• 한국안전학회지
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• 제32권5호
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• pp.54-61
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• 2017

The purpose of this study is to develop standard reference materials for safety control of construction materials considering the required performance of standard materials including flow performance incorporating particles. The flow characteristics of concrete are very complicated depending on mixing proportions of constituent materials, admixtures, amount of mixing, type of mixer, time of mixing, temperature and so forth. Uncertainties and multidimensional properties of concrete have been evaluated through various studies but there are few researches for the development of standard reference material. In this study, based on the rheological concept, the flow performance of construction materials was evaluated to understand the properties of standard reference materials and was finally obtained representing materials which simulate the standard reference materials.

• 대한안전경영과학회:학술대회논문집
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• 대한안전경영과학회 2007년도 춘계학술대회
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• pp.323-333
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• 2007

This paper presents contents of certificates, and use for reference materials. This study also introduces general requirements for the competence of reference material producers. Lastly this paper shows general and statistical principles for certification of reference materials.

• 한국안전학회지
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• 제34권5호
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• pp.111-118
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• 2019

Recently, a variety of special concrete structures have been designed in domestic and overseas construction markets and more advanced construction technology is required. Therefore, it is necessary to secure quantitative construction technology. For this purpose, it is essential to develop a standard reference material having a constant flow performance and quality to evaluate quantitative performance. On the other hand, the flowability of the concrete is greatly influenced by the flowability of the cement paste. Also, in consideration of design strength and workability, mix design is carried out at various mixing ratios according to the purpose of the site. Therefore, in this study, based on the derived components of standard reference materials for cement paste, we suggested mixing ratio of standard reference materials that can uniformly simulate the flow characteristics of cement paste according to W/C. As a result, it was found that the yield stress was determined by the ratio of water and glycerol but plastic viscosity was controled by limestone content. Finally, the ratio of standard reference materials to simulate the rheological range of cement paste by W/C was suggested.

• 한국재료학회지
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• 제16권2호
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• pp.129-136
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• 2006

In order to get basic information on the reference electrode material for the long life Al concentration sensor in zinc galvanizing melt, the workability and stability of fluorine potential cell with $CaF_2$ single crystal electrolyte were examined carefully at constant temperature for six kinds of reference materials (Zn, Sn, Cd, Bi, Pb, Al-Sn alloy + fluorides). Good workability and stability of the sensor were found in sensor with $Bi+BiF_3$ reference electrode. The Al sensor with $Bi+BiF_3$ reference electrode was assembled and was tested in Zn-Al melt with different Al concentration. The EMF was changed rapidly with the change of Al concentration and was stabilized in a short time. Thus the response of EMF was satisfactory for $CaF_2$ sensor. The correlationship between EMF from the sensor and logarithm of Al concentration has been derived from the least square regression method. E/mV=57.515log[wt% Al]+1883.3 R=0.9717 ($0.013{\leq}[wt% Al]{\leq}0.984$) The EMF from Al sensor was increased linearly against logarithm of [wt% Al]. The fluorine potential of Zn-Al melt was also calculated to be in the range of $10^{-60}{\sim}10^{-61}$ Pa for the present experiemental condition.

• 아시아태평양코퍼스연구
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• 제4권1호
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• pp.61-71
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• 2023

This study examines the effects of data-driven learning (DDL)-an approach employing corpora for inductive language pattern learning-on error identification in second language (L2) writing. The data consists of error identification instances from fifty-five participants, compared across different reference materials: the Corpus of Contemporary American English (COCA), dictionaries, and no use of reference materials. There are three significant findings. First, the use of COCA effectively identified collocational and form-related errors due to inductive inference drawn from multiple example sentences. Secondly, dictionaries were beneficial for identifying lexical errors, where providing meaning information was helpful. Finally, the participants often employed a strategic approach, identifying many simple errors without reference materials. However, while maximizing error identification, this strategy also led to mislabeling correct expressions as errors. The author has concluded that the strategic selection of reference materials can significantly enhance the effectiveness of error identification in L2 writing. The use of a corpus offers advantages such as easy access to target phrases and frequency information-features especially useful given that most errors were collocational and form-related. The findings suggest that teachers should guide learners to effectively use appropriate reference materials to identify errors based on error types.

• Bulletin of the Korean Chemical Society
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• 제35권11호
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• pp.3275-3279
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• 2014

A mass balance method for purity assessment of thermolabile organic reference materials was established by combining several techniques, including liquid chromatography with UV/VIS detector (LC-UV), Karl-Fischer (K-F) Coulometry, and thermal gravimetric analysis (TGA). This method was applied to three fluoroquinolones like enrofloxacin, norfloxacin and ciprofloxacin. LC-UV was used to analyze structurally related organic impurities based on UV/VIS absorbance spectra obtained in combination with LC separation. For all three organic reference materials, the UV/VIS spectra of the separated impurities were similar to that of the major component of the corresponding materials. This indicates that the impurities are structurally related to the respective reference material sharing common chromophores. Impurities could be quantified by comparing their absorbances at the wavelength of maximum absorbance (${\lambda}_{max}$). The water contents of the reference materials were measured by K-F Coulometry by an oven-drying method. The total inorganic impurities contents were assayed from ash residues in TGA analysis with using air as a reagent gas. The final purities estimated from results of those analytical techniques were assigned as ($99.91{\pm}0.06$), ($97.09{\pm}0.17$) and ($91.85{\pm}0.17$)% (kg/kg) for enrofloxacin, norfloxacin and ciprofloxacin, respectively. The assigned final purities would be applied to the reference materials which will be used as calibrators for the certification of those compounds in matrix CRMs as starting points for the traceability of their certified values to SI units.

• 분석과학
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• 제15권6호
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• pp.580-583
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• 2002

New approach is developed employing the overall uncertainty obtained from multiple measurements to evaluate the statistical significance for the difference between a given reference value and its measured value determined in a lab. The overall uncertainty is determined by separate combinations of the uncertainties arising from systematic and random effects. It is shown that the uncertainty term in regular t-test can be underestimated by n measurements.

• 한국환경복원기술학회지
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• 제13권2호
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• pp.95-104
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• 2010

The purpose of this study is to analyze the correlation between physical stream characteristics and bed materials in natural rivers. Accordingly, four natural rivers were selected reference streams, they were Nam river, Sumjin River, Naesung River and Han River. Grain size distributions of bed materials were gravels, cobbles and boulders in Han river and Nam river, were sand, gravels, cobbles and boulders in Sumjin river and were sand in Naesung river. Four reference streams were divided into each two reference reaches (straight and bend) by plan and profile characteristics of naturally meandering stream. Therefore various reference reaches were chosen in the aspect of physical stream characteristics and grain size distributions. The results investigated and analyzed are as follows. The streams that grain sizes distributions of river bed materials were coarse were stable because they had variety of bed slope without sediment deposition, and then the riffles frequency and the physical characteristics were various. Also, velocitydepth regime were various in four kinds, and the response parts for water level change were small, so that channel flow status were stable and excellent condition. On the other hand, sand river that grain sizes distributions of river bed materials were fine had not the variety of parameters as velocity-depth regimes, sediment deposition, channel flow status and riffles frequency, so that the physical stream characteristics were not various.

• Nuclear Engineering and Technology
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• 제48권2호
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• pp.299-303
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• 2016

Prompt gamma activation analysis using a thermal neutron-guided beam at Japan Atomic Energy Agency JRR-3M was applied for the precise determination of Si in silicon nitride ceramic reference materials [Japan Ceramic Reference Material (JCRM) R 003]. In this study, the standard addition method coupled with internal standard was used for the nondestructive determination of Si in the sample. Cadmium was used as internal standard to obtain the linear calibration curves and to compensate for the neutron beam variability. The analytical result of determining Si in JCRM R 003 silicon nitride fine powder ceramic reference materials using prompt gamma activation analysis was in good agreement with that obtained by classical gravimetric analysis. The relative expanded measurement uncertainty (k = 2) associated with the determined value was 2.4%.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.84-89
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• 2007

In order to guarantee the safety of the facility systems, one of the essential components is information on mechanical properties of materials used for the construction. However, acquisition or accumulation of the mechanical property data in industrial fields is limited because this operation does not yield profit, excepting few materials production companies. Corresponding to the urgent needs and poor economical features, the MOCIE has founded the National Center for Standard Reference Data in the KRISS and also designated the Data Center of Mechanical Properties for Metallic Materials (DCMP) as a principal operating section. The DCMP plays roles of collection, edition and evaluation of the mechanical data and development of reference standards. In this study, several functions of the DCMP and standardization procedures of mechanical properties data will be introduced the prospective of standard reference researches will be discussed based on active feedbacks from industrial fields.