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Preparation of Cellulose Nanofibril/Regenerated Silk Fibroin Composite Fibers

  • Lee, Ji Hye;Bae, Chang Hyun;Park, Byung-Dae;Um, In Chul
    • International Journal of Industrial Entomology and Biomaterials
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    • v.26 no.2
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    • pp.81-88
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    • 2013
  • Wet-spun silk fibers have attracted the attention of many researchers because of 1) the unique properties of silk as a biomaterial, including good biocompatibility and cyto-compatability and 2) the various methods available to control the structure and properties of the fiber. Cellulose nanofibrils (CNFs) have typically been used as a reinforcing material for natural and synthetic polymers. In this study, CNF-embedded silk fibroin (SF) nanocomposite fibers were prepared for the first time. The effects of CNF content on the rheology of the dope solution and the characteristics of wet-spun CNF/SF composite fibers were also examined. A 5% SF formic acid solution that contained no CNFs showed nearly Newtonian fluid behavior, with slight shear thinning. However, after the addition of 1% CNFs, the viscosity of the dope solution increased significantly, and apparent shear thinning was observed. The maximum draw ratio of the CNF/SF composite fibers decreased as the CNF content increased. Interestingly, the crystallinity index for the silk in the CNF/SF fibers was sequentially reduced as the CNF content was increased. This phenomenon may be due to the fact that the CNFs prevent ${\beta}$-sheet crystallization of the SF by elimination of formic acid from the dope solution during the coagulation process. The CNF/SF composite fibers displayed a relatively smooth surface with stripes, at low magnification (${\times}500$). However, a rugged nanoscale surface was observed at high magnification (${\times}10,000$), and the surface roughness increased with the CNF content.

Basic and Mechanical Properties by Film Type to Minimize the Sound Pressure Level of PTFE Laminated Vapor-permeable Water-repellent Fabrics (PTFE(Polytetrafluoroethylene) 라미네이팅 투습발수직물의 총음압 최소화를 위한 필름 타입 별 기본 특성과 역학 특성)

  • Lee, Kyu-Lin;Lee, Jee-Hyun;Jin, Eun-Jung;Yang, Youn-Jung;Cho, Gil-Soo
    • Fashion & Textile Research Journal
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    • v.14 no.4
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    • pp.641-647
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    • 2012
  • This study investigates the sound properties of fabric frictional sound (SPL, ${\Delta}L$, ${\Delta}f$) according to the film type of PTFE laminated vapor-permeable water-repellent fabrics in order to understand the relationship between SPL and the basic properties of fabrics such as layer, yarn type, and thickness of fiber. This study accesses their mechanical properties and determines how to control them to minimize SPL. Eight PTFE laminated water-repellent fabrics, composed of four different film types (A, B, C, D) and with two different fabrics, were used as test specimens. Frictional sounds generated at 1.21m/s were recorded by using a fabric sound generator and SPLs were analyzed through Fast Fourier Transformation (FFT). The mechanical properties of fabrics were measured by KES-FB. The SPL value was lowest at 74.4dB in film type A and highest as 85.5dB in type D. Based on ANOVA and post-hoc test, specimens were classified into less Loud Group (A, B) and Loud Group (C, D). It was shown that SPL was lower when 2 layer (instead of 3 layer), filament yarn than staple, and thin fiber than thick were used. In Group I, shearing properties (G, 2HG5), geometrical roughness (SMD), compressional properties (LC, RC) and weight (W) showed high correlation with SPL however, elongation (EM) and shear stiffness (G) did with SPL in Group II.

Dry Matter Yield of Early Maturing Italian Ryegrass (Lolium multiflorum Lam) Cultivars at Different Harvesting Times

  • Kim, Ki-Yong;Choi, Gi Jun;Lee, Sang-Hoon;Hwang, Tae-Young;Lee, Ki-Won;Ji, Hee Chung;Park, Sung Min
    • Journal of The Korean Society of Grassland and Forage Science
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    • v.36 no.4
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    • pp.376-380
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    • 2016
  • This experiment was carried out to investigate the effect of harvesting time of Italian ryegrass (Lolium multiflorum Lam; IRG) in spring on dry matter (DM) yield. IRG cultivars 'Kowinearly' and 'Greenfarm' were seeded at 50 kg/ha and grown on rice paddy fields. There was no difference in growth characteristics between both varieties before winter. However, cold tolerance of Kowinearly was higher than that of Greenfarm, as demonstrated by post-wintering growth characteristics. The heading date of both varieties was affected by the spring weather. The IRG was harvested three times at 5-day intervals beginning from 9 May. The DM yield of Greenfarm was 6,306; 7,335; and 8,109 kg/ha, and that of Kowinearly was 7,498; 9,196; and 10,449 kg/ha at the three consecutive harvests. The delay of the harvesting time for 5 and 10 days increased the DM yield of Greenfarm by 16% and 29% and that of Kowinearly by 23% and 39%, respectively, compared to the yield at first harvest (p < 0.05). Therefore, IRG harvest later than early to mid-May is expected to increase productivity. The feed values of Greenfarm were: 12.2% of crude protein (CP), 34.5% of acid detergent fiber (ADF), 57.7% of neutral detergent fiber (NDF), 61.6% of total digestible nutrients (TDN), and 72.3% of in vitro DM digestibility (IVDMD). For Kowinearly, these values were 16.4% of CP, 30.4% of ADF, 52.7% of NDF, 64.9% of TDN and 79.0% of IVDMD.

Natural Dyeing of Silk Fabrics with Black Rice Bran Extract (흑미 왕겨 추출물을 이용한 견직물의 천연염색)

  • Lee, Geun Souk;Bae, Do Gyu
    • Current Research on Agriculture and Life Sciences
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    • v.27
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    • pp.13-19
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    • 2009
  • The purpose of this study was the efficient use of the black rice bran for dyeing textiles. For this purpose, we investigated proper extracting conditions of black rice bran, dyeability and dyeing fastness of dyed silk fabrics. To find proper extracting condition of black rice bran, we extracted black rice bran with water at different temperatures($40^{\circ}C$, $60^{\circ}C$, $80^{\circ}C$), different extracting pH(pH3, pH4, pH5, pH6) and extracting time(20, 40, 60, 80, 100, 120, 140, 160, 180min.). Also we investigated the effect of dyeing time(1, 2, 3, 4, 5, 6hr.), dyeing temperature($40^{\circ}C$, $60^{\circ}C$, $80^{\circ}C$) and mordanting method(non, pre, sim, post) to examine dyeability and dyeing fastness of dyed silk fabrics. As a result, when the extracting temperature and time were $80^{\circ}C$, 3hr., respectively, extracting was best. And the higher the extracting concentration, the more the extracting amount. As the dyeing temperature and time were higher and longer, the dyeability of silk fabrics was better. With mordant, the dyeability was improved and when using premordant method better, the K/S value was maximized. The laundering fastness of the silk fabrics dyed with black rice bran was estimated to have a good grade of 3~4, however, the light fastness was poor to have a grade of 1~2.

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Effect of Grazing Stage and Intensity on the Forage Production and Nutritive Value in Orchargrass Dominant Pasture (Orchargrass 위주 혼파초지에서 방목시기와 강도가 초지생산성 및 사료가치에 미치는 영향)

  • Seo, Sung;Shin, Jae-Soon;Lee, Joung-Kyong
    • Journal of The Korean Society of Grassland and Forage Science
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    • v.16 no.1
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    • pp.53-60
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    • 1996
  • A field experiment was carried out to determine the effects of grazing stage and intensity on the forage production and nutritive value in orchardgrass dominant pasture, 1989 and 1990. The grazing stages were 20- 25m, 30-35cm and 40-45cm of plant height, and high and medium grazing intensity were set by the number of growing cows (initial body weight: 230-250kg), which was adJusted according to the pasture production. The high level of grazing intensity was 150% of medium intensity. Annual grazing frequency was 10 times in 20-25cm. 8 times in 30-35cm. and 6 times in 40-45cm of plant height. Dry matter(DM) yield was increased with increasing of plant height at grazing : 7,090kg in 20-25cm 7,882kg in 30-35n and 8,260 kgha in 40-45cm of height. Higher DM was observed at medium grazing intensity. In spring, daily DM production was more vigorous than those in summer and autumn season. Cmde protein (CP), digestible DM, and DM intake were decreased with increasing of plant height at grazing. CP content was 25.8% in 20-25cm 22.4% in 30-35m and 19.2% in 40-45cm, while the contents of neutral detergent fiber and acid detergent fiber were increased with higher plant height. Relative feed value was 11 1.2 in 20-25cm, 104.4 in 30-35n and 99.6 in 40-45cm. Also nutritive value of pre-grazing pasture plants was remarkably higher than that of post-grazing, and not significant differences of nutritive value were found between grazing intensity. From the above mults, it may be concluded that optimum plant height for grazing was 20-25cm and 30- 35cm in pasture mixtures dominated by orchardgms, and medium grazing intensity was very desirable for pasture productivity.

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THE INFLUENCE OF SELECTED CHEMICAL TREATMENTS ON THE RUMINAL DEGRADATION AND SUBSEQUENT INTESTINAL DIGESTION OF CEREAL STRAW

  • Wanapat, M.;Varvikko, T.;Vanhatalo, A.
    • Asian-Australasian Journal of Animal Sciences
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    • v.3 no.2
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    • pp.75-83
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    • 1990
  • An experiment was conducted with three ruminally and intestinally cannulated non-lactating cows of Finnish Ayrshire breed, to assess the ruminal degradation characteristics of oat (Avena sativa), rye (Secale cereale) and rice (Oryza sativa) straw by the nylon bag technique, and the subsequent post-ruminal degradation of their rumen-undegraded residues by using the mobile bag technique, respectively. The straw samples were untreated or treated with aqueous $NH_3$ or with urea solution in cold or hot water. The untreated straw samples were milled or chopped, and the treated straw samples were chopped. The constant values a, b, and c were computed according to the exponential equation, where a = intercept of degradation curve at time 0, b = potentially degradable material, c = rate of degradation of band (a+b) = maximum potential degradability (asymptote). It was found that nitrogen contents of chemically treated straw were markedly increased by both $NH_3$ and urea treatments. Milling the samples attributed to a remarkable loss at 0 h incubation time as compared to chopping of the respective samples. However, chemical treatment markedly improved the b value and the subsequent (a+b) values for dry matter, organic matter, neutral-detergent fiber, and acid-detergent fiber of the samples. Furthermore, temperature of the water used in the urea solutions was considered essential, since urea in hot water rather than in cold water seemed to enhance the overall degradability. The disappearance of rumen-incubated straw residues from the mobile bags ranged from 4.5 to 9.6% for the parameters measured. On average, the OM disappearance from bags was clearly higher for the residues of urea treated straw compared to those of ammonia treated straw, but the disappearance of NDF tended, however, to be higher on the ammonia treatment.

Performance Improvement of WDM Signals through Precompensation and Postcompensation in Dispersion Managed Optical Transmission Links with Artificial Distribution of Single Mode Fiber Length and RDPS (인위적인 단일 모드 광섬유 길이와 RDPS 분포를 갖는 분산 제어 광전송 링크에서 선치 보상과 후치 보상을 통한 WDM 신호의 성능 개선)

  • Lee, Seong-Real
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.16 no.10
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    • pp.2293-2302
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    • 2012
  • New optical transmission links technique for compensating of the distorted wavelength division multiplexed (WDM) signals due to group velocity dispersion (GVD) and self phase modulation (SPM) in single mode fiber (SMF) are proposed. The proposed optical links have optical phase conjugator (OPC) placed at nearby WDM transmitter or receiver and repeater spans with artificial distribution of SMF length and residual dispersion per span (RDPS). It is confirmed that optimal link configuration expanding effective launching power range and effective net residual dispersion (NRD) by improving system performance is that having OPC closely placed at WDM receiver and the gradually descended distribution of SMF length and RDPS of each repeater spans, related with the gradually increased optical link length. And, it is also confirmed that NRD is controlled by postcompensation in optimal optical link with OPC closely placed at WDM receiver.

Performance Improvement of WDM Channels using Inline Dispersion Management in Transmission Link with OPC Placed at Various Position (다양한 위치에 존재하는 OPC를 갖는 전송 링크에서 Inline 분산 제어를 이용한 WDM 채널의 성능 개선)

  • Lee, Seong-Real
    • Journal of Advanced Navigation Technology
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    • v.14 no.5
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    • pp.668-676
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    • 2010
  • Optimal net residual dispersions (NRDs) of inline dispersion management (DM) for compensating the signal distortion of $24{\times}40$ Gbps WDM channels in optical transmission links, in which optical phase conjugator (OPC) is placed from 250 km to 750 km by spacing 50 km in 1,000 km total transmission length of single mode fiber (SMF), are induced as a function of various ope positions. And, performance improvement of WDM channels in transmission links with the induced optimal NRD is investigated by comparing with that in transmission links with NRD = 0 ps/nm. It is confirmed that optimal NRDs are decided by displacement of OPC from mid-way of total transmission length, i.e. 500 km, and the determinating and applying of optimal NRD in case of ope displacement into transmitters is more stable and effective than that in case of ope displacement into receivers from 500 km. Also, it is shown that eye opening penalties (EOPs) of WDM channels in transmission links with optimal NRD are improved by 1.5 dB to 3 dB, which are related with OPC position, from that obtained in transmission links with fixed NRD of 0 ps/nm.

Carbon Nanotubes Reinforced Poly(ethylene terephthalate) Nanocomposites (탄소나노튜브로 강화시킨 Poly(ethylene terephthalate) 나노복합재료)

  • Choi, Soohee;Jeong, Youngjin
    • Polymer(Korea)
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    • v.38 no.2
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    • pp.240-249
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    • 2014
  • Multi-walled carbon nanotube (MWNT) reinforced poly(ethylene terephthalate) (PET) composites are studied. To increase the interfacial interactions between PET and MWNTs, the MWNTs are functionalized with bishydroxy-ethylene-terephthalate (BHET). The functionalized MWNTs are melt blended into PET matrix using a twin screw extruder. The amount of MWNTs loaded in PET matrix ranges from 0.5 to 2.0 wt%. After compounding and spinning, the filaments are post-drawn and annealed. To verify the chemical modifications of carbon nanotubes, Raman, $^1H$ NMR, XPS, TGA and FE-SEM are used. The nanocomposites are also analyzed with DSC, TGA, and UTM. These tests show that crystallization temperature and thermal degradation temperature increase due to the functionalized MWNTs. Also, tensile test shows that yield strength and toughness increase more than 30% with addition of only 1 wt% of MWNTs. These results show that the introduction of BHET onto the MWNTs is a very effective way in manufacturing MWNT/PET composite.

Dyeability and Functionality of Pine Needles Extract (part I) -Characteristics of Pine Needles Extract and Dyeing Properties of Cellulose Fiber- (솔잎 추출물의 염색성과 기능성 (제1보) -솔잎 추출물의 특성과 셀룰로오스섬유에 대한 염색성-)

  • Woo, Hyo-Jung;Lee, Jung-Soon
    • Journal of the Korean Society of Clothing and Textiles
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    • v.35 no.2
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    • pp.218-229
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    • 2011
  • Dyeing properties of cotton and ramie fabrics with pine needles colorants were studied by investigating the analysis of pine needles colorants, the effect of dyeing conditions (such as dye concentration, dyeing temperatures and times on dye uptakes), effect of mordants, and color change. The various colorfastness of dyed fabrics were evaluated for practical use; in addition, the antimicrobial ability, ultraviolet-cut ability, and deodorant ability were estimated. In the UV-Visible spectrum, the wavelength of the maximum absorption for pine needles extract was 285nm, and pine needles colorants produced a yellow color. From FT-IR and GC-MS results, it was assumed that chromophoric substance from pine needles extracts were mixed with flavonol tannin and flavanol tannin. An increased dyeing concentration resulted in a larger dye uptake and a Freundlich absorption isotherm was obtained. A larger dye uptake occurred as the dyeing time and temperature increased. Post-mordanting was more effective than pre-mordanting and the dye uptake of fabrics improved by mordanting. The colorfastness of dyed fabrics showed a low rating; however, colorfastness to washing and dry cleaning of cotton fabrics mordanted with N.Cu, and friction fastness of ramie fabric mordanted with Cu improved. The dyed fabrics showed very good antimicrobial abilities of 99.9%. In addition, the ultraviolet-cut ability and deodorant ability improved in fabrics dyed with pine needles extracts.