• Journal of Pharmaceutical Investigation
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• 제21권3호
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• pp.179-188
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• 1991

An HPLC assay method of a drug to be applied to the pharmacokinetic studies of the drug should be completely validated. The validation process for an HPLC assay method in a biological sample was discussed using the data obtained from the development of HPLC method for the simultaneous quantitation of verapamil and norverapamil in human serum. The validation criteria included were specificity, linearity, accuracy, precision, sensitivity, recovery, drug stability, and ruggedness of an assay method.

• Journal of Korean Society of Industrial and Systems Engineering
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• 제6권9호
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• pp.27-33
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• 1983

This Paper represents time-dependent stochastic variations of common discounted cash flow formulae with explicit consideration given to inflation. The cash flow, the ratio of discounting or compounding, and the rate of inflation are allowed to vary with time in a random fashion in equations for the compound amount of a single payment, present worth of a single payment, amount of an annuity, periodic deposits to accumulate a future amounts, present worth of an annuity and capital recovery And all formulae are derived for the case of discrete random variations.

• Bulletin of the Korean Chemical Society
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• 제25권11호
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• pp.1671-1675
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• 2004

A simple method for simultaneous recovery and reuse of $OsO_4$ and alkaloid ligand in the asymmetric dihydroxylation of olefins has been developed by using macroporous alkaloid resins bearing residual vinyl groups.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권4호
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• pp.1911-1930
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• 2017

Overlay routing has emerged as a promising approach to improve reliability and efficiency of the Internet. The key to overlay routing is the placement and maintenance of the overlay infrastructure, especially, the selection and placement of key relay nodes. Spurred by the observation that a few relay nodes with high betweenness centrality can provide more optimal routes for a large number of node pairs, we propose a resilient routing overlay network construction method by introducing Super-Relay nodes. In detail, we present the K-Minimum Spanning Tree with Super-Relay nodes algorithm (SR-KMST), in which we focus on the selection and connection of Super-Relay nodes to optimize the routing quality in a resilient and scalable manner. For the simultaneous path failures between the default physical path and the overlay backup path, we also address the selection of recovery path. The objective is to select a proper one-hop recovery path with minimum cost in path probing and measurement. Simulations based on a real ISP network and a synthetic Internet topology show that our approach can provide high-quality overlay routing service, while achieving good robustness.

• Herbal Formula Science
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• 제21권1호
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• pp.71-79
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• 2013

Objectives : Yijin-tang has been used in the treatment of gastrointestinal diseases such as irritable bowel syndrome, gastritis, and gastric ulcer. In this study, a high-performance liquid chromatography (HPLC) method was established for simultaneous analysis of six compounds, liquiritin, glycyrrhizin, hesperidin, 6-gingerol, homogentisic acid, and 3,4-dihydroxybenzaldehyde in Yijin-tang, a traditional Korean herbal medicinal preparation. Methods : A Gemini C18 column was used for the separation of six constituents at $40^{\circ}C$. The mobile phase using gradient elution consist of two solvent systems, 1.0% acetic acid in water (A) and 1.0% acetic acid in acetonitrile (B). The flow-rate was 1.0 mL/min and injection volume was $10{\mu}g$. The detector was a photodiode array (PDA) detector set at 254 nm and 280 nm. Results : The calibration curves of six compounds showed good linearity in various concentration ranges ($R^2{\geq}0.9997$). The limits of detection (LOD) and limits of quantification (LOQ) were 0.028-$0.192{\mu}g/mL$ and 0.093-$0.540{\mu}g/mL$, respectively. The RSD (%) of the intra and inter day validations were 0.03-0.84% and 0.05 -1.00%, respectively. Recovery was 96.14-01.90% and RSD (%) was less than 1.5%. Conclusions : The established simultaneous analysis methods will help management to improve the quality of Yijin-tang.

• KSBB Journal
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• 제29권4호
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• pp.232-238
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• 2014

The simultaneous determination of creatine monohydrate (CrM), dicyandiamide and dihydrotriazine in dietary supplements using reversed-phase high performance liquid chromatography (HPLC) was developed. Chromatography was performed on a Nuclosil 100-5 SA ($4.6{\times}250mm$) column with a mobile phase of 2.3% ammonium phosphate (pH 5.5), and UV detection at 224 nm, 212 nm, and 237 nm, respectively. The performance characteristics of HPLC were determined in terms of selectivity, linearity, precision, recovery, limit of detection (LOD), and limit of quantification (LOQ). The calibration curves were linear within the concentration range of $40.0{\sim}500.0{\mu}g/mL$ for creatine, $0.1{\sim}12.8{\mu}g/mL$ for dicyandiamide, and $0.05{\sim}6.4{\mu}g/mL$ for dihydrotriazine. The detection limits of the method were 1.09, 0.01, and $0.08{\mu}g/mL$ for creatine, dicyandiamide, and dihydrotriazine, respectively. The recoveries of creatine, dicyandiamide, and dihydrotriazine were 97.2~100.9, 92.3~106.5, and 97.2~105.5%, respectively. It is expected that the chromatographic analytical method developed in this study will be usefully applicable to simultaneous determination of creatine, dicyandiamide, and dihydrotriazine contained in dietary supplements.

• Natural Product Sciences
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• 제19권1호
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• pp.20-27
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• 2013

A simple high performance liquid chromatography - diode array detector (HPLC-DAD) method has been developed and validated for simultaneous determination of the six components (cinnamic acid, cinnamaldehyde, eugenol, atractylenolide I, atractylenolide III, and ergosterol) in Oryeongsan. In addition, identification of six marker compounds was conducted by a LC-MS/MS analysis. The six compounds in Oryeongsan were separated on Shishedo $C_{18}$ column (5 ${\mu}m$, $4.6{\times}250$ mm) at a column temperature of $30^{\circ}C$. The mobile phase was a mixture of 0.1% trifluoroacetic acid (TFA) water and acetonitrile employing gradient elution at a flow rate of 1.0 mL/min. The detection wavelength was set at 205, 250, 280, and 330 nm. The developed method had good linearity ($R^2$ > 0.9997) and the limit of detection (LOD) and limit of quantification (LOQ) were observed within the ranges 0.01~0.15 and 0.05~0.45 ${\mu}g/mL$, respectively. The relative standard deviation (RSD) values of intra- and inter-day testing were indicated that less than 3% and 90.31~103.31% of accuracy. The results of recovery test were 90.56~106.72% and RSD range was measured from 0.84 to 2.95%. In conclusion, this HPLC-DAD method has been successfully applied to the simultaneous determination of six compounds in Oryeongsan samples.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• 제20권4호
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• pp.245-251
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• 2008

The cooling load in winter is significant in buildings and hotels because of the usage of office equipments and the high efficiency of wall insulation. Hence, the development of a multi-heat pump that can cover heating and cooling simultaneously for each indoor unit is required. In this study, the operating characteristics and performance of a simultaneous heating and cooling heat pump in the heating-main operating mode were investigated experimentally. The system adopted a variable speed compressor with four indoor units and one outdoor unit with R-410A. In the heating-main mode, the cooling capacity was lower than the design cooling capacity due to the reduction of the flow rate in the indoor unit for the cooling, with the increase of the heating capacity. To solve these problems, the performance characteristics of the simultaneous heating and cooling heat pump in the heating-main mode were investigated by varying the flow rate to the indoor unit for the cooling and the compressor rotating speed. In addition, the adequate control methods were suggested to improve the system efficiency.

• Journal of Korean Foot and Ankle Society
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• 제23권4호
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• pp.154-158
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• 2019

Purpose: This study compared the radiographic and clinical outcomes of simultaneous bilateral short scarf osteotomy with those of unilateral short scarf osteotomy in hallux valgus patients. Materials and Methods: The authors undertook a retrospective chart and radiographic review between January 2015 and June 2017 to identify 15 patients (30 cases, group A) who underwent a simultaneous bilateral short scarf osteotomy. The patients were matched with 30 patients (30 cases, group B) with a unilateral short scarf osteotomy. No significant preoperative differences were observed between the two groups in terms of age, gender, American Orthopaedic Foot and Ankle Society (AOFAS) hallux score, and radiographic parameters. The clinical and radiographic follow-up was carried out at three months and one year. Results: Hallux valgus angles in groups A and B were reduced from the mean preoperative values of 32.5° and 34.7° to 12.5° and 12.2° at 12 months, respectively. The first-second intermetatarsal angles in groups A and B were also reduced from the mean preoperative values of 14.2° and 16.5° to 7.4° and 7.3° at 12 months, respectively. No significant inter-group differences in radiographic outcomes were observed. After three months, the patients in group A reported significantly worse mean pain and functional scores than group B. The mean AOFAS hallux score was higher in group B at the three-month follow-up, but this difference disappeared at the one-year followup. Conclusion: Simultaneous bilateral surgery can be offered to patients with a hallux valgus deformity requiring correction. On the other hand, they should be informed of the long recovery period.

• Journal of Ginseng Research
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• 제37권4호
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• pp.457-467
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• 2013

A quick and simple method for simultaneous determination of the 30 ginsenosides (ginsenoside Ro, Rb1, Rb2, Rc, Rd, Re, Rf, Rg1, 20(S)-Rg2, 20(R)-Rg2, 20(S)-Rg3, 20(R)-Rg3, 20(S)-Rh1, 20(S)-Rh2, 20(R)-Rh2, F1, F2, F4, Ra1, Rg6, Rh4, Rk3, Rg5, Rk1, Rb3, Rk2, Rh3, compound Y, compound K, and notoginsenoside R1) in Panax ginseng preparations was developed and validated by an ultra performance liquid chromatography photo diode array detector. The separation of the 30 ginsenosides was efficiently undertaken on the Acquity BEH C-18 column with gradient elution with phosphoric acids. Especially the chromatogram of the ginsenoside Ro was dramatically enhanced by adding phosphoric acid. Under optimized conditions, the detection limits were 0.4 to 1.7 mg/L and the calibration curves of the peak areas for the 30 ginsenosides were linear over three orders of magnitude with a correlation coefficients greater than 0.999. The accuracy of the method was tested by a recovery measurement of the spiked samples which yielded good results of 89% to 118%. From these overall results, the proposed method may be helpful in the development and quality of P. ginseng preparations because of its wide range of applications due to the simultaneous analysis of many kinds of ginsenosides.