• 분석과학
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• 제12권3호
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• pp.230-234
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• 1999

$Ba^{2+}$ 및 $Ti^{4+}$이 함유된 염산용액에서 dimethyl oxalate(DMO)가 열분해되면 barium titanyl oxalate(BTO)가 균일 생성되었다. 일정량의 hydroxy propyl cellulose(HPC)를 분산제로 사용하였고 120min의 숙성시간에서 생성된 BTO의 전 침전물을 회수하였다. 반응온도, 염화이온의 농도, $[DMO]_0/([Ba^{2+}]_0+[Ti^{4+}]_0)$의 초기 농도비, 그리고 가한 HPC가 BTO입자의 형태, 화학적 회수율, 그리고 그들의 선구물질로부터 형성된 티탄산 바륨의 특성에 영향을 미침을 알았다.

• Journal of Pharmaceutical Investigation
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• 제3권1_2호
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• pp.5-15
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• 1973

Fluorometric determination of dl-Methylephedrine hydrochloride from complex preparation were studied. According to the experimental results and considerations obtained the results for the following. (1) dl-Methylephedrine hydrochloride in Hydrochloric acid media occurs the fluorescens by Picrolonic acid and Cuppric acetate. (2) The maximum absorption fluorescence wave length of dl-Methylephedrine hydrochloride standard solution is $365m{\mu}$. (3) The relationship between the fluorescence proportions to concentration of standard solution at range of $4.2{\times}10^{-4}\;M$. $6{\times}10^{-4}M$. (4) dl-Methylephedrine hydrochloride was precisely determined even in the presence of various components, especially Chloropheniramine maleate, Dextromethorphan hydrobromide and Diphenylhydramine hydrochloride. (5) This method has high sensitivity and is simple in precedure. (6) This method be applicable with 99.79% accuracy and was 99.5% in complex preparation.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1996년도 봄 학술발표회 논문집
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• pp.24-29
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• 1996

The purpose of this study is to propose new estimation method of unit cement content in hardened concrete. In general, the quantity of cement in hardened concrete is tested by hydrochlonic acid dissolving cement paste, however, hydrochloric acid dissolves sea shell contained in sea sand and lime stone in concrete. Therefore, the tested cement content is apt to estimate greater than actual cement content. The sodium gluconate solution dissolves only cement in concrete, it is hard to dissolve sea shell and lime stone as CaCo3. The effects of the quantity, concentration and temperature of sodium gluconate solution, the ignition temperature, the ignition loss of cement on the cement content and the percentage of dissolution of cement were investigated to establish a test method. From the results of these tests, the fundamental test method for cement content of hardened concrete by sodium gluconate is proposed.

• 분석과학
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• 제8권4호
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• pp.419-425
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• 1995

A method has been investigated for the determination of selenium and tellurium in Ginseng, Ganoderma and Garlic using hydride generation atomic absorption spectrometry(HG-AAS). The concentration effects of hydrochloric acid and sodium tetrahydroborate on the hydride generation for the determination of selenium and tellurium were investigated. The method of sample decomposition was also investigated using various mineral acids, such as nitric, perchloric and sulfuric acid in the closed system, and foreign ion effects containing in the samples were studied. The calibration curves of selenium and tellurium were obtained in the range of 0~40 ppb. The detection limits(S/N=2) of selenium and tellurium are 0.1 and 0.2 ppb. Analytical data of selenium and tellurium in Garlic, Ganoderma and Ginseng are 289, 296 and 198 ng/g for selenium and 146, 127 and 110 ng/g for tellurium, respectively.

• 한국분말재료학회지
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• 제25권5호
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• pp.390-394
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• 2018

Metallic tantalum powder is manufactured by reducing tantalum oxide ($Ta_2O_5$) with magnesium gas at 1,073-1,223 K in a reactor under argon gas. The high thermodynamic stability of magnesium oxide makes the reduction reaction from tantalum oxide into tantalum powder possible. The microstructure after the reduction reaction has the form of a mixture of tantalum and magnesium oxide, and the latter could be entirely eliminated by dissolving in weak hydrochloric acid. The powder size in SEM microstructure for the tantalum powder increases after acid leaching in the range of 50-300 nm, and its internal crystallite sizes are observed to be 11.5 to 24.7 nm with increasing reduction temperatures. Moreover, the optimized reduction temperature is found to be 1,173 K as the minimum oxygen concentration is approximately 1.3 wt.%.

• 한국세라믹학회지
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• 제22권1호
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• pp.35-39
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• 1985

Synthetic mica $NaMg_{2.5}(Si_4O_{10})F_2 (Na-TSM)$ was treated with HCl solution and H-type exchange resin to investigate the chemical stability and the ion exchange by measuring the dissolution of chemical components and the exchanged $H^+$ ion. The replacement of $Na^+$ ion occurred in contact with HCl solution and H-type ion exchange resin at the surface of Na-TSM particles reached $Na^+$ ions at maximum value of 70~80%. $Mg^{2+}$ ion of octahedral layer became to dissolve from the pH2 solution and th amount of it dissolved in-creased almost proportional to $H^+$ ion concentration from around 0.02N $H^+$ ion equilibrium concentration. The crystalline structure of Na-TSM was destructed by dissolution of Mg2+ ion in cncentrated hydrochloric acid solution and resulted silica gel precipitation.

• Bulletin of the Korean Chemical Society
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• 제32권9호
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• pp.3429-3432
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• 2011

Distribution diagram of $FeCl_2$ in HCl solution indicated that $FeCl^+$ was a predominant species in strong HCl solution up to 10 M. Solvent extraction of $FeCl_2$ has been performed in the HCl concentration range from 5 to 9 M by using Alamine336 as an extractant. Interaction parameter of $FeCl^+$ for Bromley equation was estimated from our solvent extraction data. This parameter thus obtained in our study can be employed in calculating the activity coefficient of $FeCl^+$ in high concentration of HCl.

• 대한화학회지
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• 제58권1호
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• pp.25-32
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• 2014

Corrosion inhibition of 304 stainless steel (SS) in 1 M HCl by aqueous extract of coriander seeds was studied using weight loss, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and electrochemical frequency modulation (EFM) techniques. Values of inhibition efficiency obtained are dependent upon the concentration of extract and temperature. Generally, inhibition was found to increase with inhibitor concentration, but decrease with temperature. Physical adsorption mechanism has been proposed for the inhibition with Langmuir adsorption isotherm obeyed. Values of activation energy of the inhibited corrosion reaction of 304 SS are greater than the value obtained for the blank. Thermodynamic consideration reveals that adsorption of aqueous extract of coriander seeds 304 SS surface is spontaneous.

• 대한화학회지
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• 제9권2호
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• pp.71-74
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• 1965

Reduction of Ti(Ⅳ)-oxalate complex on dropping mercury electrode has been studied as a function of oxalate concentration and of pH varied with HCl. Assuming there are equilibrium $TiO(C_2O_4)_2= \;+\;2H^+\;=\;Ti^{+4}\;+\;2C_2O_4\;=\;+\;H_2O,\;K_4$ in addition to $TiO(C_2O_4)_2\;^=\;=\;TiO^{++}\;+\;2C_2O_4=\;K_2\;Ti(C_2O_4)_2\;^-\;=\;Ti^{+3}\;+\;2C_2O_4=\;K_3$ in the system cathodic wave has been well explained for that pH is higher than 0.5. The equilibrium constants $K_2,\;K_3$ and $K_4$ have been to be $2{\times}10^{-12},\;5{\times}10^{-13}$ and $10^{-11}$, respectively. The reduction of Ti(Ⅳ)-oxalate system is $Ti^{+4}\;+\;e\;{\to}\;Ti^{+3}$ in the concentration of hydrochloric acid, higher than 3M.

• 자원리싸이클링
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• 제14권1호
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• pp.55-63
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• 2005

This study investigated the electrochemical recovery of palladium in a HCl solution that is used for palladium leaching. The high acidity of HCl solution and the low concentration of Pd ions increased the cathodic overpotential and reduced the limiting current density. Lowering the current density produced dense deposits; however, they were under high tensile stress. Raising the temperature affected both the densification and the stress, which enabled the attainment of dense Pd deposits under low stress. Lowering the current density and raising the temperature up to 70$^{\circ}C$ was recommended for the recovery of palladium as sound bulk Pd deposits. Current efficiency was over 85% at the initial stage of recovery may decrease the current efficiency, since a low Pd ion concentration results in a low limiting current density.