• Analytical Science and Technology
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• v.13 no.3
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• pp.269-276
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• 2000

Chromatographic retention mechanism of seven benzoic acids in RPLC were investigated. Inorganic salt is pertinent for the measurement of dead time in benzoic acid. Logarthims of capacity factor (log k') and Hildebrand solubility parameter (${\delta}$) showed proportional relationship which imply the hydrophobic effect of the retention mechanism in RPLC. Enthalpies of solute transfer showed inverse proportion to temperature and organic modifier ratio of the mobile phase. It was found that the S value showed positive slope in plot of log k' vs. volume fraction of water in mobile phase. Free energy change increases with increasing organic volume fraction. The hydrophobicity index, ${\varphi}_0$(organic volume fraction) is inversely proportional to column temperature.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.187-188
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• 2015

본 논문은 시간영역에서 대칭좌표법을 사용한 전력품질 이벤트 검출에 관한 연구이다. sag, swell. interruption, harmonic, flicker, transients, notches, spike 등과 같은 전력품질 이벤트들이 이 방법으로 쉽게 검출된다. 본 방법은 웨이블릿, s-변환, 힐버트 변환 등의 방법이 가지고 있는 계산 부담이 없기 때문에 온라인 응용프로그램에 쉽게 사용될 수 있다. 단상 전력품질 이벤트 신호는 시간 영역에서 대칭요소를 계산하기 위하여 120도, 240도 위상차를 가지고 생성되는 다른 두 신호와 함께 이동되어 간다. 전력품질 이벤트 신호의 시작점(triggering point)은 역상분으로부터 쉽게 검출될 수 있고 이벤트는 정상분과 역상분의 합을 사용한 파형의 특징 분석으로 쉽게 분류될 수 있다. 시뮬레이션된 결과는 전력품질 이벤트의 검출과 분류를 위한 본 방법의 효과를 보여주기 위하여 다수의 전력품질 이벤트를 보여주고 있고 전력계통망 지락사고 시뮬레이션을 수행하여 유용성을 확인하였다.

• Journal of the Korean Applied Science and Technology
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• v.29 no.4
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• pp.585-593
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• 2012

The EO separation and quantitative determination of polysorbate 20, polysorbate 40, polysorbate 60 and polysorbate 80 was carried out by reversed phase HPLC. The water/acetonitrile was used for the mobile phase of gradient conditions. An YMC Pack Ph ($250mm{\times}4.6mm$ i.d., $5{\mu}m$) and Phenomenex C4 ($250mm{\times}4.6mm$ i.d., $5{\mu}m$) and the selected ELSD detector was applied. The analysis results of HPLC showed good linearity with correlation coefficient of $r^2$=0.997 in the rage of $180.2{\sim}980.5{\mu}g/mL$ and detection limit.

• Journal of the Korean Chemical Society
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• v.32 no.2
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• pp.113-121
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• 1988

The retention mechanism and separation of various aromatic sulfonic and carboxylic acids on reversed-phase liquid chromatographic column were studied in the mobile phase containing dodecyltrimethylammonium bromide (DTAB). The retention mechanism was found to be followed the ion-interaction model where the DTAB occupies a primary layer at the stationary phase while the sample anions and other co-anions in the system compete for forming the secondary layer. The capacity factors of samples were influenced by the several factors such as pH, concentration of various organic solvents, co-anions in the mobile phase and functional groups in sample molecules. Some mixtures of organic samples were attempted to separate under optimum condition.

• Journal of the Korean Chemical Society
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• v.35 no.4
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• pp.397-404
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• 1991

Nonchromophore compounds such as aliphatic acids, alcohols and tetraalkylammonium salts could be detected by indirect photometric detection on the revered-phase liquid chromatography. Benzyltriethylammonium bromide(BTEAB) was used as a detection reagent. Also, the retention mechanism and response of samples were investigated to the several factors such as pH, temperature, and concentration of MeOH as well as concentration of detection reagents in mobile phase. And some mixture of samples were able to be separated under optimum condition.

• Journal of the Korean Chemical Society
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• v.36 no.6
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• pp.849-856
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• 1992

We prepared a simple, economic and versatile preparative system for an enantiomeric separation. Hydrophobic amino acid enantiomers were resolved in the preparative scale by a centrifugal liquid chromatography on the N-hexadecyl-L-proline coated reversed phase. The factors controlling the retention and resolution of racemic amino acids such as the concentration of Cu(Ⅱ), pH of the eluent, the type and content of organic modifier, and rpm of CLC were examined. Several mg of hydrophobic amino acid enantiomers were separated preparatively. To separate all of different amino acid enantiomers, various coating material will be investigated.

• Analytical Science and Technology
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• v.7 no.3
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• pp.379-386
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• 1994

The elution behaviors in reversed-phase liquid chromatography were investigated thermodynamically for 2-hydroxy-arylazopyrazolone chelates with Ni(II), Cu(II), Co(III), Cr(III) on Novapak $C_{18}$ column. There was a good linear dependence of the capacity factor(k') on the variations of column temperature in van't Hoff plot. From this result, it was confirmed that the retention mechanism of these chelates in the reversed phase liquid chromatography system was invariant under the condition of various temperatures. For the most cases of the chelates studied, the dependence of capacity factor(1n k') on enthalpy$(-{\Delta}H)^{\circ}$, calculated by van't Hoff plot showed a good linearity(r=0.980~0.999) except [Pm(2-OH_(5-Cl)PaPz](r=0.787) and also the compensation temperatures(${\beta}$) showed constant values. The range of compensation temperature values calculated from the slope of $-{\Delta}H^{\circ}$ vs 1n k' plots was 374.3~806.9K. It was suggested that the retention of metal-2-hydroxy-arylazopyrazolone chelates in the reversed phase liquid chromatography system was largely affected by the hydrophobic effect.

• Journal of the Korean Chemical Society
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• v.36 no.5
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• pp.697-708
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• 1992

Liquid Chromatographic behavior of Ni(II) in Isonitrosoethylacetoacetate Imine(IEAA-NR), Ni(IEAA-NH)(IEAA-NR)(R = H, CH_3, C-2H_5, n-C_4H_9, C_6H_5-CH_2) chelates were investigated by reversed-phase HPLC on Micropak MCH-5 column using methanol/water as mobile phase. The optimum conditions for the separation of Ni(IEAA-NH)(IEAA-NR) chelates were examined with respect to the effect of the flow rate, sample solvent, mobile phase strength and column temperature. It was fo$und that metal chelates were properly eluted in an acceptable range of capacity factor value(0{\le}logk'{\le}1). The dependence of the logarithm of capacity factor (k') on the volume fraction of water in the binary mobile phase as well as on the liquid-liquid extraction distribution ratio (Dc) in methanol-water/n-alkane extraction system showed the good linearties, and the dependence of the logarithm of capacity factor (k') on the column temperature and on the enthalpy exhibited the good linearties, and the compensation temperature ({\beta}) from the slope was 773.47{\circ}K. It was suggested that the retention of metal chelates was largely affected by the hydrophobic effect.

• 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.

• Proceedings of the KIPE Conference
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• 2004.07b
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• pp.673-676
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• 2004

본 논문은 3상 입력전원의 불평형과 고조파문제를 대칭 좌표계를 통해 각각 정상분과 역상분으로 분리하여 동기 회전 좌표계 상에서 보상할 수 있는 알고리즘을 제안하였다. 동기 회전 좌표계 상에서 보상이 이루어지므로 UPQC와 같은 다양한 목적의 능동전력필터에 쉽게 적용될 수 있다 제안된 알고리즘의 타당성을 뒷받침하기 위해 시뮬레이션을 수행 하였다.