• Journal of Animal Environmental Science
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• v.11 no.2
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• pp.97-102
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• 2005

Anaerobic decomposition is one of the most common processes in nature and has been extensively used in waste and wastewater treatment for several centuries. New applications and system modifications continue to be adapted making the process either more effective, less expensive, or suited to the particular waste in question and the operation to which it is to be applied. Animal manure is a highly biodegradable organic material and will naturally undergo anaerobic fermentation, resulting in release of noxious odors, such as in manure storage pits. Depending on the presence or absence of oxygen in the manure, biological treatment process may be either aerobic or anaerobic. Under anaerobic conditions, bacteria carry on fermentative metabolisms to break down the complex organic substances into simpler organic acids and then convert them to ultimately formed methane and carbon dioxide. Anaerobic biological systems for animal manure treatment include anaerobic lagoons and anaerobic digesters. Methane and carbon dioxide are the principal end products of controlled anaerobic digestion. These two gases are collectively called biogas. The biogas contains $60\~70\%$ methane and can be used directly as a fuel for heating or electrical power generation. Trace amounts of ammonia and hydrogen sulfide ($100\~300\;ppm$) are always present in the biogas stream. Anaerobic lagoons have found widespread application in the treatment of animal manure because of their low initial costs, ease of operation and convenience of loading by gravity flow from the animal buildings. The main disadvantage is the release of odors from the open surfaces of the lagoons, especially during the spring warm-up or if the lagoons are overloaded. However, if the lagoons are covered and gases are collected, the odor problems can be solved and the methane collected can be used as a fuel. Anaerobic digesters are air-tight, enclosed vessels and are used to digest manure in a well-controlled environment, thus resulting in higher digestion rates and smaller space requirements than anaerobic lagoons. Anaerobic digesters are usually heated and mixed to maximize treatment efficiency and biogas production. The objective of this work was to review a current anaerobic biological treatment of animal manure for effective new technologies in the future.

• Journal of the Korea Organic Resources Recycling Association
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• v.1 no.1
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• pp.59-68
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• 1993

Change in microbial numbers during experimental composting has been investigated. The results show that bacteria and actinomycetes play an important role in decomposing the composting material. The number of bacteria has no relation to the efficiency of composting, though it greatly correlates to the decomposition ratio. Bacterial growth activity that shows potential of bacterial growth was originally proposed. The influence of pH and the decomposition ratio on the growth activity has been studied. It was clarified that the bacterial growth activity is useful in evaluating the efficiency of composting and the maturity of produced compost.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.7
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• pp.3261-3266
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• 2012

Sodium borohydride($NaBH_4$) known as the material of hydrogen generation and storage can produce the hydrogen via catalytic hydrolysis. This protide chemical could be used in the hydrogen supply system for residential and mobile fuel cells, and thus many researches and developments regarding to these chemicals and decomposition reactions have been implemented. We experimented the hydrolysis of $NaBH_4$ alkaline solution by metal oxide-supported PGM(platinum group metal) catalysts and measured the generation rate of hydrogen which is product of decomposition reaction. We compared oxides as catalyst supports, and the precious metals, Pt and Ru for the catalysts and studied the effects of amounts of catalyst added and $NaBH_4$ concentrations on the hydrogen generation rates and patterns.

• Membrane Journal
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• v.5 no.3
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• pp.119-128
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• 1995

The effects of coarsening on microstructure formation in polystyrene-cyclohexane solutions and membranes made from them were studied by scanning electron miccoscopy(SEM). Thermal analysis of the polymer solutions was carried out with a differential scanning calorimeter and the binodal curve was determined from the onset temperature of the heat of demixing peak. Using thermally induced phase separation(TIPS) and a freeze drying technique, it was demonstrated that polymer membrane microstructure can be changed significantly by controlling coarsening time and quench route. For systems undergoing phase separation by spinodal decomposition, resulting in a well interconnecmd, microporous structure with nearly uniform pore sizes, it was found that extending the phase separation time prior m freezing and solvent removal can result in a significant increase in pore or cell size which is highly dependent on both quench depth and coarsening time. Also this study has revealed the important role of polymer concentration in dictating the material continuity of the membranes.

• Journal of Environmental Science International
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• v.22 no.10
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• pp.1263-1271
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• 2013

Graphene oxide (GO)-titania composites have emerged as an attractive heterogeneous photocatalyst that can enhance the photocatalytic activity of $TiO_2$ nanoparticles owing to their potential interaction of electronic and adsorption natures. Accordingly, $TiO_2$-GO mixtures were synthesized in this study using a simple chemical mixing process, and their heterogeneous photocatalytic activities were investigated to determine the degradation of airborne organic pollutants (benzene, ethyl benzene, and o-xylene (BEX)) under different operational conditions. The Fourier transform infrared spectroscopy results demonstrated the presence of GO for the $TiO_2$-GO composites. The average efficiencies of the $TiO_2$-GO mixtures for the decomposition of each component of BEX determined during the 3-h photocatalytic processes were 26%, 92%, and 96%, respectively, whereas the average efficiencies of the unmodified $TiO_2$ powder were 3%, 8%, and 10%, respectively. Furthermore, the degradation efficiency of the unmodified $TiO_2$ powder for all target compounds decreased during the 3-h photocatalytic processes, suggesting a potential deactivation even during such a short time period. Two operational conditions (air flow entering into the air-cleaning devices and the indoor pollution levels) were found to be important factors for the photocatalytic decomposition of BEX molecules. Taken together, these results show that a $TiO_2$-GO mixture can be applied effectively for the purification of airborne organic pollutants when the operating conditions are optimized.

• Journal of the Korean Electrochemical Society
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• v.19 no.3
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• pp.57-62
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• 2016

The over-discharging phenomena in sodium-nickel chloride batteries were investigated in relation to decomposition of molten salt electrolyte and consequent metal co-deposition. From XRD analysis, the material deposited on graphite cathode current collector was revealed to be by-product of molten salt electrolyte decomposition. In particular, the result showed that the Ni-Al alloys ($Al_3Ni_2$, $Ni_3Al$ and $Al_3Ni$) were electrochemically deposited on graphite current collectors in line with over-discharging behaviors. It is assumed that the $NiCl_2$ solubility in molten salt electrolytes leads to the co-deposition of Ni-Al alloys by increasing metal deposition potential above 1.6 V (vs. $Na/Na^+$). The cell tests have revealed that the composition of molten salt electrolytes modified by various additives makes a decisive influence on the over-discharging behaviors of the cells. It was revealed that NaOCN addition to molten salt electrolytes was advantageous to suppress over-discharge reactions by modifying the characteristics of molten salt electrolytes. NaOCN addition into molten salt electrolytes seems to suppress Ni solubility by maintaining basic melts. The cell using modified molten salt electrolyte with NaOCN (Cell D) showed relatively less cell degradation compared with other cells for long cycles.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.405-406
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• 2006

Recently, the flat display modules such as plasma or TFT-LCD employ thin crystallized panels which are normally weak to high level transient mechanical energy inputs. As a result, anti-shock performance is one of the most important design specifications for TFT-LCD modules. However, most of large display module designs are generated based on engineers own experiences. Also, a large-scale analysis to evaluate complex material and structural behaviors is one of interesting topic in diverse engineering and scientific fields. The utilization of massively parallel processors has also been a recent trend of high performance computing. The objective of this paper is to introduce a parallel process system which consists of general purpose finite element analysis solver as well as parallelized PC cluster. The parallel processing system is constructed using thirty-two processing elements and the finite element program is developed by adopting hierarchical domain decomposition method. In order to verify the efficiency of the established system, an impact analysis on thin and complex sub-parts of flat display modules is performed. The evaluation results showed a good agreement with the corresponding reference solutions, and thus, the parallel process system seems to be a useful tool fur the complex structural analysis such as IT related products.

• Bulletin of the Korean Chemical Society
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• v.31 no.1
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• pp.47-51
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• 2010

A powder, containing 80 percent of blue cobalt aluminate $(CoAl_2O_4)$ crystallites, was synthesized at $210 ^{\circ}C$ using a (metal nitrate-malonic acid-ammonium hydroxide-ammonium nitrate) system. The optimal amount of concentrated ammonia water and initial decomposition temperature were determined for the blue $CoAl_2O_4$ crystallites preparation. Three $CoAl_2O_4$ precursor pastes, corresponding to the various amounts of concentrated ammonia water, were prepared by evaporating the initial solutions in an electric furnace fixed at $80 ^{\circ}C$ under a vacuum of 25 torr. The initial solution was used to dissolve the starting materials. The powder with the maximum content (80%) of blue $CoAl_2O_4$ crystallites was prepared when the prepared precursor was decomposed at $210 ^{\circ}C$. The blue $CoAl_2O_4$ crystallite content in the prepared sample decreased with increasing initial decomposition temperature. For 0.2 mole of the $Al^{3+}$ ion, the chemical compositions of the precursor corresponded to molar ratios of 0.4, 1.40, 2.56 and 2.00 for the $Co^{2+}$ ion, malonic acid, ammonia and ammonium nitrate per mole of the $Al^{3+}$ ion, respectively. The blue $CoAl_2O_4$ crystallite content in the sample decreased with the amount of ammonia deviated from the optimal value. The characteristics of the powders were examined using X-ray diffraction, optical microscopy, Fourier transformation infrared spectroscopy and the Brunauer-Emmett-Teller technique.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.24 no.2
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• pp.185-191
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• 2011

Plastic gradient from geometrically necessary dislocation(GND) can affect material behavior significantly. In this research, mechanical behavior of polycrystalline solid is investigated using the finite element method incorporating plastic gradient from long range dislocation or GND effect. Plastic gradient effect is implemented in the analysis model by considering a long range strain term as well as elastic and plastic terms in the multiplicative decomposition. In the model, gradient hardness coefficient and length parameter are used to evaluate the effect of the long range strains and sensitive study is conducted for the parameters. It is confirmed that the GND amplifies hardening response of polycrystals compared with the single crystal.

• Journal of Powder Materials
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• v.25 no.4
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• pp.316-321
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• 2018

Composites of P25 $TiO_2$ and hexagonal $WO_3$ nanorods are synthesized through ball-milling in order to study photocatalytic properties. Various composites of $TiO_2/WO_3$ are prepared by controlling the weight percentages (wt%) of $WO_3$, in the range of 1-30 wt%, and milling time to investigate the effects of the composition ratio on the photocatalytic properties. Scanning electron microscopy, x-ray diffraction, and transmission electron microscopy are performed to characterize the structure, shape and size of the synthesized composites of $TiO_2/WO_3$. Methylene blue is used as a test dye to analyze the photocatalytic properties of the synthesized composite material. The photocatalytic activity shows that the decomposition efficiency of the dye due to the photocatalytic effect is the highest in the $TiO_2/WO_3$ (3 wt%) composite, and the catalytic efficiency decreases sharply when the amount of $WO_3$ is further increased. As the amount of $WO_3$ added increases, dye-removal by adsorption occurs during centrifugation, instead of the decomposition of dyes by photocatalysts. Finally, $TiO_2/WO_3$ (3 wt%) composites are synthesized with various milling times. Experimental results show that the milling time has the best catalytic efficiency at 30 min, after which it gradually decreases. There is no significant change after 1 hour.