• Bulletin of the Korean Chemical Society
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• v.35 no.3
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• pp.821-827
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• 2014

An isotope dilution liquid chromatography tandem mass spectrometry (ID LC-MS/MS) method has been developed and applied to the determination of arsenobetaine (AsB, ${(CH_3)_3}^+AsCH_2COO^-$) from oyster candidate certified reference material (CRM). The exact matching isotope dilution approach was adopted for accurate determination of AsB using $^{13}C_2$-labeled AsB as an internal standard. Efficiencies of different AsB extraction methods were evaluated using a codfish reference material and a simple sonication method was selected as the method of choice for the certification of the oyster candidate CRM. The hydrophilic interaction liquid chromatography (HILIC) combined with electrospray ionization tandem mass spectrometry (ESI/MS/MS) in selected reaction monitoring (SRM) mode was optimized for adequate chromatographic retention and robust quantification of AsB from codfish and oyster samples. By analyzing 12 subsamples taken from each 12 bottles systematically selected from the whole oyster CRM batch, the certified value of AsB was determined as $6.60mg{\cdot}kg^{-1}{\pm}0.31mg{\cdot}kg^{-1}$ and it showed excellent between-bottle homogeneity of less than 0.42%, which is represented by relative standard deviation of 12 bottles from the CRM batch. The major source of uncertainty was the certified value of the AsB standard solution.

• Journal of the Society of Naval Architects of Korea
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• v.57 no.2
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• pp.80-87
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• 2020

As the Arctic sea ice decreases due to various reasons such as global warming, the demand for ships and offshore structures operating in the Arctic region is steadily increasing. In the case of sea ice, the anisotropy is caused by the uncertainty inside the material. For most of the research, nevertheless, estimating the ice load has been treated deterministically. With regard to this, in this paper, a four-point bending strength analysis of an ice specimen was attempted using a stochastic finite element method. First, spatial distribution of the material properties used in the yield criterion was assumed to be a multivariate Gaussian random field. After that, a direct method, which is a sort of stochastic finite element method, and a sensitivity method using the sensitivity of response for random variables were proposed for calculating the probabilistic distribution of ice specimen strength. A parametric study was conducted with different mean vectors and correlation lengths for each material property used in the above procedure. The calculation time was about ten seconds for the direct method and about three minutes for the sensitivity methods. As the cohesion and correlation length increased, the mean value of the critical load and the standard deviation increased. On the contrary, they decreased as the friction angle increased. Also, in all cases, the direct and sensitivity methods yielded very similar results.

• The Korean Journal of Pesticide Science
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• v.20 no.3
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• pp.211-220
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• 2016

This study was to develop the analytical reference material of green-pepper for multi-residue analysis of pesticides. According to the ISO Guide 35, ISO Guide 13528 and EURL-PT protocol, the homogeneity, stability, assigned value and uncertainty were calculated to assess if it was suitable to be used as the proficiency test or quality control. The values of the within-bottle standard variation ($s_{wb}$) and the between-bottle standard variation ($s_{bb}$) were 1.7~3.7% of assigned value according to the requirement of the ISO guide 35. And, the uncertainty ($u^*{_{bb}}$) due to inhomogeneity was 0.8~1.1% for all pesticides. The storage stabilities of ten-pesticides at various conditions were assessed. For all target pesticides, the slop ($b_1$) values were smaller than the corresponding values of $[t_{0.95,n-2}{\times}s(b_1)]$ specified by the ISO guide 35, indicating that there were no statistically significant decreases in the concentration of the target pesticides when the analytical reference material was stored at room temperature ($20{\sim}30^{\circ}C$) for 7 days, freezing ($-20^{\circ}C$) for 30 days and deep freezer ($-80^{\circ}C$. except for bifenthrin, fenpropathrin) for 245 days. For proficiency test by using it developed by Korea Institute of Toxicology, inter-lab test was performed with eight organization performing the residual pesticide analysis. We found that there were some different results among them. Some were assessed as questionable or unacceptable for two pesticides and one organization didn't analyze the six pesticides. From these results, this green-pepper analytical reference material containing ten-pesticides could be used as a tool for the proficiency test to improve the reliability or consistency for pesticide residue's results.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.10a
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• pp.113-118
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• 2009

A designer regards the vibration system as a linear system. However, in real world, nonlinearity of a vibration system should exist caused by various factors like manufacturing conditions or uncertain material properties. So, properties of a spring and a damper which are consisting the vibration system have statistical distribution. Therefore, a designer needs to analyze the statistical nonlinearity in a vibration system. In this paper, $1^{st}$ Taylor series expansion method and univariate dimension reduction method apply to a performance measure of nonlinear vibration system, and compare each result. And then, merits and demerits of each method are discussed. For apply more actual problem, a performance measure population is estimated based on design variable samples like properties of spring or damper.

• Journal of the Korea Furniture Society
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• v.23 no.1
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• pp.1-9
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• 2012

Sustainable furniture designs are expressed through reutilization, reuse or redesign of the whole of part of natural materials and existing products. These designs contain natural emotions and show those propensities such as uncertainty, integrity, essentiality and experimental natures. Designs that use natural materials such as wood, bamboo, cork, plants, stones and water have sufficient beauty in themselves and thus these materials are not specially processed but their essence is pursued in those designs. Of those materials, the natural material water is used to pursue the essence of aqua while presenting a new furniture design through an experimental method. The circularity of aqua shares its meaning with the circularity of sustainable designs. In addition, the liquidity of aqua will be grafted onto IT technology to express variable shapes in order to present a new direction of furniture designs.

• Proceedings of the Korea Database Society Conference
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• 1999.06a
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• pp.281-287
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• 1999

Decision class analysis (DCA) is viewed as a classification problem where a set of input data (situation-specific knowledge) and output data (a topological leveled influence diagram (ID)) is given. Situation-specific knowledge is usually given from a decision maker (DM) with the help of domain expert(s). But it is not easy for the DM to know the situation-specific knowledge of decision problem exactly. This paper presents a methodology fur sensitivity analysis of DCA under incomplete information. The purpose of sensitivity analysis in DCA is to identify the effects of incomplete situation-specific frames whose uncertainty affects the importance of each variable in the resulting model. For such a purpose, our suggested methodology consists of two procedures: generative procedure and adaptive procedure. An interactive procedure is also suggested based the sensitivity analysis to build a well-formed ID. These procedures are formally explained and illustrated with a raw material purchasing problem.

• Journal of Power System Engineering
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• v.20 no.4
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• pp.38-43
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• 2016

Safety-related equipments of Nuclear Power Plants(NPP) have to perform environmental qualification test in accordance with IEEE-323 standards. However, non-metallic materials replace new one regularly instead of the test because they are considered as consumable parts. In this study, the seven kinds of non-metallic materials are selected and their activation energy was experimentally evaluated with uncertainty analysis by using thermogravimetric analyzer(TGA). In order to obtain activation energy of non-metallic materials, mass difference, temperature raising rate and conversion rate on the specimen are analyzed. It is postulated that the three experiment conditions are important to get a reliable activation energy. This postulate was experimentally confirmed using Arrhenius equation and Flynn-Wall-Ozawa analysis.

• Proceedings of the Korea Concrete Institute Conference
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• 1989.10a
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• pp.69-72
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• 1989

It is widely recognized that the strength of reinforced concrete members has characteristics of random variations due to the variability of the mechanical properties of concrete and steel, the dimensional error as well as incorrect placement of reinforcing bars. In those sources of randomness, variations in concrete strength may be the one affecting the strength of R.C. members most. The concrete strength is usually assumed to have large uncertainty due to the variations in many factors, such as material properties, proportions of the concrete mix, methods of mixing, transporting, placing and curing, etc. In this study, the random characteristics inherent in the strength of field-cast concrete have been examined based on the data collected by testing standard cylinders made of field-cast concrete and cured under in-situ condition.

• Proceedings of the Korea Inteligent Information System Society Conference
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• 1999.03a
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• pp.281-287
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• 1999

Decision class analysis (DCA) is viewed as a classification problem where a set of input data (situation-specific knowledge) and output data(a topological leveled influence diagram (ID)) is given. Situation-specific knowledge is usually given from a decision maker (DM) with the help of domain expert(s). But it is not easy for the DM to know the situation-specific knowledge of decision problem exactly. This paper presents a methodology for sensitivity analysis of DCA under incomplete information. The purpose of sensitivity analysis in DCA is to identify the effects of incomplete situation-specific frames whose uncertainty affects the importance of each variable in the resulting model. For such a purpose, our suggested methodology consists of two procedures: generative procedure and adaptive procedure. An interactive procedure is also suggested based the sensitivity analysis to build a well-formed ID. These procedures are formally explained and illustrated with a raw material purchasing problem.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.672-675
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• 1995

Because of a sudden growth of the research of fatigue failure, recent machines or structures have been designed by damage tolerance design in many fields. Consequently, it is the most primary factor to clarity the specific character of fatique failure in the design of machines or structures considering reliability. A statistical analysis is required to analyze the outcome of an experiment or a life estimate by reason of that fatigue failure contains lots of random elements. Reliability analysis which has tukenn the place of the existing analyses in the consideration of the uncertainty of a material, is a very efficient way. Even reliability analysis, however, is not a perfect way to analyses the uncertainties of all the materials. This thesis would refer to a newly conceived data analysis that the coefficient of a system could cause the ambiguity of the relationship of an input and output.