• Analytical Science and Technology
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• v.12 no.4
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• pp.326-331
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• 1999

The metabolites of 1,2,4-trimethylbenzene (TMB) were synthesized and determined by capillary electrophoresis (CE). The optimum conditions of CE for the separation and determination of 3,4-, 2,4-, 2,5-dimethylbenzoic acid and 3,4-, 2,4-, 2,5-dimethylhippuric acid from the rat urine were as following: the fused silica capillary($75{\mu}m$ i.d. ${\times}$ 36 cm length, 29 cm to detector) was used and kept at $15^{\circ}C$. The applied voltage was 10㎸ and compounds were detected at UV 210 mnm and 254 nm. The running electrolyte was 0.1 M phosphate buffer (pH 7) containing 15 mM of ${\beta}-CD$ and 3% of 2-propanol. The relative amount of the metabolite of 1,2,4-TMB in the rat urine was 56.7% of 3,4-isomer, 30.5% of 2,4-isomer and 12.8% of 2,5-isomer. This method can be applied to the analysis of TMB-metabolites in human urine.

• Journal of the Korean Chemical Society
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• v.47 no.6
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• pp.547-552
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• 2003

Separation and determinations of Co(II) and Ni(II) ions as their 4-(2-pyridylazo)resorcinol(PAR) chelates by reversed-phase capillary high-performance liquid chromatography(RP-CpHPLC) were performed. Among many capillary columns, Vydac C4 column was selected and acetonitrile solution was used as mobile phase. The effect of pH and MeCN concentration(%) on the retention factor, k and peak intensity was examined and discussed. As a results, it was found that 22.5% MeCN and pH 5.60 was adequate as mobile phase for the separation of the two metal ions and determination of Co(II) ion, but the mobile phase condition for Ni(II) ion determination was 22.5% MeCN of pH 7.20. Detection limit(D.L., S/N=3) of Co(II) and Ni(II) ions were $2.0{\times}10{-7}$ M(14.9 ppb) and $1.0{\times}10{-6}$ M(59.2 ppb), respectively.

• Korean Journal of Food Science and Technology
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• v.26 no.1
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• pp.18-22
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• 1994

This study was designed to investigate the method of the simultaneous determination of water-soluble vitamins (thiamine, ascorbic acid, riboflavin, folic acid, cyanocobalamine, pyridoxin, nicotinic acid) by free soloution capillary electrophoresis. Factors affecting on the separation were pH of the buffer, applied voltage and temperature. On-column detection at 254 nm allowed accurate and reproducible determination of these compounds. All these compounds were separated within ca. 8 min with fused silica capillary at 20 kV.

• The Korean Journal of Rheology
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• v.3 no.2
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• pp.117-123
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• 1991

현탁액에 대한 기본적인 유변학적 특성을 조사하기 위해 입자의 부피분율에 따른 점도의 변화를 측정하였고 현탁액의 Die Swell 현상에 대해 실험적으로 규명하였다. 뉴톤성 특성을 조사하기 위해 입자의 부피 분율에 따른 점도의 변화를 측정하였고 현탁액의 Die Swell 현상에 대해 실험적으로 규명하였다. 뉴톤성 특성을 갖는 Silicone 오일을 현탁 매질 로 사용하였고 미세한 유리 구슬이 filler로써 사용되었다. 현탁액의 점도는 Couette 점도계 와 모세관 점도계를 사용하였다. 관의 입구와 출구에 대한 보정을 위해서 Bagley의 방법을 이용하였으며 중력으로 인한 Swell의 감소효과를 제거하기 위해서 분사 유체와 유사한 밀 도를 지니며 분사 유체와 섞이지 않는 유체를 담은 부력용기가 사용되었다. Die Swell 현상 은 사진을 찍고 이를 정밀한 확대경을 통해 관찰함으로써 수치적으로 값을 얻었다.

• The Korean Journal of Rheology
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• v.7 no.3
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• pp.261-266
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• 1995

원관에서 power-law 유체에 대하여 수력학적 입구길이와 입구보정계수를 측정할수 있는 새로운 방법이 개발되었다. 유변학적 성질을 측정할수 있는 긴관과 입구보정계수를 측 정할수 있는 짧은 관을 가진 새로운 모세관 점도계를 이용하여 증류수를 실험한 결과 유변 학적 성질과 입구 보정계수가 표준값과 비교하여 1%안의 오차를 얻었다. Power-law 유체 에 대한 해석 및 실험결과(Carbopol 960 용액)도 이미 보고된 값과 $\pm$6% 이내로 잘 일치하 였다.

• Journal of the Korean Geotechnical Society
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• v.26 no.4
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• pp.37-45
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• 2010

Salt cementation, a typical naturally-cemented phenomenon, may occur due to water evaporation under the change of climate. Capillary force may influence the distribution of cement in granular soils. This study addresses the effect of capillary force on salt cementation using five different techniques: cone penetration test, electrical conductivity measurement, photographic imaging technique, nondestructive imaging technique, and process monitoring by elastic wave. Glass beads modeling a particulate media was mixed with salt water and then dried in an oven to create the cementation condition. Experimental results show that salt cementation highly concentrates at the top of the small particle size specimens and at the middle or the bottom of the large particle specimens. The predicted capillary heights are similar to the locations of high salt concentration in the cemented specimens. Five suggested methods show that the behavior of salt-cemented granular media heavily depends on the capillary force.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2743-2746
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• 2007

When a small tube is dipped into a liquid surface, surface tension forces cause the liquid in the tube to rise vertically against the gravity. When the tube is flexible, hydrostatic pressure difference caused by the capillary flow deforms the tube and the deformation which narrows the flow route changes the rising velocity. We study a simple model of this elastocapillary interaction in the context of the surface-tension-driven vertical rise of a liquid between two long flexible hydrophilic sheets that are held a small distance apart at one end. We provide an analytical theory for the rise rate of the liquid and show that our experiments are consistent with the theory.

• Journal of the Korea Institute of Military Science and Technology
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• v.9 no.2 s.25
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• pp.127-135
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• 2006

Experimental studies of the cylindrical sintered-copper wick heat pipes were carried out to investigate the capillary heat transfer characteristics. Six models of the sintered-copper wick heat pipes were manufactured and tested to evaluate the heat transport limitations and the thermal characteristics. Also the performance of the heat pipes was analyzed theoretically and compared with the test results. The heat pipe models are divided into two sintered-wick groups and the nominal particle sizes are $180{\mu}m$(wick #1) and $200{\mu}m$(wick #2) respectively The experimental results showed that, the porosity of wick #1 was higher than that of wick #2, and also the wick #1 was generally superior than the wick #2 for the heat transport capability. The maximum heat transport rates were increased as the wick thicknesses and the vapor temperatures were increased.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.272-274
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• 2005

A simple method for fabricating micro/nanoscale hierarchical structures is presented using a two-step temperature-directed capillary molding technique. This lithographic method involves a sequential application of molding process in which a uniform polymer-coated surface is molded with a patterned mold by means of capillary force above the glass transition temperature of the polymer. Using this approach, multiscale hierarchical structures for biomimetic functional surfaces can be fabricated with precise control over geometrical parameters and the wettability of a solid surface can be designed in a controllable manner.

• Proceedings of the KSME Conference
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• 2005.11a
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• pp.71.2-71.2
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• 2005