In this study, the homogeneity and stability of standard samples for proficiency testing in indoor air quality within the country (formaldehyde, benzene, toluene, ethylbenzene, p-xylene, styrene, TVOC) were evaluated. The procedures and statistical analysis methods applied in ISO/IEC 13528 (2009) and KS A ISO Guide 35 (2005) were applied as evaluation methods. The homogeneity evaluation was a statistical analysis of repeated measurements of each of the 11 ports and between the 11 ports concentration data. As a result, the coefficient of variation (CV) was within the range of 1.9%~5.9%. The difference between the ports was found to be insignificant and met the statistical standard specified in KS Q ISO 13528. The stability evaluation was assessed by the change in concentration over the long-term stability of the standard samples stored for 90 days. The coefficient of variation (CV), which was within the range of 2.6%~9.0%, exhibited changes in the concentration of the long-term stored standard samples. However, the results satisfy the statistical standard specified in KS A ISO Guide 35. Overall, there is no significant difference between the homogeneity of the standard samples by the port and the stability of the long-term stored samples. Therefore, it is considered to be an appropriate method to supply standard samples in an indoor air quality proficiency test.

The National Environmental Specimen Bank (NESB) has set up a plan to develop reference materials in the facility for assuring analytical quality and validating analytical methods for its monitoring samples. Some of the crucial characteristics that reference materials must consist of are homogeneity and stability of both intra and inter-bottles. In this study, we examined the homogeneity and stability of cryogenically-milled muscle samples, from Common Carp (Cyprinus carpio) for total mercury. Homogeneity was tested using ANOVA analysis and regression analysis was used to test short-term stability. The variations of total mercury concentration did not significantly differ between the intra and the inter-bottle (F=0.8, p=0.37). Additionally, relative standard deviation of the total mercury concentration showed low values (2.28%). For the short-term stability test, total mercury variations were not statistically significant as demonstrated by the result of the regression analysis (F ratio = 3.11, p = 0.18). This suggests that the cryogenic-milling process has statistically proven the degree of homogeneity and short-term stability for samples of carp muscles in the chemical analysis for total mercury.

The National Environmental Specimen Bank (NESB) has been sampling and cryogenically preserving various wildlife specimens to monitor bio-accumulations of chemical pollutants since 2010. Recently, the NESB set up a plan to develop reference materials at their facility to assure the analytical quality of and validate the analytical methods for their monitoring samples. One of the crucial characteristics of reference materials is intra- and inter-bottle homogeneity. In this study, we used ANOVA for total mercury concentrations in some samples to validate their homogeneities after milling and homogenization. We examined the intra- and inter-bottle homogeneities of two cryogenically-milled samples (Korean mussel (Mytilus coruscus) and black-tailed gull’s egg (Larus crassirostris). The variations in the total mercury concentrations were not significantly different intra- and inter-bottle (mussel: F=0.74, p=0.67; gull egg: F=1.96, p=0.10). Additionally, the relative standard deviations of the total mercury concentrations showed low values (mussel: 2.02%, gull egg: 1.78%). Therefore, the cryogenic-milling process statistically proves the homogeneity of the materials of mussels and sea gull eggs for chemical analysis for total mercury.

우리나라 전국 43개 기후관측지점을 대상으로 기후 건조지수 추세의 시간적(월별, 계절별, 연별) 동질성을 분석하였다. 또한 43개 기후관측지점을 9개 지역으로 구분하여 이들 각 지역과 전체 9개 지역을 대상으로 시간적 및 지역적인 기후 건조지수 추세의 동질성 유무와 추세정도를 파악하였다. 분석을 위해 43개 기후관측지점의 월별, 계절별 그리고 연별 건조지수를 강수량과 FAO Penman-Monteith식으로 계산된 잠재증발산량으로부터 산정하였다. 또한 산정된 지수를 이용하여 Mann-Kendall 추세분석을 실시하였고, 추세분석 결과(Z scores)를 이용하여 기후 건조지수 추세의 시간적 및 지역적 동질성 분석을 실시하였다. 분석결과에 의하면 9개 각 지역과 전체 9개 지역에서 기후 건조지수 추세는 시간적 및 지역적으로 동질성이 있는 것으로 나타났으나, 추세의 동질성 정도 및 추세정도는 시간적 및 지역적으로 다른 양상을 보였다.