• IE interfaces
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• v.6 no.1
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• pp.55-65
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• 1993

A nonstandard instrument used in the filed frequently becomes out-of-calibration due to environmental noise, misuse, aging, etc. A substantial amount of loss may result if such nonstandard instrument is used to check product quality and performance. Traditional periodic calibration at the calibration center is not capable of detecting out-of-calibration status while the instrument is in use, and therefore, statistical methods need to be developed to check the status of a nonstandard instrument in the field between calibrations. Developed in this paper is a unified measurement assurance model in which statistical calibration at the calibration center and measurement assurance test in the filed are combined. We developed statistical procedures to detect changes in precision and in the coefficients of the calibration equation. Futher, computational experiments are conducted to evaluate how the power of test varies with respect to the parameters involved. Based upon the computational results we suggest procedures for designing effective measurement assurance tests.

• Steel and Composite Structures
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• v.10 no.6
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• pp.475-487
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• 2010

Most of steel structures in various industries are subjected to corrosion due to environmental exposure. Corrosion damage is a serious problem for these structures which may reduce their carrying capacity. These aging structures require maintenance and in many cases, replacement. The goal of this research is to consider the effects of corrosion by developing a model that estimates corrosion loss as a function of exposure time. The model is formulated based on average measured thickness data collected from three severely corroded I-beams (nearly 30 years old). Since corrosion is a time-dependent parameter. Analyses were performed to calculate the lateral buckling capacity of steel beam in terms of exposure time. Minimum curves have been developed for assessment of the remaining lateral buckling capacity of ordinary I-beams based on the loss of thicknesses in terms of exposure time. These minimum curves can be used by practicing engineers for better estimates on the service life of corrosion damaged steel beams.

• Korean Journal of Materials Research
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• v.7 no.8
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• pp.650-653
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• 1997

In large generators in power plants, stator winding insulations is exposed to a combination of thermal, electrical, mechanical, environmental stresses in service. These combined stresses cause insulation aging which leads to final insulation breakdown. In order to identify the breakdown mechanism, the stator winding insulation materials which are composed of mica-epoxy is analyzed by the component of materials with EDS, SEM techniques. We concluded that the potassium ions of mica are replaced by hydrogen ions at boundary area of mica-epoxy and/or mica-mica. It is proposed that through these phenomena, the conductive layers of potassium ions enable high voltage fields of multiple stresses to create voids and microcracks.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.121-122
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• 2006

Paralleled with the development of new materials we need to develop methods and techniques to reveal the environmental interaction and impact of the new materials. Small changes in the chemical structure or product formulation may render the product less environmentally adaptable. Degradation products formed from PLLA were identified after aging in different environments and their assimilation in the biotic environment was shown. Green and degradable hydrogels could be designed from renewable hemicelluloses and lactic acid. Hemicelluloses are a renewable and highly interesting raw material source for new green polymers.

• The Research Journal of the Costume Culture
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• v.13 no.6 s.59
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• pp.990-998
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• 2005

The purpose of the study was to examine Korean elderly women's attitudes toward fashion and to determine formal jacket designs preferred by them. The subjects of the study were older than 50 years who will become aging population in 2014. For data collection, interview investigated 200 copies of questionnaire were collected, and available data used final analysis were 174 volumes. As the results of the principal components factor analysis, it revealed 4 attitudinal factors including cautious attitude, fashion-conscious attitude, ostentatious attitude, and easy-conscious attitude. The subjects divided into two groups, highly involved group and lowly involved group, for each factor. As the result of preference differences by the degree of each attitude, it revealed that the attitudes toward fashion products would significantly influence elderly women's jacket design preferences. The results of the study show that they are a diverse group whose consumer needs and wants vary dramatically and give initial information to assist designing appropriate formal jacket for elderly women.

• Toxicological Research
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• v.7 no.1
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• pp.93-112
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• 1991

This study was carried out to investigate the various factors on induction of experimental hepatocarcinogenesis in Sprauge-Dawley rats. The experimental animals were divided into three Experiment. Experiment I, II and III were began rats with initial age of 6, 16 and 55 weeks, respectively. All Experiment were injected intrapertioneal with diethylnitrosamine (DENA` 200 mg/kg) as an intiator and group 3, 4 of Experiment I, II and III were fed on diet containing 0.02% 2-acetylaminofluorene (2-AFF) as a promoter for 6 weeks. Three weeks after two-thirds partial hepatectomy was performed in group 2, 4 of Experiment I & II and group 3 of Experiment III.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.214-218
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• 2007

With the development of high speed railway, traction motors play a critical role in the operation of railway vehicle. This paper describes the use of 1000 pF coupler as a on-line partial discharge (PD) measurement for the assessment of railway traction motor. The PD tests are performed with developed PD analyzer and the 5 model coils such as thermal, electrical, mechanical and environmental aging respectively at various AC voltages. On-line PD tests using 1000 pF couplers show that PD patterns can be detected successfully at 2.3 kV.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.1248-1253
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• 2007

Urban transit or subway stations generally service for a long period of several decades. And, the urban transit or subway is public transportation which lots of people takes every day. During the service time, they are inevitably damaged from environmental corrosion, material aging, fatigue, and the coupling effects with long-term loads and extreme loads. The included damage accumulates and performance degenerates due to the above factors. They would inevitably reduce the resisting capacity of station against the disaster; even they result in collapse with the structural failure under extreme loads. And, if disaster such as earthquake, fire, etc. happens, it causes huge property damage and threatens the human lives. Because of these above reasons, the intelligent health surveillance system should be researched and developed for ensuring the safety of station. In this paper, the research plans of the intelligent health surveillance system of urban transit station are presented. And also, the development or establishment directions of this system are suggested.

• Proceedings of the Korean Society of Toxicology Conference
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• 2003.05a
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• pp.76-76
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• 2003

Oxidative stress is considered to be associated with many diseases, such as inflammatory and cardiovascular diseases, aging, and cancer. An important etiological mechanism of these diseases may be a causal relationship between the presence of oxidants and the generation of lipid hydroperoxides derived from enzymatic reactions or xenobiotic metabolism. (omitted)

• Computers and Concrete
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• v.12 no.4
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• pp.377-392
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• 2013

This paper investigates prediction models estimating the hydration properties of concrete, such as the compressive strength, the splitting tensile strength, the elastic modulus,and the autogenous shrinkage. A prediction model is suggested on the basis of an equation that is formulated to predict the compressive strength. Based on the assumption that the apparent activation energy is a characteristic property of concrete, a prediction model for the compressive strength is applied to hydration-related properties. The hydration properties predicted by the model are compared with experimental results, and it is concluded that the prediction model properly estimates the splitting tensile strength, elastic modulus, and autogenous shrinkage as well as the compressive strength of concrete.