• Journal of Hydrogen and New Energy
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• v.13 no.1
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• pp.42-51
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• 2002

Methane can be converted directly to hydrogen by pyrolysis. The reaction is highly endothemic and heat must be supplied at high temperatures. Gibbs free energy minimization calculations have been carried out for the methane pyrolysis to determine equilibrium products. The calculation parameters are the temperature, the initial H/C ratio, the pressure and Gibbs energies of each substance. Methane, ethylene, acetylene, benzene, naphthalene, and hydrogen are the main products. Excluding hydrogen, it is observed that ethylene and aromatics(benzene+naphthalene) are predominant products below 1400K, whereas acetylene is significantly formed above 1400K. Hydrogen dilution increases the selectivities for ethylene and acetylene and decreases the selectivity for aromatics. Increasing the pressure also decreases the decomposition of methane.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.4
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• pp.63-71
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• 2010

Modular design is a very important design methodology that allows designers to develop a product family at low product development and production cost. This design methodology is also very powerful for products that require frequent design changes due to customer requirements. Most research on modular design is focused on the modularization based on functional decomposition, physical interface and manufacturing process of parts. In this paper, we propose a modularization method that takes size of human body parts into consideration for products which have physical interactions with the products such as office chairs and sport machines. Evaluation of modular design is based on dependence measurement between every pair of components in the design. In addition we proposed a module sizing method for the maximization of customer satisfaction in MC(Mass Customization) environment.

• Journal of Microbiology and Biotechnology
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• v.28 no.2
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• pp.305-313
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• 2018

A microbial consortium, TMC7, was enriched for the degradation of natural lignocellulosic materials under high temperature. TMC7 degraded 79.7% of rice straw during 15 days of incubation at $65^{\circ}C$. Extracellular xylanase was effectively secreted and hemicellulose was mainly degraded in the early stage (first 3 days), whereas primary decomposition of cellulose was observed as of day 3. The optimal temperature and initial pH for extracellular xylanase activity and lignocellulose degradation were $65^{\circ}C$ and between 7.0 and 9.0, respectively. Extracellular xylanase activity was maintained above 80% and 85% over a wide range of temperature ($50-75^{\circ}C$) and pH values (6.0-11.0), respectively. Clostridium likely had the largest contribution to lignocellulose conversion in TMC7 initially, and Geobacillus, Aeribacillus, and Thermoanaerobacterium might have also been involved in the later phase. These results demonstrate the potential practical application of TMC7 for lignocellulosic biomass utilization in the biotechnological industry under hot and alkaline conditions.

• Journal of the Korean Wood Science and Technology
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• v.34 no.5
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• pp.59-66
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• 2006

The thermal properties of wood flour, Hwangto, and maleated polyethylene (MAPE) reinforced HDPE composites were investigated in this study. The thermal behavior of reinforced wood polymer composites was characterized by means of thermogravimetric (TGA) and differential scanning calorimetric (DSC) analyses. Hwangto and MAPE were used as an inorganic filler and a coupling agent, respectively. According to TGA analysis, the increase of wood flour level increased the thermal degradation of composites in the early stage, but decreased in the late stage. On the other hand, Hwangto reinforced composites showed the higher thermal stability than virgin HDPE, from the determination of differential peak temperature ($DT_p$). Decomposition temperature of wood flour and/or Hwangto reinforced composites increased with increase of heating rate. From DSC analysis, melting temperature of reinforced composites little bit increased with the addition of wood flour or Hwangto. As the loading of wood flour or Hwangto to HDPE increased, overall enthalpy decreased. It showed that wood flour and Hwangto absorbed more heat energy for melting the reinforced composites. Hwangto reinforced composites required more heat energy than wood flour reinforced composites and virgin HDPE. Coupling agent gave no significant effect on the thermal properties of composites. Thermal analyses indicate that composites with Hwangto are more thermally stable than those without Hwangto.

• Economic and Environmental Geology
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• v.32 no.1
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• pp.101-111
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• 1999

Sedimentary organic matter, exposed to continental surficial environment, reacts with oxygen supplied from the atmosphee and forms carbon-containing oxidation products. Knowledge of the rate and mechanisms of sedimentary organic matter weathering is important because it is one of the major controls on atmospheric oxygen level through geologic time. Under the abiological conditions, the oxidation rate of coal organic matter by molecular oxygen is enhanced by the increase of oxygen concentration and temperature. At ambient temperature and pressure, aqueous coal oxidation results in the formation of dissolved $CO_2$ dissolved organic carbon and solid oxidation products which are all quantitatively significant reaction products. The effects of pH, ultraviolet light, and microbial activity on the weathering of sedimentary organic matter are poorly contrained. Based on the results of geochmical and environmental studies, it is believed that the photochemical reaction should play an important role in the decomposition and oxidation of sedimentary organic matter removed from the weathering profile. At higher pH conditions, the production rate of DOC can be accelerated due to base catalysis. These high molecular weight oranic matter can react with man-made pollutants such as heavy metal ions via adsorption/desorption or ion exchange reactions. The effect of microbial activity on the oxidative weathering of sedimentary organic matter is poorly understood and remains to be studied.

• The KIPS Transactions:PartB
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• v.10B no.3
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• pp.273-280
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• 2003

Recommender System can help users to find products to Purchase. A representative method for recommender systems is collaborative filtering (CF). It predict products that user may like based on a group of similar users. User information is based on user's ratings for products and similarities of users are measured by ratings. As user is increasing tremendously, the performance of the pure collaborative filtering is lowed because of high dimensionality and scarcity of data. We consider the effect of dimension deduction in collaborative filtering to cope with scarcity of data experimentally. We suggest that SVD improves the performance of collaborative filtering in comparison with pure collaborative filtering.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2008.04a
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• pp.178-182
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• 2008

The bleached red algae fiber(BRAF) showed very similar crystallinity to the cellulose, furthermore, it has higher thermal decomposition temperature than that of the microcrystalline cellulose(MCC). Polypropylene biocomposites reinforced with BRAF have been fabricated with various BRAF contents by compression molding method and their mechanical and thermomechanical properties have been studied. The mechanical strength as tensile, impact and flexural modulus of BRAF/PP biocomposites were gradually improved with increasing the BRAF content, and thermal property which against the thermal expansion was markdly improved, especially. These results are compared with chopped non-woody fibers as Henequen or Kenaf, BRAF was more effective for fabrication of biocomposites reinforced small-sized fibers. The red algae fiber reinforced biocomposites has the applicability such as electronics, biodegradable products and small-structure composites.

• Journal of the Korean Society of Propulsion Engineers
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• v.15 no.5
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• pp.48-53
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• 2011

We investigated thermal stability improvement of exo-tetrahydrodicyclopentadiene (exo-THDCP) with thermal stabilizers (additives). The reaction products were sample during the reactions. The compositions of products were determined by gas chromatography-mass spectrometry (GC-MS) to measure thermal decomposition products of exo-THDCP and to specify mechanism for thermal stabilizers. Hydrogen donors (thermal stabilizers) such as 1,2,3,4-tetrahydroquinoline (THQ), benzyl alcohol (BnOH) increased thermal stability of exo-THDCP. These materials donated hydrogen to radical of exo-THDCP produced after initiation of exo-THDCP. We found that stabilization of exo-THDCP radicals decreased activity of primary products of exo-THDCP and lowered formation of secondary products (above-$C_{11}$ products).

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.45 no.1
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• pp.42-51
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• 2013

In this study, oil palm biomass such as empty fruit bunch (EFB) and palm kernel shell (PKS) was used as raw materials for making pellets. Hardwood sawdusts were also mixed with EFB and PKS for making pellets. For improving a bad forming behavior in a pelletizer, 1 to 3 per cent of corn starch based on oven-dried weight biomass was added. The starch contributed to the decrease of dust generation in addition to the improvement of forming capability during pellet forming. Heating values of every pellets made of EFB and PKS were higher than 4,300 kcal/kg for the first grade pellet, irrespective of addition of sawdusts. However, the pellets made of EFB and PKS had ash contents over 3 per cent, which made it impossible to be applied for home use. Instead, they could be applied for industrial use. For studying their combustion characteristics, the pellets from the mixtures of EFB, PKS and sawdusts were analyzed using thermal gravimetric analyzer (TGA). From the TGA results, thermal decomposition of EFB and PKS occurred following three including endothermic reaction and dehydration, devolatilization of the major chemical components, and finally combustion of residual lignin and char.

• Journal of Hydrogen and New Energy
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• v.16 no.3
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• pp.262-268
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• 2005

[ $Zn(BH_4)_2$ ](8.4 wt% theoretical hydrogen storage capacity powders have been successfully synthesized by mechanochemical reaction from mixtures of $ZnCl_2$ and $NaBH_4$ powders in a 1:2 molar ratio in different times. $$ZnCl_2+2NaBH_4{\rightarrow}Zn(BH_4)_2+2NaCl$$ (1) $Zn(BH_4)_2$ powders were characterized by X-ray diffractometry(XRD), and Furier Transform Infrared spectrometry(FT-IR). The thermal stabilities of $Zn(BH_4)_2$ powders were studied by Differential scanning calorimetry(DSC), Thermogravimetry analysis(TGA), and Mass spectrometry(MS). $Zn(BH_4)_2$ can be tested for hydrogen evolution without further purification. The reaction to yield hydrogen is irreversible, the other products being compounds of Zn, and borane. $Zn(BH_4)_2$ thermally decomposes to release borane and hydrogen gas between about 85 and 150$^{\circ}C$.