• Journal of the Korean Ceramic Society
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• v.56 no.3
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• pp.298-301
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• 2019

This paper details the synthesis of α-FeOOH (goethite) rods through the reaction of iron (III) nitrate with KOH as a strong base, and shape control of the particles for use as a yellow inorganic pigment. The crystal phase of the α-FeOOH crystal with OH content according to the addition of KOH and the change in morphology were investigated. The optical properties varied with the aspect ratios, and the yellowness increased with increasing aspect ratio. However, the enhanced chromaticity characteristics reversed beyond a certain critical aspect ratio. Thus, the relative optimal aspect ratio of the α-FeOOH rods as a vivid yellow inorganic pigment was derived. The morphology and coloration of the prepared rods were investigated in detail using X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-vis spectroscopy, and CIE Lab color parameter measurements.

• Macromolecular Research
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• v.16 no.8
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• pp.734-740
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• 2008

A new crosslinked, poly(acrylic acid)-based, dehydrating agent was synthesized through solution polymerization. The Taguchi method, a robust experimental design, was adopted to optimize the synthetic conditions based on the moisture and water absorbing capacities of the dehydrating agent. The method applied for the experiment was a standard L27 ($3^8$) orthogonal array with eight parameters and three levels. By analyzing the variance of the test results, the most effective parameters to control the moisture absorbing capacity (MAC) and its rate were the kind of alkaline base (LiOH, NaOH, or KOH) used as a neutralizing agent of the acrylic acid monomer and the degree of neutralization: The maximum MAC of 40% was achieved at only 2 hat $32^{\circ}C$ and 50% RH when KOH was used as a base and the degree of neutralization was 90%, respectively. However, the water absorbing capacity (WAC) of the resulting dehydrating agent was very low at 158 g/g, indicating that WAC is unaffected by MAC and its rate in this system. The surface morphologies of the agents were examined using scanning electron microscopy (SEM).

• Elastomers and Composites
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• v.51 no.2
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• pp.99-105
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• 2016

Alkoxy modified silicone (PAMS) was synthesized from hydroxyl-terminated polydimethylsiloxane (OH-PDMS) and vinyltrimethoxysilane (VTMO) under alkali catalyst (NaOH and KOH) at room temperature ($25^{\circ}C$) via condensation polymerization. Then, the structural verification of the synthesized PAMS was confirmed using $^1H$-NMR and FT-IR spectroscopy. The reaction rate of PAMSs was studied in terms of the concentration variation of alkali catalyst. The reaction rate increased with the concentration of alkali catalyst, but no correlation between conversion and concentration of alkali catalyst was observed.

• Current Research on Agriculture and Life Sciences
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• v.1
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• pp.55-65
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• 1983

The purpose of this study is to find out influences of several chemicals on the solubility of cocoon sericin in water, and there are several results of use to control the solubility of cocoon sericin in water. The results obtained are summarized as follows : The chemical which shows the strongest accelerating power of the solubility of cocoon sericin in water is Sodium Hydroxide (NaOH), the second is Potassium Hydroxide (KOH), the third is Sodium Silicate ($Na_2SiO_3$), and the weakest is Sodium Bicarbonate ($NaHCO_3$) in order among noticed silk-reeling accelerators. The chemical which shows the strongest inhibiting power of the solubility of cocoon sericin in water is Form Aldehyde (HCHO), the second is Ammonium Alum ($Al_2(SO_4)_2{\cdot}(NH_4)_2SO_4{\cdot}24H_2O$), the third is Acetic Acid ($CH_3COOH$), the weakest is Hydrochloric Acid(HCl) in order among noticed silk-reeling inhibitors. Particulary Hydrochloric Acid (HCl), which is expected to show strong inhibiting power of the solubility of cocoon sericin in water, shows accelerating power of the solubility of cocoon sericin at high temperature over 80 degrees of Celsius thermometer in water.

• Journal of the Korea Concrete Institute
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• v.24 no.6
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• pp.745-752
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• 2012

This paper studies the effect of the compressive strength for combined alkali-activated slag mortars. The effect of activators such as alkali type and dosage factor on the strength was investigated. The alkalis combinations made using five caustic alkalis (sodium hydroxide (NaOH, A series), calcium hydroxide ($Ca(OH)_2$, B series), magnesium hydroxide ($Mg(OH)_2$, C series), aluminum hydroxide ($Al(OH)_3$, D series), and potassium hydroxide (KOH, E series)) with sodium carbonate ($Na_2CO_3$) were evaluated. The mixtures were combined in different dosage at 1M, 2M, and 3M. The study results showed that the compressive strength of combined alkali-activated slag mortars tended to increase with increasing sodium carbonate. The strength of combined alkali-activated slag mortars was better than that of control cases (without sodium carbonate). The result from scanning electron microscopy (SEM) analysis confirmed that there were reaction products of calcium silicate hydrate (C-S-H) and alumina-silicate gels from combined alkali-activated slag specimens.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.11 no.5
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• pp.185-189
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• 2001

Amorphous aluminium phosphate powders were synthesized as a single phase by neutralization reaction of a stoichiometric mixture of $Al_2(SO_4)_3$ and $H_3PO_4$ using the NaOH or KOH solution and subsequently by the hydrothermal precipitation method. The synthesis conditions were as follows : starting materials; $Al_2(SO_4)_3$ and $H_3PO_4$,pH ranges of neutralization reaction; between 5.6 and 6.0, temperature ranges of hydrothermal reaction; between 170 and $180^{\circ}C$,time ranges of hydrothermal reaction; between 4 and 5hs. Under such synthesis conditions, the products are obtained as amorphous aluminium phosphate powders of 0.1~0.3$\mu\textrm{m}$ in size and are Eitted to USP (United Standard Pharmacopoeia) test.

• Resources Recycling
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• v.9 no.1
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• pp.63-69
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• 2000

Ferromanganese dust is an oxide substance of Mn. If imprities are removed and oxidation degree is controlled, the dust can be recycled for soft ferrite materials. The ferromanganese dust contained about 7 kinds of impurities, expecially about 9000 ppm of $SiO_2$ contents of the ferromanganese dust from 9000 ppm to under 500 ppm by fritting method. The $SiO_2$ in ferromanganese dust can be converted into water soluble compounds by alkali fritting and removed by water leaching. KOH and NaOH were used. The most effective conditions to get rid of $SiO_2$ from the dust are that the weight ratio of alkali to ferromanganese dust is 1.75 and fritting is run at $550^{\circ}C$ for 1 hour.

• Composites Research
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• v.35 no.6
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• pp.394-401
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• 2022

Two polymer precursors, polyvinylidene chloride-resin (PVDC-resin) and polyvinylidene fluoride (PVDF), are assembled into the microporous carbon by pyrolysis. Microporous carbon is advantageous as an electrode for supercapacitors that store electric charges through ion adsorption/desorption. The pyrolysis also turns the various heteroatoms of two precursors into functional groups, contributing to the additional charge storage. The analysis of the porous structure and function group during carbonization are important to develop the carbon for energy storage. Here, we analyzed the functional groups of two polymer-derived carbons through X-ray photoelectron spectroscopy. The electrochemical properties of the functional groups were explored in various pH electrolytes. The specific capacitance of two carbons in the acidic electrolyte (1 M H₂SO₄) was improved compared to that in the neutral electrolyte (0.5 M Na₂SO₄) due to the faradaic charge/discharge reaction of the quinone functional group. In particular, the carbon electrode derived from PVDC-resin exhibits a lower capacity than the carbon from PVDF due to the small micropores. In the alkaline electrolyte (6 M KOH), the highest specific capacitance and rate capability were obtained among the three electrolytes for both electrodes based on the facile adsorption of the constituent electrolyte ions (K⁺, OH^-).

• Korean Journal of Plant Resources
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• v.21 no.2
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• pp.144-147
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• 2008

This study was conducted to clarify the characteristics of seed germination and to promote the germination rate in Pollia japonica Thunb. that was pointed to protect by the Office of Forestry in 1997. It was better the germination rate and the growth of in the light than those of in the darkness. The seed germination of Pollia japonica showed the highest germination rate at $20^{\circ}C$ any other treated temperature. To increase the germination rate of Pollia japonica, it was conducted priming treatments and storage treatments at $4^{\circ}C$. Priming treatments using 1% NaOH, 1% KOH for 30min were effective compared to control, but soaking of 100mg/L GA3 for 24 hours, 1% NaOCl for 30min were not useful. It was higher in wet storage than in dry storage. Wet storage of seeds showed a germination rate with 95.3% in 90-day treatment, which improved 55.3% than dry storage in 90-day.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.05a
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• pp.481-486
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• 2001

Ground granulated blast-furnace slag shows very high strength when proper alkali-activator exists. This paper deals with setting time, heat evolution rate and the strength development of alkali-activated slag cement activated by KOH, Ca(OH$)_{2}$, $Na_{2}$ $So_{4}$ , and alum(potassium aluminum sulfate). Alkali-activated slag mortar is studied by comparison with GGBF slag cement mortar. The experimental results indicate that for moisture curing at $25^{\circ}C$, the addiction of either 4% $Na_{2}$ $So_{4}$ or 4% alum increases the strength of GGBF slag cement mortar consisting of 50% GGBF slag and 50% portland cement at early age. Strength of activated GGBF slag cement mortars at 1, 3 and 7 days exceeded that of GGBF slag cement mortar. A conduction calorimeter was used to monitor early age hydration.