• Journal of the Korean Recycled Construction Resources Institute
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• v.2 no.4
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• pp.354-359
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• 2014

The objective of this study is to examine the fatigue behavior in compression of normal-weight and lightweight concrete mixtures with high volume supplementary cementitious material(SCM). The selected binder composition was 30% ordinary portland cement, 20% fly-ash, and 50% ground granulated blast-furnace slag. The targeted compressive strength of concrete was 40 MPa. For the cyclic loading, the constant maximum stress level varied to be 75%, 80%, and 90% of the static uniaxial compressive strength, whereas the constant minimum stress level was fixed at 10% of the static strength. The test results showed that fatigue life of high volume SCM lightweight concrete was lower than the companion normalweight concrete. The value of the fatigue strain at the maximum stress level intersected the descending branch of the monotonic stress-strain curve after approximately 90% of the fatigue life.

• Computers and Concrete
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• v.22 no.2
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• pp.183-196
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• 2018

The rheological behaviour of high strength self compacting concrete (HS-SCC) studied through an experimental investigation is presented in this paper. The effect of variation in supplementary cementitious materials (SCM) $vis-{\grave{a}}-vis$ four different types of processed crushed sand as fine aggregates is studied. Apart from the ordinary Portland cement (OPC), the SCMs such as fly ash (FA), ground granulated blast furnace slag (GGBS) ultrafine slag (UFS) and micro-silica (MS) are used in different percentages keeping the mix -paste volume and flow of concrete, constant. The combinations of rheology, strength and durability are equally important for selection of mixes in respect of high-rise building constructions. These combinations are referred to as the rheo-strength and rheo-durability which is scientifically linked to performance based rating. The findings show that the fineness of the sands and types of SCM affects the rheo-strength and rheo-durability performance of HS-SCC. The high amount of fines often seen in fine aggregates contributes to the higher yield stress. Further, the mixes with processed sand is found to offer better rheology as compared to that of mixes made using unwashed crushed sand, washed plaster sand, washed fine natural sand. The micro silica and ultra-fine slag conjunction with washed crushed sand can be a good solution for high rise construction in terms of rheo-strength and rheo-durability performance.

• Transactions of Materials Processing
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• v.10 no.1
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• pp.35-41
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• 2001

The high temperature deformation behavior of SCM 440 can be characterized by the hot torsion test in the temperature ranges of $900^{\circ}C$~$1100^{\circ}C$ and strain rate ranges of 0.05/sec~5/sec. The aim of this paper is to establish the quantitative equation of the volume fraction of dynamic recrystallization (DRX) as a function of processing variables, such as strain rate ($\varepsilon$), temperature (T), and strain ('$\varepsilon$). During hot deformation, the evolution of microstructure could be analyzed from work hardening rate ($\theta$). For the exact prediction of dynamic softening mechanism the critical strain ($\varepsilon_c$), the strain for maximum softening rate ($\varepsilon^*$ and Avrami' exponent (m') were quantitatively expressed by dimensionless parameter, Z/A, respectively. The transformation-effective strain-temperature curve for DRX could be composed. It was found that the calculated results were agreed with the experimental data for the steel at any deformation conditions.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05a
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• pp.5-21
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• 2006

Traditional standards and specifications for concrete have largely been prescriptive, (or prescription-based), and can sometimes hinder innovation and in particular the use of more environmentally friendly concretes by requiring minimum cement contents and SCM replacement levels. In December 2004, the Canadian CSA A23.1-04 standard was issued which made provisions (a) for high-volume SCM concretes, (b) added new performance requirements for concrete, and (c) clearly outlined the requirements and responsibilities for use in performance-based concrete specifications. Also, in December 2003, the CSA A3000 Hydraulic Cement standard was revised. It (a) reclassified the types of cements based on performance requirements, with both Portland and blended cements meeting the same physical requirements, (b) allows the use of performance testing for assessing sulphate resistance of cementitious materials combinations, (c) includes an Annex D, which allows performance testing of new or non-traditional supplementary cementing materials. From a review of international concrete standards, it was found that one of the main concerns with performance specifications has been the lack of tests, or lack of confidence in existing tests, for judging all relevant performance concerns. Of currently used or available test methods for both fresh, hardened physical, and durability properties, it was found that although there may be no ideal testing solutions, there are a number of practical and useful tests available. Some of these were adopted in CSA A23.1-04, and it is likely that new performance tests will be added in future revisions. Other concerns with performance standards are the different perspectives on the point of testing for performance. Some concrete suppliers may prefer processes for both pre-qualifying the plant, and specific mixtures, followed only with testing only 'end-of-chute' fresh properties on-site. However, owners want to know the in-place performance of the concrete, especially with high-volume SCM concretes where placing and curing are important. Also, the contractor must be aware of, and share the responsibility for handling, constructability, curing, and scheduling issues that influence the in-place concrete properties.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2016.05a
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• pp.126-127
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• 2016

In this research, the optimum combination of fly ash (FA) and blast furnace slag (BS) was deduced by analyzing the performance of high volume supplementary cementitious materials (SCMs) cement mortar depending on various combinations of cement, FA, and BS. As a result, increased workability was shown with increased the portion of FA, while air content, setting time, and compressive strength were decreased.

• IE interfaces
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• v.18 no.3
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• pp.234-246
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• 2005

A silicon wafer is a highly customized product made to the individual order varying its electrical and physical characteristics. Therefore, it has distinctive supply chain structure that is different from highly standardized commodity product. For high-volume/high-standardization product, it is general that a main stream of information flow initiated by the production planning of the manufacturers is usually directed to push both ways in a supply chain: upstream to the suppliers and downstream to the customers. Contrastingly, for low-volume/high-customization product, the information flow triggered by the fluctuating customer demand usually propagates upward to the suppliers through the manufacturers. Furthermore, for R &D based hi-technology product like silicon wafer, the interactive information feedback mechanism between manufacturer and customer, which is essential to the new product development process, is to be embedded in the supply chain. This article is a case study of supply chain management system of LG Siltron, a major Korean silicon wafer manufacturer. The SCM system entails special information structure fitting well typical high-variety/high-customization product, and also gives application possibilities to the R&D based high-technology product made to the individual customer order.

• Physical Therapy Korea
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• v.29 no.4
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• pp.255-261
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• 2022

Background: For the elderly, masticatory function is one of the most important oral functions and the masticatory ability is related to the wearing of dentures. Many older people wear dentures for their masticatory function, but a significant number of older people who use dentures have found that they feel uncomfortable when performing their daily activities, such as performing masticating functions or talking. Objects: The purpose of this study is to investigate how the forward head posture (FHP), respiratory function and thickness of masseter (MS), and sternocleidomastoid (SCM) are affected by the presence or absence of dentures in the elderly, and what kind of correlation there is between these variables. Methods: The study was conducted on 11 patients in the normal group and 13 in the denture group. The participant's cognitive ability was evaluated using Mini-Mental State Examination Korean (MMSE-K), and the FHP was evaluated by measuring the craniovertebral angle (CVA). The thickness of the MS and SCM muscles were measured using ultrasound, and respiration was measured with a spirometry. As for the statistical method, the correlation of each variable was investigated using Spearman's correlation coefficient. Results: In the normal group, there was a significant correlation between forced vital capacity (FVC) and forced expiratory volume in 1 second (FEV1) (p < 0.001), and in the denture group, FVC and FEV1 (p < 0.001), maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP) (p < 0.001), CVA and Lt. MS (p = 0.012). Conclusion: CVA and Lt. MS of the denture group have a high negative correlation, it is related that the thickness of MS may be thick when the elderly wearing dentures are FHP.

• Journal of the Korean Recycled Construction Resources Institute
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• v.3 no.3
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• pp.228-236
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• 2015

In this research, the influence of painting materials and applying timing on carbonation and chloride resistances of high volume SCMs concrete was evaluated. As a durability improving method, comparative tests were conducted with painting materials of ERCO (emulsified refined cooking oil), RCO (refined cooking oil), WR (water repellent agent), and ERCO + WR and with painting timings of right after demolding, and 28 days after the wet curing. From the experiment results, in the case of carbonation and chloride resistance, the carbonation depth and chloride penetration depth were decreased when the painting materials were applied in 28 days of wet curing. Additionally, for painting materials, with the order of ERCO, RCO, ERCO+WR, and WR, the carbonation and chloride penentration was delayed. Hence it is considered that ERCO shows the most favorable performance of resistance against carbonation and chloride penetration.

• Journal of the Korean earth science society
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• v.35 no.2
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• pp.104-114
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• 2014

The variation of acidity, conductivity, and ion components in precipitation depending on the dominant wind direction was investigated from January, 2009 to December 2009 in Busan, Korea. Both southwesterly and northeasterly winds were dominant in Busan area. The volume-weighted mean acidity showed pH 7, and the high conductivity indicated 200 ${\mu}scm^{-1}$ in westerly wind. The volume-weighted mean equivalent concentration showed higher value of $K^+$ and $Cl^-$ in all wind directions. The composition ratio of $NO{_3}^-/SO{_4}^{2-}$ showed over 3 in northerly wind. The neutralization factors have been found to have higher value for potassium ion in northeasterly, easterly, southwesterly, and westerly winds compared with different wind directions, which indicated significant neutralization of acidic components over the region by potassium. Also, the concentration of sea salt has been found over 800 ${\mu}sm^{-3}$ in northeasterly and southwesterly winds. Air masses passing through Manchuria, Inner Mongolia plateau, China, and Russia in spring, autumn, and winter covered Busan, Korea in northerly, westerly, and northwesterly winds. However, air masses passing through the ocean in summer covered Busan, Korea in easterly, northeasterly, and southwesterly winds. Therefore, the variation of acidity, conductivity, and ionic components contained in precipitation shows each seasonal characteristics with prevailing wind systems between the continental and coastal area in Busan, Korea.

• Journal of Korea Port Economic Association
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• v.30 no.4
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• pp.219-254
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• 2014

Due to the recent development of globalization and supply chain management, growth of international trade has led to increasing cargo volume around the world. Since maritime logistics environments have changed, increased container ship size, improvement of harbor equipment, global port operation and rapid technological development have had an significant effects on shipping and port industry, which is contributing to competitiveness of port. Since a larger volume of port throughputs are generally regarded as an indicator of the more competitive port, inefficient port operation could reduce its competitiveness. On the other hand, high efficient ports could increase their competitive power while increasing cargo volume. This study aims at comparing competitiveness of the ports in the Northeast Asia by investigating changes of container throughputs and evaluating efficiency performance of ports. Shift-Share analysis and Data Envelopment Analysis(DEA) have been conducted with 21 Northeast Asian ports and then separated them into 4 groups for comparative analysis to identify competitive position of each port. The results of this study show that Incheon and Gwangyang port have been decreased container cargo volume, while volume of Busan port would increase by means of active marketing, various route development and incentive policy for the port.