• Journal of the Korea Concrete Institute
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• 제14권3호
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• pp.349-356
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• 2002

This research deals with the properties of fresh and hardened high-performance concrete(HPC) incorporating high-reactivity metakaolin(HRM). The properties of fresh and hardened state concrete were investigated included air content, slump flow, setting time, heat of hydration, compressive strength, resistance to chloride-ion penetration, abrasion and repeated freezing and thawing. The properties of the HRM concrete were also compared with those of the portland cement concrete and silica fume(SF) concrete. The laboratory test results indicate that HRM material can be used as a supplementary cementitious material to produce high-performance concrete.

• Journal of Family Resource Management and Policy Review
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• 제24권2호
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• pp.89-108
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• 2020

The purpose of this study was to analyze the factors influencing life satisfaction in widowhood among older females. Using the sixth Korean Retirement and Income Study (KReIS) supplementary survey data, a total sample of 1,471 women aged 65 or older whose spouse had died were selected, divided into 508 young-old (65-74), 745 middle-old (75-84), and 218 oldest-old (85+). Then, factors influencing the life satisfaction of these three groups were analyzed, based on a combination of perceived health and interpersonal satisfaction levels. It was found that among the young-old group, a higher level of subjective health perception indicated by monthly income and material support and interpersonal satisfaction linked to more frequent participation in community gathering combined for an overall higher level of life satisfaction. For the middle-old group, higher life satisfaction was provided by monthly income, informational support, and material support for subjective health perception and no diseases for interpersonal satisfaction. The oldest-old group with higher life satisfaction referred to monthly income for subjective health perception and no experience in donation activities for interpersonal satisfaction. Based on these findings, this study provides implications for policy and practice to improve the life satisfaction of elderly women who have experienced their spouse's death.

• Advances in concrete construction
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• 제5권1호
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• pp.31-48
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• 2017

Supplementary cementitious materials (SCM) have turned out to be a vital portion of extraordinary strength and performance concrete. Metakaolin (MK) is one of SCM material is acquired by calcinations of kaolinite. Universally utilised as pozzolanic material in concrete to enhance mechanical and durability properties. This study investigates the fresh and hardened properties of conventional concrete (CC) and self compacting concrete (SCC) by partially replacing cement with MK in diverse percentages. In CC and SCC, partial replacement of cement with MK varies from 5-20%. Fresh concrete properties of CC are conducted by slump test and compaction factor tests and for SCC, slump flow, T500, J-Ring, L-Box, V-Funnel and U-Box tests. Hardened concrete characteristics are investigated by compressive, split tensile and flexural strengths at age of 7, 28 and 90 days of curing under water. Carbonation depth, water absorption and density of MK based CC and SCC was also computed. Fresh concrete test results indicated that increase in MK replacement increases workability of concrete in a constant w/b ratio. Also, outcomes reveal that concrete integrating MK had greater compressive, flexural and split tensile strengths. Optimum replacement level of MK for cement was 10%, which increased mechanical properties and robustness properties of concrete.

• Computers and Concrete
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• 제23권1호
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• pp.37-47
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• 2019

In view of the increasing utility of concrete as a construction material, the major challenge is to improve the quality of construction. Nowadays the common problem faced by many of the concrete plants is the shortage of river sand as fine aggregate material. This led to the utilization of locally available materials from quarries as fine aggregate. With the percentage of fines present in Crushed Rock Fines (CRF)or crushed sand is more compared to river sand, it shows a better performance in terms of fresh properties. The present study deals with the formulation of SCC mix design based on the chosen plastic viscosity of the mix and the measured plastic viscosity of cement pastes incorporating supplementary cementitious materials with CRF and river sand as a fine aggregate. Four different combinations including two binary and one ternary mix are adopted for the current study. Influence of plastic viscosity of the mix on the fresh and hardened properties are investigated for SCC mixes with varying water to cement ratios. It is observed that for an increasing plastic viscosity of the mix, slump flow, T500 and J-ring spread increased but V-funnel and L-box decreased. Compressive, split tensile and flexural strengths decreased with the increase in plastic viscosity.

• Journal of the Korean Recycled Construction Resources Institute
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• 제12권1호
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• pp.82-93
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• 2024

Since the cement industry generates more than 60 % of CO₂ during the clinker production process, supplementary cementitious materials are used worldwide to reduce CO₂ efficiently. Mainly used supplementary cementitious materials such as blast furnace slag and fly ash, which are used in various industries including the cement industry, concrete admixtures, and ground solidification materials. However, since their availability is expected to decrease in the future according to the carbon neutrality strategy of each industry, new supplementary cementitious materials should be used to achieve the cement industry's goal for increasing the additive content of Portland cement. Limestone is a material that already has a large amount in the cement industry and has the advantage of high grinding efficiency, so overseas developed countries established Portland limestone cement standards and succeeded in commercialization. This study was an experimental study conducted to evaluate the possibility of utilizing domestic PLC, the effect of fineness and replacement ratio on the physical properties of cement was investigated, and the environmental impact of cement was evaluated by analyzing CO₂ emissions.

• IE interfaces
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• 제12권4호
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• pp.575-585
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• 1999

This study develops and operating software for a model plant. The model plant consists of an AS/RS system, two machining centers, an assembly line, and supplementary material handling equipments. Devices of each component are connected with the IBS RT24 DIO 16/16-T I/O module. Each I/O module communicates digital signals with the INTERBUS controller board via SUB-D 9 Connector cable. This study is a previous stage for developing an educational CIM software. Petri Nets is used for modelling the storage/retrieval of the AS/RS system, the flow of workpieces and the assembly line for parts. The operating software is coded with Microsoft Visual $C^{++}$ 5.0 and Interbus Library which is a software driver for the controller board. The operating software can be run on a MS Windows 95. Microsoft Access is used for the implementation of databases for BOM, AS/RS, and parts.

• Journal of Applied Biological Chemistry
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• 제60권1호
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• pp.29-33
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• 2017

The methanol extract of Rhododendron mucronulatum for. albiflorum (RMFA) stems inhibited aldose reductase (AR) activity. The RMFA fractions obtained by stepwise extraction with solvents of different polarity were tested for AR inhibition in vitro using the lens of a rat. Among them, the ethyl acetate (EtOAc) fraction inhibited AR more than the other fractions. Quercetin (1) from the EtOAc fraction showed a high AR inhibition with $IC_{50}$ of $2.11{\mu}M$. The stems of RMFA contained the highest amount (5.12 mg/g extract) of quercetin. Our results suggest that RMFA, which contained quercetin, could be a useful material for the development of supplementary functional foods.

• Asian Pacific Journal of Cancer Prevention
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• 제14권12호
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• pp.7761-7762
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• 2013

Alternative strategies such as visual inspection of cervix with acetic acid, are real time, economical and easily implemented methods for cervical cancer screening. However, variable sensitivity and specificity have been observed in various community based studies. The possible reasons could include variation in man power training, light source used for visualization, and preparation of diluted (4-5%) acetic acid and its storage. A standardized protocol for training, teaching material (easy to understand in the local language) for trainees, supervision and reinforcement by intermittent and supplementary training to check the quality of their observation, a standard protocol for preparation dilute acetic acid and its storage and a standard good light source (equivalent to day light) are needed to minimize the variation in sensitivity and specificity of VIA in community settings.

• Journal of Aerospace System Engineering
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• 제7권3호
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• pp.58-64
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• 2013

The paper presents the comprehensive studies of ISTQB(International Software Testing Qualification Board) for the reliable software development system in term of various aspects. It is critical to understand how the software testing is achieved is to efficiently manage the development process, to reduce the development cost, and to ultimately ensure the safety of the entire software system. This study may provide an enriched understanding about the rationale and true intent the behind software development model and testing design methods of ISTQB on software developer, test analysts, test engineers. In addition, this paper may serve as a useful supplementary material for the avionic engineers to establish the new regulations in avionic industries.

• Proceedings of the Korea Concrete Institute Conference
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• 한국콘크리트학회 2003년도 가을 학술발표회 논문집
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• pp.277-280
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• 2003

The purpose of this study is for the active use of the fly ash, which is a by-product of the combustion pulverizes coal thermal power plants, to compensate for the lack of landfill and for conservation of energy, by using fly ash as the supplementary cementitious material, and to prove its possibility as the related products of the cement. First of all, we examined strength development of Micro grinding fly ash by elevating its fineness and using $Na_{2}SO_{4}$ as an activator to elevate pozzolanic reaction of fly ash. Following fly ash replacement ratio and curing temperature we hope to prove its properties to suggest its possibility in the concrete and cement industry. In case of water curing, the more fineness and higher annexing of activator is, the higher strength is, and the higher curing temperature is the more pozzolanic reaction happens.