• Clean Technology
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• v.14 no.4
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• pp.281-286
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• 2008

Absorption rate of carbon dioxide was measured in the aqueous polyacrylamide (PAA) solution containing triethanolamine (TEA) of $0{\sim}2.0\;kg\;mol/m^3$ in a flat-stirred vessel with an impeller of 0.05 m and agitation speed of 50 rpm at $25^{\circ}C$ and 101.3 kPa. The chemical absorption rate of $CO_2$ was estimated by mass transfer mechanism based on the film theory using the physicochemical properties containing the liquid-side mass transfer coefficient of $CO_2$ and the kinetics of reaction between $CO_2$ and TEA to compare with the measured rate. The aqueous PAA solution acted as a reducing agent by viscoelastic property of non-Newtonian liquid based on the same viscosity of the solution.

• Journal of the Korean Association of Geographic Information Studies
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• v.21 no.4
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• pp.1-13
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• 2018

Both Platform as a Service (PaaS) as one of the cloud computing service models and the e-government (e-Gov) standard framework from the Ministry of the Interior and Safety (MOIS) provide developers with practical computing environments to build their applications in every web-based services. Web application developers in the geo-spatial information field can utilize and deploy many middleware software or common functions provided by either the cloud-based service or the e-Gov standard framework. However, there are few studies for their applicability and performance in the field of actual geo-spatial information application yet. Therefore, the motivation of this study was to investigate the relevance of these technologies or platform. The applicability of these computing environments and the performance evaluation were performed after a test application deployment of the spatial image processing case service using Web Processing Service (WPS) 2.0 on the e-Gov standard framework. This system was a test service supported by a cloud environment of Cloud Foundry, one of open source PaaS cloud platforms. Using these components, the performance of the test system in two cases of 300 and 500 threads was assessed through a comparison test with two kinds of service: a service case for only the PaaS and that on the e-Gov on the PaaS. The performance measurements were based on the recording of response time with respect to users' requests during 3,600 seconds. According to the experimental results, all the test cases of the e-Gov on PaaS considered showed a greater performance. It is expected that the e-Gov standard framework on the PaaS cloud would be important factors to build the web-based spatial information service, especially in public sectors.

• Journal of the Korean Electrochemical Society
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• v.19 no.3
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• pp.87-94
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• 2016

In order to improve performances of submicrometer-sized Si negative electrode which shows larger volumetric change than nano-sized Si, composite binders are introduced by blending between poly(phenanthrenequinone) (PPQ) conductive polymer binder and poly(acrylic acid) (PAA) having good adhesion strength due to its carboxyl functional group. Blending between PPQ and PAA shows an effect that the adhesion strength of the Si electrode with the composite conductive binder is greatly improved after blending and this makes its better stable cycle performance. Blending ratios between PPQ and PAA in this work are 2:1, 1:1, 1:2 (by weight) and the best capacity retention at 50th cycle is observed in the electrode with the blending ratio 2:1 (named QA21). This is because that PPQ plays a role of conductive carbon among the Si particles or between Si particles and Cu current collector and PAA binds effectively the particles and the current collector. According to this synergetic effect, the internal resistance of the Si electrode with the blending ratio 2:1 is the smallest value. In addition, the Si electrode with PPQ-PAA composite binder shows the better stable cycle performance than the electrode with conventional super-P conductive carbon (20 wt.%).

• Clean Technology
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• v.18 no.1
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• pp.57-62
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• 2012

Aqueous poly (vinyl alcohol) (PVA) solution was modified by using hydrophobic vinyltriethoxysilane (VTEOS) and then adding different amounts of poly (acrylic acid) (PAA) to the resulting solution. Thermal and mechanical properties, contact angle, water vapor transmission rate (MVTR) and oxygen gas transmission rate ($O_2TR$) of the film samples fabricated by these solutions were investigated. The glass transition temperature (Tg) of the VTEOS-modified films was sightly increased and the value remained unchanged according to the amount of PAA. The tensile strength of the VTEOS-modified films was found to be 9.48~10.72 $kg/mm^2$ which showed no significant difference compared with that of PVA. The film prepared with VTEOS-modified PVA/PAA (= 90/10), of which the swelling and solubility were measured to be 198% and 0%, respectively, showed improved water-resistance. The MVTR and $O_2TR$ for the PET film (thickness 50 ${\mu}m$) coated with VTEOS-modified PVA/PAA (= 90/10) film (thickness 2.5 ${\mu}m$) were measured to be 11.04 $g/m^2/day$ and 3.1 $cc/m^2/day$, respectively.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.5
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• pp.10-16
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• 2016

This work investigates the size and dispersion characteristics of silver nanoparticles synthesized by a liquid phase reduction method using PAA. The experimental variables were the molecular weight and doses of the PAA, reducing agent, dispersant, and organic solvent (ethanol-acetone). UV-visible spectrophotometer results confirm the formation of the silver particles, and SEM indicates size in the nanometer range. As the ultrasonication time increases, there is a tendency toward smaller agglomerates of nanoparticles. The agglomerates were dispersed into 1-5 agglomerates of particles by ultrasonication for 3 hours or more. Relatively spherical nanoparticles were produced with a completely homogeneous dispersion and size of 49.56-85.75 nm by ultrasonication using BYK-192, a dispersant containing copolymer with a pigment affinic group. The average size of the silver nanoparticles was increased to 36.82, 50.66, and 56.06 nm with increasing molecular weight of PAA. Also, the size of the nanoparticles increased with the capping of PAA on the surfaces of the nanoparticles when increasing the amount of PAA. The addition of hydrazine as a reducing agent produced relatively small particles because many nuclei were created by the reduction reaction. The ethanol-acetone solvent helped with the regular arrangement of the silver nanoparticles.

• Journal of The Korean Society of Inherited Metabolic disease
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• v.22 no.1
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• pp.28-36
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• 2022

Purpose: Detection of abnormal metabolites in plasma amino acid (PAA) and urine organic acid (UOA) analyses has been used to diagnose clinical mitochondrial diseases, such as Leigh syndrome. In this study, the diagnostic values and effectiveness of PAA and UOA analyses were reviewed. Methods: This was a retrospective study of patients with Leigh syndrome who were diagnosed between 2003 and 2018 in a single tertiary care center. Through a whole mitochondrial sequencing and nuclear DNA associated mitochondrial gene panel analysis, 19 patients were found to be positive for mitochondrial DNA (mtDNA) mutation-associated Leigh syndrome, and 57 patients were negative. Their PAA and UOA analyses results were then compared. Results: In the comparison of the PAA and UOA analyses results between the two groups, no abnormal metabolites showed obvious differences between the mtDNA mutation-positive Leigh syndrome and mtDNA mutation-negative Leigh syndrome groups. Conclusion: PAA and UOA analyses are inappropriate test methods for diagnosing Leigh syndrome or screening of mtDNA mutation-associated Leigh syndrome. However, UOA analysis might still be a suitable screening test for Leigh syndrome.

• Progress in Superconductivity
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• v.11 no.2
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• pp.87-91
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• 2010

We fabricated the polyacrylic acid (PAA)-doped $MgB_2$ bulks and characterized their lattice parameters, actual C substitutions, microstructures, and critical properties. The boron (B) powder was mixed with PAA using N,N-dimethylformamide as solvent and then the solution was dried out at $200^{\circ}C$ and crushed. The C treated B powder and magnesium powder were mixed and compacted by uniaxial pressing at 500 MPa, followed by sintering at $900^{\circ}C$ for 1 h in high purity Ar atmosphere. We observed that the PAA doping increased the MgO amount but decreased the grain size, a-axis lattice constant, and critical temperature ($T_c$), which is indicative of the C substitution for B sites in $MgB_2$. In addition, the critical current density ($J_c$) at high magnetic field was significantly improved with increasing PAA addition: at 5 K and 6.6 T, the $J_c$ of 7 wt% PAA-doped sample was $6.39\;{\times}\;10^3\;A/cm^2$ which was approximately 6-fold higher than that of the pure sample ($1.04\;{\times}\;10^3\;A/cm^2$). This improvement was probably due to the C substitution and the refinement of grain size by PAA doping, suggesting that PAA is an effective dopant in improving $J_c$(B) performance of $MgB_2$.

• Polymer(Korea)
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• v.30 no.2
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• pp.162-167
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• 2006

Polyamic acid (PAA) was prepared from cyclobutane-1,2,3,4-tetracarboxylic dianhydride (CBDA) and 4,4'-fiaminodiphenyl ether (DDE). In order to impart a photosensitivity to the PAA, diazonaphthoquinone (DNQ) derivative (DI) was added. However, the addition of the DI was not enough to inhibit the dissolution of the PAA for a aqueous alkal solution. Therefore, we had synthesized poly(amic acid ester)s by an adding 1,2-epoxy-3-phenoxypropane to the PAA. That is, an acidity of the PAA could be controlled by an esterification reaction of 1,2-epoxy-3-phenoxypropane with the PAA. Significant difference of a dissolution rate of the poly(amic acid ester) between an o(posed and unexposed area was observed at an acid content of 60% and less. Resolution of the positively patterned film showed about $25{\mu}m$ at the exposure dose of $200mJ/cm^2$.

• Elastomers and Composites
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• v.42 no.3
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• pp.177-185
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• 2007

Polyamic acid(PAA)/organoclay nanocomposites containing phosphorous were prepared by solution blending of phosphorylated PAA(PPAA) and organically modified montmorillonite(O-MMT) as a type of layered clays. The nanocomposites were characterized by FT-IR, DSC, TGA, PCFC, SEM, and XRD. The preparation of nanocomposites was confirmed by FT-IR and XRD. SEM pictures showed that the organoclay was dispersed well in the PAA matrix relatively. XRD results indicated that the O-MMT layers were intercalated. The thermal stability and flame retardancy of O-MMT/PPAA nanocomposites were higher than those of pure PAA. PCFC results also showed that the heat release capacity and total heat release values of O-MMT 4 wt%/PPAA-0.2, 0.4, 0.6 composites were decreased with increasing the mole ratio of phosphorous. It was found that the nanocomposite films had the potential to be used as a fire safe material.

• Polymer(Korea)
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• v.37 no.6
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• pp.784-793
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• 2013

A two-step method for obtaining poly(N-isopropylacrylamide) (PNIPAAm) from poly(acrylonitrile) (PAN) was investigated in order to find a feasibility of imparting thermo-responsive property onto textile fiber materials. PAN was converted to poly(acrylic acid) (PAA) by hydrolysis at a first-step, and then PAA was converted to PNIPAAm at a second step via an amidation reaction of PAA with isopropylamine (IPA) in DMF medium using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) as catalysts. High content of carboxylic groups at the first step was obtained by the successive alkaline and acid hydrolysis of PAN. The degree of conversion of PAA to PNIPAAm at the second step was dependent on the amount of catalysts EDC and NHS. PNIPAAm converted from PAA through amidation reaction showed a lower critical solution temperature (LCST) behavior when the conversion was higher than about 53%.