• Journal of the Korean Solar Energy Society
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• v.22 no.3
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• pp.57-65
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• 2002

The photocatalytic degradation of TCE using solar energy in POFR was studied. The use of solar energy was investigated in plastic optica fiber photocatalytic reactor (POFR). In POFR, the main parameters of photocatalytic degradation of TCE were lihgt intensity, thickness of $TiO_2$-coated film on plastic fiber core, the same of total $TiO_2$-coated surface area with changed length. We studied the apparent photonic efficiency and photocatalytic degradation rate of TCE in POFR. The apparent photonic efficiency of various light intensities was decreased by an incresed intensities. The photocatalytic activities of $TiO_2$-coated optical fiber reactor system depended on the coating thickness, and total clad-stripped surface area of POF. Photocatalytic degradation of trichloroethylene ($C_2HCl_3$, TCE) in the gas-phase was elucidated by using $TiO_2$-coated plastic optical fiber reactor. In TCE degradation, in-situ FTIR measurement resulted in mineralization into $CO_2$.

• Journal of Ocean Engineering and Technology
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• v.12 no.3 s.29
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• pp.31-41
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• 1998

Single fiber fragmentation technique was used to evaluate the change of interfacial properties by degradation of fiber tensile strength in the fiber reinforced composites. The influences of fiber tensile strength on the interfacial properties have been evaluated by the fragmentation specimens(weak fiber samples) of glass fiber/epoxy resin that was made using the pre-degraded glass fiber in distilled water at $80^{circ}C$ for specified periods. The effects of the immersion time on the interfacial properties in the distilled water at $80^{circ}C$ also have been evaluated by the fragmentation specimens(original fiber samples) of glass fiber/epoxy resin that was made using the received glass fiber. As the result, the tensile strength of glass fiber was decreased with the increasing of the treatment time in the distilled water at $80^{circ}C$ and the interfacial shear strength was independent of the change of the glass fiber strength in the single fiber fragmentation test. But in the durability test using the single fiber fragmentation specimen, interfacial shear strength decreased with the increasing of the immersion time in distilled water ar $80^{circ}C$. And it turned out that the evaluating of interfacial shear strength using original fiber tensile strength was valuable in the durability test for the water environment by the single fiber fragmentation technique.

• Textile Coloration and Finishing
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• v.29 no.4
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• pp.181-194
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• 2017

The biodegradability of polylactic acid(PLA) fabrics was evaluated by two methods: enzyme and soil degradation. Three different enzymes were selected to evaluate. Degradation times were measured at optimal enzyme treatment conditions. Biodegradation by enzymatic hydrolysis was compared with soil degradation. As a result, biodegradation created cracks on the fiber surface, which led to fiber thickening and shortening. In addition, new peak was observed at $18.5^{\circ}$ by degradation. Moreover, cracks indicating biofragmentation were confirmed by enzyme and soil degradation. By enzyme and soil degradation, the weight loss of PLA fabrics was occurred, there through, the tensile strength decreased about 25% by enzyme hydrolysis when 21 days after, and 21.67% by soil degradation when 60 days after. Furthermore, the biodegradability of PLA fabrics by enzymatic and soil degradation was investigated and enzymatic degradation was found to be superior to soil degradation of PLA fabrics. Among the three enzymes evaluated for enzymatic degradation, alcalase was the most efficient enzymes. This study established the mechanism of biodegradation of PLA nonwovens, which might prove useful in the textile industry.

• Polymer(Korea)
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• v.29 no.5
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• pp.508-517
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• 2005

The thermal degradation behavior and reliability analysis were investigated using dynamic thermogravimetric analysis (TGA) and accelerated degradation test (ADT) to characterize the dynamic parameters related to thermal degradation of plastic meterials for household electric appliances. In addition, the weathering of the plastic were performed by ADT using Xenon uc, and the color difference of the samples after ADT were measured with Color Eye 3010 specoophotometer. he activation energy for thermal degradation of the samples increased with increasing the rate of weight loss. The Kim-Park method was found to be more effective analysis in describing thermal degradation of plastic meterials. Plastic materials were very sensitive to ultra-violet rays in faster degradation.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2002.10a
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• pp.43-47
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• 2002

Weight loss experiments have been performed for unidirectional carbon fiber/epoxy laminates under both isothermal and cyclic thermal conditions. It was found that weight losses were the result of both specimen-geometry dependent oxidative degradation and volumetric geometry dependent thermal degradation. Thermal degradation was found to play a major role in the overall weight loss process, and photomicrographs of cross-sectioned, aged specimens confirmed this fact. A method to predict the effect of isothermal environment on the weight loss was introduced and found to be in good agreement with experimental data at temperatures near Tg (glass transition temperature).

• Steel and Composite Structures
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• v.19 no.6
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• pp.1531-1548
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• 2015

The aim of this study is to investigate the relationship between Barcol hardness (H) and flexural modulus (E) degradation of composite sheets subjected to flexural fatigue. The resin transfer molding (RTM) method was used to produce 3-mm-thick composite sheets with fiber volume fraction of 44%. The composite sheets were subjected to flexural fatigue tests and Barcol scale hardness measurements. After these tests, the stiffness and hardness degradations were investigated in the composite sheets that failed after around one million cycles (stage III). Flexural modulus degradation values were in the range of 0.41-0.42 with the corresponding measured hardness degradation values in the range of 0.25-0.32 for the all fatigued composite sheets. Thus, a 25% reduction in the initial hardness and a 41% reduction in the initial flexural modulus can be taken as the failure criteria. The results showed that a reasonably well-defined relationship between Barcol hardness and flexural modulus degradation in the distance range.

• Macromolecular Research
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• v.12 no.5
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• pp.466-473
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• 2004

We have used FT-IR spectra to explain the effects of hydrogen bonding between chitosan and polycaprolactam (PA6). A dynamic mechanical analysis study suggested that the optimum chitosan and PA6 miscibility under the conditions of this experiment were obtained at a blending ratio of 40:60. We studied the thermal degradation of chitosan blended with PA6 (chitosan/PA6) by thermogravimetric analysis and kinetic analysis (by the Ozawa method). Dry chitosan and PA6 exhibited a single stage of thermal degradation and chitosan/PA6 blends having> 20 wt% PA6 exhibited at least two stages of degradation. In chitosan/PA6 blends, chitosan underwent the first stage of thermal degradation; the second stage proceeded at a temperature lower than that of PA6, because the decomposition product of chitosan accelerated the degradation of PA6. The activation energies of the blends were between 130 and 165 kJ/mol, which are also lower than that of PA6.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.669-672
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• 2006

Recently, large efforts have been made to develop and understand the behavior of Fiber Reinforced Concrete. As in the static loading cases, many researches have been done. However, a few studies have been conducted in cyclic behaviors of FRC. The main objective of the present work is to investigate the cyclic behavior of fiber reinforced concrete with theoretical method. First, cyclic constitutive relations which describe the crack bridging stress considering non-uniform interfacial bond degradation in short randomly oriented fiber reinforced matrix composites under uniaxial cyclic tension were considered. A cyclic degradation model of single fiber based on micromechanics also taken into consideration. As an example, fatigue analysis for ECC with PVA fiber was conducted using proposed equations. Results shows that proposed method can establish a basis for analyzing cyclic behavior of fiber reinforced composites.

• Composites Research
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• v.14 no.4
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• pp.15-26
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• 2001

Interfacial properties and microfailure degradation mechanisms of the bioabsorbable composites fur implant materials were investigated using micromechanical technique and nondestructive acoustic emission (AE). As hydrolysis time increased, the tensile strength, the modulus and the elongation of poly(ester-amide) (PEA) and bioactive glass fibers decreased, whereas these of chitosan fiber almost did not change. Interfacial shear strength (IFSS) between bioactive glass fiber and poly-L-lactide (PLLA) was much higher than PEA or chitosan fiber/PLLA systems using dual matrix composite (DMC) specimen. The decreasing rate of IFSS was the fastest in bioactive glass fiber/PLLA composites whereas that of chitosan fiber/PLLA composites was the slowest. AE amplitude and AE energy of PEA fiber decreased gradually, and their distributions became narrower than those in the initial state with hydrolysis time. In case of bioactive glass fiber, AE amplitude and AE energy in tensile failure were much higher than in compression. In addition, AE parameters at the initial state were much higher than those after degradation under both tensile and compressive tests. In this work, interfacial properties and microfailure degradation mechanisms can be important factors to control bioabsorbable composite performance.

• Asian-Australasian Journal of Animal Sciences
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• v.12 no.2
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• pp.186-188
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• 1999

This study was conducted to investigate the effects of four levels (0, 10, 20, 40 %) of sugar-beet pulp (SB pulp) supplementation to Italian ryegrass hay (IRG hay) on the fiber degradability of IRG hay in the rumen of goats. The following results were obtained: Degradabilities of DM, NDF, ADF and hemicellulose of IRG hay in the rumen increased significantly (p<0.05) by 10 % level supplementation of SB pulp to IRG hay. This was probably due to the increased numbers (p<0.05) of total viable bacteria, pectin-fermenting, xylan-fermenting and cellulolytic bacteria in the rumen in the increased supply of degradable pectic substances and hemicellulose at 10% level supplementation of SB pulp pectin. In 40% supplementation of SB pulp, ruminal pH was lowered by the fermentation of increased amount of molasses from SB pulp, resulting in the depression of growth of fiber fermenting bacteria and hence the decrease in degradabilities of cell wall fractions. It was suggested from this study that the sugar-beet pulp supplementation to forages at the level of 10% in the total diet increased fiber degradation of forage in the rumen of goats.