• Proceedings of the KIEE Conference
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• 1992.07b
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• pp.1142-1146
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• 1992

This paper deals with the operation analysis of the half-bridge parallel-resonant converter with P.W.M. control. The converter operates at fixed frequency, in the continuous and discontinuous current mode. A simplified theorectical steady-state analysis is developed and the converter characteristics are presented.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 2007.11a
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• pp.159-162
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• 2007

• Proceedings of the KSEEG Conference
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• 2005.04a
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• pp.78-81
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• 2005

• Proceedings of the SAREK Conference
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• 2004.06a
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• pp.215-215
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• 2004

• 대한생식의학회:학술대회논문집
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• 2001.11a
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• pp.109.2-109.2
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• 2001

• Proceedings of KOSOMES biannual meeting
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• 2017.11a
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• pp.84-84
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• 2017

• Analytical Science and Technology
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• v.15 no.1
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• pp.67-71
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• 2002

The residual analysis and half-life time of imidazole fungicide prochloraz in soils (silty clay) were investigated by gas chromatography equipped electron capture detector (GC-ECD). The soil samples were extracted acetone/hexane(1:1) solvent and analyzed after separated by $LC-NH_2$ Sep-Pak solid column. Linear sensitivity of standard calibration curve was Y = 268.8600X + 0.0664, $R^2=0.9998$ between 0.05~1.00 ng. The detection limit was 0.02 mg/L and the average recoveries were 94.5~97.3% from the standard additional experiments with 0.10 and 0.40 mg/L. The half-life time was 24.4 days in room laboratory and 7.6 days in the field test soil.

• Korean Journal of Plant Taxonomy
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• v.38 no.4
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• pp.359-369
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• 2008

The mature fruit wall structures were investigated in Lapsana communis, its six subspecies and the four species of Lapsanastrum (Asteraceae; Lactuceae). Lapsanastrum differs from Lapsana communis in some features: two or three protrudent costae verse equally developed costae, hairly versus glabrous exocarp, respectively. Moreover, Lapsana has no sclerenchymatous‐fiber cells in mesocarp, while Lapsanastrum has sclerenchymatous fiber cells. The differences in fruit wall structure between Lapsana and Lapsanastrum obviously support the separation of Lapsanastrum from Lapsana s. lat.

• Journal of Pharmaceutical Investigation
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• v.30 no.4
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• pp.279-282
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• 2000

Simple and precise high-performance liquid chromatographic (HPLC) assay was developed and validated for the determination of a HMG-CoA reductase inhibitor, $lovastatin^{TM}$ and its active metabolite (mevinolinic acid) in human plasma. The method involved solid phase extraction of mevinolinic acid and internal standard using Sep-Pak Cartridge. Samples were analyzed by reversed-phase HPLC using $Capcell-Pak\;C_{18}$ column with ultraviolet detection at 238 nm. The quantitation limit of mevinolinic acid was 2 ng/ml and the calibration curve was linear over the range of 2-50 ng/ml $(r^2>0.999)$ with human plasma. The analyses of quality control samples indicated that the normal values could be predicted with an accuracy >97%. The intra- and inter-day coefficients of variation for the analyses were <10%. The average recoveries were similar (79%) for mevinolinic acid and methylmevinolinic acid. The method described has been successfully applied to the quantification of mevinolinic acid in about 1,000 human plasma samples over six-month period.

• Horticultural Science & Technology
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• v.34 no.6
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• pp.871-877
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• 2016

Recycling nutrient solutions in closed hydroponic production systems is usually accompanied by an imbalance of nutrient solutions when concentration is controlled according to electrical conductivity (EC) levels. This study investigated whether it was possible to automatically control the concentrations of five essential elements nitrogen (N), phosphorus (P), potassium (K), calcium (Ca) and magnesium (Mg) using only N, K and Ca ion sensors. N, P, K, Ca, and Mg uptake was measured in the nutrient solution, and relationships between absorbed ions were analyzed through twice-repeated experiments in lettuce. Results confirmed that the pattern of $PO_4$ ion uptake was similar that of N, and the pattern of Mg ion uptake was similar that of Ca. $PO_4$ ion uptake was most highly correlated with N, and Mg was most highly correlated with Ca. Regression coefficients of N and $PO_4$ were significantly different at 1.04 and 0.55, respectively, but were similar between Ca and Mg at 0.35 and 0.40, respectively. Additional experiments were conducted to measure nutrient uptake in pak choi and rose plants, both to confirm the results from the first experiment in lettuce, and to assess possible application to other crops. Coefficients of determination both for N and $PO_4$, and Ca and Mg were considerably high ($R^2=0.86$) in cultured pak choi, and similar results were observed in cultured rose ($R^2=0.87$ and 0.73, respectively). Regression coefficients for cultured pak choi were 0.56 and 0.24, respectively, and for rose were 0.51 and 0.16, respectively. Although the results obtained for N and $PO_4$ were not consistent between the lettuce experiments, N and $PO_4$ have similar regression coefficients for all crops. No common coefficient was found between Ca and Mg.