• Title/Summary/Keyword: chemical measurement

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Development of a Nutritional Supplement Certified Reference Material for Elemental Analysis

  • Lee, Jong Wha;Heo, Sung Woo;Kim, Hwijin;Lim, Youngran;Lee, Kyoung-Seok;Yim, Yong-Hyeon
    • Mass Spectrometry Letters
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    • v.9 no.4
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    • pp.105-109
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    • 2018
  • A certified reference material (CRM) for the analysis of inorganic nutrients in nutritional supplements has been developed. Accurate mass fractions of chromium (Cr), iron (Fe), copper (Cu), and zinc (Zn) were determined by isotope dilution inductively coupled plasma mass spectrometry (ID ICP/MS). The measurement results were used to assign certified values for the CRM, which were metrologically traceable to the definitions of the measurement units in the International System of Units (SI). Production of a candidate reference material (RM) and the certification processes are summarized. Each nutrient in the CRM showed good homogeneity, which was estimated using relative standard deviations of the measurement results of twelve bottles in a batch. This CRM is expected to be an important reference to improve reliability and comparability of nutrient analyses in nutritional supplements and related samples in analytical laboratories.

Measurement uncertainty for QC/QA applied to the chemical analysis (화학 분석 결과의 QA/QC를 위한 측정 불확도)

  • Woo, Jin-Chun;Oh, Sang-Hyub;Kim, Byoung-Moon;Bae, Hyun-Kil;Kim, Kwang-Sub;Kim, Young-Doo
    • Analytical Science and Technology
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    • v.18 no.6
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    • pp.475-482
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    • 2005
  • The expression of uncertainty applied to the chemical analysis is highly recommended with increasing demands upon the systematic quality assurance and control(QA/QC) with ISO 17025. For the quantification of quality source, 7 major common sources of uncertainty, normally contributing to the quality of the chemical analysis, were selected from QA/QC literatures of chemical analysis. They were classified into repeatability, drift, uncertainty in standards, linearity of calibration, homogeneity, stability of sample, and matrix effect. And, the quantification of the sources by means of measurement uncertainty was proposed as a prerequisite steps for QA/QC. Examples applied to the quantification procedures of modelling, combination and expression of standard uncertainty for the 7 major common sources were presented as a reference guide for QA/QC in chemical analysis.

Rheometry of complex fluids

  • Mewis, Jan;Moldenaers, Paula
    • Korea-Australia Rheology Journal
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    • v.11 no.4
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    • pp.313-320
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    • 1999
  • The difficulties involved in measuring rheological characteristics of complex fluids are discussed. Possible measurement errors, related to the complex nature of the sample, are reviewed. They are explained in terms of the various physical and chemical mechanisms that can cause them. This leads to possible strategies and techniques for avoiding measurement errors and for obtaining useful structural information from rheological experiments on complex materials. Finally, future evolutions in rheometry are discussed.

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Work Environment Measurement Results for Research Workers and Directions for System Improvement (연구활동종사자 작업환경측정 결과 및 제도개선 방향)

  • Hwang, Je-Gyu;Byun, Hun-Soo
    • Journal of Korean Society of Occupational and Environmental Hygiene
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    • v.30 no.4
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    • pp.342-352
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    • 2020
  • Objectives: The characteristics of research workers are different from those working in the manufacturing industry. Furthermore, the reagents used change according to the research due to the characteristics of the laboratory, and the amounts used vary. In addition, since the working time changes almost every day, it is difficult to adjust the time according to exposure standards. There are also difficulties in setting standards as in the manufacturing industry since laboratory environments and the types of experiments performed are all different. For these reasons, the measurement of the working environment of research workers is not realistically carried out within the legal framework, there is a concern that the accuracy of measurement results may be degraded, and there are difficulties in securing data. The exposure evaluation based on an eight-hour time-weighted average used for measuring the working environment to be studied in this study may not be appropriate, but it was judged and consequently applied as the most suitable method among the recognized test methods. Methods: The investigation of the use of chemical substances in the research laboratory, which is the subject of this study, was conducted in the order of carrying out work environment measurement, sample analysis, and result analysis. In the case of the use of chemical substances, after organizing the substances to be measured in the working environment, the research workers were asked to write down the status, frequency, and period of use. Work environment measurement and sample analysis were conducted by a recognized test method, and the results were compared with the exposure standards (TWA: time weighted average value) for chemical substances and physical factors. Results: For the substances subject to work environment measurement, the department of chemical engineering was the most exposed, followed by the department of chemistry. This can lead to exposure to a variety of chemicals in departmental laboratories that primarily deal with chemicals, including acetone, hydrogen peroxide, nitric acid, sodium hydroxide, and normal hexane. Hydrogen chloride was measured higher than the average level of domestic work environment measurements. This can suggest that researchers in research activities should also be managed within the work environment measurement system. As a result of a comparison between the professional science and technology service industry and the education service industry, which are the most similar business types to university research laboratories among the domestic work environment measurements provided by the Korea Safety and Health Agency, acetone, dichloromethane, hydrogen peroxide, sodium hydroxide, nitric acid, normal hexane, and hydrogen chloride are items that appear higher than the average level. This can also be expressed as a basis for supporting management within the work environment measurement system. Conclusions: In the case of research activity workers' work environment measurement and management, specific details can be presented as follows. When changing projects and research, work environment measurement is carried out, and work environment measurement targets and methods are determined by the measurement and analysis method determined by the Ministry of Employment and Labor. The measurement results and exposure standards apply exposure standards for chemical substances and physical factors by the Ministry of Employment and Labor. Implementation costs include safety management expenses and submission of improvement plans when exposure standards are exceeded. The results of this study were presented only for the measurement of the working environment among the minimum health management measures for research workers, but it is necessary to prepare a system to improve the level of safety and health.

A Study on the Evaluation of Brinell Standard Hardness Tester and Automatic Indentation Measurement System (브리넬 경도 표준 시험기 및 압입 자국 자동 측정장치의 특성 평가에 대한 연구)

  • Bahng, G.W.;Tak, Nae-Hyung
    • Journal of the Korean Society for Heat Treatment
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    • v.12 no.4
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    • pp.294-302
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    • 1999
  • Evaluation of Brinell standard hardness tester was carried out to secure its application as a national standard for Brinell hardness. Accuracies and reliabilities in load application, indenter diameter and indentation measurement were tested through evaluation of these components. The accuracies of load application for various loading conditions were within the limit of ISO and KS specifications. Errors in the indentation measurement due to the difference in personnel characters were successfully removed by utilising automatic indentation measurement system. In overall, the tester and the indentation measuring system were found to be eligible as a national standard of Brinell hardness.

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Measurement of Adsorption Characteristic Using a Quartz Crystal Resonator (수정진동자를 이용한 흡착특성의 측정)

  • Kim, Byoung Chul;Sung, Ick Gi;Yamamoto, Takuji;Kim, Young Han
    • Korean Chemical Engineering Research
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    • v.47 no.3
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    • pp.368-372
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    • 2009
  • A technique to measure the adsorption characteristic of surface area and pore size distribution is proposed and its performance is examined. While the existing equipment utilizes liquid nitrogen, the proposed uses carbon dioxide at the room temperature leading to the small measuring device with easy operation and short measurement time. The performance of the device has been examined with micro-particle carbon cryogel and bamboo activated carbon. The results from the proposed device compared with those of the adsorption apparatus indicate that the measurement of meso-porous material is comparable but micro-porous material gives some error.

A Study on the Measurement of Halitosis of Human Mouth with Chemical Gas Sensor Arrays (화학 가스센서를 활용한 구취측정 방법에 관한 연구)

  • Lee, Seok-Jun;Kim, Sun-Tae;Kim, Han-Soo
    • Journal of Sensor Science and Technology
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    • v.20 no.4
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    • pp.279-285
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    • 2011
  • This study was carried out to apply chemical gas sensors for the identification of bad breath which is one of the important sensitive problem for the humans' daily life. Seven sensors, including five semiconductor sensors and two electrochemical sensors, were tested for the three panels three times in several conditions. The results showed that the reproducibility of sensors were generally good, and electrochemical sensors showed better reproducibility while semiconductor sensors showed better sensitivity. No rinsing before measurement showed relatively better results in terms of both sensitivity and reproducibility. Semiconductor gas sensors for hydrogen sulfide shows the highest sensitivity, and it was recommended to use the odor-free bag for the measurement of bad breath.