• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.1065-1068
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• 2008

Marine bridges are readily deteriorated due to the exposure to marine environment. The concrete deterioration occurred by corrosion of steel in concrete is mainly relevant to chloride in seawater. Chloride ions penetrate through porous concrete, and then reach to the reinforcing steel, and finally corroded them. The corrosion by-products(rusts) increase the volume as much as 6 to 10 times of origin steel. this creates expanding pressure and tensile stress, which cause the structures cracking and spalling. Sometimes the rebar corrosion is accelerated, and then collapsed catastrophically. In order to prevent corrosion damage, it is important to understand well regarding the reason of concrete corrosion, the quantification of its damage, and protection method/system to stop or to mitigate the corrosion. In this study, slab specimens were fabricated to evaluate the effect of cathodic protection which was simulated to marine bridges, and/or port structures. Zn-mesh sacrificial anode has been applied as a chathodic protection system and accelerated test conditions, i.e. temperature and salt concentration have been used in this study.

• Preventive Nutrition and Food Science
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• v.19 no.4
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• pp.321-326
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• 2014

In this study, we developed a method to quantify esculetin (6,7-dihydroxycoumarin) in plasma and tissues using HPLC coupled with ultraviolet detection and measured the level of esculetin in rat plasma after oral administration. The calibration curve for esculetin was linear in the range of 4.8 ng/mL to 476.2 ng/mL, with a correlation coefficient ($r^2$) of 0.996, a limit of detection value of 33.2 ng/mL, and a limit of quantification value of 100.6 ng/mL. Recovery rates for the 95.2 ng/mL and 190.5 ng/mL samples were 95.2% and 100.3%, within-runs and 104.8% and 101.0% between-runs, respectively. The relative standard deviation was less than 7% for both runs. In the pharmacokinetic analysis, the peak plasma esculetin level was reached 5 min after administration ($C_{max}=173.3ng/mL$; $T_{1/2}=45min$; $AUC_{0{\sim}180min}=5,167.5ng{\cdot}min/mL$). At 180 min post-administration (i.e., after euthanasia), esculetin was only detectable in the liver ($30.87{\pm}11.33ng/g$) and the kidney ($20.29{\pm}7.02ng/g$).

• Natural Product Sciences
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• v.22 no.2
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• pp.93-101
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• 2016

For efficient quality control of the Samryeongbaekchul-san decoction, a powerful and accurate an ultra-performance liquid chromatography (UPLC) coupled with electrospray ionization (ESI) tandem mass spectrometry (MS) method was developed for quantitative analysis of the thirteen constituents: allantoin (1), spinosin (2), liquiritin (3), ginsenoside Rg1 (4), liquiritigenin (5), platycodin D2 (6), platycodin D (7), ginsenoside Rb1 (8), glycyrrhizin (9), 6-gingerol (10), atractylenolide III (11), atractylenolide II (12), and atractylenolide I (13). Separation of the compounds 1 - 13 was performed on a UPLC BEH $C_{18}$ column ($2.1{\times}100mm$, $1.7{\mu}m$) at a column temperature of $40^{\circ}C$ with a gradient solvent system of 0.1% (v/v) formic acid aqueous-acetonitrile. The flow rate and injection volume were 0.3 mL/min and $2.0{\mu}L$. Calibration curves of all compounds were showed good linearity with values of the correlation coefficient ${\geq}0.9920$ within the test ranges. The values of limits of detection and quantification for all analytes were 0.04 - 4.53 ng/mL and 0.13 - 13.60 ng/mL. The result of an experiment, compounds 2, 6, 12, and 13 were not detected while compounds 1, 3 - 5, and 7 - 11 were detected with 1,570.42, 5,239.85, 299.35, 318.88, 562.27, 340.87, 12,253.69, 73.80, and $115.01{\mu}g/g$, respectively.

• Journal of the Korean Society of Food Science and Nutrition
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• v.11 no.3
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• pp.1-4
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• 1982

By high performance liquid chromatography, separation and quantification of glucoalkaloids $({\alpha}-chaconine$and${\alpha}-solanine)$ from potato (Solanum tuberosum, var. May Queen) was established using periderm and cortex. $Nucleosil-NH_2\;(10{\mu}m)$ was packed in two stainless steel columns ($4.0\;ID{\times}15\;cm$ and $4.0\;ID{\times}25\;cm$) which were connected in sequence and eluted with the mixture of tetrahydrofuran, phosphoric acid buffer and acetonitrile (50 : 25 : 25, v/v/v) at the flow rate of 1ml/min. and the absorbance were read at 208 nm. Retention time was 6.92 min. for ${\alpha}-chaconine$ and 10.96 min. for ${\alpha}-solanine$ with complete separation. This method took 12 min. per sample and seemed best. ${\alpha}-Chaconine$ and ${\alpha}-solanine$ were found much in periderm than in cortex.

• Journal of Acupuncture Research
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• v.23 no.5
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• pp.69-77
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• 2006

Background : Mesenchymal stem cells (MSCs) are present in most of the tissue matrix, taking part in their regeneration when injury or damage occurs. The aim of this study was to investigate the presence of cells with pluripotential characteristics in human subchondral bone and the capacity of these cells to differentiate to osteoblast. Methods : Human subchondral bone were digested with collagenase. Isolated cells were cultured with a-MEM, 15% FBS, 10-8M dexamethasone and 50 ng/mL ascoric acid. Cells from 0 day(isolated cells), 7 day (first subculture) and 14 days (third subculture) were used to carry out phenotypic characterization experiments flowcytometry analysis with 11 monoclonal antibodies) and osteogenic differentiation experiments. Osteogenic differentiation of cells was assessment by quantification of bone extracellular matrix components by following analysis: alkaline phosphatase(ALP) stains to detect ALP activity, RT-PCR and western blot to detect osteocalcin (OCN), osteopontin (OPN) and type I collagen(Col I), and Alizarin red stains to detect calcium deposition. Results : Flowcytometry analyses showed that in our population more than 98% of cells were positive for MSC markers: SH-2(CD105, 99%), CD29 (95%), CD73 (95%). Cells were negative for hematopoietic markers (CD11b, CD34, and CD45). Furthermore, cells showed positive stain to multipotent markers such as CDl17 (c-kit) (15.1%), and CD166 (74.9%), and cell adhesion molecules such as CD54 (78.1%) and CD106 (63.5%). The osteogenic specific marker analyses showed that the culture of these cells for 7 and 14 days stimulates ALP, OCN, OPN and Col I synthesis by RT-PCR and Western blot analysis. Also, after 14 days in the culture of MSCs induces mineralization by Arizarin red stain. Conclusion : In this work, we demonstrated a new and efficient method for osteoblastic differentiation of human subchondral bone stem cells. As MSCs takes part in reparative processes of adult tissues, these cells could play an important role in osteogenesis.

• Journal of Climate Change Research
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• v.6 no.4
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• pp.319-330
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• 2015

This study was carried out to predict the optimal growth site and estimate carbon stocks of Quercus acuta, evergreen broad-leaved trees in warm temperate zone according to climate change. The criterion for the optimal site prediction was created by quantification method with quantitative and qualitative data, collected from growth factors of stands and environmental factors of survey sites of 42 plots in Q. acuta by study relationship between growth of tree and site environmental factors. A program for the optimal site prediction was developed by using GIS engine tools. To prediction of the suitable growth site of Quercus acuta, developed program in this study applied to Wando in Jeollanam-do, distributing a various evergreen bread-leaved trees of warm temperate zone. In the results from analysis of the optimal site prediction on Q. acuta, the characteristics of the optimal site showed as follows; site environmental features of class I (the best site class for Q. acuta) was defined as 401 ~ 500 m of altitude, $21{\sim}25^{\circ}$ of slope with above hillside, residual of deposit convex of slope type with west of aspect. The area and carbon stocks of optimal site prediction by class for Q. acuta in classI showed 147.1 ha (2.5%), total 316.5 tC/ha, total $1,161tCO_2/ha/yr$ of class I, 2,703.5 ha (46.3%), total 5,817.4 tC/ha, total $21,331tCO_2/ha/yr$ of class II, 2,845.5 ha (48.6%), total 6,123.0 tC/ha, total $2,845.5tCO_2/ha/yr$ of class III and 153.7 ha (2.6%), total 330.7 tC/ha, total $1,213.7tCO_2/ha/yr$ of class IV.

• Journal of Ginseng Research
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• v.37 no.1
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• pp.135-141
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• 2013

A rapid, sensitive and selective analytical method was developed and validated for the determination of compound K, a major intestinal bacterial metabolite of ginsenosides in human plasma. Liquid-liquid extraction was used for sample preparation and analysis, followed by liquid chromatography tandem spectrometric analysis and an electrospray-ionization interface. Compound K was analyzed on a Phenomenex Luna C18 column ($100{\times}2.00$ mm, 3 ${\mu}m$) with the mobile phase run isocratically with 10 mM ammonium acetate-methanol-acetonitrile (5:47.5:47.5, v/v/v) at a flow rate of 0.5 mL/min. The method was validated for accuracy (relative error <12.63%), precision (coefficient of variation <9.14%), linearity, and recovery. The assay was linear over the entire range of calibration standards i.e., a concentration range of 1 ng/mL to 1,000 ng/mL ($r^2$ >0.9968). The recoveries of compound K after liquid-liquid extraction at 1, 2, 400, and 800 ng/mL were $106.00{\pm}0.08%$, $103.50{\pm}0.19%$, $111.45{\pm}5.21%$, and $89.62{\pm}34.46%$ for intra-day and $85.40{\pm}0.08%$, $94.50{\pm}0.09%$, $112.50{\pm}5.21%$, and $95.87{\pm}34.46%$ for inter-day, respectively. The lower limit of quantification of the analytical method of compound K was 1 ng/mL in human plasma. The developed method was successfully applied to a pharmacokinetic study of compound K after oral administration in ten of healthy human subjects.

• Bulletin of the Korean Chemical Society
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• v.32 no.8
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• pp.2648-2656
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• 2011

A simple HPLC-DAD method was developed and validated to determine B group vitamin content (thiamine, riboflavin, nicotinamide, pantothenic acid, pyridoxine and folic acid) in supplemented food samples, i.e., infant formula, cereal, low-calorie food, a multi-vitamin pill and a vitamin drink. In this study, the most significant advantages were simultaneous determination of the six B group vitamins in various food matrices and a small number of sample treatment steps that required only an organic solvent, acetonitrile. Moreover, this method prevents reduction of column durability, because the mobile phase does not contain ion-pairing reagents. Analytes were separated on a Develosil RPAQUEOUS $C_{30}$ (4.6 mm ${\times}$ 250 mm, 5 ${\mu}M$ particle size) column with a gradient elution of acetonitrile and 20 mM phosphate buffer (pH 3.0) at a flow rate between 0.8 and 1.0 mL/min. Detection was performed at 275 nm, except for that of pantothenic acid (205 nm). The calibration curves for all six vitamins showed good linearity with correlation coefficients ($r^2$) higher than 0.995. The developed method was validated with respect to linearity, intra- and inter-day accuracy and precision, limit of quantification (LOQ), recovery and stability. The method showed good precision and accuracy, with intra- and inter-assay coefficients of variation less than 15% at all concentrations. The recovery was carried out according to the standard addition procedure, with yields ranging from 89.8 to 104.4%. This method was successfully applied to the determination of vitamin B groups in supplemented food products.

• Journal of the Mineralogical Society of Korea
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• v.28 no.3
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• pp.245-253
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• 2015

The performance of $TiO_2$ photo-catalytic oxidation process is significantly dependent on the amount of hydroxyl radicals produced during the process, and it is an essential prerequisite to quantify its production. However, precise and accurate methods for quantification of hydroxyl radicals have not been developed so far. For this reason, this study was initiated to compare existing methods for analysis of hydroxyl radicals produced by $TiO_2$ photo-catalytic oxidation and to propose a new method to overcome the limitation of established methods. To simulate $TiO_2$ photo-catalytic oxidation process, Degussa P25 which has been widely used as a standard $TiO_2$ photo-catalyst was used with the dose of 0.05 g/L. The light source of process was UVC mercury low-pressure lamp (11 W, $2,975mW/cm^2$). The results indicate that both potassium iodide (KI)/UV-vis spectrometer and terephthalic acid (TPA)/fluorescence spectrometer methods could be applied to qualitatively measure hydroxyl radicals via detection of triiodide ion ($I_3{^-}$) and 2-hydroxyterephthalic acid which are produced by reactions of iodine ion ($I^-$) and TPA with hydroxyl radicals, respectively. However, it was possible to quantitatively measure hydroxyl radicals using TPA method coupled with high-performance liquid chromatograph (HPLC). The analytical results using TPA/HPLC method show that hydroxyl radical of 0.013 M was produced after 8 hours operation of photo-catalytic oxidation under specific experimental conditions of this study. The proposed method is expected to contribute to precise the evaluation of the performance of photo-catalytic oxidation process.

• Natural Product Sciences
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• v.21 no.1
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• pp.20-24
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• 2015

Cyanidin-3-glucoside (C3G) and cyanidin-3-rutinoside (C3R) were isolated by high-performance countercurrent chromatography (HPCCC) using a two-phase solvent system composed of tert-butyl methyl ether/n-butanol/acetonitrile/water/trifluoroacetic acid (1 : 3 : 1 : 5 : 0.01, v/v) to give pure C3G (34.1 mg) and C3R (14.3 mg) from 1.5 g crude mulberry fruit extract. Using the pure C3G and C3R, a reliable high-performance liquid chromatography (HPLC) method was developed and validated to determine the C3G and C3R contents in mulberry fruit. C3G and C3R were separated simultaneously using an Eclipse XDB-C18 column ($4.6{\times}250mm$ I.D., $5{\mu}m$) coupled with a photodiode array detector (PDA). The gradient elution of the mobile phase consisting of acetonitrile (0.5% formic acid) and water (0.5% formic acid) was applied (1.0 mL/min), and the detection wavelength was 520 nm. The calibration curves of C3G and C3R showed good linearity (both with $r^2=0.9996$) in the concentration range $15.625-500{\mu}g/mL$, and the relative standard deviations (RSD%) of intra- and inter-day variability were in the ranges 2.1 - 8.2% and 4.1 - 17.1%, respectively. The accuracies were ranged 96.5 - 102.6% for C3G and C3R, respectively. The developed HPLC method was used to determine the contents of C3G and C3R in newly harvested mulberry from eight different provinces of Korea.