• International Journal of Internet, Broadcasting and Communication
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• v.7 no.2
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• pp.96-104
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• 2015

Fischer Tropsch reaction is one of the interesting topic for renewable and clean energy. Polymerization of carbon monoxide or carbon dioxide with hydrogen over metal supported catalyst can produce long chain hydrocarbons. Synthetic liquid hydrocarbons are promising alternative to fossil fuels. This research work has been focused on the synthesis of Fe based catalyst for Fischer Tropsch reaction. Mesoporous silica (MS) support prepared by a precipitation method using two different washing solution, distilled water (DW) and acid in ethanol solution (ET), and different calcination temperature. Then, Fe/MS was prepared by an incipient wetness impregnation method. All of samples were systematically characterized using various physical and chemical techniques. TEM and XRD analysis were used to ensure that the cubic Ia3d mesostructure is stable after calcination. FTIR spectra are useful to ascertain the existence of template in the support. TPR studies were also used to understand the nature of Fe species and their reducibility. The results reveal that washing the support with distilled water and calcination at $550^{\circ}C$ can efficiently remove the triblock copolymer templates. The existence of template in the support affects the textural properties of all catalyst investigated.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.1
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• pp.24-30
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• 2004

Analysis model for the two-phase catalytic reactor is presented. With the progress in development of micro thermofluidic devices, needs fur understanding of the phenomena in two phase reaction in cm scale has been arisen. To investigate thermal and reactive performance of down scaled two phase reactor simple analysis model that is a kind of lumped flow model is proposed. Analysis model presented is based on the experiment on mm scale model reactor. Target experiment is catalytic decomposition of 70wt％ hydrogen peroxide with existence of perovskite L $a_{0.8}$S $r_{0.2}$Co $O_3$ catalyst. It is composed of balance equations of mass and energy. Each phase is considered to be a species fur the simplicity. Axial diffusion and transversal distribution of properties are neglected. Two phase catalytic reaction is modeled as successive gasification of liquid lump around catalyst and reaction in gas phase. Heat transfer is modeled by model function ofNu number. Modeled Nu is expressed as Nu=N $u_{0}$ (1＋ $a_1$( $a_2$ $T^{-}$ $a_3$)exp( $a_4$ $T^{-1}$)exp( $a_{5}$ z). Transfer coefficients are determined by the comparison of experimental results. With the model, heat transfer characteristics are investigated. Also by the mass transfer coefficient, characteristics in mass transfer is investigated. With the result basic understanding on design and analysis of mm scale two-phase reactive device is obtained. Also it can be further applied to micro scale reactive device fabricated by micromachining.ing..

• Applied Chemistry for Engineering
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• v.3 no.1
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• pp.1-6
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• 1992

In this energy and environment conscious age, methanol has come to attention increasingly since the well established process is commercially available to produce methanol from abundant low grade carbonaceous resources ; methane, carbon dioxide, coal and biomass etc. Methanol is a Clean energy source which is a readily storable and transportable liquid. It is elaborated to correlate power generation, city gas and chemical feed stocks including transportation fuel, enhancing the national efficiency of resource utilization as well as reducing the environmental problems for the future via C1 technology. It is emphasized that $CO_2$ could be used to produce methanol as a mean of hydrogen storage as in the nature, which will alleviate the environmental problem such as green house effect.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2006.06a
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• pp.111-116
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• 2006

The microstickes control effects of some fixing agents, including an inorganic PAC, an organic polyamine (PA) and polydiallydimethyl ammonium chloride (Pdadmac), and a high cationic starch (HCS), were investigated, together with their effects on wet end performances and physical properties of handsheets. Despite that the HCS and Pdadmac had lower cationic charge densities than the PA and PAC (the HCS being even lower), they gave higher zeta potentials to fibers, and lower turbidities, cationic demands and residual COD contents to the pulp liquid phases than the PA and PAC did. In all cases, the HCS showed even better effects than the Pdadmac. In addition, drainage speed was also much higher by the HCS treatments although paper formation was worsened. All the phenomena showed that the HCS can fix more dissolved and colloidal substances to cellulose fibers, indicating that the HCS functioned mainly with flocculation and even hydrogen bonding mechanisms. Data on optical properties further indicated that the HCS interacted preferentially with colloidal substances, since it fixed more 'dirty' microstickes to fibers which decreased more sheet brightness while increasing more sheet opacity (with both higher light absorption and scattering coefficients). Interestingly, the organic fixing agents did not decrease tensile, tearing, and folding strengths of paper sheets made from 100% recycled newsprint pulp, except when they were dosed in high amounts. On the contrary, the inorganic PAC had more serious negative effects on the strength properties, especially on folding endurance. The study suggested that proper use of the HCS can lead to better microstickies control effects than traditional agents and methods.

• The Journal of Korean Medicine
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• v.34 no.4
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• pp.12-20
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• 2013

Objectives: This study compared Gumiganghwal-tang (GGT) decoctions produced using different pressure levels for various extraction times to determine the optimal extraction conditions through hydrogen ion concentration (pH), total soluble solids content (TSSC), extraction yield, and content of chemical compounds. Methods: Decoctions were prepared by the pressure levels of 0 or $1kgf/cm^2$ for 30-180 min. The pH and TSSC were measured, the extraction yield was calculated, and the amounts of the chemical compounds were determined using high performance liquid chromatography. Results: The higher pressure and longer extraction time decreased the pH value, while those conditions increased TSSC and extraction yield: the decoction produced in 180 min by pressurized method showed the minimum value of pH, but maximum values of TSSC and extraction yield. The chemical compounds showed higher amounts in decoctions produced by non-pressurized methods than pressurized methods and their amounts were decreased over the peak extraction time in both pressurized and non-pressurized methods. The results of regression analysis confirmed the correlative influences of the pressure and extraction time on pH, TSSC, and extraction yield. Conclusions: This study suggests that pressure and extraction time influence the compositional constituents in GGT decoctions, and the non-pressurized method for 120 min should be chosen as the optimal extraction condition for the preparation of GGT decoction.

• Journal of the Korean Society of Visualization
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• v.17 no.3
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• pp.24-31
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• 2019

Recently, an air-lift bio-reactor operated by micro bubbles has been utilized to product hydrogen fuel. To enhance the performance, characteristics of hydrodynamics inside the bio-reactor were analyzed using a numerical simulation for two-phase flow. An Eulerian model was employed for both of liquid and gas phases. The standard k-ε model was used for turbulence induced by micro bubbles. A Population Balance Model was employed to consider size distribution of bubbles. A hollow cylinder was introduced at the center of the reactor to reduce a dead area which disturbs circulation of CO bubbles. An appropriate diameter of the draft tube and hollow cylinder were optimized for better performance of the bio-reactor. The optimum model could be obtained when the cross-sectional area ratio of the hollow cylinder to the reactor, and the width ratio of the riser to the downcomer approached 0.4 and 3.5, respectively. Consequently, it is expected that the optimum model could enhance the performance of the bio-reactor with the homogeneous distribution and higher density of CO, and more effective mixing.

• Journal of Korean Society of Water and Wastewater
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• v.25 no.2
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• pp.223-230
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• 2011

An electrolytic oxidation process was applied to remove odorous compounds from non-point odor sources including wastewater pipelines and manholes. In this study, a distance between the anode and the cathode of the electrolytic process was varied as a system operating parameters, and its effects on odor removal efficiencies and reaction characteristics were investigated. Odor precursors such as sediment organic matters and reduced sulfur/nitrogen compounds were effectively oxidized in the electrolytic process, and a change in oxidation-reduction potential (ORP) indicated that an stringent anaerobic condition shifted to a mild anoxic condition rapidly. At an electrode distance of 1 cm and an applied voltage of 30 V, a system current was maintained at 1 A, and the current density was 23.1 $mA/cm^{2}$. Under the condition, the removal efficiency of hydrogen sulfide in gas phase was found to be 100%, and 93% of ammonium ion was removed from the liquid phase during the 120 minute operating period. Moreover, the sulfate ion (${SO_4}^{2-}$) concentration increased about three times from its initial value due to the active oxidation. As the specific power consumption (i.e., the energy input normalized by the effective volume) increased, the oxidation progressed rapidly, however, the oxidation rate was varied depending on target compounds. Consequently, a threshold power consumption for each odorous compound needs to be experimentally determined for an effective application of the electrolytic oxidation.

• The Korean Journal of Nuclear Medicine
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• v.28 no.2
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• pp.167-171
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• 1994

Ethylcystein dimer (ECD) was synthesized by dimerizatlon of L-thiazolidine-4-carboxylic acid in liquid ammania with sodium metal and successive esterification in ethanolic solution of hydrogen chlorde. The purified product was labeled with $^{99m}Tc$ in the presence of sodium glucarate(pH= 5.6) and stannous chloride. Best result was obtained from the preparation con sisting of 0.1mg ECD, $40{\mu}l$ of 0.4M sodium glucarate (pH=5.6), and $20{\mu}g$ of stannous chloride. The labeling efficiency was 90% with previous condition. The labeled $^{99m}Tc$-ECD was stable at least for 3 hours in PBS(pH=7.4) at room temperature. About 10mCi of $^{99m}Tc$-ECD was injected to normal volunteer, and SPECT image of brain was obtained by triple head camera 10 minutes after inection. The image showed similar distribution of radioactivity in brain with that of HMPAO image.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2001.04a
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• pp.18-25
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• 2001

A new wood-degrading fungus Trichophyton rubrum LKY-7 secretes a high level of laccase in a glucose-peptone liquid medium. The production of laccase by the fungus was barely induced by 2,5-xylidine. The laccase has been purified to homogeneity through three chromatography steps in an overall yield of 40%. The molecular mass of the purified laccase was about 65 kDa by sodium dodecyl sulfate polyacrylamide gel electrophoresis. The purified laccase had the distinct blue color and had basic spectroscopic features of a typical blue laccase: two absorption maxima at 278 and 610 nm and a shoulder at 338 nm. The N-terminus of the laccase has been sequenced, revealing high homology to laccases from wood-degrading white-rot fungi such as Ceriporiopsis subvermispora. The enzyme had a "low" redox potential (0.5 V vs normal hydrogen electrode), yet it was one of the most active laccases in oxidizing a series of representative substrates/mediators. Compared with other fungal laccases, the laccase has a very low Km value with ABTS [2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid] as a substrate and a very high Km value with violuric acid as a substrate. The laccase has the isoelectric point of 4.0. The laccase had very acidic optimal pH values (pH 3-4) while it was more stable at neutral pH than at acidic pH. The laccase oxidized hydroquinone faster than catechol and pyrogallol. The oxidation of tyrosine by the laccase was not detectable under the reaction conditions. The laccase was strongly inhibited by sodium azide and sodium fluoride. fluoride.

• Proceedings of the Materials Research Society of Korea Conference
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• 2012.05a
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• pp.88.1-88.1
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• 2012

Silicon nanowires (SiNWs), due to their unusual quantum-confinement effects that lead to superior electrical and optical properties compared to those of the bulk silicon, have been widely researched as a potential building block in a variety of novel electronic devices. The conventional means for the synthesis of SiNWs has been the vapor-liquid-solid method using chemical vapor deposition; however, this method is time consuming, environmentally unfriendly, and do not support vertical growth. As an alternate, the electroless etching method has been proposed, which uses metal catalysts contained in aqueous hydrofluoric acids (HF) for vertically etching the bulk silicon substrate. This new method can support large-area growth in a short time, and vertically aligned SiNWs with high aspect ratio can be readily synthesized with excellent reproducibility. Nonetheless, there still are rooms for improvement such as the poor surface characteristics that lead to degradation in electrical performance, and non-uniformity of the diameter and shapes of the synthesized SiNWs. Here, we report a facile method of SiNWs synthesis having uniform sizes, diameters, and shapes, which may be other than just cylindrical shapes using a modified nanosphere lithography technique. The diameters of the polystyrene nanospheres can be adjustable through varying the time of O2 plasma treatment, which serve as a mask template for metal deposition on a silicon substrate. After the removal of the nanospheres, SiNWs having the exact same shape as the mask are synthesized using wet etching technique in a solution of HF, hydrogen peroxide, and deionized water. Different electrical and optical characteristics were obtained according to the shapes and sizes of the SiNWs, which implies that they can serve specific purposes according to their types.