• Proceedings of the KIPE Conference
• /
• 2008.06a
• /
• pp.466-468
• /
• 2008

본 논문에서는 불평형, 고조파, 잡음 등에 의해 왜곡된 3상 전원으로부터 정확한 위상각을 검출하는 PLL(Phase Locked Loop) 방법을 제안한다. 역상분과 고조파를 포함하는 왜곡된 3상 전원을 동기좌표계 d-q축 전압으로 변환하면 기본파 성분에 의한 일정한 d-q축 전압에 역상분과 고조파에 의한 맥동이 포함된 형태의 전압이 된다. 상태관측기는 이러한 전압에서 맥동성분을 제거하고 기본파 전압만 추출하여 이를 동기좌표계 PLL의 입력으로 사용함으로써 왜곡된 전원조건에서도 정확한 위상각을 검출할 수 있다. 시뮬레이션을 통해 제안된 방법의 성능을 검증하였다.

• Journal of the Korean Chemical Society
• /
• v.30 no.2
• /
• pp.224-230
• /
• 1986

Dodecyltrimethylammonium bromide (DTAB) was examined as a counter-ion in the separation of aromatic sulfonic acids on alkylmodified silica (ODS) column by reversed-phase ion-pair chromatography. The capacity factor of acids was investigated and separation was attempted. The capacity factor of samples was influenced by the several factors such as a concentration of counter-ion, concentration of methanol, kinds and concentration of electrolyte in mobile phase as well as kinds and position of functional group in samples. Some mixtures of samples were able to be separated under optimum condition.

• Journal of the Korean Chemical Society
• /
• v.32 no.5
• /
• pp.452-457
• /
• 1988

Capacity factors (k') of some inorganic anions including $BF_4^{-1}$ were measured on cetylpyridinium coated column, and with dynamic system using tetrabutylammonium salicylate on PRP-1 reversed-phase column, respectively. After optimum separation condition was obtained this method was applied to the determination of boron in some different type samples.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.17 no.5
• /
• pp.55-64
• /
• 2003

• Proceedings of the Korean Nuclear Society Conference
• /
• 2003.10a
• /
• pp.446.1-446.1
• /
• 2003

• Analytical Science and Technology
• /
• v.11 no.6
• /
• pp.436-439
• /
• 1998

Ginseng saponins were analysed using reversed-phase high performance liquid chromatography with several columns. The optimum conditions were as following : reverse phase column; Novapak $C_{18}$ ODS column ($3.9mm{\times}150mm$, $5{\mu}m$), acetonitrile/water binary mobile phase gradient controller system, solvent flow rate; 1.5 mL/min, and UV (203 nm) detector. The complete separation of ginsenoside $Rb_1$, $Rb_2$, Rc, Rd, Re, Rf and $Rg_1$ was achieved within 50 min. The regression coefficients of the calibration curves for seven ginsenosides were 0.98~0.99.

• Journal of the Korean Chemical Society
• /
• v.38 no.7
• /
• pp.502-508
• /
• 1994

The measurement of trace amounts of uranium(VI) and thorium(VI) in the solutions containing high concentration of dissolved salts was carried out. The procedure using reversed phase liquid chromatography with trace enrichment techniques has been developed to cope with the high salt content of the samples. 2 ml of sample were passed through a small C_{18}$ reversed phase enrichment column with ${\alpha}$-HIBA eluent (0.11 M, pH 5.5) where the uranium and thorium were separated from other constituents and concentrated. The uranium and thorium were then backflushed from the column onto a deactivated C_{18}$ reversed phase analytical column where furthe separation was achieved with a mixed eluent (pH3.0, 0.17M ${\alpha}$-HIBA/0.0038 M 1-pentanesulfonate). The separated species were determined spectrophotometrically by postcolumn reaction with Arsenazo III, the chromogenic reagent. Detection limits were found within 1 ppb range for both species.

• Journal of the Korean Chemical Society
• /
• v.43 no.1
• /
• pp.7-119
• /
• 1999

• Journal of the Korean Applied Science and Technology
• /
• v.20 no.3
• /
• pp.183-197
• /
• 2003

• Journal of the Korean Chemical Society
• /
• v.42 no.2
• /
• pp.197-202
• /
• 1998

1-(2-Pyridylazo)-2-Naphthol (PAN) has been widely used as a spectrophotometric reagent and metallochromic indicator for many metal ions. In this work, the chelate reagent of PAN was used as mobile phase additive for the separation of metal ions by reversed phase chromatography. Metal ions could be detected by monitoring the effluent at 570 nm with spectrophotometric detector. In order to investigate retention behaviors of the metal ions, the chromatograms and capacity factors were obtained as the variation of pH, ionic strength and composition of organic modifier in mobile phase. Under the obtained optimum conditions, the mixtures of Fe(III), Ni(II), Cu(II), Zn(II) and Co(II) could be separated successfully and the calibration curves under the recommended conditions showed an excellent linearity. The detection limits(S/N) were feasible at the nanogram level.