• Title/Summary/Keyword: Fabric Effect

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Buckling Behavior of Sandwich Composite Columns by Varying Hole Size and Hole Position (원공 크기 및 원공 위치에 따른 샌드위치 복합재 기둥의 좌굴 거동)

  • Lee, Sang-Jin;Yoon, Sung-Ho
    • Composites Research
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    • v.25 no.1
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    • pp.19-25
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    • 2012
  • The study investigated the buckling behavior of sandwich composite columns with different hole sizes and hole positions when they were applied to a compressive load. The columns consisted of 1.7mm thick faces of glass fabric/epoxy and 23mm, 37mm, 48mm, and 61mm thick cores of urethane-foam. Different hole sizes with the diameter of 25mm and 38mm were considered in this experiment. To evaluate the effect of hole position on the buckling behavior, we considered three types of hole position: 25mm diameter hole located at the center, 25mm diameter hole at 1/4 position from the center to the end of the column, and 25mm diameter hole at 1/2 position from the center to the end of the column. According to the results, buckling and maximum loads of the column having 25mm diameter hole were lower by 10% compared to those of the column without hole, whereas the loads for the column having 38mm diameter hole were 30% less than those of the column without hole. Hole position appeared to have no effect on buckling and maximum loads. Major failure modes were observed as follows: the core shear failure for the thin columns having 23mm and 37mm thick cores, and the face-core debonding for the thick columns having 48mm and 61mm thick cores.

Elastic Wave Characteristics in Cemented Engineered Soils (고결된 Engineered Soils의 탄성파 특성)

  • Lee, Chang-Ho;Yoon, Hyung-Koo;Lee, Woo-Jin;Lee, Jong-Sub
    • Journal of the Korean Geotechnical Society
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    • v.24 no.2
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    • pp.87-97
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    • 2008
  • Behaviors of cemented engineered soils, composed of rigid sand particle and soft rubber particle, are investigated under $K_o$ condition. The uncemented and cemented specimens are prepared with various sand volume fractions to estimate the effect of the cementation in mixtures. The vertical deformation and elastic wave velocities with vertical stress are measured. The bender elements and PZT sensors are used to measure elastic wave velocities. After cementation, the slope of vertical strain shows bilinear and is similar to that of uncemented specimen after decementation. Normalized vertical strains can be divided into capillary force, cementation, and decementation region. The first deflection of the shear wave in near field matches the first arrival of the primary wave. The elastic wave velocities dramatically increase due to cementation hardening under the fixed vertical stress, and are almost identical with additional stress. After decementation, the elastic wave velocities increase with increase in the vertical stress. The effect of cementation hinders the typical rubber-like, sand-like, and transition behaviors observed in uncemented specimens. Different mechanism can be expected in decementation of the rigid-soft particle mixtures due to the sand fraction. a shape change of individual particles in low sand fraction specimens; a fabric change between particles in high sand fraction specimens. This study suggests that behaviors of cemented engineered soils, composed of rigid-soft particles, are distinguished due to the cementation and decementation from those of uncemented specimens.

A Study on Carbon Nano Materials as Conductive Oilers for Microwave Absorbers (전자파 흡수체를 위한 전도성 소재로서의 탄소나노소재의 특성에 대한 연구)

  • Lee, Sang-Kwan;Kim, Chun-Gon;Kim, Jin-Bong
    • Composites Research
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    • v.19 no.5
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    • pp.28-33
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    • 2006
  • In this paper, we have studied the complex permittivities and their influence on the design of microwave absorbers of E-glass fabric/epoxy composite laminates containing three different types of carbon-based nano conductive fillers such as carbon black (CB), carbon nano fiber (CNF) and multi-wall nano tube (MWNT). The measurements were performed fur permittivities at the frequency band of 0.5 GHz$\sim$18.0 GHz using a vector network analyzer with a 7 mm coaxial air line. The experimental results show that the complex permittivities of the composites depend strongly on the natures and concentrations of the conductive fillers. The real and imaginary parts of the complex permittivities of the composites were proportional to the filler concentrations. But, depending on the types of fillers and frequency band, the increasing rates of the real and imaginary parts with respect to the filler concentrations were all different. These different rates can have an effect on the thickness in designing the single layer microwave absorbers. The effect of the different rates at 10 GHz was examined by using Cole-Cole plot; the plot is composed of a single layer absorber solution line and measured permittivities from these three types of composites. Single layer absorbers of 3 different thicknesses using carbon nano materials were fabricated and the -10 dB band of absorbing performances were all about 3 GHz.

Stress-strain Relations of Concrete Confined with Tubes Having Varying GFRP Layers (수적층 및 필라멘트 와인딩을 이용한 GFRP튜브로 구속된 콘크리트의 압축 거동)

  • Lee, Sung Woo;Choi, Sokhwan
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.28 no.6A
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    • pp.861-872
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    • 2008
  • Concrete-filled glass fiber reinforced polymer tubes are often used for marine structures with the benefit of good durability and high resistance against corrosion under severe chemical environment. Current research presents results of a comprehensive experimental investigation on the behavior of axially loaded circular concrete-filled glass fiber reinforced polymer tubes. This paper is intended to examine several aspects related to the usage of glass fiber fabrics and filament wound layers used for outer shell of piles subjected to axial compression. The objectives of the study are as follows: (1) to evaluate the effectiveness of filament winding angle of glass fiber layers (2) to evaluate the effect of number of GFRP layers on the ultimate load and ductility of confined concrete (3) to evaluate the effect of loading condition of specimens on the effectiveness of confinement and failure characteristics as well, and (4) to propose a analytical model which describes the stress-strain behavior of the confined concrete. Three different types of glass fiber layers were chosen; fabric layer, ${\pm}45^{\circ}$ filament winding layer, and ${\pm}85^{\circ}$ filament winding layer. They were put together or used independently in the fabrication of tubes. Specimens that have various L:D ratios and different diameters have also been tested. Totally 27 GFRP tube specimens to investigate the tension capacity, and 66 concrete-filled GFRP tube specimens for compression test were prepared and tested. The behavior of the specimens in the axial and transverse directions, failure types were investigated. Analytical model and parameters were suggested to describe the stress-strain behavior of concrete under confinement.

Development of Antibacterial Hood and Filter for Medical Powered Air Purifying Respirators (PAPR) (의료용 전동공기청정호흡기(PAPR)용 항균성 후드 및 필터 개발)

  • Eunjoo Koh;Nahyun Cho;Yong Taek Lee
    • Membrane Journal
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    • v.33 no.6
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    • pp.398-408
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    • 2023
  • This work developed a hood and filter for antibacterial protective clothing for medical powered air purifying respirators (PAPR) that can be used in medical settings and quarantine against infectious diseases such as Zika virus, Middle East respiratory syndrome (MERS), and coronavirus disease-19 (COVID-19). The hood material of the protective clothing was made of polypropylene spunlace nonwoven fabric (SFS) was used for withstand wind pressure and external physcial pressure. Forthermore, in order to reduce the user's risk of infection, phytoncide-based materials were used on the outer-surface of the hood to achieve a 99.9% antibacterial effect, and the inner-surface were treated with hydro-philic materials to improve absorbency by 25%. In addition to evaluating the artificial blood penetration resistance, dry mi-croorganism penetration resistance, wet bacteria penetration resistance, and bacteriophage penetration resistance required for medical protective clothing hoods, it received a passing evaluation of levels 2-6. Meanwhile, as a result of evaluating the performance of the antibacterial treated spunlace high efficiency particulate air (HEPA) filter, excellent antibacterial properties, dust removal rate, and differential pressure effect were confirmed. All performance evaluations were conducted by an accredited certification body in accordance with the medical PAPR certification standards.

A Study on Soviet Constructive Fashion in 1920s (1920년대 소비에트 구성주의 패션에 관한 연구)

  • 조윤경;금기숙
    • Journal of the Korean Society of Costume
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    • v.36
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    • pp.183-203
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    • 1998
  • The wave of Avant-garde swept away all in the unique social background so called 'October Revolution' and the early 1900 Russian society which was able to absorb and accept anything. The Russian avant-garde has been affected by the Cubism and the Futurism those had peculiarly appeared in the early twentieth century, spreaded out to three spheres: the Suprematism, the Rayonism and the Constructivism. The Russian Constructivism has appeared in this background, concretely and ideally ex-pressed the ideology of the revolution into the artistic form and made an huge influence to the whole Russian society. The Constructivist like Tatlin, naum Gabo, Pevaner, Rodchenko, Stepanova, Popova and Exter gave great effect on the Soviet Constructive fashion design in 1920's after the Revolution. The Soviet costume in 1920s hold in common the characteristicss of the Constructive graphic as it is, geometrical and abstractive form, energetic and motility. In fashion design, these graphic qualities have been showed as the application of geometrical form and architectural image, physical distortion and transformation. And in textile design, the simple, dynamical presentation has been appeared. We can classify the Soviet costume at this time into three occasions. The first term is from late 1910 th mid 1920, and it is altered from folk costume design to modern one. With Lamanova as the first on the list, using the folk mitif, the Constructive expression of simple form has been gradually revealed in design. Designers like Makarova, Pribylskaia and Mukhina produced the plane, simple chemise style with the decoration of the Russian traditional motif. From early to late 1920 is the second term, and it is at the pick of the most active processing of the Constructive design. Not only at the costume in daily life but also at the theatrical costume and textile, the con-structive design has been represented all avail-able fields. Many Constructivists including Stepanova, Popova, Exter and Rodchenko took part in the textile design and costume design so as to evlvo their aesthetic concept. The third term is from late 1920 to early 1930. The socialistic realism has dominated over the whole culture and art, the revolutionary dynamic motif has been presented also in textile design. The formative features of Soviet Constructive fashion design are; silhouette, from, motif, color and fabric. The first, the silhouette : a straight rectangular silhouetted has been expressed through the whole period and a volumed one with distorted human body shape has introduced in the theatrical costume design. The second, the form: many lengthened rectangular forms have been made at beginnings, but to the middle period, geometrical, architectural forms have been more showed and there are energy and movement in design. At the last period, only a partial feature-division has been seen. The third, the motif; no pattern or ethnic motif has been partly used at beginnings, a figure like circle, tri-angle has gradually appeared in textile design. At latter period, a real-existent motif like an airplane has been represented with graphing and simplicity. The fourth, the color ; because of insufficient dyeing, neutral color like black or grey color has been mainly covered, but after middle term, a primary color or pastel tone has been seen, contrast of the fabric; without much development of textile industry after the Revolution, thick and durable fabrics have been the main stream, but as time had going to the last period, fabrics such as linen, cotton, velvet and silk have been varously choesn. At the theatrical costume, new materials like plastics and metals that were able to accentuate the form. The pursuit of popularity, simplicity and functionalism that the basic concept of Constructive fashion is one of the "beauty" which has been searching in modern fashion. And now we can appreciate how innovative and epochal this Soviet Constructive fashion movement was.ement was.

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Effect of Organic Matter Ratios in Substrate and Mulching Materials on Growth of Liatris spicata under Non-irrigated Green Roofs (무관수 옥상녹화에서 유기질 비료와 멀칭재에 따른 리아트리스(Liatris spicata) 생육 반응)

  • Ju, Jin-Hee;Yoon, Yong-Han
    • Journal of the Korean Institute of Landscape Architecture
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    • v.40 no.2
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    • pp.130-137
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    • 2012
  • This research evaluated the effectiveness of organic matter ratios in substrate and mulching materials under mn-irrigated condition green roofs by measuring the effects on growth of Liatris spicata. Four mulching materials were installed, i. e. nun-mulched control(CON), volcanic ash soils(VAS), non-woven black fabric mat(NBM) and pine bark(PAK). Three levels of organic maller volume percentage in an amended soil were evaluated, amended soil: organic matter=100:0($A_1O_0$), amended soil: organic matter=80:20($A_4O_1$) and amended soil: organic matter=50:50($A_1O_1$). Plant height, number of leaves, diameter of flower stalk, number of florets, chlorophyll contents, shoot fresh and dry weight were recorded from April to September, 2010, and survival rate was examined on May 2011 of the following year. In the $A_1O_0$, the number of leaves, number of florets and chlorophyll contents were higher in Liatris spicata grown on NBM than other mulching treatments. Especially, plant height, shoot fresh and dry weight were significantly higher. However, it resulted the lowest survival rate than other mulching treatments. 2. In the $A_4O_1$, the plant height, number of leaves, number of florets, shoot fresh and dry weight were higher than other mulching treatments, but there was no significant difference except for the plant height of Liatris spicata grown on NBM. The survival rate was decreased by 40~60%, compared with $A_1O_0$, after overwintering. 3. In the $A_1O_1$, the plant height, number of leaves, diameter of flower stalk, number of florets, chlorophyll contents, shoot fresh and dry weight were slightly higher than other mulching treatments, but there was no significant difference from Liatris spicata grown on NBM and VAS. The survival rate was observed by 0% over all mulching treatments after overwintering. Therefore, the non-woven black fabric mat(NBM) promoted the Liatris spicata's growth and flowering compared with other mulching treatments. However, the survival rate was decreased significantly, and the organic matter ratios were increased after overwintering under non-irrigated green roofs.

A Study on the Preparation of Solvent-Free Low Foaming Scouring Agents (무용제형 저기포성 정련제의 제조에 관한 연구)

  • Keun, Jang-Hyoun;Kim, Seung-Jin;Hahm, Hyun-Sik;Park, Hong-Soo
    • Applied Chemistry for Engineering
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    • v.4 no.4
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    • pp.760-769
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    • 1993
  • Solvent-free low foaming scouring agents(LFSA) were prepared by blending of polyoxyethylene(30) octadecylbenzylammonium chloride(POAC), block copolymer of propylene oxide-ethylene oxide[p(PO-b-EO) glycol], Sedlan FF-200(FF-200) and sulfonic acid-amine condensate of polyoxyethylene(10) nonylphenyl ether(PSAC). In consequence of several tests, FF-200/POAC/p(PO-b-EO) glycol/PSAC/water (20g/10g/5g/5g/60g) mixture (LFSA-5) showed good cleaning power, penetrating ability, emulsifiability and stability to alkali, and gave less problem in water pollution. Scouring effect of LFSA-5 was investigated by the change of percentage of exhaustion before and after scouring at various dyeing temperatures. The percentage of exhaustion of the unscoured PET fabric was 4.5% at $70^{\circ}C$, while that scoured with LFSA-5 was 1.3% at the same temperature, which proved LFSA-5 to be a good scouring agent. Moreover, the foaming power of LFSA-5 measured by Ross and Miles method was 6mm foam height immediately after foaming, and that measured by Ross and Clark method was less than 300mm foam height at $30^{\circ}C$, and 20mm at $80^{\circ}C$. As a result, LFSA-5 proved a good low foaming scouring agent.

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The Effect of Washing Conditions on the Dimension and Mechanical Properties of Spandex Yarns (세척조건에 스판덱스사의 길이와 기계적 성질에 미치는 영향)

  • Chung, Hae-Won;Kim, Mi-Kyung
    • Journal of the Korean Society of Clothing and Textiles
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    • v.29 no.12 s.148
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    • pp.1619-1626
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    • 2005
  • The durability of a stretch fabric is mainly related to the change in the dimension and mechanical properties of elastomeric fibers during wearing and washing. In this study, we examined the effects of washing temperature, presoaking time and the number of washing cycles on the change in length, tenacity, elongation at break, and permanent elongation after six repeated cycles of $100\%$ extension and relaxation of spandex yams with varying fineness and with a different rate of extension during heat-set. The spandex yarns continued to shrink as the wash temperature and the number of wash cycles increased. In addition, the finer spandex yams decreased in length more than the thicker yams. The increase in temperature and presoaking time tended to cause a slight decrease in the tenacity and elongation at break of the spandex yarns. Permanent elongation of the spandex yams also increased as the temperature, presoaking time and the number of washing cycles increased. Moreover, an extended presoaking time followed by washing at $40\%$ like repeated washing cycles showed the great increase in the permanent elongation of spandex yams. The thinner spandex yin had a better elasticity than the thicker one, since the former had a lower permanent elongation percentage than the latter. Based on the DSC thermograms, the melting points of the spandex yarns after washing were almost the same as those of the spandex yarns before washing.

Improving Dyeability of Safflower Yellow Colorants on Cellulose Fibers (홍화 황색소의 셀룰로오스 섬유에 대한 염착성 증진)

  • Shin, Youn-Sook;Cho, A-Rang;Yoo, Dong-Il
    • Journal of the Korean Society of Clothing and Textiles
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    • v.31 no.12
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    • pp.1754-1760
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    • 2007
  • To improve poor dye uptake of safflower yellow colorants, cellulose fibers were pretreated with chitosan. The effect of chitosan pretreatment on the dyeability of safflower yellow colorants to cotton, ramie, and rayon was investigated in terms of dye uptake, color, and colorfastness. Irrespective of fiber types, dye uptake increased continuously with increase in chitosan concentration. Chitosan pretreatment improved dye uptake up to 5.6 times for cotton, 7.2 times for ramie, and 3.7 times for rayon. For cotton and ramie, the shade of dyed fabric changed YR color to Y color with increase in chitosan concentration. Dyed rayon fabrics showed Y color irrespective of chitosan concentration. Shades got darker and deeper with increasing chitosan concentration. Shades of chitosan pretreated fabrics were shifted differently depending on dyeing temperature within same fabrics. In common, the color of all dyed fabrics changed to YR at 50 and $70^{\circ}C$ while Y color at 30 and $90^{\circ}C$. V and C value decreased with increase in dyeing temperature and resulted in darker and duller color, in general. Light fastness was fair while washing fastness was poor. It was confirmed that ultrasonic dyeing method enhanced dye uptake more than 30% for cotton and ramie fabrics compared to the conventional automatic machine dyeing method. However, no difference in dye uptake between two dyeing methods was found for rayon.