• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.1
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• pp.39-46
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• 2013

This study aims to develop a plastic aspheric lens for a 13-megapixel mobile phone camera by injection-compression molding. A mold for injection-compression molding experiments was fabricated with a movable upper plate and four springs. During cavity filling for an aspheric lens with a thickness ratio of 2, a weldline was formed under conventional injection molding, whereas no weldline was formed under injection-compression molding with a compression stroke of 0.3 mm. The flow patterns were in good agreement with the simulation results. The birefringence decreased as the compression stroke increased, and the birefringence produced by injection-compression molding was very low and more uniform compared with that produced by injection molding. In addition, the bulk birefringence of an assembly composed of four plastic lenses was significantly affected by the orientation of the lenses to be mounted.

• Mass Spectrometry Letters
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• v.8 no.2
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• pp.23-28
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• 2017

Arctigenin is the main active ingredient of Fructus Arctii, which has been reported with a variety of therapeutic activities including anti-cancer, anti-inflammation, anti-virus, and anti-obesity effects. In this study, a simple and sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated for the determination of arctigenin in rat plasma. The assay utilized a simple protein precipitation with methanol and the mobile phase consisted of 100% methanol and water containing 0.1% formic acid (65:35 v/v). Arctigenin and the internal standard (psoralen) were monitored using a positive electrospray turbo ionspray mode with multiple reaction monitoring transitions of m/z $373.2{\rightarrow}136.9$ and m/z $187.2{\rightarrow}130.9$, respectively, and total chromatographic run time was within 5 min. The lower limit of quantification (LLOQ) of arctigenin was 5 ng/mL in the rat plasma. The intra- and inter-day accuracy of arctigenin at LLOQ and matrix-matched quality control samples ranged 97.4 - 104.8% and 97.2 - 102.0%, respectively. The intra-day precision was within 4.80% and the inter-day precision was within 5.92%. Application of the present method was demonstrated through a pharmacokinetic study after intravenous and oral administration of arctigenin in male Sprague Dawley rats.

• Korean Journal of Soil Science and Fertilizer
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• v.48 no.5
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• pp.391-396
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• 2015

Arsenic (As) contamination of agricultural soils resulting from mining activity has caused major concern due to the potential health risk. Therefore the current study was carried out to investigate the relationship between fractionation of As in soil and rice uptake and to provide a basic information for adequate management of As contaminated agricultural soil. Twenty agricultural soils and rice affected by the abandoned mining sites were collected. Soil chemical properties and As concentrations (total and sequential extracted) in soils were determined and As concentrations in polished rice were analyzed. The average concentration of As in non-specifically adsorbed (F1), specifically adsorbed (F2), amorphous hydrous oxides of Fe and Al (F3), crystalline hydrous oxides of Fe and Al (F4) and residual phase (F5) were 0.08, 1.38, 10.34, 3.26 and $10.98mgkg^{-1}$, respectively. Both soil pH and available phosphorus were positively correlated with the concentrations of As in F1 and F2. These results indicate that increasing the soil pH and available phosphorus can significantly increase the easily mobile fractions of As (F1 and F2). The average concentration of As in polished rice was $0.09mgkg^{-1}$. The concentrations of As in F1 and F2 showed a positive correlation with the concentrations of As in polished rice. Therefore soil pH and available phosphorus affect the distribution of As fractionation in soils and thus affect As bioavailability.

• Analytical Science and Technology
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• v.32 no.3
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• pp.96-104
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• 2019

Agastache rugosa, known as Korean mint, is a medicinal plant with many beneficial health effects. In this study, a simple and reliable HPLC-UV method was proposed for the quantification of rosmarinic acid (RA) in the aqueous extracts of A. rugosa. RA was selected as a quantification marker due to its easiness in procurement and analysis. The developed method involved chromatographic separation on a $C_{18}$ column ($250{\times}4.6mm$, $5{\mu}m$) at room temperature. The mobile phase consisted of water and acetonitrile both containing 2 % acetic acid and was run at a flow rate of $1mL\;min^{-1}$. The method was validated for specificity, linearity, precision, and accuracy. It was specific to RA and linear in the range of $50-300{\mu}g\;mL^{-1}$ ($r^2=0.9994$). Intra-day, inter-day, and inter-analyst precisions were ${\leq}0.91%\;RSD$, ${\leq}1.40%\;RSD$, and 1.94 % RSD, respectively. Accuracy was 93.3-95.9 % (${\leq}1.21%\;RSD$). The method could be applied to three batches of bulk samples and three batches of lab scale samples, which were found to be $0.64({\pm}0.04)mg\;g^{-1}$ and $0.48({\pm}0.02)mg\;g^{-1}$ for the dried raw materials of A. rugosa. The results show that the proposed method can be used as a readily applicable method for QC of health functional foods containing the aqueous extracts of A. rugosa.

• The Korean Journal of Food And Nutrition
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• v.32 no.2
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• pp.148-154
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• 2019

The aim of this study was to select compounds for the standardization of fermented Kalopanax pictus Nakai (KP-F), to develop the analysis method using HPLC-PDA and to perform method validation. KP-F is a fermented powder developed to improve the original physiological activities and create a new functionality. Eleutheroside E, Acanthoside B, and Syringaresinol were selected as the standard compounds and developed our own method for simultaneous analysis. The analyte was isolated using C18 column with a gradient elution of 0.05 M phosphoric acid in water and methanol as the mobile phase at a flow rate of 1 mL/min and detected at 210 nm. As a result, all standard compounds showed good linearity with an $R^2$ (coefficient of correlation) of 1.000 and for the limit of detection range of $0.710{\sim}0.831{\mu}g/mL$, and the limit of quantification as $2.150{\sim}2.520{\mu}g/mL$. The precision was RSD (%) of less than 4.80%, while the accuracy was 4.70%>RSD (%) for the range 102.44~110.48%. In conclusion, the developed analysis method is suitable for the detection of Eleutheroside E, Acanthoside B, and Syringaresinol in KP-F.

• Journal of Biomedical and Translational Research
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• v.19 no.4
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• pp.130-139
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• 2018

This study aimed to analyze a high-performance liquid chromatography (HPLC) separation using a pentafluorophenyl column of parent drug hydroxychloroquine (HCQ) and its active metabolite, desethylhydroxchloroquine (DHCQ) applying to determine bioequivalence of two different formulations administered to patients. A rapid, simple, sensitive and specific liquid chromatography-tandem mass spectrometry (LC-MS/MS) method has been developed and validated for bioanalysis of HCQ and its metabolite DHCQ in human whole blood using deuterium derivative $hydroxychloroquine-D_4$ as an internal standard (IS). A triple-quadrupole mass spectrometer was operated using electrospray ionization in multiple reaction monitoring (MRM) mode. Sample preparation involves a two-step precipitation of protein techniques. The removed protein blood samples were chromatographed on a pentafluorophenyl (PFP) column ($50mm{\times}4.6mm$, $2.6{\mu}m$) with a mobile phase (ammonium formate solution containing dilute formic acid) in an isocratic mode at a flow rate of 0.45 mL/min. The standard curves were found to be linear in the range of 2 - 500 ng/mL for HCQ; 2 - 2,000 ng/mL for DHCQ in spite of lacking a highly sensitive MS spectrometry system. Results of intra- and inter-day precision and accuracy were within acceptable limits. A run time of 2.2 min for HCQ and 2.03 min for DHCQ in blood sample facilitated the analysis of more than 300 human whole blood samples per day. Taken together, we concluded that the assay developed herein represents a highly qualified technology for the quantification of HCQ in human whole blood for a parallel design bioequivalence study in a healthy male.

• Korean Journal of Plant Resources
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• v.31 no.6
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• pp.652-659
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• 2018

In this study, baicalin, as a marker substance of Scutellariae Radix, was quantitatively analyzed by a high performance liquid chromatography-photodiode array detector (HPLC-DAD). We identified wogonoside, baicalein, and wogonin in the Scutellariae Radix by a high performance liquid chromatography-electrospray ionization-mass spectrometer (HPLC-ESI-MS). The baicalin was separated on a Xterra C18 column ($5{\mu}m$, $4.6{\times}250mm$) using mobile phase consisting of 38% acetonitrile in 0.68% phosphoric acid. The baicalin spectrum in the Scutellariae Radix extracts was coincided by comparing with UV-visible spectrum (200-550 nm) of baicalin standard in the library. The amount of baicalin in Scutellariae Radix was 10.46%, which is higher than KFDA's guideline. The marker substances of Scutellariae Radix showed a strong base peak $[M]^+$ in the positive detection mode following as; baicalin (m/z; $271[MH^+-sugar]^+$, $447[M+H]^+$), wogonoside (m/z; $285[MH^+-sugar]^+$, $461[M+H]^+$), baicalein (m/z; $271\;[M+H]^+$), wogonin (m/z; $285[M+H]^+$). These results are consistent with the fragment pattern and molecular weight of standard components from literature.

• Analytical Science and Technology
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• v.32 no.4
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• pp.139-146
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• 2019

A simple and reliable analytical method based on high-performance liquid chromatography-ultraviolet detection was established for the analysis of the flowers of Chrysanthemum morifolium (CM). Luteolin-7-O-glucoside (LU7G) was chosen as a target analyte considering its content, availability, and ease of analysis. Chromatographic separation of LU7G was achieved using a Phenomenex Gemini $C_{18}$ column ($250{\times}4.6mm$, $5{\mu}m$) run with a mobile phase consisting of 0.5 % acetic acid in water and 0.5 % acetic acid in acetonitrile at a flow rate of $1.0mL\;min^{-1}$. The detection wavelength and column temperature were set at 350 nm and $40^{\circ}C$, respectively. Method validation was performed according to the AOAC guidelines and the method was specific, linear ($R^2=0.9991$ for $50-300{\mu}g\;mL^{-1}$), precise (${\leq}3.91%$RSD), and accurate (100.1-105.7 %). The limits of detection and quantification were 3.62 and $10.96{\mu}g\;mL^{-1}$, respectively. The established method was successfully applied to determine the contents of LU7G in various batches of bulk CM extracts and labscale CM extract. The developed method is a readily applicable method for the quality assessment of CM and its related products.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.05a
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• pp.68-70
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• 2014

Korean e-goverment has shown its development phase upgrade following the world' e-government evolution. By United Nations, Korea was ranked number one in e-government yet it was not even in top ten for past years. Even now, a number of Korean government organizations such as Ministry of Security and Public Administration and Ministry of Science, ICT and Future Planning have presented and executed various directions and strategies (for example, e-gov 3.0). On the other hand, World Economic Forum put Korea out of top 10 in Networked Readiness Index and hence wireless mobile communication of Korea is a weak point making difficulties for smart office and Bring Your Own Device (BYOD) implementation. This paper details the analysis of leading countries' strategies and policies on m-Government and provides some suggestions for Korean m-government.

• Journal of Digital Convergence
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• v.17 no.8
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• pp.407-413
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• 2019

The purpose of this study is to measure the shopping experience of a more specific SNS shopping service, limited to shopping through the Instagram of the Millennial Generation. Based on the AISAS purchasing phase, a qualitative study was conducted on the user experience of SNS shopping services in parallel with the survey and in-depth interviews. As a result of the study, the aesthetic experience appeared mainly in the Attention stage and the Interest stage, the emotional experience in the Action stage and the Share stage, and the cognitive experience in the Search stage. While there have been many empirical studies on the impact of SNS on consumer behavior to date, this study is meaningful in that it has led to a contextual study of the user experience on SNS shopping services. The research is expected to help establish a brand and service strategy differentiated from existing mobile shopping services when providing SNS shopping services in the future.