• 한국생활과학회지
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• 제22권5호
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• pp.461-476
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• 2013

This study aims to provide practical information of both color and hands of cotton fabrics dyed with persimmon dye powder for natural dyeing fashion industries by investigating dyeing behavior and color gamut, by testing mechanical properties depending on color characteristics, and finally by evaluating dyeing fastness. As results, the persimmon dye powder obtained by extracting the fruits to final solid powder was found as containing tannin and it partially coated between and on fibers similarly to traditionally dyed one. The K/S values of non-mordanted fabric and two differently mordanted ones with Fe and Cu seemed to reach their equilibrium from 800, 800, and 600% (owf), respectively. Yellow-red was the only one hue shown while tones were various as pale (p), light grayish (ltg), soft (sf), dull (d), grayish (g), and dark grayish (dkg). In mechanical properties, the dyed fabrics with p and ltg tended to be less altered than undyed ones whereas d and d kg by higher bath concentrations could be applied to boxy silhouette owing to their increased stiffness and less stretchability. Although fastness to dry cleaning and stain was good, color change by washing and rubbing needed to be improved.

• 한국의류학회지
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• 제19권6호
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• pp.955-967
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• 1995

This study was performed to investigate the physical and chemical properties of the 5 kinds of fabrics dyed with persimmon juice and undyed fabrics. The difference between dyed and undyed fabrics was checked experimentally. Obtained results are as follows. 1. Bending length and flex stiffness were increased after dyeing, and tensile strength of waif i3l fabrics except Ramie was also increased. 2. Abrasion resistance was improved in Ramie and Hemp after dyeing but the rest of fabrics were decreased. 3. Crease resistance of dyed fabrics was roughly worse than that of undyed fabrics. 4. Air permeability remarkably increased after dyeing and this fact estabilished that the traditional Gal-01 was cool clothing. 5. Water repellency in Cotton 1 and Polyester rises but the rest of fabrics were not changed. Therefore it is found that this repellency related to the their fabric counts. 6. Blocking effect of UV light and visible ray was increased in all dyed fabrics. Especially dyed Cotton 1 and Polyester blocked UV light almost perfectly. 7. The colorfastness to soaping and sunlight was proved to less than 3 grade in all fabrics after dyeing. It indicates that this colorfastness became worse owing to dyeing. 8. The colorfastness to dry cleaning and water was decided to more than 3 grade in all fabrics. 9. The colorfastness of the dyed fabrics to sweat after exposing to man-made acid sweat solution was good so that was decided above 3 grade. However after exposing to man-made alkalic sweat solution it became worse owing to dyeing.

• 한국자동차공학회논문집
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• 제15권6호
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• pp.50-61
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• 2007

The structural stiffness, strength and stability on the bodyshell and floor structures of the Korean Low Floor Bus composed of laminate, sandwich panels and metal reinforced frame were evaluated. The laminate composite panel and facesheet of sandwich panel were made of WR580/NF4000 glass fabric/epoxy laminate, while aluminum honeycomb or balsa was applied to the core materials of the sandwich panel. A finite element analysis was used to verify the basic design requirements of the bodyshell and the floor structure. The use of aluminum reinforced frame and honeycomb core was beneficial for weight saving and structural performance. The symmetry of the outer and inner facesheet thickness of sandwich panels did not affect the structural integrity. The structural strength of the panels was evaluated using Von-Mises criterion for metal structures and total laminate approach criterion for composite structures. All stress component of the bodyshell and floor structures were safely located below the failure stresses. The total laminate approach is recommended to predict the failure of hybrid sandwich composite structures at the stage of the basic design.

• 한국항해항만학회지
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• 제32권9호
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• pp.699-703
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• 2008

Fiber reinforced plastics (FRP) have been widely used because of their high specific strength, high specific stiffness and etc. Although these kinds of FRP have various merits in applications, it has been had one of the complicated problems to manufacture their wooden mold. For these reasons, the simple methods to manufacture the mold required in the FRP industries. To improve these kinds of problems, the molding system using composite materials was developed. By this new manufacturing techniques and high functional FRP composite mold was built. Comparing with wooden mold, the process efficiencies of frame manufacturing process and inner mold manufacturing process were improved approximately 40% and 70%, respectively.

• 한국철도학회논문집
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• 제10권2호
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• pp.201-210
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• 2007

Sandwich composites made of glass fabric epoxy facesheets with aluminum honeycomb core or balsa core is considered for the structural design of bodyshell of a Korean Low Floor Bus. Initially, in order to select the optimal facesheet and core materials in design stage, the flexural response of a sandwich composite is a critical importance. In this study, theoretical formula which could easily and quickly evaluate and obtain the flexural responses such as deflection and flexural stiffness of a sandwich composite subjected to external load was established. This theory could calculate the flexural responses of sandwich composites with narrow as well as wide width and with facesheets of unequal thickness, and also distinguish between the bending and shear effects of deflection. Finite element analysis using ANSYS V10.0 was used to offer the best elements for real sandwich composites, and flexural test according to ASTM C393 was conducted to compare with the results of theoretical formula and finite element analysis. The results show that the flexural responses of sandwich composites using proposed theoretical formula is in good agreement with those of experiment and finite element method.

• Carbon letters
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• 제12권4호
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• pp.249-251
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• 2011

Carbon/epoxy woven composites are prominent wear-resistant materials due to the strength, stiffness, and thermal conductivity of carbon fabric. In this study, the effect of oilabsorption on the wear behaviors of carbon/epoxy woven composites was investigated. Wear tests were performed on dry and fully oil-absorbed carbon/epoxy woven composites. The worn surfaces of the test specimens were examined via scanning electron microscopy to investigate the wear mechanisms of oil-absorbed carbon/epoxy woven composites. It was found that the oil absorption rate was 0.14% when the carbon/epoxy woven composites were fully saturated. In addition, the wear properties of the carbon/epoxy woven composites were found to be affected by oilabsorption. Specifically, the friction coefficients of dry and oil-absorbed carbon/epoxy woven composites were 0.25-0.30 and 0.55-0.6, respectively. The wear loss of the oilabsorbed carbon/epoxy woven composites was $3.52{\times}10^{-2}\;cm^3$, while that of the dry carbon/epoxy woven composites was $3.52{\times}10^{-2}\;cm^3$. SEM results revealed that the higher friction coefficient and wear loss of the oil-absorbed carbon/epoxy woven composites can be attributed to the existence of broken and randomly dispersed fibers due to the weak adhesion forces between the carbon fibers and the epoxy matrix.

• 동력기계공학회지
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• 제10권2호
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• pp.117-123
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• 2006

Woven fabrics composites are used as primary structural components in many applications because of their superior properties that offer high specific strength and stiffness. However, the complexity of the fabric structure makes understanding of their failure behavior very difficult. Also, laminate woven fabrics CFRP have unique failure mechanisms such as fiber bridging, fiber/matrix crack and so on. In particular, the delamination phenomenon of the composite materials is one of the most frequent failure mechanisms. So, we estimated interlaminar fracture and damage in composites using as ENF specimen by a 3 point bending test. And AE characteristics were examined for crack propagation on plain woven CFRP. We obtained the following conclusions from the results of the evaluation of the 3 point bending fracture test and AE characteristic estimation. AE counts of maximum crack length were obtained as $85.97{\times}10^4\;and\;93{\times}10^3\;for\;a_0/L=0.3$ and 0.6, respectively. Also the maximum amplitudes were over 80dB at both $a_0/L=0.3\;and\;0.6$. $G_{IIc}$ at that's $a_0/L$ ratio were obtained with $1.07kJ/m^2\;and\;3.79kJ/m^2$.

• 한국의류산업학회지
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• 제6권5호
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• pp.660-666
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• 2004

This article describes the change of hand value of chitosan crosslinked cotton fabrics. The chitosan crosslinked cotton fabrics were manufactured by mercerizing process using epichlorohydrin(ECH) as crosslinkins agent, 2% aqueous acetic acid as a solvent of chitosan and ECH, and 20% aqueous sodium hydroxide as a mercerizing agent and crosslinking catalyst. Cotton fabrics were dipped in the mixed solution of chitosan and ECH, picked up by mangle, mercerized and crosslinked in NaOH solution, and finally wash and dry. Mechanical and physical properties of the chitosan crosslinked fabric were investigated using Kawabata Evaluation System(KES) and other instruments. Tensile energy and tensile strain were decreased with the increase of the concentration of chitosan. Tensile resilience, compression resilience bending rigidity, bending hysteresis, shear stiffness, shear hysteresis, coefficient of friction, geometrical roughness, compression linearity, compressional energy, and thickness were increased with the increase of the concentration of chitosan. On the other hand, bending rigidity, bending hysteresis, coefficient of friction, geometrical roughness, compressional resilience, and thickness were increased with the increase of the concentration of crosslinking agent(epichlorohydrin).

• 패션비즈니스
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• 제22권2호
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• pp.107-117
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• 2018

Nettle fiber, a sustainable fiber, was applied to the fabrication of denim to identify changes in textile appearance and formation. For the weaving of nettle denim, nine specimens, distinguished by three kinds of composite use of nettle fiber and three stages of fabrication processes, were used. The kinetic characteristics of the nine specimens were measured by the KES-FB system, and the images of the specimens of finished denim textiles, captured with a CCD Camera, were analyzed. In terms of the extensibility (EM) of nettle denim, all specimens showed post-processing increase, thereby suggesting an easy transformation of the textile as a source material for denim fabric. The effects of washing on the woven formation of denim were also identified. The geometric roughness (SMD), the problematic property of bast-fiber-like nettle fiber, was found to be decreased by washing. In terms of the bending rigidity (B) of the textile, the post-processing shrinking percentage of elastic nettle denim was found to decrease; all specimens that underwent bio-washing only also manifested that post-processing elasticity increased. To improve the draping of nettle denim, a mixed spinning together with washing were found to be advantageous. In terms of the shear stiffness (G), which is closely associated with the appearance of clothes, the formation of textile was improved regardless of the types of processing, including bio-washing and bleach washing.

• 대한기계학회논문집A
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• 제29권11호
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• pp.1551-1559
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• 2005

This paper explains manufacturing process and experimental studies on a composite carbody of Korean tilting train. The composite carbody with length of 23m was manufactured as a sandwich structure composed of a 40mm-thick aluminium honeycomb core and 5mm-thick woven fabric carbon/epoxy face. In order to evaluate structural behavior and safety of the composite carbody, the static load tests such as vertical load, end compressive load, torsional load and 3-point support load tests have been conducted. These tests were performed under Japanese Industrial Standard (JIS) 17105 standard. From the tests, maximum deflection was 12.3mm and equivalent bending stiffness of the carbody was 0.81$\times$10$^{14}$ kgf$\cdot$mm$^{2}$ Maximum stress of the composite body was lower than 12.2$\%$ of strength of the carbon/epoxy. Therefore, the composite body satisfied the Japanese Industrial Standard.