• Journal of Soil and Groundwater Environment
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• v.19 no.3
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• pp.104-110
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• 2014

In order to study gross alpha analysis method using LSC, the efficiency tests with uranium standard materials were performed and then compared with the GPC method (US EPA 900.0 method) using 15 groundwater samples. For 15 groundwater samples, the average efficiencies of the GPC and LSC method were 7~11% and 90%, respectively. The average precisions of the GPC and LSC method were 16.16% and 6.00%, respectively. Also, The average standard deviations for 15 samples were 7.38 pCi/L and 2.95 pCi/L, respectively. The determination coefficient of the tested results by two methods was 0.9948. As a result, the LSC method tested in this study was applicable for the screening of the gross alpha and showed the advantages in the gross alpha measurement due to the simple measurement procedures.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• autumn
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• pp.291-294
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• 2001

This study has established an appraisal standard to select VE subject when they evaluate of design VE by using of a qualify model in an early design step and has suggested an improvement method for importance's estimation method of an appraisal standard. An importance's estimation method is to arrangement of geometric average method using an AHP method to this study, When an evaluation of a quality model, we estimate an importance by establishing of an appraisal standard of economics, construction, security, environmental influence, maintenance, etc.

• Journal of Korean Society on Water Environment
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• v.37 no.6
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• pp.510-519
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• 2021

Volatile Organic Compounds (VOCs) in sediments, which can cause human health problems, have been monitored in Korea since 2014. Measured VOC concentrations can be affected by matrix type and the volatility of target substances. In this study, (1) VOCs volatility and the influence of matrix interference were confirmed, and (2) internal standards (IS) method was applied to improve analytical method. For these purposes, method detection limit (MDL), calibration linearity, precision and accuracy of VOCs were compared in various matrices using the IS. Some of VOCs in sediments showed different peak areas and reduced rates compared to water matrix. It was suggested that adsorption properties of sediments hindered the migration to vapor during heat pretreatment in headspace method. A calibration curve was created in clean sand. Recovery rates for the calibration curve method and IS applying method were 64.1~83.1% and 99.1~119.3%, respectively. Relative standard deviations ranged from 11.1% to 21.6% for the calibration curve method and those for IS ranged 4.7% to 13.7%. In case of real sediment, calibration curve and 1,2-Dichlorobenzene-d4 (ODCB) among IS were not suitable. The average recovery rate of Fluorobenzene (FBZ) increased by 56.4% and Relative Standard Deviation (RSD) by 4.7%. However, the recovery rate was increased in the samples with large values of igniting intensity. This study confirmed that influence of the matrix of VOCs in sediment, and addition of IS materials improved precision and accuracy. Although IS corrects volatilization and adsorption, it is recommended that more than two types of IS should be added rather than single.

• Journal of Korean Society on Water Environment
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• v.21 no.5
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• pp.431-441
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• 2005

The study was carried out to improve and regulate the drinking water quality standard and drinking water quality monitoring substances. For the reliability and safety of finished water, It has been monitored for trace organic and inorganic compounds of 333 in finished water of water treatment plants during 1989 to 2003. As a result of monitoring, 51 compounds were detected from 333 compounds, and it has been regulated the drinking water quality standard of 26 substances and 20 mitoring substance. Improvement and regulation method of the drinking water quality standard was performed by comparing and analyzing with detection concentration, detection frequency, risk assessment and foreign drinking water quality standard.

• Korean Journal of Environmental Agriculture
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• v.14 no.3
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• pp.338-344
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• 1995

The wet ash method has been used as an official standard procedure for the analysis of Cd in brown rice in Korea, but this method involves several disadvantages. Thus, four analytical methods were compared in this experiment in order to find a more efficient method for the Cd analysis in brown rice. Evaluation was made based on both the Cd recovery percentages from the Cd-spiked samples and the relationships between Cd contents obtained by the official procedure and other methods. Results showed that ashing 50g brown rice at $600^{\circ}C$(dry ash method) recovered nearly 80% of the spiked Cd. This recovery percentage was a little lower than that of the wet ash method(87%) but higher than those of other methods. The dry ash method had the lowest standard deviations and revealed the highest correlation coefficient($r=0.98^{\ast\ast}$) in Cd contents with the standard wet ash method. These results demonstrated that the dry ash method, ashing 50g brown rice at $600^{\circ}C$, would be as efficient as the wet ash method and could be employed as a recommended procedure for the Cd analysis of brown rice.

• Bulletin of the Korean Chemical Society
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• v.30 no.9
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• pp.2032-2038
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• 2009

The amount of phenol and NaOH for the colorimetric determination of ammonia in Korean standard methods (KSM) is found to be highly excessive compared to the standard methods of several other countries. The absorbance of indophenol formed by the Berthelot reaction for ammonia analysis was measured under the various reaction conditions classified in experiment groups 1, 2, 3, 4 and KSM and American standards methods (ASM), and the relationships between the absorbance of indophenol and concentration of ammonia were compared. The amount of phenol can be reduced to 10 g (current 25 g in KSM) and NaOH can be reduced to 1.76 g (current 11 g in KSM) for the preparation of 200 mL phenate solution, and the absorbance sensitivity increased. The concentration of the phenol and NaOH correlatively affect the pH of the solution, which is a critical variable in achieving the maximum sensitivity and rapid and stable color development.

• Environmental Engineering Research
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• v.13 no.3
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• pp.136-140
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• 2008

$TiO_2$ photocatalyst has been known to exhibit a notable disinfecting activity against a broad spectrum of microorganisms. A lot of commercial $TiO_2$ photocatalyst products have been developed for antimicrobial purposes. However, a standard method has not yet been proposed for use in testing antimicrobial activity. In this study, we developed a $TiO_2$ photocatalytic adhesion test method with film as the standard testing method for the evaluation of antimicrobial activity. This method was devised by modifying the previous antimicrobial products test method, which has been widely used, and considering the characteristics of $TiO_2$ photocatalytic reaction. The apparatus for testing the antimicrobial activity was composed of a Black Light Blue (BLB) lamp as UV-A light source, a Petri dish as the cover material, and a polypropylene film as the adhesion film. The standard $TiO_2$ photocatalyst sample, Degussa P25 $TiO_2$ - coated glass, could only be used once. The optimal initial concentration of the microorganism, proper light intensity, and light irradiation time were determined to be $10^6$ CFU/mL, 1.0 mW/$cm^2$, and 3 hr, respectively, for testing and evaluating antimicrobial activity on the $TiO_2$ surface.

• Korean Journal of Microbiology
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• v.44 no.1
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• pp.43-48
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• 2008

Standard sample for quality control of total coliform measurement was procured by addition of nalidixic acid and cephalexin as bacteriostatic agents to Escherichia coli cultured broth. After making the standard sample, the number of E. coli was measured by fluorescence microscopic count method and plate count method by 12 hr interval. The numbers of E. coli remained unchanged for at least for 48 hr at room temperature which ranged from 3.5 to $4.2{\times}10^5\;cells/ml$ and from 1.0 to $1.2{\times}10^4\;CFU/ml$ by direct fluorescence microscopic count method and plate count method, respectively. This result suggests that microbial standard sample with bacteriostatic agents of nalidixic acid and cephalexin is usable for quantitative quality control.

• Journal of Environmental Health Sciences
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• v.47 no.3
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• pp.292-301
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• 2021

Objectives: Wearing medical masks has been recommended since the declaration of coronavirus disease-19 (COVID-19) as a pandemic disease. Certified medical masks are evaluated according to filtration efficiency and facial inhalation resistance. However, some people use non-certified common masks. This study aimed to evaluate various non-certified commercial masks based on the certification criteria for medical masks. Methods: Twenty mask products (three anti-droplet, three disposable dental, eight fashion, three cotton, and three children's masks) were selected. For performance evaluation, filtration efficiency and facial inhalation resistance tests were conducted. The evaluation method followed the certification method for KF-certified masks of the Ministry of Food and Drug Safety (MFDS) and the N95 respirator of the National Institute for Occupational Safety and Health (NIOSH). Results: None of the 20 masks met the KF94 certification standard set by the MFDS. Four and three masks respectively met the KF80 certification standard and the N95 standard of NIOSH. Filtration efficiency was significantly higher in three-layer masks than in single layer masks. Pleated-type masks had higher filtration efficiency than cone-type masks. There was no correlation between the structure of masks and facial inhalation resistance. Conclusion: While no masks complied with the KF94 certification standard, a few masks met the KF80 and the N95 certification standards of NIOSH. Although some people wear non-certified commercial masks, protection from aerosols is not guaranteed by such masks. Evaluation of the protection efficiency of non-certified mask against microbiological infection is needed for the prevention of infectious disease.

• Journal of Korean Society for Atmospheric Environment
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• v.23 no.5
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• pp.515-525
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• 2007

In this study, various techniques for measurement and analysis of PAHs in the ambient air were verified in order to select a more reliable method. Sampling and analysis of PAHs were done by the EPA TO-13a method. QA/QC of the measurement was conducted to minimize errors in sampling and analyzing processes. The linearity of calibration curve of the PAH standards was good ($R^2{\geq}0.99$). Audit accuracy was evaluated using 5 internal standards of PAHs ($Naphthalene-d_8,\;Acenaphthene-d_{10},\;Phenanthrene-d_{10},\;Chrysene-d_{12},\;Perylene-d_{12}$). Relative standard deviations of the internal standard of the PAHs were ranged from 6.22% for $acenaphthene-d_{10}$ to 8.11% for $chrysene-d_{12}$. To evaluate the surrogate recoveries, two field surrogate standards of PAHs ($fluoranthene-d_{10},\;benzo(a)pyrene-d_{12}$) and two extract surrogate standards of the PAHs ($fluorene-d_{10},\;pyrene-d_{12}$) were spiked into all samples before field sampling and sample extraction, respectively. Recoveries of field the surrogate standards ranged from $80.4{\pm}12.2%$ for $fluoranthene-d_{10}$ to $66.2{\pm}12.8%$ for $benzo(a)pyrene-d_{12}$. Extraction recoveries of the surrogate standards ranged from $70.4{\pm}10.2%$ for $fluorene-d_{10}$ to $77.6{\pm}10.8%$ for $pyrene-d_{10}$. The detection limit of benzo(a)pyrene among 16 PAHs standards for quantitation was 20 pg.