95%.

• Earthquakes and Structures
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• 제22권4호
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• pp.355-372
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• 2022

The study is part of an experimental program on full-scale Un-Reinforced Masonry (URM) wall panels strengthened with Textile reinforced mortars (TRM). Eight brick walls (two with and five without central opening), were tested under the diagonal tension (shear) test method in order to investigate the strengthening system effectiveness on the in-plane behaviour of the walls. All the URM panels consist of the innovative components, named "Orthoblock K300 bricks" with vertical holes and a thin layer mortar. Both of them have great capacity and easy application and can be constructed much more rapidly than the traditional bricks and mortars, increasing productivity, as well as the compressive strength of the masonry walls. Several parameters pertaining to the in-plane shear behaviour of the retrofitted panels were investigated, including shear capacity, failure modes, the number of layers of the external TRM jacket, and the existence of the central opening of the wall. For both the control and retrofitted panels, the experimental shear capacity and failure mode were compared with the predictions of existing prediction models (ACI 2013, TA 2000, Triantafillou 1998, Triantafillou 2016, CNR 2018, CNR 2013, Eurocode 6, Eurocode 8, Thomoglou et al. 2020). The experimental work allowed an evaluation of the shear performance in the case of the bidirectional textile (TRM) system applied on the URM walls. The results have shown that some analytical models present a better accuracy in predicting the shear resistance of all the strengthened masonry walls with TRM systems which can be used in design guidelines for reliable predictions.

• 한국염색가공학회지
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• 제35권3호
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• pp.179-187
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• 2023

In this study, we developed a microfiber-based flexible pressure sensor with high sensitivity and excellent skin breathability. A nonwoven fabric composed of microfibers was prepared by electrospinning, which resulted in excellent moisture permeability of the sensor (143 g∙m^-2∙h^-1). In particular, high-pressure sensitivity (0.36 kPa^-1) was achieved by introducing submicron structures on the microfiber surface by controlling the ambient humidity during electrospinning. The fabrication technology of the microfiber-based flexible pressure sensors reported in this study is expected to contribute to the commercialization of flexible pressure sensors applicable to long-term wearable health monitoring as well as virtual/augmented reality and electronic skin applications.

• 한국염색가공학회지
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• 제25권1호
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• pp.65-69
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• 2013

PET fabrics of various luster, fiber thickness(denier), and weaving structure were dyed at the same conditions and determined their grey scale by using naked eyes, computer color matching (CCM) system, and real industry color (RIC) device to evaluate the effectiveness of RIC device developed in this study. As for the luster of fabrics, bright PET showed more differences when compared with semi-dull and full-dull. PET in both naked eyes and RIC device since the RIC device provide the real image of fabrics to observers. As for the fiber thickness, the results of naked eyes and RIC device were very similar while the result of CCM showed lower color grade. Finally, as for the weaving structures of PET fabrics, all the test results by naked eyes, CCM, and RIC device showed almost same grey scales. In these regards, the RIC device developed in this study was comparable to naked eyes by providing the real image of fabrics, however it was difficult to compare the very bright colors such as yellow and fiber thickness(denier) and weaving structure of fabrics.

• 한국항공우주학회지
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• 제44권11호
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• pp.941-948
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• 2016

직물 복합재료는 높은 비강성과 비강도를 가지며 일방향 복합재료에 비해 면외 방향 특성과 충격 및 층간분리에 대한 특성이 우수하여 항공우주 구조물의 주재료로 적용되고 있다. 본 논문에서는 2차원 평직 복합재료의 반복단위격자에 대한 기하학적 모델을 정의하고 유효강성을 예측하였다. 반복단위격자의 기하학적 형상은 다양한 프리폼 제작변수에 의해 결정될 수 있으며, Naik의 모델을 바탕으로 섬유다발간의 간극을 추가적으로 고려하는 수정된 기하학적 모델을 제시하였다. 평직 복합재료의 유효 강성은 반복단위격자에 대한 섬유다발 이산화 기법과 등변형률 가정 기반의 응력 평균화 기법을 사용하여 예측되었다. 또한 섬유다발간의 간극의 크기에 따른 강성의 변화를 평가하였으며, 기존 모델과 시편 시험 데이터와의 비교를 통해 강성 예측 결과를 검증하였다.

• 접착 및 계면
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• 제21권2호
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• pp.51-57
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• 2020

최근 산업활동을 통해 배출되는 유해 오염물질 제거에 대한 관심이 증가하고 있다. 본 연구에서는 수증기 활성화 법을 이용하여 활성탄소섬유를 제조하고, 이의 유해가스 흡착 및 전기화학적 감응 특성을 분석하였다. 활성탄소섬유의 균일한 기공 구조, 활성 반응 면적 및 반응 위치를 조절하기 위하여, 활성화 온도(750-850 ℃) 및 활성화 시간(30-240 min)을 조절하였고, 다양한 활성화 조건을 통해 제조된 활성탄소섬유의 SO₂와 NO 가스 흡착 및 가스 센서를 통한 감응 특성을 분석하였다. 특히, 850 ℃에서 45 min동안 수증기 활성화 반응을 통해 제조된 활성탄소섬유가 가장 높은 비표면적(1,041.9 ㎡/g)과 기공 특성(0.42 ㎤/g)을 보였으며, 우수한 SO₂ (1.061 mg/g) 및 NO (1.210 mg/g) 가스 흡착 특성을 보였다.