• 대한임상검사과학회지
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• 제40권1호
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• pp.18-25
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• 2008

In classical titrimetric analyses, the major concern is the concentration of titrant, usually the aqueous solution of hydrochloric acid or sodium hydroxide, that could be changed as time goes by and it is accompanied with the inaccuracy of the resulting data. And the statistical approach, the nonlinear regression analysis, which is a well-known statistical method, was introduced to determine the accurate concentration of the titrant and the exact value of parameters, $K_a$, r, $C_a$, $C_b$, for 0.01 M aqueous solutions of analytes, sodium pyruvate, sodium acetate, sodium bicarbonate, ammonium hydroxide, ammonium chloride and acetic acid at $25^{\circ}C$. We used Gauss-Newton method for the linearlization of the nonlinear titration system and the two-parameter fitting showed appreciable convergent data for the parameters of the analytes set with the various range of $K_a$ value.

• Journal of Pharmaceutical Investigation
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• 제4권1_2호
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• pp.46-54
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• 1974

A new spectrophotemetric method was estalished for the determination of oleic acid. This method is based on the 1,2-dichloroe-thane extraction of the ion-pair formed between methylene blue and oleic acid. But the absorbance of an ion-pair in the 1,2-dichloroe-thane layer was variable with the temperature, the ion-pair was extracted back into a diluted hydrochloric acid solution. The maximum absorbance of the acid extract observed at $660m{\mu}$ and a lineal relationship was observed from the initial amount over the range of $50-800{\gamma}/ml$ of oleic acid in the aqueous phase. The composition ratio of the ion-pair formed between methylene blue and oleic acid was determined to be 2 : 1 by both the mole ratio and continuous variation methods.

• 약학회지
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• 제45권1호
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• pp.34-38
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• 2001

The Phellodendri Cortex of Phellodendron amurense (Rutaceae) is known to contain a number of isoquinoline alkaloid, and berberine, palmatine, jateorrhizine, phellodendrine and magnoflorine are the major constituents of protoberberine alkaloids. For the determination of protoberberine alkaloids from Phellodendri Cortex and berberine chloride from the preparation, the new spectrophotometric method was developed with a simple and selective sample clean-up using thiocyanatocobaltate[II] complex ion. Samples were extracted with 0.1 mM hydrochloric acid, potassium biphthalate reagent, thiocyanatocobaltate reagent and 1.2-dichloroethane for 60 min. The absorbance of protoberberine alkaloid complexes in 1.2-dichloroethane solution was measured at 625 nm. Calibration curve for berberine was linear over the concentration range of 0.05~0.30 mg/ml 1.2-dichloroethane. The method proved to be rapid, simple and reliable for the determination of protoberberine alkaloids from Phellodendri Cortex and berberine chloride from the preparation.

• 한국자원리싸이클링학회:학술대회논문집
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• 한국자원리싸이클링학회 2006년도 춘계임시총회 및 제27회 학술발표대회
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• pp.86-89
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• 2006

전해 생성된 염소를 이용하여 구리를 침출하는 연구를 수행하였다. 염산농도 $1molL^{-1}$, 반응온도 $25^{\circ}C$, 교반속도 400rpm 조건에서 전류밀도 $10mA/cm^{2}$의 경우 반응온도에 상관없이 구리의 침출속도가 동일하였으나 $Cl_{2}$ 생성량이 충분한 $40mA/cm^{2}$의 경우 온도가 높을수록 구리의 침출속도가 증가하였다. 침출된 구리농도가 6g/L 부근에 도달하면 염소의 공급속도에 상관없이 구리의 침출이 둔화되었다. 이는 구리-염소 착화물의 형성과 관련된 것으로 생각된다.

• Journal of information and communication convergence engineering
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• 제9권4호
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• pp.461-465
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• 2011

An aluminum doped zinc oxide (AZO) film for front contacts of thin film solar cells, in this work, were deposited by r.f. magnetron sputtering, and then etched in diluted hydrochloric acid solution for different times. Effects of surface texturing on the electro-optical properties of AZO films were investigated. Also, to clarify the light trapping of textured AZO film, amorphous silicon thin film solar cells were fabricated on the textured AZO/glass substrate and the performance of solar cells were studied. After texturing, the spectral haze at the visible range of 400 ~750 nm increased substantially with the etching time, without a change in the resistivity. The conversion efficiency of amorphous Si solar cells with textured AZO film as a front electrode was improved by the increase of short-circuit current density ($J_{sc}$), compared to cell with flat AZO films.

• Bulletin of the Korean Chemical Society
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• 제1권2호
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• pp.54-57
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• 1980

Trichloromethylphosphonyl dichloride was prepared by the aluminium chloride method. We synthesized several heterocyclic compounds containing phosphorus atom by the stepwise esterification of trichloromethylphosphonyl dichloride with ethylene glycol, 2-mercaptoethanol, ethylene diamine, and 2-aminoethanol and the resulting heterocyclic compounds are 2-trichloromethyl-1,3,2-dioxa-, 2-trichloromethyl-1,3,2-thioxa-, 2-trichloromethyl-1,3,2-diaza-, 2-trichloromethyl-1,3,2-diaza-, and 2-trichloromethyl-1,3,2-oxazaphospholane-2-oxide. The best results were obtained in the solution of triethylamine as hydrochloric acid trapping agent. The structure of five-membered heterocyclic phosphonates were characterized by their IR, NMR, and elementary analysis and the mass spectra of the compounds were analyzed.

• 대한금속재료학회지
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• 제47권6호
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• pp.349-355
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• 2009

In the solvent extraction of Ru(IV) with Alamine336, it was found that Ru took part in the reaction as $RuCl_{6}_^{2-}$ in the HCl concentration range of 1 to 5 M. Interaction parameter between hydrogen ion and $RuCl_{6}_^{2-}$ was estimated by applying Bromley equation to the extraction data. From the mixed solutions of Pd(II) and Ru(IV), the distribution coefficients of Pd were found to be higher than those of Ru in the experimental ranges. Separation factor between Pd and Ru rapidly increased with the decrease of Alamine336 concentration. About 60% of the Ru from the mixed solutions was extracted by TBP at 8.3 M HCl, while Pd was not extracted in the HCl concentration range of 1.6 to 8.3 M.

• Korean Journal of Chemical Engineering
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• 제35권12호
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• pp.2468-2473
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• 2018

Nitrogen-doped activated carbon fibers (ACFs) were prepared by chemical vapor deposition using melamine powder and acetonitrile for introducing quaternary nitrogen on the commercial ACFs, subsequently heated at $950^{\circ}C$ and activated by steam. Adsorption experiments of nitrate in aqueous solution were also conducted to evaluate adsorption capacity of the prepared ACFs using ion chromatography. The amount of introduced nitrogen content and nitrogen species on activated carbon fibers was examined by CHN elemental analyzer and X-ray photoelectron spectroscopy, respectively. As a result, adsorption capacity of quaternary nitrogen-doped ACF (ST-ML-AN-ST) was 0.75 mmol/g, indicating ca. two-times higher than that of untreated ACF (0.38 mmol/g). According to the adsorption data, the Langmuir isotherm model was the best fit. The prepared samples were also regenerated using hydrochloric acid. After regeneration, the adsorption capacity of the nitrogen-doped ACF (ST-ML-AN-ST) showed ca. 80% on average, implying that a portion of nitrates was adsorbed on the prepared ACFs irreversibly.

• Bulletin of the Korean Chemical Society
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• 제17권8호
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• pp.730-735
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• 1996

The layered perovskite oxide, KSr2Nb3O10, was synthesized. The interlayer potassium cations were readily exchanged by protons in hydrochloric acid solution to give the protonation compound, HSr2Nb3O10·0.5H2O. The intercalation compounds, [NH3(CH2)nNH3]xSr2Nb3O10, were also obtained by acid-base reactions between the protonation compound and organic bases, 1,n-alkyldiamines. The interlayer distances in the intercalation compounds were linearly increased with the increase of the number of carbon (Δc/Δn=1.05 Å) in 1,n-alkyldiamines. The intercalated alkyldiammonium ions formed a paraffin-like monolayer with average tilting angle (θ) of ca. 56°. The intercalation reactions occurred stoichiometrically. The thermal decomposition process of the intercalation compounds showed distinct three steps due to the desorption of hydrated water, the decomposition of organic moiety, and the decomposition of Sr-related compounds.

• 대한약학회:학술대회논문집
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• 대한약학회 2003년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.2-2
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• pp.112.1-112.1
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• 2003

The qualitative and quantitative analysis of MDMA and MDA in hair samples by GC/MS were reported. Hairs were collected from subjects aged 22-37 years, who were suspected of abusing MDMA. After washing with methanol, hair samples were cut into small pieces, extracted with methanol containing 1 percent hydrochloric acid for 20th, and the solution was evaporated. MDMA or MDA in the extract were determined by GC/MS using selected ion monitoring after derivatization with trifluoroacetic anhydride. (omitted)