• Transactions of the Korean Society of Mechanical Engineers A
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• v.31 no.3 s.258
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• pp.295-303
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• 2007

Degradation behaviors of filament-winded composites have been evaluated under the accelerated environmental test of high temperature, water immersion and thermal impact conditions. Two kinds of laminated composites coated by an urethane resin have been used: carbon-fiber reinforced epoxy(T700/Epon-826, CFRP) and glass-fiber reinforced phenolic (E-glass/phenolic, GFRP). For tensile strength of $0^{\circ}$ composites, CFRP showed little degradation while GFRP did high reduction by 25% under the influence of high temperature and water However for water-immersed $90^{\circ}$ composites tensile strength of both CFRP and GFRP showed high reduction. Bending strength and modulus of $90^{\circ}$ composites were largely reduced in water-immersion as well as high temperature environment. Urethane coating on the composite surface improved the bending properties by 20%, however hardly showed such improvement for water-immersed $90^{\circ}$ composites. In case of shear strength and modulus, both CFRP and GFRP showed high reduction by water-Immersion test but did a slight increase by high temperature and thermal impact conditions.

• Journal of the Korean GEO-environmental Society
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• v.9 no.3
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• pp.45-50
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• 2008

In this work, stainless steel mesh-supported activated carbons were prepared using phenolic resin and cellulose fiber. $ZnCl_2$ was used as a activation reagent in this work. $ZnCl_2$-chemical activation method has been proposed to produce highly porous activated carbons. The objectives of this work were to develop an optimal condition for manufacturing activated carbon assemblies screen from stainless steel mesh and phenolic resin. The iodine number was more increased over activation temperature of $450^{\circ}C$. Iodine number was 657 mg/g at activation temperature of $550^{\circ}C$, penolic resin concentration 20% and $ZnCl_2$ concentration 15%. Iodine number was 1359.4 mg/g when 10% cellulose added to these conditions.

• Journal of the Korean Society of Food Culture
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• v.28 no.5
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• pp.502-511
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• 2013

This study evaluated the composition two popular species of edible bamboo shoots in Korea (Phyllostachyspubescens and Sinoarundinarianigra) and the effect of their abundant dietary fiber on intestinal microorganisms in healthy young women. The ranges of total moisture, crude protein, crude lipid, crude ash, and dietary fiber content were 87.190.8, 2.943.5, 0.150.39, 0.411.05, and 4.206.15% (wet weight basis), respectively. Moisture and crude ash content increased after heat treatment; however, crude protein, crude lipid, and dietary fiber content were reduced after heating. The major minerals found in bamboo shoots were potassium, phosphorous, sulfur, magnesium, and calcium. In addition, glucose and fructose were abundant free sugars, while asparagine and tyrosine were the most abundant free amino acids. Approximately 70% of the total free fatty acids found in bamboo shoots were linoleic acid and linolenic acid. The ascorbic acid content was 6.60~17.56 mg/100 g (wet weight basis), and one phenolic compound, p-hydroxy benzoic acid, was 0.10.2% (wet weight basis) and detected by HPLC analysis. The intake of bamboo shoots for seven days significantly increased viable cell counts of Lactobacillus spp. and reduced viable cell counts of Bacteriodes spp. in feces (p<0.05). In our data, bamboo shoots may be useful in the food industry as high dietary fiber ingredients.

• Journal of the Korea Institute of Military Science and Technology
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• v.23 no.5
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• pp.475-484
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• 2020

Individual curing process of each layer in two resin composites can be caused the separation between two layers. In this study, co-curing process for two resin composites is suggested to improve the inter-layer bonding. Glass fiber reinforced composites with phenolic and epoxy resins were manufactured by co-curing process, and several types of glass/phenolic composites were considered to confirm the application on two resin composites. Experiments for smoke resistance, scratch resistance and flexural strength were carried out to verify requirements corresponding to thermal and mechanical environments. It was validated that two resin composites with phenolic resin impregnated prepreg exhibits good thermal and mechanical characteristics, and it can serve as highly effective composite structures in aerospace and many industry areas.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.05a
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• pp.45-49
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• 2006

The thermal degradation of carbon fiber reinforced phenolic composites have been studied at high temperature by using thermogravimetry analysis (TGA). The aim is that ultimately it can be used to predict the service temperature during solid rocket firing for any level and type of mechanical loading and to recommend protection systems required. To simulate the high heating rate in firing condition, the modified thermal decomposition constant (1000 K/min) was used for FEM analysis. The temperature distribution and the thickness of thermal decomposition were estimated well and we could predict the thickness of thermal decomposition within ${\pm}1mm$.

• Land and Housing Review
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• v.10 no.3
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• pp.23-32
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• 2019

Vacuum Insulation Panel(VIP) has the lowest thermal conductivity among present insulations. It is composed of envelope, core material and getter. Aluminum film is usually used as the envelope of VIP, and it is important component to decide the useful life of VIP. In this research, the thermophysical properties of incombustible fiber glass core VIP were investigated with the possibility of its architectural applications. The results of this research can be summarized as follows: 1) The thermal conductivity of 20mm-thick fiber glass core VIP is resulted as 0.00177W/m·K, which means that 20mm-thick VIP can meet all the reinforced insulation guideline and it can be used in any envelope of any region in Korea. 2) As a result of the test of incombustion and gas toxicity, fiber glass core VIP was suitable for incombustible material. 3) As the test result for the long term thermal conductivity, fiber glass core VIP was found out that it would keep above 10 times insulating performance than polystyrene foam and glass fiber. 4) To meet the thermal transmittance of 0.12W/㎡K, limited-combustible insulation of expanded polystyrene foam and phenolic foam should be used respectively as thick as above 280mm and 170mm, incombustible VIP can meet the same insulation level with 20mm thickness. 5) The price competitiveness of incombustible VIP to meet the thermal transmittance of 0.12W/㎡·K was about 1,500won/㎡ higher than that of phenolic foam.

• Carbon letters
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• v.6 no.4
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• pp.234-242
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• 2005

Bending and tensile properties of 2D cross-ply C/C composites with processing heat treatment temperature (HTT) are evaluated. C/C composites used are made from two types of PAN based T700 and M40 carbon fibers with phenolic resin as carbon matrix precursor. Both the types of composites are heat treated at different temperatures (ranging from 750 to $2800^{\circ}C$) and characterized for bending and tensile properties. It is observed that, real density and open porosity increases with HTT, however, bulk density does show remarkable change. The real density and open porosity are higher in case T-700 carbon fiber composites at $2800^{\circ}C$, even though the density of M40 carbon fiber is higher. Bending strength is considerably greater than tensile strength through out the processing HTT due to the different mode of fracture. The bending and tensile strength decreases in both composites on $1000^{\circ}C$ which attributed to decrease in bulk density, thereafter with increase in HTT, bending and tensile strength increases. The maximum strength is in T700 fiber based composites at HTT $1500^{\circ}C$ and in M40 fiber based composites at HTT $2500^{\circ}C$. After attending the maximum value of strength in both types of composite at deflection HTT, after that strength decreases continuously. Decrease in strength is due to the degradation of fiber properties and in-situ fiber damages in the composite. The maximum carbon fiber strength realization in C/C composites is possible at a temperature that is same of fiber HTT. It has been found first time that the bending strength more or less 1.55 times higher in T700 fiber composites and in M40 fiber composites bending strength is 1.2 times higher than that of tensile strength of C/C composites.

• Membrane Journal
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• v.20 no.4
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• pp.312-319
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• 2010

Carbon membrane materials have received considerable attention for the gas separation including hydrocarbon mixture of ingredients of the volatile organic compounds(VOCs) because they possess their higher selectivity, permeability, and thermal stability than the polymeric membranes. The use of activated carbon membranes makes it possible to separate continuously the VOCs mixture by the selective adsorption-diffusion mechanism which the condensable components are preferentially adsorbed in to the micropores of the membrane. The activated carbon hollow fiber membranes with uniform adsorptive micropores on the wall of open pores and the surface of the membranes have been fabricated by the carbonization of a thin film of phenolic resin deposited on porous alumina hollow fiber membrane. Oxidation, carbonization, and activation processing variables were controlled under different conditions in order to improve the separation characteristics of the activated carbon membrane. Properties of activated carbon hollow fiber membranes and the characterization of a gas permeation by pyrolysis conditions were studied. As the result, the activated carbon hollow fiber membranes with good separation capabilities by the molecular size mechanism as well as selective adsorption on the pores surface followed by surface diffusion effective in the recovery hydrocarbons have been obtained. Therefore, these activated carbon membranes prepared in this study are shown as promising candidate membrane for separation of VOCs.

• Natural Product Sciences
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• v.22 no.1
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• pp.60-63
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• 2016

The study is a pioneering effort to determine the mineral, nutritional, and phytochemical composition and phenolic content and to determine the free radical scavenging activity of Gigantochloa levis (Blanco) Merr, a native bamboo species (locally known as "bolo") in the Philippines. Proximate analysis showed that air-dried G. levis leaves contain 15.8% ash, 22.6% crude protein, 1.2% crude fat, 29.3% crude fiber, and 19.7% total sugar. Phytochemical tests indicated the presence of diterpenes, triterpenes, saponins, phenols, tannins, and flavonoids in both the ethanolic and aqueous leaf extracts, while phytosterols were only detected in the ethanolic extract. Folin-Ciocalteu assay determined the total phenolic content in gallic acid equivalents (GAE) to be $85.86{\pm}3.71$ and $32.32{\pm}1.01mg\;GAE/100g$ dried sample for the ethanolic and aqueous extracts, respectively. The total phenolic content in quercetin equivalents (QE) was $74.44{\pm}3.11$ and $29.43{\pm}0.85mg\;QE/100g$ dried sample for the ethanolic and aqueous extracts, respectively. The radical scavenging activity of the different solvent fractions containing varying concentrations of the extract was determined using the 2, 2-diphenyl-1-picrylhydrazyl (DPPH) assay. The ethyl acetate and 1-butanol fractions were found to have the highest radical scavenging activity. Mineral analysis via Energy Dispersive X-Ray Spectrometry (EDS) of the ash of G. levis leaves showed that Si is the major component, followed by K and Mg. These results point to the potential of G. levis leaves as a source of minerals and bioactive compounds with medicinal value.

• Korean Journal of Materials Research
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• v.4 no.7
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• pp.733-740
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• 1994

Oxidized-PAN fiber reinforced composite(OFRP), carbon fiber reinforced composite(CFRP), aramid fiber reinforced composite(AFRP), and glass fiber reinforced composite(GFRP) were fabricated with phenolic resin matrix by hot press molding. We tested the friction coefficient and wear rate varying with fiber weight fraction and observed the effect of fibers according to characteristics of individual reinforcement. When the amount of aramid fiber was 45wt%, average friction coefficient was maximum value of 0.353~0.383, where as, when the amount of pitch based carbon fiber was 45wt%, average friction coefficient was the lowest value of 0.164~0.190. The wear rate of AFRP and CFRP was low, but that of GFRP and OFRP increases drastically in the case of increasing of fiber weight fraction. Wear diagram of OFRP was unstable, but that of CFRP and AFRP was a bit stable. Through very unstable diagram of GFRP, we found that friction stability of GFRP was the lowest.