• Advances in concrete construction
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• 제9권2호
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• pp.195-205
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• 2020

In this study, effect of recycled aggregates and polypropylene fibers on the response of conventionally reinforced concrete element subjected to tensile loading in terms of tension stiffening and strain development was experimentally investigated. For this purpose, concrete prisms of 100 × 100 mm cross section and 500 mm length having one central deformed steel re-bar were cast using fibrous and non-fibrous Recycled Aggregate Concrete (RAC) with varying percentages of recycled aggregates (0%, 25%, 50%, 75% and 100%) and tested under uniaxial tensile load. For all fibrous RAC mixes, polypropylene fibers were used at constant dosage of 3.15 kg/㎥. Effect of recycled aggregates and fibers on the compressive strength of concrete was also explored in this study. Through studying tensile load versus global axial deformation of composite and strain development in concrete and steel, it was found that replacement of natural aggregates with recycled aggregates in concrete negatively affected the cracking load, tension stiffening and strain development, and this negative effect was observed to be increased with increasing contents of recycled aggregates in concrete. The results of this study showed that it was possible to minimize the negative effect of recycled aggregates in concrete by the addition of polypropylene fibers. Reinforced concrete element constructed using concrete containing 50% recycled aggregates and polypropylene fibers exhibited cracking behavior, tension stiffening and strain development response almost similar to that of concrete element constructed using natural aggregate concrete without fiber.

• 자연과학논문집
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• 제8권1호
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• pp.145-151
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• 1995

건열일축연신법에 의한 합성섬유의 연신은 높은 유리전이온도 때문에 대략 $150^{\circ}C$이상의 온도에서 행하여 지고 있다. 그러나, 팽윤습열연신법은 유기용매를 팽윤제로 사용하여 미세구조를 변화시키기 때문에 낮은 온도에서 연신 할 수 있는 특징을 갖고 있다. 본 연구에서는 비교적 낮은 온도인 $70^{\circ}C$에서 팽윤습열 일축연신에 의한 100% 아크릴섬유의 고강도화에 대하여 연구하였다. 연신능력은 연신일에 의하여 계상하였으며, 이 연신일은 연신응력과 변형 그리고 초기영율에 의하여 좌우됨을 알 수 있었다. 연신은 아크릴 섬유의 고강도를 위해 필요한 요인임을 확인할 수 있었다. 또한, 아크릴 섬유의 고강도화를 위한 분자배향도 및 결정화도 증가에 따른 연신조건의 효과와 물성 변화에 대하여 비교. 검토하였다.

• 펄프종이기술
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• 제41권3호
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• pp.49-59
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• 2009

The bast fibers of paper mulberry were dyed by using sappan wood, gardenia, and gallnut extracted under various extraction conditions. The surface absorption rates, color, and sunlight fastness of the dyed fibers were compared to those of the dyed cotton and silk. The K/S values of silk showed the highest values, followed by gallnut, gardenia, and sappan wood. The optimum extraction conditions of the dye materials were 20 g/L (input amount of dye materials per liter), $90^{\circ}C$ (extraction temperature), and 30 minutes (extraction time). The values of saturation were observed to increase with the increase of the amount of dye materials, extraction time, and extration temperature. However, no effect were found on the values of hue and lightness. In all samples, the developed colors dyed by sappan wood and gardenia were the series of YR, and Y, respectively. The colors of dyed cotton and bast fibers of paper mulberry by gallnut were the series of Y and the dyed silk showed the series of YR. The values of saturation of the bast fibers of paper mulberry by sappan wood and gardenia showed the highest values of saturation, followed by cotton, and silk. In the case of gallnut, cotton showed the highest values of saturation, followed by the bast fibers of paper mulberry, and silk. The sunlight fastness were not improved in all dyeing conditions.

• Weed & Turfgrass Science
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• 제3권3호
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• pp.196-205
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• 2014

최근 화석 자원의 의존성을 경감시키자는 차원에서 천연섬유에 대한 관심이 연구계 및 산업계에서 새롭게 대두되고 있다. 본 연구는 잡초중에서 새로운 천연섬유로서 이용될만한 자원을 탐색하기 위한 기초자료를 얻기 위하여 21종의 잡초종자 섬유를 수집하여 이들의 형태적 또는 분류적 특징을 조사하였다. 본 연구에서 설정한 분류지표에 따라 분류해 보았을 때 총 13가지 유형으로 나뉘어져(A0T3, A0S3, B0N0, B1N0, B2N0, B2N1, B0S3, B0T3, C0N0, C1N0, D0N0, D0S3, E1T3) 각 종자마다 독특한 특징의 섬유를 가지고 있음을 알 수 있었으며, 서로 유사한 특징을 보여 그룹화 할 수 있었던 종은 B0T3 type으로서 붉은서나물, 방가지똥, 큰방가지똥, 개쑥갓, 벌씀바귀, 보리뺑이, 솜방망이 등이 있었고, D0S3 type으로서 강아지풀, 수크령이 있었고, B2N0 type으로서 조뱅이와 엉겅퀴가 있었다. 섬유의 분지 유무을 보았을 때, 분지없이 한가닥의 섬유가 밀생하여 존재하는 것이 대부분이었고, 한 개의 주경에 여러개의 섬유가 분지되어 존재하는 것으로서 사위질빵과 큰부들이 있었다. 특이하게도 지칭개는 여러 개의 주경에 여러 개의 섬유가 분지되어 존재하는 특징을 보였다. 또한 섬유 표면에 피침형 돌기 발생 정도를 보았을 때, 피침형 돌기 없이 매끄러운 형태를 지니는 것은 지칭개, 박주가리, 물억새, 띠, 사위질빵 등이었고 나머지는 피침형 돌기가 미약하게 존재하거나 피침형 돌기가 현저하게 발달한 것들이었다. 섬유 구성세포 형태의 경우, 세포 격막 없이 한 개의 장세포로 이루어진 종들로서는 지칭개, 박주가리, 물억새, 띠, 사위질빵 등이 있었고, 나머지는 두개이상의 장세포가 다발로 뭉쳐 있는 특징을 보였다. 전반적으로 수집의 용이성, 생산성, 종자섬유의 물적 성질들을 볼 때 향후 실용화 가능성이 있을 것으로 여겨져 추가 검토가 필요한 잡초 종은 붉은서나물, 띠, 지칭개, 박주가리, 큰부들 등 이었다.

• 한국의류산업학회지
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• 제11권5호
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• pp.818-826
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• 2009

Dyeability of microbial violacein produced from Chromobacterum violaceum CV107 on to multifiber fabrics has been studied. The bluish-purple colourants were produced by cultivation of Chromobacterum violaceum using LB liquid medium for 2 days. The colourant was extracted with 80% acetone and identified as violacein by LC/MS analysis. The violacein could be dyed on not only natural fibers such as Cotton, Silk and Wool but also synthetic fibers such as Diacetate, Triacetate, Creslan 61 and Nylon 66. Maximum K/S values were shown at 540-580 nm according to different fiber with color appearance of purple or blue. An optimum pH and temperature under dyeing condition were 10 and $70^{\circ}C$, respectively. Any mordants were not improved colour density and quality on various fabrics. From this studies, pigments produced microbe have a high potentials for natural dyeing on fabrics. Finally, development of new colourants from microbe has made a possible change for new dyeing field in respects of eco-friend and repeatability of natural dyeing for apparels.

• 한국의류학회지
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• 제35권4호
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• pp.431-441
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• 2011

Microbial colorants produced from Zooshikella sp. were developed as a reddish dye for fabrics. The reddish colorants were extracted from cell mass of Zooshikella sp. using 100% ethanol and were identified as prodiginine by 1H-NMR and FT-IR analysis. Microbial prodiginine had a maximum spectrophotomatric absorbance at 530nm and were chemically stable and 30 to $60^{\circ}C$. The microbial prodiginine could dye natural fibers such as cotton, silk, and wool as well as synthetic fibers such as nylon. The maximum K/S values of the dyed fiber were shown at 540 run with a color appearance of RP (reddish purple). Silk and nylon had an excellent dyeability among the experimental fibers. The optimum pH for the dyeing of experimental fibers was at pH 3.0 and dyeability was improved as the temperature increased. The cover change of dyed multifiber fabrics with the microbial prodiginine were measured after washing with detergents and a dry cleaning solvent for the selection of a proper fabric against microbial prodiginine. Among the experimental fibers, silk and nylon did not show significant color change after washing. Therefore, under the criteria of dyeability, silk and nylon were excellent fabrics for being dyed by microbial prodiginine.

• 패션비즈니스
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• 제9권1호
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• pp.57-66
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• 2005

In natural dyeing, a number of supplementary methods have been practiced since deep shades of the dyed fabrics are not developed satisfactorily. The methods include using the mordants effectively or subjecting the fabrics to reiterated dyeing processes. In this study, we obtained deep shades in the dyeing of fabrics using Rhusjara ica as the dyestuff and applied chitosan to the fabric specimens in order to diversify the colors. Silk fibers and PET(polyethylene terephthalate) fibers were pretreated using chitosan, and subsequently dyed using different types of mordants. As the mordanting agents, Al, Sn, and Fe were employed. Various shades have been resulted in since the interactions of the mordants are different toward the silk fibers and PET fibers. In this study, we investigated the effect of the chitosan treatment along with the change of the mordanting agents on the color change for the silk and PET fibers.

• 한국의류학회지
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• 제13권4호
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• pp.370-379
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• 1989

In previous paper, the optical behavior of coloring matter of Cromwell under several conditions were investigated. In this paper, the fading behavior of color solution extracted from Growell by methanol, dyeing properties of this color on the silk fibers in water and methanol, the three property of color of dyed silk fabrics, and fading behavior of dyed silk fabrics with Cromwell color under light and washing were discussed.

• Carbon letters
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• 제12권3호
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• pp.131-137
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• 2011

Kenaf fibers, cellulose-based natural fibers, were used as precursor for preparing kenafbased carbon fibers. The effects of carbonization temperature ($700^{\circ}C$ to $1100^{\circ}C$) and chemical pre-treatment (NaOH and $NH_4Cl$) at various concentrations on the thermal change, chemical composition and fiber morphology of kenaf-based carbon fibers were investigated. Remarkable weight loss and longitudinal shrinkage were found to occur during the thermal conversion from kenaf precursor to kenaf-based carbon fiber, depending on the carbonization temperature. It was noted that the alkali pre-treatment of kenaf with NaOH played a role in reducing the weight loss and the longitudinal shrinkage and also in increasing the carbon content of kenaf-based carbon fibers. The number and size of the cells and the fiber diameter were reduced with increasing carbonization temperature. Morphological observations implied that the micrometer-sized cells were combined or fused and then re-organized with the neighboring cells during the carbonization process. By the pre-treatment of kenaf with 10 and 15 wt% NaOH solutions and the subsequent carbonization process, the inner cells completely disappeared through the transverse direction of the kenaf fiber, resulting in the fiber densification. It was noticeable that the alkali pre-treatment of the kenaf fibers prior to carbonization contributed to the forming of kenaf-based carbon fibers.

• 대한의용생체공학회:의공학회지
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• 제43권1호
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• pp.61-70
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• 2022

Natural and synthetic forms of calcium phosphate cement (CPC) have been widely used in bone repair and augmentation. The major challenge of injectable CPC is to deliver the cells without cell death in order to regenerate new bone. The study objective was to investigate for the potential of stem cell-laden gelatin fibers containing injectable, nanocrystalline CPC to function as a delivery system. Gelatin noddle fiber method was developed to delivered cells into nCPC. Experimental groups were prepared by mixing cells with nCPC, mixing cell-laden gelatin fibers with nCPC and mixing cell-laden gelatin fibers containing BMP-2 with nCPC. Media diffusion test was conducted after dissolving the gelatin fibers. SEM examined the generated channels and delivered cell morphology. Fibers mixed with nCPC showed physical setting and hardening within 20 min after injection and showed good shape maintenances. The gelatin fibers mixed nCPC group had several vacant channels generated from the dissolved gelatin. Particularly, proliferation and attachment of the cells were observed inside of the channels. While live cells were not observed in the cell mixed nCPC group, cells delivered with the gelatin fibers into the nCPC showed good viability and increased DNA content with culture. Cell-laden gelatin fiber was a novel method for cell delivery into nCPC without cell damages. Results also indicated the osteogenic differentiation of gelatin fiber delivered cells. We suggest that the cell-laden gelatin fibers mixed with nCPC can be used as an injectable cell delivery vehicle and the addition of BMP-2 to enhances osteogenesis.