• Fire Science and Engineering
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• v.33 no.4
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• pp.1-8
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• 2019

Reaction-to-fire performance of pipe insulation materials should be approved in accordance with KS standards prior to installing water-based suppression systems because several fire accidents are initiated from insulation materials around ceilings or concealed space. A small room test to evaluate the reaction-to-fire performance of the polyethylene foam and elastomeric pipe insulation materials was conducted according to ISO 20632. Different fire growth rate and heat release rate are observed depending on the materials and construction methods. In order to improve a fire safety, the reaction-to-fire performance of pipe insulation material needs to be subdivided with regard to the heat release rate and smoke generation. Furthermore, the characteristics of the applying space are also required to be considered. Subsidiary materials for installation process such as tape and adhesive are found to provide an adverse effect to maintain a fire safety.

• Korean Chemical Engineering Research
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• v.55 no.1
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• pp.13-18
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• 2017

Sodium borohydride, $NaBH_4$, shows a number of advantages as hydrogen source for UAV PEMFC (Unmaned Aerial Vehicle Proton Exchange Membrane Fuel Cells). In order to use for UAV, the weight and volume of byproduct should be small after $NaBH_4$ hydrolysis reaction. Therefore, the weight and volume of byproduct were studied after $NaBH_4$ hydrolysis reaction using unsupported catalyst. The effect of catalyst type, concentration of $NaBH_4$, concentration of NaOH and thickness of catalyst pack on the weight and volume of byproduct were studied. Most of byproduct was $NaB(OH)_4$ and superficial volume of byproduct increased due to foam evolved from byproduct. The weight and volume of byproduct were not affected by concentration of NaOH used stabilizer. The weight of byproduct decreased as concentration of $NaBH_4$ solution increased, but maximum volume of byproduct obtained at 23 wt% of $NaBH_4$. Suitable defoaming agent reduced the volume of byproduct.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.33 no.5
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• pp.196-201
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• 2023

In order to improve the efficiency of the water splitting system for hydrogen energy production, the high overvoltage in the electrochemical reaction caused by the catalyst in the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) must be reduced. Among them, transition metal-based compounds (hydroxide, sulfide, etc.) are attracting attention as catalyst materials to replace currently used precious metals such as platinum. In this study, Ni foam, an inexpensive metal porous material, was used as a support and β-Ni(OH)₂ microcrystals were synthesized through a hydrothermal synthesis process. In addition, changes in the crystal morphology, crystal structure, and water splitting characteristics of β-Ni(OH)₂ microcrystals synthesized by doping Fe to improve electrochemical properties were observed, and applicability as a catalyst in a commercial water electrolysis system was examined.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.34 no.1
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• pp.30-35
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• 2024

In order to improve the efficiency of the water splitting system for hydrogen production, the high overvoltage in the electrochemical reaction caused by the catalyst in the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) must be reduced. Among them, transition metal-based compounds are attracting attention as catalyst materials that can replace precious metals such as platinum that are currently used. In this study, nickel foam, an inexpensive metal porous material, was used as a support, and Fe-doped β-Ni(OH)₂ microcrystals were synthesized through a hydrothermal synthesis process. In addition, in order to improve OER properties, changes in the shape, crystal structure, and water splitting characteristics of Fe-Mo co-doped β-Ni(OH)₂ microcrystals synthesized by co-doping with Mo were observed. The changes in the shape, crystal structure, and applicability as a catalyst for water splitting were examined.

• Macromolecular Research
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• v.17 no.11
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• pp.856-862
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• 2009

This study examined the effects of liquid and solid additives on the morphological, mechanical and thermal insulating properties of rigid polyurethane foams (PUFs). The PUFs synthesized with tetramethylsilane (TEMS) as a liquid-type additive showed a smaller average cell size and lower thermal conductivity than those with the aerosil 200 and clay 30B as solid-type additives. When TEMS was added, the average cell size of the PUF became more uniform and finer due to the reduced surface tension of the polymer solution, which increased the nucleation rate and number of bubbles produced and reduced cell size. The PUFs with TEMS showed the highest closed cell contents among the PUFs prepared using TEMS, aerosil 200 and clay 30B. This suggests that the insulation properties of PUF can be determined by both the size of the cell structure and the amount of closed cell contents in the system. The compression and flexural strengths of the PUF increased slightly when the aerosil 200, clay 30B and TEMS were added compared those of the neat PUF. The reaction profiles of the PUFs showed a similar gel and tack tree time with the reaction time among the PUFs synthesized with three different additives and neat PUF. This suggests that the nucleating additives used in this study do not affect the bubble growth of the chemical reaction, and the additives may act as nucleating agents during the formation of PUF. From the above results of the cell size, thermal conductivity, closed cell contents and reaction profile of the PUFs, liquid-type nucleating agent, such as TEMS, is more effective in decreasing the thermal conductivity of the PUF than solid-type nucleating agent, such as aerosil 200 and clay 30B.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.34 no.3
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• pp.92-97
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• 2024

To improve the efficiency of water splitting systems for hydrogen production, the high overvoltages of electrochemical reactions caused by catalysts in the oxygen evolution reaction (OER, Oxygen Evolution Reaction) must be reduced. Among them, LDH (Layered Double Hydroxide) compounds containing transition metal such as Ni, are attracting attention as catalyst materials that can replace precious metals such as platinum that are currently used. In this study, nickel foam, an inexpensive metallic porous material, was used as a support, and NiCo LDH (Layered Double Hydroxide) nanocrystals were synthesized through a hydrothermal synthesis process. In addition, changes in the shape, crystal structure, and water decomposition characteristics of the Mo-doped NiCo LDH nanocrystal samples synthesized by doping Mo to improve OER properties were observed.

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.209-212
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• 2001

Aircraft industry is developed very fast so titanium scrap was generated to manufacture. Titanium scrap was wasted and used to deoxidize cast iron so we are study recycling of it. In this research were studied that metal hydride of reacted in hydrogen chamber of AMS4900, 4901, return scrap titanium alloy and sponge titanium granule. The temperature of hydrogenation was 40$0^{\circ}C$ in the case of pure sponge titanium but return scrap titanium alloy were step reaction temperature at 40$0^{\circ}C$ and 50$0^{\circ}C$, and after the hydride of titanium alloy were crushed by ball mill for 5h. Titanium hydride contains to 4wt.% of hydrogen theoretically as theory. It was determined by heating and cooling curve in reaction chamber. The result of XRD was titanium hydride peak only that it was similar to pure titanium. Titanium hydride Powder particle size was about 45${\mu}{\textrm}{m}$, and recovery ratio was 95w% compared with scrap weight for a aluminum foam agent.

• Journal of the Korean Applied Science and Technology
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• v.3 no.1
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• pp.57-64
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• 1986

1-(carboxyalkyl) trimethyl ammonium chlorides such as 1-(carboxyundecyl) trimethyl ammonium chloride and 1-(carboxytridecyl) trimethyiammonium chloride were synthesized by the reaction of ${\alpha}-bromoalkanoic$ acid with trimethyl amine hydrochloride. In other hand, (carboxymethyl) alkyl dimethyl ammonium chlorides such as (carboxymethyl) dodecyl dimethyl ammonium chloride and (carboxymethyl) tetradecyl dimethyl ammonium chloride were synthesized by the reaction of alkyl dimethylamine with sodium chloroacetate. The four kinds of alky carboxy betaine such as 2-(trimethylammonio) dodecanoate, 2-(trimethyl ammonio) tetradecanoate, (dodecyl dimethylammonio) ethanoate and (tetradecyl dimethyl ammonio) ethanoate were prepared from 1-(carboxyalkyl) trimethyl ammonium chlorides or (carboxymethy1) alkyl dimethyl ammonium chlorides. The surface activities including surface tension, emulsifying power, foaming power, foam stability, deflocculating effect, effectiveness of wettability and solubilizing effect were measured and also critical micelle concentration and hydrophilic-lipophilic. balance(HLB) were evaluated. These carboxy betaines show good surface activities as O/W type emulsifing agent and detergent.

• Journal of the Korean Applied Science and Technology
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• v.18 no.2
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• pp.95-102
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• 2001

Recently, there has been considerably interested in the development to new functional gemini type anionic surfactant, sodium bis-n-alkyl sulfonatosuccinate, had been synthesized through the addition reaction of sodium bisulfite to bis-n-alkyl maleate, in which water was azeotropically distilled by adding benzene to the reaction system, gave a good yield. All the surface activities including krafft point, surface tension, emulsion power and foaming were measure and cmc was evaluated in dilute solution. This results showed a lower ability in $27{\sim}30dyne/cm$ than single-chain surfactant with $32{\sim}35dyne/cm$ to surface tension. Also its cmc value much smaller in $(6.5{\sim}10){\times}10^{-4}mca{\ell}/{\ell}$ than single-chain surfactant with $(40{\sim}45){\times}10^{-4}mca{\ell}/{\ell}$ concentration. In foaming ability and foam stability of gemini surfactant had especially a good ability in approximately $100{\sim}150ml$, and in emulsing power they exhibited a good emulsing phase and stability, and Krafft points were $0{\sim}10^{\circ}C$.

• Journal of the Korean Applied Science and Technology
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• v.25 no.2
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• pp.115-122
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• 2008

The hydrosilylation is an addition reaction of Si-H bond to unsaturated double bonds, which provides a convenient mechanism to synthesize poly(dimethylsiloxane-co-methylsiloxane)copolymer having siloxy units in polymer backbone. In this study, Poly(dimethylsiloxane-co-methylsiloxane) copolymer was synthesized through the polymerization reaction of cyclopentasiloxane with poly(methyl-hydrogen) siloxane. Silicone-hydrogen functional group of the poly(dimethylsiloxane-co-methylsiloxane) copolymer was substituted to the alkyl groups by hydrosilylation. And their structure was analyzed with FT-IR, H-NMR and GPC instruments, respectively. Surface tension of the synthetic compounds is increased from 22dyne/cm to 25dyne/cm according to increase additional EO moles. The cmc which was evaluated by surface tension was ranged $10^{-5}$ to $10^{-4}mol/L$ and it was decreased according to increase of dimethyl siloxyl content. HLB number of these surfactants was evaluated 9.5 to 11.5 range. These silicone surfactants is applied to self-emulsifier defoamer and personal care products as surface tension depressant, emulsifier, foam control agent.