• 한국대기환경학회지
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• 제18권5호
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• pp.355-362
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• 2002

There has been relatively a few studies that focused on evaluation of uncertainty for standard methods by which criteria pollutants are analyzed in ambient air. Especially, uncertainty evaluation has not been made yet for sampling and analysis of airborne NO$_2$. Ambient NO$_2$ has been thought to be a major criteria pollutant worldwide because of the potential of ozone formation as well as of its own toxicity. In this study, we tried to assess uncertainties associated with the every step of sampling and of analytical procedure of Griess-Saltzman method. Quality assurance (QA) and quality control (QC) were also emphasized with the uncertainty characterization. The use of Griess-Saltzman method for ambient NO$_2$ analysis showed very uniform daily concentration distribution with the mean of 10.8 ppb and the standard deviation of 1.08ppb during the sampling period. However, seven daily samples collected at the same sampling time and place exhibited highly different concentration distribution. Therefore, we evaluated uncertainties associated with sampling and analysis through the precise application of ISO Guide. Estimates of expanded uncertainties for a total of 62 samples fell in a relatively broad range of 5.17% to 11.85%. On the other hand. the expanded uncertainties were smaller for the high concentration range of greater than 15ppb.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume II
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• pp.647-650
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• 2006

Compact Airborne Spectrographic Imager (CASI) hyperspectral imagery was acquired over the Little Miami River Watershed (1756 square miles) in Ohio, U.S.A., which is one of the largest hyperspectral image acquisition. For the development of a 4m-resolution land cover dataset, a hierarchical approach was employed using two different classification algorithms: 'Image Object Segmentation' for level-1 and 'Spectral Angle Mapper' for level-2. This classification scheme was developed to overcome the spectral inseparability of urban and rural features and to deal with radiometric distortions due to cross-track illumination. The land cover class members were lentic, lotic, forest, corn, soybean, wheat, dry herbaceous, grass, urban barren, rural barren, urban/built, and unclassified. The final phase of processing was completed after an extensive Quality Assurance and Quality Control (QA/QC) phase. With respect to the eleven land cover class members, the overall accuracy with a total of 902 reference points was 83.9% at 4m resolution. The dataset is available for public research, and applications of this product will represent an improvement over more commonly utilized data of coarser spatial resolution such as National Land Cover Data (NLCD).

• The International Journal of Costume Culture
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• 제12권2호
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• pp.141-152
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• 2009

In this study, the business structure and characteristics of buying offices used by buyers for apparel productions through global sourcing were analyzed in specifics. Data were acquired through in-depth interviews of twelve merchandisers at representative apparel buying offices. The results of this study can be summarized as following. The business structure of a buying office varied depending on the functions, the item characteristics of products to be manufactured or the characteristics of the major buyers who were the customers. Overall, teams were formed by brands or organizations were formed by functions. Functional teams were divided within each brand team when business teams were divided by brands and personnel was divided by brands occasionally within each functional team when business teams were divided by functions. Business teams were composed of MR which managed the overall business about orders such as factory sourcing, price decision and production management and teams with various specialized skills. The teams with specialized skills were composed of Technical team, Fabric Development team, Colorist team, Quality Assurance (QA) or Quality Control (QC) team, Logistics team, Factory Audit team, and etc. For the future directions on the improvements, ways to increase international competitiveness of buying offices need to be researched and many expressed the opinion that it would be effective to move the offices to countries close to buyers or manufacturing locations as most buyers demand lower prices and shorter lead time than before and it is increasing trend for buyers and factories to do business directly without buying offices in the middle.

• 한국환경과학회지
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• 제13권6호
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• pp.519-525
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• 2004

Air pollution from the Daegu industrial complex (Die) in Korea has been a common nuisance and cause of complaints for nearby residents. The current study measured the indoor and outdoor levels of six VOC (benzene, toluene, ethylbenzene, and three isomeric xylenes) at two residential areas with a different proximity to the ODIC, plus the ambient levels at two industrial areas within the boundary of the DDIC. The QA/QC program included the range of correlation coefficient (0.94-0.99) for calibration curves, within the permissible range. Toluene was the most abundant VOC in the ambient air both in residential and industrial areas. Both indoor and outdoor air concentrations of all target VOC except benzene were higher in residential area near the DIC compared to that further away from the DIC. Moreover, the ambient air concentrations of all target VOC except benzene for two industrial sites (A and B) were significantly higher than the outdoor or indoor air concentrations in the two residential areas. The findings further suggested that VOC ambient levels measured in a residential area near the DIC be used as a potential indicator of odor-causing unidentified air pollutants transported from the DIC. Moreover, it was found that the elevated ambient toluene levels outweighed the indoor sources with respect to the environmental exposure of residents nearby the DIC. However, in the residential area further away from the DIC, the toluene indoor sources outweighed the outdoor sources.

• 농약과학회지
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• 제15권4호
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• pp.529-544
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• 2011

분석표준화 관련 국제기관인 ISO, CIPAC 등은 농약제품 시험기관에 대한 정도관리(QC), 숙련도 시험 및 분석법 검증을 수행하기 위한 요구조건을 지침서로 제시하고 있다. 일반적으로, 숙련도 시험은 시험기관의 분석능력 평가를 위하여 시험기관간 비교시험을 바탕으로 시험기관의 수행능력과 기술능력 정도를 판단할 수 있다. 분석법 검증 절차는 정도관리(QC)에서 중요한 단계 중 하나로 특이성, 선택성, 직선성 등의 항목들이 포함되며, 대부분의 국제기관이 농약제품 중 주요성분에 대한 정량분석법에서 재현성, 정확성 및 정밀성 등을 요구하고 있다. 본 연구에서는 농약 이화학시험 분석기관의 시험연구과정 및 결과에 대한 신뢰성을 높이기 위해 국내 외 정도관리에 관한 지침서를 비교 검토하여 국제적으로 표준화된 지침서에 적합한 구체적이고, 효율적인 농약 이화학시험 분석기관의 농약분석법 검증절차 및 시험기관 정도관리 체계(안)를 제안하고자 한다.

• 자원환경지질
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• 제37권1호
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• pp.49-59
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• 2004

The concectration and distribution of contaminants obtained from a contaminated land investigation or an environmental geochemistry survey constitutes the basis of a decision-making process on environmental policies or of scientific researches. As the quality of data determines the reliability of the result, the investigation plan should be adjusted according to the purpose of the investigation. In general, the effort to improve the data quality had been focused mainly on the QA/QC procedures in laboratories. The rapid progress of analytical instrument has also contributed toward improving the analytical precision to a sacrificable degree. Nevertheless, in many cases, it is not the analytical precision that needs improvement for the better precision of overall measurement process: it is rather during the sampling process in the field that is responsible for the poor precision. To assess the data quality on a measured value, ISO recommends to provide information on "measurement uncertainty" along with the measured value. The measurement uncertainty in an environmental measurement context can be explained as the statistical number that expresses the degree of the uncertainty stemming from the sampling and analytical procedures. There is a cost involved in order to improve the precision of sampling and analytical methods so as to decrease the degree of measurement uncertainty. The economical point of compromise in an investigation planning can be achieved when the allowable degree of uncertainty has been set before-hand. The investigation can then be planned accordingly not to exceed the uncertainty limit. Furthermore, if the measurement uncertainty estimated from the preliminary investigation can be separated into sampling and analytical uncertainties, it can be used as a criterion where the resources for the investigation should be allotted cost-effectively to reinforce the weakest link of the whole investigation process. This paper aims to present a method of estimating the level of measurement uncertainty of a measured contamination concentration at a site used as an example and to show how the estimated uncertainty can be applied to serve the particular purpose of an investigation.

• 한국대기환경학회지
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• 제15권4호
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• pp.403-415
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• 1999

To properly assess air pollution levels, application of quality assurance and quality control(QA/QC) is believed to be an essential step. In order to cope with such scientific principle, a field study was designed with an aim of comparing: 1) the methods of calibration for airborne pollutants and 2) the protocols developed for their measurements. Measurements were made at Han Yang University, Seoul during 29 May through 1 June 1998 under the management of the Division of Measurements and Analysis(DMA) of Korean Society for Atmospheric Environment(KOSAE). In this work, we report our results of intercomparative measurements on several gaseous criteria pollutants that were investigated mainly by the two institutes-Seoul National University(SNU) and the Korean Research Institute for Standards and Science(KRISS). Although measurements of major gaseous pollutants had been made routinely by many scientific institutes and organizations in Korea, most scientists involved in those studieswere obliged to do their experiments on the basis of their own procedural steps spaning from the preparation of gaseous standards to the methodological selections for the calibration. Hence, this campaign offered a unique opportunity to examine many important aspects on the measurements of these important gaseous pollutants. In the course of our study, we investigated the compatibility of data sets obtained by the two institutes in concert with reference data sets collected concurrently from a government-managed monitoring station. On the basis of our study, we conclude that different data sets made by different participants during this campaign agree well within the reasonable range of uncertainties.low, which indicated that during this period the potential acidity of precipitation was high but the neutralizing capacity was low. For Spring, pAi was very low but pH was slightly high. This was likely due to the large amount of $CaCO_3$ in the soil particles transported over a long range from the Chinese continent that were incorporated into the precipitation, and then neutralized the acidifying species with its high concentraton.

• 한국환경과학회지
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• 제22권4호
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• pp.471-479
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• 2013

The present study was conducted to judge the applicability of field quality control by children's goods manufacturers by assessing the contents of heavy metals such as Pb and Cd in outdoor play goods for children through measurement using Portable XRF and comparing the results through detailed analyses using ICP. Heavy metal contents of 711 part samples of 505 products were measured using XRF. According to the results, the ratio of products that exceeded the Pb and Cd content standards specified under the Quality Management and Safety Control of Industrial Products Act were 2.4% and 2.6%. Many products certified for self-regulated safety exceeded the standards and thus it was considered that harmful chemical material centered safety management systems would be necessary. Detailed ICP analyses of some products were compared and the results showed deviations of 0.9~80.8% from XRF results. The reasons for this are deviations in the characteristics of measured cross sections and the homogeneity of samples resulting from sample preparation methods, etc. Therefore, it is considered that field quality control will be applicable if measuring methods are efficiently established based on product characteristics and calibration curve preparation methods are established through quality control.

• 한국대기환경학회지
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• 제32권3호
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• pp.305-319
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• 2016

This study was carried out to evaluate the performance of two sampling methods, i.e., adsorbent tubes and canisters, for the measurement of ambient volatile organic compounds (VOCs). A total of 24 target VOCs were selected from a list of 48 priority hazardous air pollutants (HAPs) in Korea. The two sampling methods were investigated with a wide range of performance criteria such as repeatability, linearity, and lower detection limits. In addition, mean relative errors (MRE) and mean duplicate precisions (MDP) were estimated by inter-lab comparison studies for duplicate field samples. Precisions for the two methods appeared to be well comparable with the performance criteria recommended by USEPA TO-15 and TO-17 for canister and adsorbent methods, respectively. Correlations and variations between the VOCs concentrations determined by the two methods were generally good in most cases. However, MREs and MDPs for individual VOCs appeared to be widely ranged, depending on each VOC. This implies that the two methods have its own advantages and disadvantages in determining a variety of VOCs in ambient air, and neither of which has absolute superiority. Finally, 9 of 24 VOCs were found to be difficult to determine by either methods due to their unstability in a canister, and lack of appropriate standard materials. Thus, it is suggested that development of measurement methods for such unstable VOCs is an urgent task from a viewpoint of HAPs management.

• 한국대기환경학회지
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• 제33권3호
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• pp.241-250
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• 2017

Recently, there has been growing interest in the emission characteristics and behavior of anthropogenic mercury compounds from emission sources. It is required to establish a standard for reliable mercury measurement method. Therefore, this study has evaluated the applicability of the new measurement method; Continuous Emission Monitoring (US EPA 30A, CEM). In addition, the reliability evaluation was conducted through Ontario Hydro Method (ASTM D6784, OHM) and Sorbent trap method (US EPA Method 30B). As a monitoring result for three months via CEM from cement kiln, the maximum mercury compounds concentration was about $600{\mu}g/Sm^3$. This is because of the various of raw materials and fuel, and the absence of mercury-control device. The mercury compounds concentrations of OHM, Sorbent trap and CEM were 13.64 $(3.33{\sim}32.41){\mu}g/Sm^3$, $13.94(5.97{\sim}23.44){\mu}g/Sm^3$ and $14.68(6.19{\sim}26.75){\mu}g/Sm^3$, respectively. The relative standard deviations (% RSD) of the three methods were 5.1~40.9%. The result of this study suggest that it is possible to apply the CEM in the cement kiln when, QA/QC such as calibration is verified.