• Analytical Science and Technology
• /
• v.10 no.5
• /
• pp.386-394
• /
• 1997

The standard samples for the calibration of PIXE analysis were prepared using the single element standard samples and sulfur and chlorine compounds. The diluted standard solutions were dropped on the non-hole nuclepore film and dried. Standard sample of six elements of Ca, Cr, Co, Cu, Se and Sr had close agreement between the measurement and theoretical values. According to the theoretical study about the effects of thick samples on the accuracy of the PIXE analysis, the reduction of X-ray yields in the thick sample can not be neglected for the sample thicker than $100{\mu}g/cm^2$.

• Journal of environmental and Sanitary engineering
• /
• v.21 no.4 s.62
• /
• pp.29-38
• /
• 2006

This study included the development of analytical method for determining perchlorate in water sample. The analytical condition was referred in EPA 314.0 method which use ion chromatography and the concentrator column was replaced by the guard column. Concentrating 10mL raw or treated water sample on to AGl6 guard column made it possible to get the LOD(Limit of Detection) of $0.73\;{\mu}g/L$. The total run time was 11 minutes and during run time next sample could be concentrated on AGl6 guard column. Compared to the Concentration method which needed manual operation, the Direct Injection method could screen the many water samples. The LOD of the Direct Injection method was higher and the sensitivity was lower than that of the Concentration method. The RSDs(Relative Standard Deviations) were lower than 2.5 % for peak height and 0.7 % for retention time in pre-concentration methods. This method Showed good reproducibility and reliability and it was thought the deviations of recovery value could be reduced by considering column capacity and making water sample homogeneous. Matrix Elimination could be done using the pre-concentration method if perchlorate were in complex matrix of sample.

• Proceedings of the Korean Environmental Health Society Conference
• /
• 2004.12a
• /
• pp.80-80
• /
• 2004

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

• Korean Journal of Environmental Biology
• /
• v.32 no.3
• /
• pp.211-215
• /
• 2014

In order to accurately estimate the litter mass, we evaluated the required sample sizes across 13 chronosequence stands for five years (1994~1996, 2003~2004) in northern hardwood forests in New Hampshire, USA. It was found that the number of required litter traps in our stands (0.25~0.5 ha) within ${\pm}10%$ of the sample mean was appeared to be similar or higher than the 15 litter traps installed in this study. Notably, in 1994 and 1995, the number of required litter trap was twice higher than the 15 litter traps. Further, within ${\pm}20%$ of the sample mean, the number of required litter traps was less than 10 across all 13 stands for five years, which indicates that we can reduce the sample size. Precisely, the number of sample size had increased in stands with steep and high elevation, but no relations with stand age across 13 stands were observed. Based on these results, we suggest that it is important to sample litter mass for several years, in order to determine the number of appropriate sample size, and stands with steep and high elevation may need more litter traps.

• Journal of Korean Society of Environmental Engineers
• /
• v.35 no.2
• /
• pp.137-143
• /
• 2013

This study is to develop the production method of stepwise dilution gas for the evaluation of complex odor concentration by orifice tube. The basic orifice tube for 10 and 30 times of dilution sample was made at first, and with the combination of the basic orifice tubes we can continuously manufacture the stepwise dilution sample gas for air dilution sensory test ; 10, 30, 100, 300, 1,000, 3,000 times etc. The hole size of orifice tube was 0.84 mm for 10 times of dilution sample, and was 0.34 mm for 30 times. Dilution sample gas made with the basic orifice tube have an excellent reproducibility, 2%RSD. In addition, over 90% of correlation was shown between the sample made by the orifice tube and the sample by the syringe dilution method. Because there was no concentration drift of dilution gas with changes of connected pump flow, the basic orifice tube could be mounted directly with a vacuum suction box, and could be used simply as a tool for the evaluation of odor, especially on site.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2004.03b
• /
• pp.873-881
• /
• 2004

A serious of EK remediation tests on contaminated soil are performed under unsaturated conditions and analyzed for electrical potential, water content, pH and so on. The results indicated that electrical potential and pH distributions in the sample are dependent on the amount and inward/outward flow of hydrogen ion. Specially, for the closed system the water content is largely decreased with the flow of hydrogen. The maximum electrical conductivity is measured at the catholyte of CEM(Sealing) test and directly related to the remedial efficiency. Although pHs in the region near to the anode are similarly developed, the different concentration of lead is measured with the electrical gradient contrary to the lead concentration dependent on pH within the sample.

• International Journal of Human Ecology
• /
• v.11 no.2
• /
• pp.15-23
• /
• 2010

This study explored genetic and environmental contributions to optimism, depressive symptoms, and the association between the two using a genetically informative sample from the Nonshared Environment and Adolescent Development project (NEAD: D. Reiss; J. M. Neiderhiser; E. M. Hetherington; & R. Plomin, 2000. At Time 1 of the longitudinal NEAD study, the sample consisted of 720 samesex twins and sibling pairs from two parent families. The study used parent, adolescent, and observer ratings of depressive symptoms as well as adolescent ratings of optimism. The results revealed that genetic influences explained approximately half of the variability in optimism and depressive symptoms. Nonshared environmental influences also substantially contributed to optimism and depressive symptoms. Bivariate genetic analyses (which partitioned the covariance between optimism and depressive symptoms into genetic and environmental components) indicated that genetic influences accounted for a moderate percentage of the association.

• Korean Journal of Organic Agriculture
• /
• v.12 no.4
• /
• pp.377-397
• /
• 2004

The objectives of this study are to find out, the fact-analysis of environmental friendly farm households around the Chuam Dam through the sample survey, 2) the developing strategies to improve the EPA on the assumption that is the conservation of Chuam Dam's water quality. The data used in this study comes from 75 sample farm households. The developing strategies to improve the EPA around Chuam Dam was found out that the efficiency measure of land utilization around CImam Dam, producing of high quality and safety agricultural products, promoting of the EPA connected with tourist agriculture, improving of the EPA products and supporting of price and income. In conclusion, there must be strategic measures to increase the income of environmental friendly farmers and to conserve the Chuam Dam's water quality.

• Journal of Radiation Protection and Research
• /
• v.46 no.3
• /
• pp.127-133
• /
• 2021

Background: Phosphogypsum is material produced as a byproduct in fertilizer industry and is generally used for building materials. This material may contain enhanced radium-226 (²²⁶Ra) activity concentration compared to its natural concentration that may lead to indoor radon accumulation. Therefore, an accurate measurement method is proposed in this study to determine ²²⁶Ra activity concentration in phosphogypsum sample, considering the potential radon leakage from the sample container. Materials and Methods: The International Atomic Energy Agency (IAEA) phosphogypsum reference material was used as a sample in this study. High-purity germanium (HPGe) gamma spectrometry was used to measure the activity concentration of the ²²⁶Ra decay products, i.e., ²¹⁴Bi and ²¹⁴Pb. Marinelli beakers sealed with three different sealing methods were used as sample containers. Due to the potential leakage of radon from the Marinelli beaker (MB), correction to the activity concentration resulted in gamma spectrometry is needed. Therefore, the leaked fraction of radon escaped from the sample container was calculated and added to the gamma spectrometry measured values. Results and Discussion: Total activity concentration of ²²⁶Ra was determined by summing up the activity concentration from gamma spectrometry measurement and calculated concentration from radon leakage correction method. The results obtained from ²¹⁴Bi peak were 723.4 ± 4.0 Bq·kg^-1 in MB1 and 719.2 ± 3.5 Bq·kg^-1 in MB2 that showed about 5% discrepancy compared to the certified activity. Besides, results obtained from ²¹⁴Pb peak were 741.9 ± 3.6 Bq·kg^-1 in MB1 and 740.1 ± 3.4 Bq·kg^-1 in MB2 that showed about 2% difference compared to the certified activity measurement of ²²⁶Ra concentration activity. Conclusion: The results show that radon leakage correction was calculated with insignificant discrepancy to the certified values and provided improvement to the gamma spectrometry. Therefore, measuring ²²⁶Ra activity concentration in TENORM (technologically enhanced naturally occurring radioactive material) sample using radon leakage correction can be concluded as a convenient and accurate method that can be easily conducted with simple calculation.