• Title/Summary/Keyword: Short Fiber

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The Improvement of the Opacity and Printing Strength of Fancy Paper Overlaid Plywood

  • Kuo Lan-Sheng;Perng Yuan-Shing;Wang Eugene I-Chen;Yen Chen-Fa;Kao Tsuen-Han
    • Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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    • 2006.06a
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    • pp.91-98
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    • 2006
  • The purpose of this study is to investigate the opacity and printing strength of MG paper overlaid plywood. The printing strength of ink on MG paper can be evaluated effectively by a formula $E^{*2}=[(L^{*})^{2}+(a^{*})^{2}+(b^{*})^{2}]^{1/2}$ that we proposed. Higher E value indicates good printing strength of ink-on-paper. We also assess the real color of translucent printed MG paper with a formula CIE ${\bigtriangleup}E^{*}$ (color difference between a pile of same paper to be opaque and fancy paper laminated board). In addition, the color difference on paper surface caused by the color of wood-based board (bottom) can be evaluated by a formula of Pc. No. Generally, an acceptable appearance quality of fancy boards is ${\bigtriangleup}E^{*}$ <2.0 and small Pc.No. value. The experimental results showed that Japan-made MG papers -J1, J2 and J3 have better printing strength and gloss than that of Taiwan-made paper (T1). The reason for this was that Taiwan-made paper has poor printing strength and low gloss, which might be correlated to the fiber compositions in paper. Higher printing strength can be seen for short fiber containing handsheets when comparing to that of handsheets. Nonetheless, low-freeness sheets gives better printing strength than that of high-freeness sheets. High-opacity MG paper gives good opacifying effect to the fancy paper laminated wood-based boards. Comparing the surface color of 2 kinds of fancy paper laminated boards, paperboard T1 laminated with high-opacity fancy paper showed slight color difference. The same results can be seen for $??g/m^{2}$ handsheets. Higher-opacity Acacia and Eucalyptus bleached sulfate pulps (short fiber) gives higher opacifying effect on the plywood when comparing to Northan pine and Radiata pine sulfate pulps(long fiber). The former ones also showed small color differences when comparing the color differences between the color of fancy paper and laminated paper board. Additionally, the color of bottom plywood can't be shown through for the high-opacify surface paper adhered to. Besides, the PC No of the base paper laminated board is small as well. Apparently, we can add colorants to the binders for the manufscture of various handsheets ($30g/m^{2}$) with various pulp mix ratios to increase the opacity of paperboards to certain extents. When we using yellow and brown binders in paper laminated board, the color difference between Acacia and Eucalyptus handsheets overlaid boards decreasing to 2.0 (acceptable ${\bigtriangleup}E^{*}$ <2.0, hard to discern), but not much improvement for Northern and Radiata pines. Definitely, show-through defects can be discernible for lower opacity papers. In general, admirable printing strength of fancy paper by which glued to plywood can be made with high-opacity paper and colored binders techniques.

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Flexural Behavior of FRP Bar Reinforced HSC Beams with Different Types of Reinforcing Bar and Fiber (이질 보강근 및 섬유와 함께 보강된 FRP 보강근 보강 고강도 콘크리트 보의 휨 거동)

  • Yang, Jun-Mo;Shin, Hyun-Oh;Min, Kyung-Hwan;Yoon, Young-Soo
    • Journal of the Korea Concrete Institute
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    • v.23 no.3
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    • pp.273-280
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    • 2011
  • Ten high-strength concrete beam specimens, which have various combinations of different types of flexural reinforcement and short fibers were constructed and tested. Six beams were reinforced with two layers of steel, CFRP, and GFRP bar combinations. The other four beams were reinforced with two layers of single type CFRP and GFRP bars, with steel and synthetic short fibers. An investigation was performed on the influence of the parameters on the load-carrying capacity, post cracking stiffness, cracking pattern, deflection behavior, and ductility. The low post cracking stiffness, large deflection, deep crack propagation, large crack width, and low ductility of FRP bar-reinforced beams were controlled and improved by positioning steel bars in the inner layer of the FRP bar layer. In addition, the addition of fibers increased the first-cracking load, ultimate flexural strength, and ductility as well as the deep propagating cracks were controlled in the FRP bar-reinforced concrete beams. The increased ultimate concrete strain of fiber-reinforced concrete should be determined and considered when FRP bar-reinforced concrete members with fibers are designed.

Single-walled Hollow Nano-tubes and Nano-balls Assembled from the Aluminogermanante Precursors (Aluminogermanate Precursor의 자기조합(Self-assembly)을 통한 단일 벽을 갖는 나노-볼형 및 나노-튜브형 광물 유도)

  • Song, Yun-Goo;Bac, Bui Hoang;Lee, Young-Boo
    • Economic and Environmental Geology
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    • v.42 no.5
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    • pp.501-507
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    • 2009
  • Ordered single-walled hollow aluminogermanate (ALGE) nano-balls(NBs) and nano-tubes(NTs) have been self-assembled from the ALGE precursors having an Al/Ge ratio of 1.33 using simple pH-control. The hollow ALGE NBs with average monodisperse diameters of 5 nm and chemistry of Al/Ge=1.5~1.6 were formed through structural assembly in the ALGE solution (Al/Ge=1.33) highly basified to pH=13(Na/Al=28~30) and followed by immediate acidification to pH=9. When the basified solution(pH=13) were acidified to pH=4, ALGE S-NTs (Short-fiber nano-tubes) with diameters of 3.3 nm, 15~20 nm in length, and chemistry of Al/Ge=2.6~2.8 were successfully synthesized. Whereas the solution was basified to pH=9, and subsequently acidified to pH=4, L-NTs(Long-fiber nano-tubes) with >100 nm in length were synthesized for the first time. The self-assembly of the hollow NBs, S-NTs, and L-NTs form the ALGE precursors can be explained by the degree of $H^+$-dissociation of the -Ge-OH inner surfaces, which was controlled by amount of $Na^+$ and pH conditions of ALGE precursor solutions. This results indicate that target forms of ALGE nanomaterials can be synthesized by simple pH controls.

Reliability of Quantitative Sensory Testing Using Current Perception Thresholds in the Mandibular Nerve Area (하악신경영역에서 전류인지역치를 이용한 정량적 감각신경 검사의 재현성 조사)

  • Choi, Hee-Hun;Kim, Mee-Eun;Kim, Ki-Suk
    • Journal of Oral Medicine and Pain
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    • v.36 no.2
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    • pp.131-137
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    • 2011
  • Current Perception Threshold (CPT) using Neurometer($Neurometer^{(R)}$ CPT/C) is thought as one of easy and noninvasive QST(qunatitative sensory testing) tools for A${\beta}$, A${\delta}$ and C fibers within a relatively short time. However, conflicts about its reliability still exist. This study aimed to evaluate the reliability of CPTs evaluation and find a way to increase its reliability. Two examiners separately tested CPTs at each side of the mandibluar nerve areas for ten healthy male adults (average age of 22.4 years) three times with an intervals of a week during three weeks. Mean CPTs were compared between the right and left sides of the mandibular nerve area and between the three examinations on the each side. While CPTs at 2000 Hz(A${\beta}$ fiber) showed statistically significant side differences in all three examinations (p<0.05), significant side difference was found in only one examination at 250 Hz(A${\delta}$ fiber) and no difference at 5 Hz(C fiber). Comparing CPTs on the each side of the mandibular nerve area, all examinations at all sensory nerve fibers showed the least CPTs at the 1st examinations. CPTs at 250 Hz(A${\delta}$ fiber) and 5 Hz(C fiber) were significantly different between the first and the following examinations (p<0.05) and there was no significant difference between 2nd and 3rd examinations. The results of this study indicated that CPTs at 250 Hz(A${\delta}$ fiber) and 5 Hz(C fiber) are reliable but CPTs at 2000 Hz(A${\beta}$ fiber) is not appropriate for evaluation of side differences in the mandibular nerve area. In addition, it is suggested that repeated examination be helpful to increase reliability of the CPT evaluation.

Studies on the Breeding of the Response to short photoperiod, Fiber weight, and Qualitative characters and of the Associations Among these characters in Kenaf (섬유용양마의 육종에 관한 연구 -단일반응성과 섬유종의 유전 및 연소)

  • Johng-Moon Park
    • KOREAN JOURNAL OF CROP SCIENCE
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    • v.4 no.1
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    • pp.115-124
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    • 1968
  • It was shown that the most desirable characters for kenaf are high-fiber weight and moderately early maturity. Therefore, the objectives of this research on this crop is to find varieties possessing these characteristics. The experiments covered in this report provided new information relative to segregation, mode of inheritance, estimate of the number of genes involved in fiber weight and their response to short day length of 10 hours and the qualitative characters, such as, color of stem, capsule, petiole and shape of leaves. The associations which exist among these characters are also indicated. Fiber weight per plant, days to flowering, Stem color, Petiole color, Capsule color, and shape of leaves were studied in parental, $F_1$.$F_2$and backcross populations of a cross between Dashkent, a low-fiber weight but early maturing kenaf variety, and G 38 F-1, a high-fiber weight but late maturing kenaf variety. Crosses were made using the varieties, Dashkent and G 38 F-1 as parents. The Dashkent parent had the following characteristics: green stems, capsules and petioles and lobed shaped leaves; 105.8234 mean-days to flowering in the field, and 106.9222 mean-days under 10 hours short day treatment. The other parent, G 38 F-1 had red stems yellow capsules and red petioles and unlobed shaped leaves; 149.8921 mean-days to flowering in the field, and 62.3684 mean-days under 10 hours short day treatment. Both of the parents, $F_1$, $F_2$, $BC_1$ ($F_1$ X Dashkent, ) and $BC_2$($F_1$ ${\times}$ G38F-1) of the kenaf cross were grown at the Crops Experiment Station, Suwon, Korea in 1965. Color of stems, petioles and capsules, and shape of leaves were noted to be simply inherited as a single factor. Red stem color was dominant over green stem color, red petiole color was dominant over green petiole, lobed shaped leaves were dominant over unlobed shaped leaves and yellow capsules were dominant over green capsule. It was, also, noted that the factor for color of petiole was linked with the factor for shape of leaf with a 11.9587 percent recombination value, however no interaction or linkage were found among the color of stem and capsule color. Using Powers partitioning method, theoretical means and frequency distributions for each population, the days to flowering were calculated with the assumption that two gene pairs were involved. The values obtained fitted the theoretical values. In general this would indicate that Dashkent and G 38 F -1 were differentiated by two gene pairs. Heritability values were calculated as the percent of additive genetic variance. Heritability value of days to flowering, 89.5% in the broad sense and 79.91% in the narrow sense, indicated that the selection for this character would be effective in relatively early generations. Particularly, high positive correlations were found between days to flowering and the color of petioles and shape of leaves. However, there was no relation between days to flowering and capsule color nor between these and stem color. On the basis of the results of this experiment there is evidence that the hereditary factor for shape of leaves and the color of petioles is linked with an effective factor or factors for the characters of days to flowering. The association was sufficiently close to offer a possible simple and efficient means of selection for moderately early mat. uring plants by leaf shape and petiole color selection. Again using Powers partitioning method the frequency distribution for each population to the fiber weight were calculated with the assumption that two gene pairs, AaBb, were involved. Both phenotypic and genotypic dominance were complete. The obtained value did not agree with the theoretical value for $F_2$ and $BC_1$ ($F_1$ ${\times}$ Dashkent.) It seems that Dashkent and G 38 F-1 were differentiated by two major gene pairs but some the other minor genes are necessary. It is certain that the hereditary factor for shape of leaves and color of petioles is linked with an effective factor or factors for fiber weight. Also, high. yielding plants with moderately early maturity were found in the $F_2$ population. Thus, simultaneous selection for high-fiber yield and moderately early maturing plants should be possible in these populations. Phenotypic and genotypic correlation coefficients between fiber weight per plant and days to flowering, stem height and stem diameter were calculated. In general, genotypic correlations are higher than the phenotypic correlation. The highest correlation is found between stem height and fiber weight per plant (0.7852 in genotypic and 0.4103 in phenotypic) and between days to flowering and fiber weight per plant (0.7398 in genotypic and 0.3983 in phenotypic.) It was also expected that the selection of high stem height and moderately early maturing plants were given the efficient means of selection for high fiber weight.

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Effect of Compressibility on Flow Field and Fiber Orientation in the Filling Stage of Injection Molding (사출성형의 충전시 고분자용융액의 압축성이 유동장과 단섬유 배향에 미치는 영향)

  • Lee, S.C.;Ko, J;Youn, J.R.
    • The Korean Journal of Rheology
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    • v.10 no.4
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    • pp.217-226
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    • 1998
  • The anisotropy caused by the fiber orientation, which is inevitably generated by the flow during injection molding of short fiber reinforced polymers, greatly influences dimensional accuracy, mechanical properties, and other quality of the final product. Since the filling stage of the injection molding process plays a vital role in determining fiber orientation, an accurate analysis of flow field for the filling stage is needed. Unbalanced filling occurs when a complex or a multi-cavity mold is used leading to development of regions where the fiber suspension is under compression. It is impossible to make an accurate calculation of the flow field during filling with the analysis assuming incompressible fluid. A mold with four cavities with different filling times was produced to compare the numerical analysis results with the experimental data. There was a good agreement between the experimental and theoretical results when the compressibility of the polymer melt was considered for the numerical simulation. The fiber orientation states for compressible and incompressible fluids were also compared qualitatively as well as quantitatively in this study.

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The Effects of Insoluble Polymers on Water Stability of Carbon Fiber Reinforced Polymer-MDF Cementitious Composites (불용성 폴리머가 탄소섬유 보강 Polymer-MDF 시멘트 복합재료의 기계적 특성에 미치는 영향)

  • 김태진;박춘근
    • Composites Research
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    • v.12 no.3
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    • pp.84-90
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    • 1999
  • High alumina cement(HAC) and polyvinyl alcohol(PVA) based macro-defect-free(MDF) cement composites were reinforced using short carbon fibers, 3mm in length, 1-4% in weight fraction and insoluble polymers such as polyurethane, epoxy, phenol resin, in order to increase mechanical properties and water stability. The specimens were manufactured by the low heat-press(warmpress) method. In addition, the interface and the cross-linking reaction of cement and polymers was also studied by the SEM and TEM. Flexural strength of HAC/PVA based MDF cementitious composites was proportionally decreased with increasing fiber contents due to the undensified structure around fibers. The flexural strength of insoluble polymer added specimen was decreased with increasing fiber contents, while water stability was dramatically improved. Epoxy resin added specimen showed the highest strength with increasing fiber contents, compared with other specimens. The water stability of fiber content 4% added specimen immersed in water presented about 95%, 87% at 3 and 7 days immersed in water, respectively. The interfacial adhesive strength of fiber-matrix was very much improved due to cross linking reaction of polymer and metal ions of cement. Tensile strength of insoluble polymers added composites as linearly increased with increasing the fiber contents. The epoxy resin added specimen also showed highest tensile strength. The 4% fiber added specimen presented 30~80% higher strength than controlled specimen.

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A Study on the Behavior of Buried Flexible Pipes with Soil Condition (지반조건에 따른 지중매설 연성관의 거동에 관한 연구)

  • Lee, Hyoung-Kyu;Park, Joon-Seok
    • Journal of the Korean Geosynthetics Society
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    • v.13 no.1
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    • pp.33-40
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    • 2014
  • In general, pipes buried underground can be classified into either rigid or flexible pipe. Glass fiber reinforced thermosetting polymer plastic (GFRP) pipe can be considered as one of typical flexible pipes for which the soil-pipe structure interaction must be taked into account in the design. In this paper, we present the result of an investigation pertaining to the short-term and long-term behavior of buried GFRP pipe. The mechanical properties of the GFRP pipe produced in the domestic manufacturer are determined and the results are reported in this paper. In addition, Ring deflection is measured by the field tests and the finite element analysis. Also, the extrapolation using these techniques typically extends the trend from data gathered over a period of approximately 5,232 hours, to a prediction of the property at 50 years, which is the typical maximum extrapolation time. Therefore, it was investigated that the long-term ring deflection of GFRP pipe estimated by methods for Monod-type.

Analysis for Properties of Particle or Short Fiber Reinforced Composites based on Micromechanics under Pure Shear (전단응력하의 분산형 복합재료에 미시역학적인 특성평가)

  • 조영태;임광희
    • Composites Research
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    • v.15 no.3
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    • pp.11-17
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    • 2002
  • Cracking of the reinforcements is a significant damage mode in particle or short-fiber reinforced composites because the broken reinforcements lose load carrying capacity. This paper deals with elastic stress distributions and load carrying capacity of intact and cracked ellipsoidal inhomogeneities. Three dimensional finite element analysis has been carried out on intact and broken ellipsoidal inhomogeneities in all infinite body under pure shear. For the intact inhomogeneity, the stress distribution is uniform in the inhomogeneity and non-uniform in the surrounding matrix. On the other hand, for the broken inhomogeneity, the stress in the region near crack surface is considerably released and the stress distribution becomes more complex. The average stress in the inhomogeneity represents its load carrying capacity, and the difference of average stresses between the intact and broken inhomogeneities indicates the loss of load carrying capacity due to cracking damage. The broken inhomogeneity with higher aspect ratio maintains higher load carrying capacity.

A Study on Finite Element Methods for HSS(Hollow Square Section) Steel Columns Strengthened with Carbon Fiber Reinforced Polymer Plastic(CFRP) Sheets (탄소섬유쉬트(CFRP Sheets)로 보강된 각형강관(HSS)기둥의 유한요소해석 연구)

  • Park, Jai Woo;Yoo, Jung Han
    • Journal of Korean Society of Steel Construction
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    • v.28 no.3
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    • pp.185-194
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    • 2016
  • This paper presents the finite element method results for HSS(Hollow Square Section) steel columns strengthened with Carbon Fiber Reinforced Polymer Plastic(CFRP) sheets. 6 specimens were fabricated and the specimen groups were non-compact short columns, slender short columns, and non-compact long columns. Test parameter was the number of CFRP ply. The finite element analysis was performed by using ANSYS Workbench V.14.0 and the results of FEM were compared with those of Test for failure mode, load-displacement curve, maximum load, and initial stiffness. The comparisons between experimental observations and computed results show that the analyses provided good correlation to actual behavior. Finally, the buckling stress were calculated according to the AISC cold-formed structure provision and the retrofitting effect were verified for each section type.