• Korean Chemical Engineering Research
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• v.57 no.1
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• pp.65-72
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• 2019

In this study, heterogeneous ion exchange membranes were prepared by casting method with various mixing ratios of PPO ion-selective solution and ion exchange resin. Then heterogeneous bipolar membranes were prepared by using this. The water content of heterogeneous cation and anion exchange membranes were 60~80% respectively, the ion exchange capacity was 2.81~3.26 meq/g, 2.31~2.74 meq/g and electrical resistances were $1.65{\sim}1.45{\Omega}{\cdot}cm^2$ and $1.55{\sim}1.05{\Omega}{\cdot}cm^2$. The tensile strength of heterogeneous bipolar membrane was lower than that of PPO resin before functionalization ($700Kg_f/cm^2$). The tensile strength of heterogeneous bipolar membrane with catalyst layer was lower than that of non-catalytic heterogeneous bipolar membrane. The water splitting voltage of the heterogeneous bipolar membrane with catalyst layer was low and stable at a minimum of 1.7~1.8 V, maximum 3.9~4.0 V, and the water splitting voltage of the non-catalytic heterogeneous bipolar membrane was constant at 3.8~4.0 V.

• Applied Chemistry for Engineering
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• v.25 no.5
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• pp.503-509
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• 2014

The carbon/porous silica composite membrane was fabricated in a simple manner, which could be successfully for the simultaneous separation and production of chiral epoxides and 1,2-diols, based on their differences in hydrophilic/hydrophobic natures. The chiral Co(III)-$BF_3$ salen catalyst adopted in the membrane reactor system has given the very high enantioselectivity and recyclability in hydrolysis of terminal epoxides such as ECH, 1,2-EB, and SO. The optically pure epoxide and the chiral catalyst were collected in the organic phase after hydrolysis reaction. The hydrophilic water-soluble 1,2-diol product hydrolyzed by chiral salen diffused into the aqueous phase through the SBA-16 or NaY/SBA-16 silica composite layer during the reaction. The water acted simultaneously as a reactant and a solvent in the membrane system. One optical isomer was obtained with high purity and yield, and furthermore the catalysts could be recycled without observable loss in their activity in the continuous flow-type membrane reactor.

• Korean Chemical Engineering Research
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• v.47 no.3
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• pp.362-367
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• 2009

Recently, the use of formic acid as a fuel for direct liquid fuel cells has emerged as a promising alternative to methanol. In the work presented herein, we evaluated direct formic acid fuel cells(DFAFCs) with various components under operating conditions, for example, the thickness of the proton exchange membrane, concentration of formic acid, gas diffusion layer, and commercial catalyst. The thickness of the proton exchange membrane influenced performance related to the fuel cross-over. To optimize the cell performance, we investigated on the proper concentration of formic acid and catalyst for the formic acid oxidation. Consequently, membrance-electrode assembly(MEA) consisted of $Nafion^{(R)}$-115 and the Pt-Ru black as a anode catalyst showed the maximum performance. This performance was superior to the DMFCs' one.

• Applied Chemistry for Engineering
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• v.32 no.4
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• pp.409-416
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• 2021

Dimensionally stable electrodes are one of the important components in electrochemical water treatment processes. In the manufacturing of the dimensionally stable electrodes, the type of metal catalyst coated on the surface of the metal substrate, the coating and sintering methods substantially influence their performance and durability. In this study, using Ir-Ru-Ta ternary metal coating, various electrodes were prepared depending on the coating method under the same pre-treatment and sintering conditions, and its performance and durability were studied. As a coating method, brush and spray coating were used. As a result, the reduction in the amount of catalyst ink was achieved because more amount of metal could be coated for the electrode using spraying with the same amount of catalyst ink. In addition, the spray_2.0_3.0 electrode prepared by a specific spray coating method shows the phenomenon of cracking and the uniform coating of the ternary metal on the surface of the coating layer, and results in a high electrochemically active specific surface area, and the decomposition performance of 4-chlorophenol was superior to the other electrodes. However, it was found that there was no significant difference in durability depending on the coating method.

• Clean Technology
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• v.27 no.1
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• pp.61-68
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• 2021

Selective catalytic reduction (SCR) is widely used as a method of removing nitrogen oxide in large-capacity thermal power generation systems. Uniform mixing of the injected ammonia and the inlet flue gas is very important to the performance of the denitrification reduction process in the catalyst bed. In the present study, a computational analysis technique was applied to the ammonia injection system design process of a denitrification facility. The applied model is the denitrification facility of an 800 MW class coal-fired power plant currently in operation. The flow field to be solved ranges from the inlet of the ammonia injection system to the end of the catalyst bed. The flow was analyzed in the two-dimensional domain assuming incompressible. The steady-state turbulent flow was solved with the commercial software named ANSYS-Fluent. The nozzle arrangement gap and injection flow rate in the ammonia injection system were chosen as the design parameters. A total of four (4) cases were simulated and compared. The root mean square of the NH3/NO molar ratio at the inlet of the catalyst layer was chosen as the optimization parameter and the design of the experiment was used as the base of the optimization algorithm. The case where the nozzle pitch and flow rate were adjusted at the same time was the best in terms of flow uniformity.

• Clean Technology
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• v.28 no.4
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• pp.316-322
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• 2022

The flow pattern at the inlet of the catalyst layer in a selective catalytic reduction (SCR) system is one of the key parameters influencing the performance of the denitrification process. In the curved diffusing parts between the ammonia injection grids and the catalyst layers, guide vanes are installed to improve flow uniformity. In the present study, a numerical simulation has been performed to investigate the effect of the geometrical configuration of the guide vanes on the aerodynamic characteristics of a denitrification facility. This application has been made to the existing SCR process in a large-scaled coal-fired power plant. The flow domain to be solved covers the whole region of the flow passages from the exit of the ammonia injection gun to the exit of the catalyst layers. ANSYS-Fluent was used to calculate the three-dimensional steady viscous flow fields with the proper turbulence model fitted to the flow characteristics. The root mean square of velocity and the pressure drop inside the flow passages were chosen as the key performance parameters. Four types of guides vanes were proposed to improve the flow quality compared to the current configuration. The numerical results showed that the type 4 configuration was the most effective at improving the aerodynamic performance in terms of flow uniformity and pressure loss.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.1
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• pp.216-221
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• 2017

Reducing optical reflection in the visible light range, in order to increase the share of transmitted light and avoid the formation of ghost images in imaging, is important for polymer lens applications. In this study, polymer lenses with refractive indices of n=1.56, 1.60, and 1.67 were fabricated by the injection-molding method with a polymer lens monomer, dibutyltin dichloride as the catalyst and an alkyl phosphoric ester as the release agent. To investigate their anti-reflection (AR) effects, various AR coating structures, viz. a multi-layer AR coating structure, tri-layer AR coating structure with a discrete approximation Gaussian gradient-index profile, and tri-layer AR coating structure with a quarter-wavelength approximation, were designed and coated on the polymer lens by an E-beam evaporation system. The optical properties of the polymer lenses were characterized by UV-visible spectrometry. The material properties of the thin films, refractive index and surface roughness, were analyzed by ellipsometry and AFM, respectively. The most effective AR coating structure of the polymer lens with low refractive index, n=1.56, was the both side coating of multi-layer AR coating structure. However, both side coating of the tri-layered discrete approximation Gaussian gradient-index profile AR coating structure gave comparable results to the both side coating of the multi-layer AR coating structure for the polymer lens with a high refractive index of n=1.67.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.11
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• pp.689-695
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• 2016

The performance of proton exchange membrane fuel cells (PEMFC) is strongly related to the water flow and accumulation in the gas diffusion layer (GDL) and catalyst layer. Understanding the behavior of fluid from the characteristics of the media is crucial for the improvement of the performance and design of the GDL. In this paper, a numerical method is proposed to calculate the design parameters of the GDL, i.e., permeability, tortuosity, and effective diffusivity. The fluid flow in a channel filled with randomly packed hard spheres is simulated to validate the method. The flow simulation was performed by lattice Boltzmann method with bounce back condition for the solid volume fraction in the porous media, with different values of porosities. Permeability, which affects the flow, was calculated from the average pressure drop and the velocity in the porous media. Tortuosity, calculated by the ratio the average path length of the randomly injected massless particles to the thickness of the porous media, and the resultant effective diffusivity were in good agreement with the theoretical model. The suggested method can be used to calculate the parameters of real GDL accurately without any modification.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.3
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• pp.223-233
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• 2011

A ceramic monolithic catalyst is a honeycomb structure that consists of two layers. The honeycomb structure is regarded as a continuum in structure and heat-flow analysis. The equivalent mechanical properties of the honeycomb structure were determined by performing finite element analysis (FEA) for a test specimen. Bending strength experiments and FEA of the test specimen used in ASTM C1674-08 standard test were performed individually. The bonding coefficient between the cordierite ceramic layer and the washcoat layer was almost zero. The FEA test specimen was modeled on the basis of the bonding coefficient. The elastic modulus, Poisson's ratio, and the thermal properties of the ceramic monolithic substrate were determined by performing the FEA of the test specimen.

• Journal of the Korean Solar Energy Society
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• v.32 no.5
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• pp.118-123
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• 2012

Water balance has a significant impact on the overall fuel cell performance. Maintenance of proper water management should provide an adequate membrane hydration and avoidance of water flooding in the catalyst layer and gas diffusion layer. Considering the important of advanced water management in PEM fuel cell, this study proposes a simple one dimensional water transportation model of PEM fuel cell for use in a dynamic condition. The model has been created by assumption that the output is the water liquid saturation difference. The liquid saturation change is the total difference between the additional water and the removal water on the system. The water addition is obtained from fuel cell reaction and the electro osmotic drag. The water removal is obtained from capillary transport and evaporation process. The result shows that the capillary water transport of low temperature fuel cell is high because the evaporation rate is low.