• Korean Journal of Environmental Agriculture
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• v.30 no.3
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• pp.288-294
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• 2011

BACKGROUND: Methylmercury is analyzed by HPLC-ICP/MS because of the simplicity for sample preparation and interference. However, most of the pre-treatment methods for methylmercury need a further pH adjustment of the extracted solution and removal of organic matter for HPLC. The purpose of this study was to establish a rapid and accurate analytical method for determination of methylmercury in fish by using HPLC-ICP/MS. METHOD AND RESULTS: We conducted an experiment for pre-treatment and instrument conditions and analytical method verification. Pre-treatment condition was established with aqueous 1% L-cysteine HCl and heated at $60^{\circ}C$ in microwave for 20 min. Methylmercury in $50{\mu}L$ of filtered extract was separated by a C18 column and aqueous 0.1% L-cysteine HCl + 0.1% L-cysteine mobile phase at $25^{\circ}C$. The presence of cysteine in mobile phase and sample solution was essential to eliminate adsorption, peak tailing and memory effect problems. Correlation coefficient($r^2$) for the linearity was 0.9998. The limits of detection and quantitation for this method were 0.15 and $0.45{\mu}g/kg$ respectively. CONCLUSION: Result for analytical method verification, accuracy and repeatability of the analytes were in good agreement with the certified reference materials values of methylmercury at a 95% confidence level. The advantage of the established method is that the extracted solution can be directly injected into the HPLC column without additional processes and the memory effect of mercury in the ICP-MS can be eliminated.

• Journal of Sensor Science and Technology
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• v.7 no.4
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• pp.243-253
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• 1998

PVC membrane, which has been used for membrane of electrolyte sensors, shortened sensor lifetime due to poor adhesion to sensor surface and exhibited difficulty in standardization and mass-production. To overcome these problems, the membrane solution was prepared with neutral carrier, matrix(TEOS:DEDMS=1:3), solvent(ethanol), and a catalyzer(HCl). The fabricated electrolyte sensors showed typical electrical characteristics of MISFET (metal-insulator-semiconductor field-effect transistor). The K-, Ca- and Na-ISFETs showed sensitivity of 53, 25 and 50 mV/decade in wide concentration range, respectively. The response time was about 90 seconds and the drift was 0.05mV/hour. These results suggest that the sol-gel method and the lift-off technique can be applied to formation of membranes and expected to improve mass-productivity, standardzation of the sensors.

• Korean Journal of Medicinal Crop Science
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• v.21 no.6
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• pp.486-492
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• 2013

This study has been conducted to establish the optimal extraction process and HPLC analysis method for the determination of marker compounds as a part of the materials standardization for the development of health functional food materials from Astragali radix. Five extraction conditions including the shaking extraction at room temperature and the reflux extraction at $85^{\circ}C$ with 30%, 50% and 95% ethanol were evaluated. Reflux extraction with 50% ethanol showed the highest extraction yield as $27.27{\pm}2.27%$, while the extraction under reflux with 95% ethanol showed significantly the lowest yield of $10.55{\pm}0.24%$. The quantitative determination methods of calycosin-7-O-${\beta}$-D-glucoside and calycosin as marker compounds of Astragali radix extracts were optimized by HPLC analysis using a Thermo Hypersil column ($4.6{\times}250mm$, $5{\mu}m$) with the gradient elution of water and acetonitrile as the mobile phase at the flow rate of $0.8mLmin^{-1}$ and a detection wavelength of 230nm. The HPLC/UV method was applied successfully to the quantification of two marker compounds in Astragali radix extracts after validation of the method with the linearity, accuracy and precision. The contents of calycosin-7-O-${\beta}$-D-glucoside and calycosin in 50% ethanol extracts by reflux extraction were significantly higher as $1,700.3{\pm}30.4$ and $443.6{\pm}8.4{\mu}g-1$, respectively, comparing with those in other extracts. The results indicate that the reflux extraction with 50% ethanol at $85^{\circ}C$ is optimal for the extraction of Astragali radix, and the established HPLC method are very useful for the evaluation of marker compounds in Astragali radix extracts to develop the health functional material from Astragali radix.

• Korean Journal of Environmental Agriculture
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• v.29 no.1
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• pp.33-38
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• 2010

To improve the existing nitrogen recommendation method based on chemical properties of soils and to establish new recommendation rates of nitrogen fertilizer due to different types of soils, the application rates of nitrogen fertilizer were examined in different soils of 12 experimental rice paddy fields. The application rates of nitrogen fertilizer estimated by soil-testing were higher than the rates of nitrogen standard recommendation that has been used. The application rates for minimum rice productivity ranged from a low of 168 kg/10a in sandy soil to a high of 315 kg/10a in saline soil. Amounts of nitrogen absorption in rice were proportional to the application amounts of nitrogen fertilizer in soils. Nitrogen use efficiency was the highest, 36.7%, in immatured paddy field and it was inversely proportional to the application amounts of nitrogen. the rice tasty value was the highest in the soils without nitrogen application, and also it was the lowest in the saline soils with or without nitrogen application. As comparing with the nitrogen application rates obtained by the existing nitrogen recommendation method, optimal nitrogen application rates estimated by the standardization of nitrogen application efficiency rate, environmental index, and rice quality were 1.0 fold in the well adapted soil and sandy soil fields, 0.92 fold in the immatured soil field, and 0.83 fold in the saline soil field.

• Journal of Food Hygiene and Safety
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• v.25 no.1
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• pp.43-48
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• 2010

This research was conducted to know application of Photostimulated luminescence (PSL) and Thermoluminesce(TL) methods by irradiation dose for leaching tea, sauces and starch approved in Korea. Leaching tea, sauces and starch powder were treated with $^{60}Co$ gamma ray at dose 0~10 kGy for detection trial whether they are irradiated or not by measuring PSL and TL for whole samples. PSL values were less than threshold value 700 and were, negative for non-irradiated samples but more than 5,000 and were positive for irradiated ones. PSL results of leaching tea and sauces showed the correct identification for non-irradiated and irradiated samples, respectively except starch samples. To enhance the reliability of the TL result, the first glow curve (TL1) was compared with the second glove curve (TL2) obtained after a re-irradiation step at 1 kGy. The TL ratio ($TL_1/TL_2$) was in good agreement with the reported TL threshold for both the non-irradiated (< 0.1) and irradiated (> 0.1) samples. TL results of leaching tea, sauces, starch showed the correct identification for non-irradiated and irradiated samples, respectively. This study was performed to know application of PSL and TL methods for leaching tea, sauces and starch, and the methods were able to detect the irradiation products.

• Journal of Gastric Cancer
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• v.3 no.4
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• pp.206-213
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• 2003

Purpose: The clinical implication of p53 mutation in gastric cancer is still unclear, as shown by the discordant results that continue to be reported in the literature. Materials and Methods: To assess p53 gene mutation, tumor p53 overexpression, and serum anti-p53 antibody, we employed a polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) analysis, an immunohistochemistry using monoclonal antibody DO-7, and an enzymelinked immunosorbent assay (ELISA), respectively. Results: Of 169 surgical specimens of gastric cancer, mutation at exon $5\∼8$ of the p53 was identified in 33 ($19.5\%$) and was significantly correlated with lymph node metastasis. Overexpression of p53 was found in 62 specimens ($36.7\%$) and had a significant correlation with tumor differentiation. Serum anti-p53 antibody was positive in 18 patients ($10.7\%$). Twenty-three of the mutated tumors ($69.7\%$) and 39 of the non-mutated tumors ($28.7\%$) displayed immunoreactivity. Twelve of the immunopositive tumors ($19.4\%$) and 6 of the immunonegative tumors produced anti-p53 antibody. These differences were statistically significant (P<0.001 and P=0.005, respectively). There was no significant difference in survival according to the mutation of p53. Conclusion: Mutation and overexpression of p53 can be easily detected by immunohistochemistry. However, standardization of the immunohistochemical staining method, as well as guidelines for interpreting the stained result, will produce concordant results and thereby improve clinical application.

• Journal of Korean Academy of Nursing Administration
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• v.9 no.3
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• pp.353-366
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• 2003

Purpose: This study was to define the care time of elderly in long-term care facilities and to compare and analysis the care time by staff and facility types. Method: The data were collected from 530 elderly over sixty, residing in two long-term care hospitals for dementia, three long-term care hospitals for the elderly and two skilled nursing facilities. Care time for individual residents was measured the total time spent by nurses, aides. Result: The average care time measured by nursing staff was 158.6 minutes a day. The average care time for one resident by nurse was 40.4 minutes, and by aides, 118.2 minutes. The difference of the care time showed statistical significance between long-term care facility types(p<0.001) : average care time for dementia hospital(199.1min) was twice as long as that of skilled nursing facility(94.1min). Conclusion: The results of the study showed that the care time differentiates care time provided to elderly in long-term care facilities in Korea. The study suggests the need to emphasize the importance of standardization of level of staff and service programs by the long-term facilities.

• Korean Journal of Soil Science and Fertilizer
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• v.40 no.5
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• pp.369-376
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• 2007

This experiment was carried out to investigate optimum conditions of coir-based substrates for the red pepper plug seedlings. Eleven different coir based substrates prepared by mixing of coir, vermiculite, rice hull, perlite, zeolite, mixed at different ratios were tested. The physical and chemical properties of the substrates were analyzed by the CEN (European committee for standardization) method. Fresh and dry weights of shoot and root, leaf area, root length, and T/R ratio (dry shoot weight/dry root weight) were determined at 55 days after sowing. The results showed that the growing media CRZ 8(coir:rice hull: vermiculite=8:1.9:0.1) and CVSZ 6(coir:silver vermiculite: zeolite=6:3.9:0.1) can successfully be used for pepper plug seedlings judging from dry weight and T/R ratio of the plug seedlings. The optimal range of total pore space, water volume, air volume, easily available water content and water buffering capacity of the coir-based growing substrates for pepper plug seedlings were in the range of 92~94%, 52~60%, 32~43%, 18~21%, and 0.9~8%, respectively.

• Journal of Food Hygiene and Safety
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• v.28 no.2
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• pp.188-193
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• 2013

Anatoxin-a, saxitoxin and neosaxitoxin are produced by Aphanizomenon flos-aquae that is a sort of the cyanobacteria phylum. Therefore, it is not permitted for food materials in Korea. Traditionally, the classification of cyanobacteria has been based on morphological characters such as trichome width, cell size, division planes, shape, and the presence of character such as gas vacuole. But, some diagnostic features, such as gas vacuole or akinetes, can show variation with different environmental or growth conditions and even be lost during cultivation. Therefore, we developed detection method for functional foods containing Aph. flos-aquae by PCR. To design the primer, 16S rRNA region of Aph. flos-aquae, Spirulina laxissima, and Spirulina spp. registered in the GeneBank (www.ncbi.nlm.nih.gov) have been used and for comparative analysis, BioEdit ver. 7.0.9.0. was used. As a result, we was design AFA-F1/AFA-R1 (363 bp) primer for the differentiation Aph. flos-aquae from chlorella, spirulina, green tea, and spinach. Also, it could be distinguished chlorella and spirulina products those are made to contain 1% Aph. flos-aquae.

• Journal of The Korean Astronomical Society
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• v.49 no.5
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• pp.175-192
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• 2016

CCD photometric observations of the globular cluster (GC), M53 (NGC 5024), are performed using the 1.8 m telescope at the Bohyunsan Optical Astronomy Observatory in Korea on the same nights (2002 April and 2003 May) as the observations of the GC M92 (NGC 6341) reported by Cho and Lee using the same instrumental setup. The data for M53 is reduced using the same method as used for M92 by Cho and Lee, including preprocessing, point-spread function fitting photometry, and standardization etc. Therefore, M53 and M92 are on the same photometric system defined by Landolt, and the photometry of M53 and M92 is tied together as closely as possible. After complete photometric reduction, the V versus B − V , V versus V − I, and V versus B − I color-magnitude diagrams (CMDs) of M53 are produced to derive the relative ages of M53 and M92 and derive the various characteristics of its CMDs in future analysis. From the present analysis, the relative ages of M53 and M92 are derived using the Δ(B − V ) method reported by VandenBerg et al. The relative age of M53 is found to be 1.6 ± 0.85 Gyr younger than that of M92 if the absolute age of M92 is taken to be 14 Gyr. This relative age difference between M53 and M92 causes slight differences in the horizontal-branch morphology of these two GCs.