• Cross-Cultural Studies
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• 제34권
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• pp.259-284
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• 2014

$Ren{\acute{e}}$ Char and Yi Yuk-Sa have similarities to be accepted as representative poet of resistance in France and South Korea's history of literature. These similarities lead us to make a comparative study on two poets not having any positive influencing relationship. Their experiences as a independence fighter have a great effect on their whole works. This study applies concept of "Po-ethica" to compare features and values about their works. This concept anticipates ethical and existential throwbacks not an aesthetic throwback. Their poems are remarkable that they not only present a ethical perspectives surpassing the "lettrism" but also show the lyricism in poems of resistance surpassing patriotic and ideological appeal. This lyricism results from the pursuits of a true life not a confidence of the goodness. The similarities and differences in their works can be a clue for rediscovering the meaning and values of poems of resistance. Rilke said, "The Poem is the experience". Char's poems are more experiential than any other poet's poems. His poems of resistance show a personal life than deconstruction of discourse such as nationality and father land. On the other hand, Yuk-Sa's poems show a prospect of nature and the macrocosm. This naturalization of a resistance surpass a pastoral attitude of forgetting their phases of the times and reality. Therefore, their "Po-ethica" of resistance is valid today.

• Journal of the Korea Safety Management & Science
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• 제25권1호
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• pp.61-66
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• 2023

The purpose of this study is to compare and analyze the flame retardant performance of Japanese cypress(Chamaecyparis obtusa) plywood, commonly used in indoor decoration, furniture, and tableware, by treating it with three different fire retardants with different primary ingredients. The experiment was conducted in compliance with Article 31, Paragraph 2 of the Enforcement Decree of the Fire Facilities Installation and Management Act and Articles 4 and 7-2 of the Flame Retardant Performance Standards. After flame time, after glow time, char length, and char area were measured. As a result, first, after flame time was measured at 0 seconds regardless of whether the flame retardant treatment was applied. Second, after glow time was relatively long, measuring 22.7 seconds without treatment, which is likely due to the weak fire resistance and high concentration of carbon monoxide generated by the chemical characteristics of the Japanese cypress itself. Third, it was confirmed that the effects of the primary ingredient, phosphorus, in the flame retardant treatment varied depending on the technological development of the manufacturers of the same species of Japanese cypress plywood. In the future, it is expected that the results of this study will provide fundamental data to select flame retardant treatments that show high flame retardant performance according to the botanical characteristics of the wood.

• Advances in environmental research
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• 제12권1호
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• pp.17-40
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• 2023

This article presents studies of the adsorption process in a continuous system of fluoride solutions at a concentration of 30 mg/L using a bone char packed in fixed-bed columns, as well as regeneration studies in the same system using HNO₃, HCl and NaOH at 0.01, 0.1 and 1 M. The Thomas Model, Artificial Neural Networks (ANNs), Numerical Integration and Mass Transfer Zone were used for the modeling of asyemmetrical breakthrough curves obtained from the fluoride adsorption on bone char. The maximum adsorption capacity of the breakthrough curves was estimated, and various design parameters of the columns were obtained for the different operating conditions. Results showed that an improvement in the modeling capabilities of the Thomas model can be obtained using ANNs. Moreover, ANNs are useful for determining reasonable and accurate design parameters of packed-bed adsorption columns. This modeling approach can be useful for the process system engineering of dynamic adsorption systems involved in the field of water treatment and purification. It is important to highlight that the obtained results indicate that, when using HCl or HNO₃ at a concentration of 0.1 M, a large number of adsorption-desorption cycles are obtained and, therefore, the highest values of adsorption capacity, which leads to a reduction in operation costs.

• Elastomers and Composites
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• 제58권2호
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• pp.70-80
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• 2023

The effect of phenylphosphonic acid (PPOA) on polyurethane (PU) thermal stability was studied through Fourier transform infrared spectroscopy and Thermogravimetric analysis. To synthesize PPOA-modified PUs (PPOA-PUs), polyether-type diols (Mw=62, 106, 190, 419, 605) were chemically modified with PPOA and then reacted with 4,4'-dicyclohexylmethane diisocyanate (H₁₂MDI) and 4,4-diphenylmethane diisocyanate (MDI). During thermal decomposition in air, the PPOA embedded in the PUs formed intumescent phosphocarbonaceous char. Below 400℃, PPOA-H₁₂MDI-PUs were more unstable, as PPOA decomposed at lower temperatures than phenyl groups and aliphatic ethers. Above 550℃, the thermal stability of PUs followed this order: PPOA-MDI-PUs > PPOA-H₁₂MDI-PUs > MDI-PUs > H₁₂MDI-PUs. At 700℃, unmodified PUs had no residue, while the PPOA-MDI-PU residue was 4.4~23.0 wt.% and the PPOA-H₁₂MDI-PU residue was 1.5~17.5 wt.%. The enhanced thermal stability of PPOA-MDI-PUs at high temperatures can be attributed to the synergetic effect of PPOA and phenyl groups on the formation of phosphocarbonaceous char.

• Resources Recycling
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• 제15권1호
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• pp.12-19
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• 2006

Rice straw is one or the main renewable energy sources in Korea. Bio-oil is produced from rice straw with a lab-scale equipment mainly with a fluidized bed and a char removal system. It was investigated how the reaction temperature affected the production of bio-oil and the efficiency of a char removal system. To elucidate how the temperature depended on the production of bio-oil, experiments were conducted at $466^{\circ}C,\;504^{\circ}C\;and\;579^{\circ}C$, respectively. The mass balance was established in each experiment, and the produced gas and oil were analyzed with the aid of GCs and a GC-MS system. The char removal system is composed of a cyclone and a hot filter. Tn the experiments, we observed that the production of bio-oil was decreased with temperature, and the bio-oil contained very useful chemicals.

• Korean Chemical Engineering Research
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• 제53권6호
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• pp.746-754
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• 2015

In this study, we investigated the effects of the temperature on the coal/biomass $char-CO_2$ gasification reaction under isothermal conditions of $700{\sim}900^{\circ}C$ using the lignite(Indonesia Eco coal) with biomass (korea cypress). Ni catalysts were impregnated on the coal by the ion-exchange method. Four kinetic models which are shrinking core model (SCM), volumetric reaction model (VRM), random pore model (RPM) and modified volumetric reaction model (MVRM) for gas-solid reaction were applied to the experimental data against the measured kinetic data. The Activation energy of Ni-coal/biomass, non-catalyst coal/biomass $Char-CO_2$ gasification was calculated from the Arrhenius equation.

• Polymer(Korea)
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• 제29권4호
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• pp.338-343
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• 2005

The thermal degradation of ABS/PC/triphenyl phosphate compounds in the presence of transition metal chloride catalysts has been studied by thermogravimetric analysis (TGA). The reaction of transition metal chloride catalysts (cobalt chloride, ferric chloride, nickel chloride and zinc chloride) and ABS/PC/triphenyl phosphate compounds has been found to occur during the thermal degradation of the compounds. In a nitrogen atmosphere, char formation is observed, and $3\~13\%$of the reaction product is non-volatile at $600^{circ}$. The resulting enhancement of char formation in a nitrogen atmosphere has been explained as a catalytic crosslinking effect of transition metal chloride catalysts. On the other hand, transition metal chloride catalyzed char formation of ABS/PC/triphenyl phosphate compounds in air was unsuccessful due to the oxidative degradation of the char at a higher temperature.

• Journal of the Korean Society of Combustion
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• 제22권4호
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• pp.19-26
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• 2017

This study investigates the gasification of coal char by $CO_2$ under high pressures in a drop tube furnace(DTF). The rate constants are derived for the shrinking core model using the conventional method based on the set reactor conditions. The computational fluid dynamic(CFD) simulations adopting the rate constants revealed that the carbon conversion was much slower than the experimental results, especially under high temperature and high partial pressure of reactants. Three reasons were identified for the discrepancy: i) shorter reaction time because of the entry region for heating, ii) lower particle temperature by the endothermic reaction, and iii) lower partial pressure of $CO_2$ by its consumption. Therefore, the rate constants were corrected based on the actual reaction conditions of the char. The CFD results updated using the corrected rate constants well matched with the measured values. Such correction of reaction conditions in a DTF is essential in deriving rate constants for any char conversion models by $H_2O$ and $O_2$ as well as $CO_2$.

• Applied Chemistry for Engineering
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• 제20권6호
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• pp.675-680
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• 2009

This article describes NO emission characteristics in SM coal combustion. Combustion experiments was performed in the method of increasing temperature after feeding coal and feeding coal after increasing temperature. NOx emission is in inverse proportion to combustion temperature at the fuel rich condition and it was caused by conversion fuel N to $N_{2}$ at the strong reduction condition. In addition, feeding gas flow rate increased as total fuel NOx increase by conversion of fuel N to NO at the oxidation condition. It could be separated in total fuel-N, volatile-N, char-N to NO according to analysis of total fuel NO emission from char combustion at each temperature. In the result, almost total NOx emission was caused by volatile-N in SM-coal.

• Journal of Energy Engineering
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• 제20권4호
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• pp.346-352
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• 2011

The experiment was designed to study the char oxidation kinetics of pulverized coals commonly utilized in Korean power plants. The kinetics has been estimated using the Semenov's thermal spontaneous ignition theory adapted to coal char particle ignition temperature. The ignition temperature of coal char particle is obtained by a direct measurement of the particle temperature with photo detector as well as by means of a solid thermocouple which is used as both a heating and a measuring element. The ignition temperatures for subbituminous coal, Wira, and bituminous coal, Yakutugol, have been measured for 4 sizes in the range of 0.52-1.09 mm. The ignition temperature of the particle increases with the increasing diameter. The results were used to calculate the activation energy and the pre-exponential factor. As a result, the kinetic parameters are in an agreement with ones reported from other investigations.