• Transactions of the Korean hydrogen and new energy society
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• v.26 no.3
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• pp.227-233
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• 2015

In this study, we evaluate catalytic activity of Pd/C catalyst that is synthesized by modified polyol method. With such formed Pd/C is used as anodic catalyst for direct formic acid fuel cell (DFAFC) and performances of the DFAFC are measured to verify whether the new catalyst is effective for enhancing DFAFC performance and to determine optimal loadings of the Pd/C needed for obtaining best DFAFC performance. Pd particle distribution of the Pd/C catalyst is analyzed by TEM, while its catalytic activity is estimated by using cyclic voltammogram (CV) as measuring formic acid oxidation reaction and active surface area. As a result of that, the Pd/C catalyst synthesized by modified polyol shows better catalytic activity and DFAFC performance with small loading amount of Pd/C. When loading amount of Pd/C is $1.5mgcm^{-2}$, maximum power density of DFAFC adopting the catalyst is $122mWcm^{-2}$.

• Journal of Adhesion and Interface
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• v.22 no.1
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• pp.8-15
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• 2021

In this study, a polyol was prepared using Jeffamine D-400 as a propylene glycol-based diamine to impart flexibility to the urethane-modified epoxy, and a urethane-modified epoxy was synthesized using the polyol. Urethane-modified epoxy synthesized with existing Bisphenol A diglycidyl ether (BADGE) epoxy, a curing agent, and a curing accelerator are mixed to prepare an epoxy adhesive, and shear strength is measured by measuring adhesion strength. As a result, shear strength and shear elongation tended to increase. These results are due to the high crosslinking density. It is believed that it can be applied to structural adhesives that are restricted in use.

• Journal of Environmental Science International
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• v.21 no.4
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• pp.507-515
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• 2012

To improve the mechanical properties of hydroxyapatite (HA)/waterborne polyurethane (WBPU) composites, the hydroxyl group of HA was modified by urethane reactions: the hydroxyl groups of HA were reacted with aliphatic or cyclic diisocyanate, and then the modified HAs were extended by adding polyol and/or ${\varepsilon}$-caprolactone. Composites were prepared by the prepolymer process method: the modified HA was directly pured into the urethane reaction of isocyanate and polyol. The properties of modified HA/WBPU composites were investigated by thermogravimetric analysis, tensile strength, and water resistance. The results showed that the reactivity of aliphatic diisocyanate to the hydroxy group of HA was faster than that of cyclic one. Comparing to those of pure HA/WBPU composite films, the thermal stability, water resistance, and mechanical properties of the modified composite films increased with a degree of modification of HA.

• Journal of the Microelectronics and Packaging Society
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• v.20 no.3
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• pp.11-18
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• 2013

Interest in copper nanoparticles has increased as an alternative for substituting silver nanoparticles because of its lower cost and less electromigration effect than silver. In this paper, the recent research trends and main results in wet-chemical synthesis of sub-100 nm Cu nanoparticles were summarized. The characteristics of synthesis were discussed with a classification such as modified polyol synthesis, modified hydrothermal synthesis, solvothermal synthesis, and the others, focussing on effects of capping agents, reductants, and pH. Information on the oxidation of synthesized copper nanoparticles were additionally commented.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.1290-1292
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• 2009

Modified-polyol protocol was utilized for synthesis of green-emitting ($^5D_4-^7F_j$ transitions of $Tb^{3+}$ ion) nanocrystalline $LaPO_4:Ce^{3+}$, $Tb^{3+}$ phosphors. Experimental parameters including chemical composition and annealing temperature were optimized to produce highly efficient, uniformly sized nanophosphors. Spin-deposited layer of $LaPO_4:Ce^{3+}$, $Tb^{3+}$ nanophosphors on glass substrate exhibited a transmittance of more than 80 %, indicating their efficacy for transparent display.

• Transactions of the Korean hydrogen and new energy society
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• v.25 no.4
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• pp.378-385
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• 2014

In this research, we investigate electrical performance and electrochemical properties of graphene supported Pt (Pt/G) and PtM (M = Ni and Y) alloy catalysts (PtM/Gs) that are synthesized by modified polyol method. With the PtM/Gs that are adopted for oxygen reduction reaction (ORR) as cathode of proton exchange membrane fuel cells (PEMFCs), their catalytic activity and ORR performance and electrical performance are estimated and compared with one another. Their particle size, particle distribution and electrochemically active surface (EAS) area are measured by TEM and cyclic voltammetry (CV), respectively. On the other hand, regarding ORR activity and electrical performance of the catalysts, (i) linear sweeping voltammetry by rotating disk electrode and rotating ring-disk electrode and (ii) PEMFC single cell tests are used. The TEM and CV measurements demonstrate particle size and EAS of PtM/Gs are compatible with those of Pt/G. In case of PtNi/G, its half-wave potential, kinetic current density, transferred electron number per oxygen molecule and $H_2O_2$ production % are excellent. Based on data obtained by half-cell test, when PEMFC singlecell tests are carried out, current density measured at 0.6V and maximum power density of the PEMFC single cell employing PtNi/G are better than those employing Pt/G. Conclusively, PtNi/Gs synthesized by modified polyol shows better ORR catalytic activity and PEMFC performance than other catalysts.

• Journal of the Microelectronics and Packaging Society
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• v.19 no.2
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• pp.61-66
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• 2012

Bismuth(Bi) nanoparticles were synthesized at room temperature by a modified polyol process using bismuth(III) carbonate basic as precursor. In addition, some characteristics of the synthesis with respect to the exchange of a capping agent/surface stabilizer and solvent type were observed. When polyvinylpyrroldone was added, the finest Bi nanoparticles were synthesized in diethylene glycol(DEG), while the coarsest nanoparticles were formed in polyethylene glycol(PEG). The particle size immediately after synthesis was proportionate to final particle size which was determined by particle growth through coalescence and aggregation during drying. As a result, the finest Bi particles with the diameter range of several tens of nanometers - 300 nm were finally obtained in DEG. Regardless of the type of capping agent/surface stabilizer, extensive coalescence and aggregation behavior occurred in PEG, resulting in final products agglomerated with coarse particles.

• Transactions of the Korean hydrogen and new energy society
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• v.27 no.3
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• pp.283-289
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• 2016

In this study, electrochemical characterizations of PdCu/C catalysts that are synthesized by modified polyol method are investigated. Most of all, amount of ethylene glycol (EG) that is used as main component for catalyst synthesis is mainly modulated to optimize synthetic condition of the PdCu/C catalyst, For evaluations about catalytic activity and performance of direct formic acid fuel cell (DFAFC), half cell and full cell tests are implemented. As a result, when amount of EG is 4M, catalytic activities of the PdCu/C catalyst such as peak current of formic acid oxidation and active surface area are best, while maximum power density of DFAFC using the optimized PdCu/C catalyst is better than that using commercial Pd/C (30 wt%) by 6%. Based on that, PdCu/C catalyst synthesized by modified polyol method plays a critical role in improving (i) catalytic activity for formic acid oxidation and (ii) DFAFC performance by employing as anodic catalyst.

• Journal of the Korean Applied Science and Technology
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• v.27 no.3
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• pp.300-309
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• 2010

Melamincyanurate(MC), as an non halogen flame retardant are used as the polymer and plastic materials. In this study, melamine and cyanuric acid were used for the synthesis of MC. The optimum condition of synthetic MC were controlled by different molar ratio of melamine to cyanuric acid. MC was modified by coupling reaction with four different agents. The influences of modified MC were based on the coupling agent types. Preparation methods are available to offer the prospect of improved morphology control deposit stability in polyol. The results reveal that glycidoxypropyltrimethoxysilane(GDS) has the best storage stability. The best properties were obtained with melamine and cyanuric acid from 1:1 molar ratio. Modification of MC through coupling agent can efficiently enhanced the deposit stability in polyol up to 30 %.

• Bulletin of the Korean Chemical Society
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• v.31 no.11
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• pp.3145-3150
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• 2010

Ruthenium catalysts modified by selenium have been introduced as alternative materials to Pt in Direct methanol fuel cells (DMFCs). RuSe nano-particles were synthesized on the Vulcan XC72R carbon supports via polyol method. The prepared catalysts were electrochemically and physically characterized by cyclic voltammetry (CV,) linear sweep voltammetry, methanol tolerance test, X-ray diffraction (XRD), Transmission electron microscopy (TEM), Energydispersive Spectrometer (EDS) and X-ray photoelectron spectroscopy (XPS). Increasing the Se concentration up to 20 at % increased the electro-catalytic activity for the oxygen reduction. By increasing Se amount, Ru metallic form on the surface was increased. The $Ru_{80}Se_{20}$/C catalysts showed the highest oxygen reduction reaction (ORR) activity and outstanding methanol tolerant property in half cell tests as well as single cell test.