• 유변학
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• 제10권3호
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• pp.131-136
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• 1998

아역청탄을 이용하여 제조된 CWM(Coal-Water Mixture)연료의 유변학적 특성을 측 정함으로써 음이온 계면활성제 Temol-N, 안정제 Xanthan 및 전해질 등의 첨가제에 대한 성능을 평가하고 최적첨가조성을 결정하였다. 계면확성제의 흡착으로 인해 석탄입자는 음전 하를 띠게 되었고 표면에 전기이중층이 생성되었다. 전기 이중층의 전기적 반발력이 입자의 응집을 막았고 CWA 슬러리의 점도를 감소시켰다. 또한 Xanthan과 NaOH의 첨가로 인해 분산안정성 및 침강안정성이 향상되는 것을 관찰하였다. CWM에서 석탄입자가 차지하는 부 피비를 무게비로 전환하여 표현하고 분산계에서 입자의 부피비에 따른 점도변화를 예측하는 실험식인 Krieger-Dougherty 식과 Frankel-Acrivos 식에 적용하였다. 점도 실험값을 가지 고 식의 변수들을 결정해 본결과 CWM이 나타내는 점도의 석탄함량에 따른 변화를 위 식 들이 비교적 정확시 나타내 주는 것을 확인하였다.

• 한국재료학회:학술대회논문집
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• 한국재료학회 1998년도 한국재료학회 춘계학술발표강연 및 논문개요집
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• pp.110-110
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• 1998

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2002년도 추계학술발표회요약집
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• pp.369-369
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• 2002

• 한국재료학회:학술대회논문집
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• 한국재료학회 1997년도 한국재료학회 춘계학술발표회
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• pp.56-56
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• 1997

• 한국응용과학기술학회지
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• 제20권4호
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• pp.324-331
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• 2003

Particulate leaching method for the preparation of porous PLLA scaffolds was carried out and especially, the effect of PLLA/$CHCl_3$ solution concentration on the salt leaching rate and the pore structure of PLLA scaffolds were considered. It was found that maintaining lower PLLA/$CHCl_3$ concentration and higher $CHCl_3$ evaporation temperature in the preparation of PLLA/NaCl mixtures resulted in the enhancement of salt leaching rat e and higher porosity. This is understood that those conditions could minimize the formation of dense PLLA layer on the surface of PLLA/NaCl mixture as well as introducing better porosity on the surface. Higher salt leaching temperature accelerated the salt leaching rate but it seems that there is no influence on the porosity of PLLA scaffolds.

• 생약학회지
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• 제40권2호
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• pp.103-108
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• 2009

GCSB-5 preparation is a purified extract from a mixture of 6 medicinal plants(Acanthopanacis Cortex, Achyranthis Radix, Saposhnikoviae Radix, Cibotii Rhizoma, Glycine Semen Nigra, Eucommiae Cortex) that have been widely used for the treatment of various bone disorders. The aim of this study was to investigate HPLC analysis method and screening of standard compound on Saposhnikoviae Radix for quality standardization of a medicinal crude drug GCSB-5. Standard compound of Saposhnikoviae Radix was decided with cimifugin by isolation and instrumental analysis such as NMR. HPLC analysis method for the simultaneous determination of cimifugin was established for the quality control of the medicinal plants of Saposhnikoviae Radix species, GCSB-5 raw material and preparation. And validation of HPLC analysis methods were conformed for verification of HPLC methods by check to specificity, linearity, intra-day precision, inter-day precision and accuracy following ICH guideline.

• 대한화학회지
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• 제60권4호
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• pp.251-256
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• 2016

This paper describes the synthesis of alkali metal salts of urea (ureates) and their application to the direct preparation of 4-nitrosoaniline from nitrobenzene via nucleophilic aromatic substitution of hydrogen. Sodium and potassium ureates were readily prepared from the reaction of urea with sodium hydride, metal methoxides, and metal hydroxides. The effect of ureates as nucleophiles on the conversion of nitrobenzene to 4-nitrosoaniline was investigated and compared with that of a urea-metal hydroxide mixture. It was found that the ureates were superior for producing 4-nitrosoaniline owing to their higher thermal stability of the ureate. The ureate obtained from the treatment of urea with sodium hydride gave the highest yield for the preparation of 4-nitrosoaniline. The ureates generated from the reaction of urea with metal hydroxide also gave high yields of 4-nitrosoaniline. Catalytic hydrogenation of 4-nitrosoaniline afforded polymer-grade 1,4-benzenediamine in quantitative yield.

• Journal of Pharmaceutical Investigation
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• 제16권2호
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• pp.72-75
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• 1986

A convenient high performance liquid chromatographic method was established for the quantitative determination and content uniformity test of aclatonium napadisilate preparation. This method was more simple to make the sample solution for injection, and easy to determine the content in the preparation. Aclatonium napadisilate was chromatographed using a $Lichrosorb-NH_2$ column $(4mm\;{\times}\;25\;cm$, and acetonitrile-water mixture (83:17) as an eluent at a flow rate of 1.8 ml/min. RI-detector response was linear over a range of $0.5{\sim}2.0%$ aclatonium napadisilate under above conditions. Reproducibility studies gave relative standard deviation of 1.29%.

• 분석과학
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• 제21권1호
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• pp.25-33
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• 2008

Organic disulfide compounds are having higher theoretical capacity than the conventional cathode material and are considered as the important storage material. Here, we are reporting the preparation of poly (2,2'-dithiodianiline) PDDA/multiwall carbon nanotubes, (MWCNTs) composites under different experimental conditions. Amine functionalized and unfunctionalized MWCNTs were independently used for the preparation of composites. Composites were prepared in the presence of cetyl trimethyl bromide (CTAB), a cationic surfactant, and also in the absence of CTAB. A physical mixture of PDTDA and MWCNTs was formed with unfunctionalized MWCNTs. Grafting of PDDA onto MWCNTs was performed by chemical oxidative polymerization of 2, 2'-dithiodianiline in the presence of amine functionalized MWCNTs. The composites of MWCNTs and PDTDA were characterized for structure, morphology and thermal properties through Fourier transform infrared spectroscopy, Fourier transform Raman spectroscopy, scanning electron microscopy and UV-visible spectroscopy. The composite materials prepared by this method are expected to find applications as electrode materials for lithium batteries.

• 한국세라믹학회지
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• 제28권4호
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• pp.315-323
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• 1991

The preparation of zirconium carbide powders by the halogenide process of ZrCl4-C-Mg system (1:1:2, molar ratio) was studied between 300。 and 120$0^{\circ}C$ under Ar gas flow (200 mι/min). The formation mechanism and kinetics of zirconium carbide and characteristics of the synthesized powder were examined by TG-DTA, XRD, SEM and PSA. 1) The formation mechanism of zirconium carbide were as follows, above 30$0^{\circ}C$ ZrCl4(S)+Mg(s)longrightarrowZrCl2(s)+MgCl2(s) above 40$0^{\circ}C$ ZrCl2(S)+Mg(s)longrightarrowZr(s)+MgCl2(s) above 50$0^{\circ}C$ Zr(s)+C(s)longrightarrowZrC(s) 2) The apparent activation energy of the reduction-carbonization at temperature of 800$^{\circ}$to 100$0^{\circ}C$ was 11.9 kcal/mol. 3) The lattice parameter and the crystallite size of ZrC which was produced from the mixture powder of ZrCl4, C and Mg (1:1:2, molar ratio) at 100$0^{\circ}C$ for 1 h were 4.700A and 180A, respectively. 4) The powders obtained from the mixture powder of ZrCl4, C and Mg(1:1:2, molar ratio) at 100$0^{\circ}C$ for 1 h were agglomerate with the average size of about 13${\mu}{\textrm}{m}$ in SEM micrograph.