• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.209-210
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• 2009

In constuction work, the early compressive strength in reference to the demolding time of side forms is significant on reducing the construction time and improving the economical efficiency. Therefore, this study is investigated the effect of the kind and replacement ratio of mineral admixture on the development of early strength.

• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.421-422
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• 2010

The decision of the form removal time which leads the early assuring strength of the concrete from apartment construction is the fact which is important from reducing the period of works and the economical efficiency side. This study investigates practical application of early strength concrete for reduction of working preiod in apartment construction.

• Journal of the Korean Ceramic Society
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• v.36 no.2
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• pp.130-135
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• 1999

The enhanced slag fineness and the batch water of low water-to-cement ratio(W/C) were employed in order to improve the early strength of blast-furnace slag blended cement at low temperature. A grinding aid was used to grind the blast-furnace slag into the fineness of 6,280$\textrm{cm}^2$/g (Blaine), and this fine slag was then homogeneously mixed with the ordinary Portland cement to produce the blast-furnace slag blended cement containing 40% slag by weight composition. On the other hand, the batch water could be reduced from W/C=0.50 (KS L 5105) to W/C=0.33 through a commercial, naphthalene type superplasticizer. Through the method mentioned above, the early strength of the blast-furnace slag blended cement at low temperature could be enhanced even somewhat higher than the Portland cement strength. And the microsturcture of the cement was studied by both the pore structure analysis and the A.C. impedance measurement.

• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.3
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• pp.182-189
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• 2018

Controlled low strength material(CLSM), known as flowable fill is used sewer. This paper evaluates flowability, segregation, early strength and excavatability of CLSM made using standard soils such as SM, ML, CL, CH. Also, various mix proportions of CLSM containing kaolinite, red soil, Joomun Jin standard soil were developed and the mixing ratio optimized. It was considered as the flowability and early strength were severly affected by W/B, S/B, and early strength and flowability depend on standard soils which means the satisfaction conditions of CLSM were variety of standard soil conditions. Finally, not only optimal mixing proportions were deducted according to standard soil condition but confirmed effectiveness of bleeding and excavatability.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.41 no.11
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• pp.743-748
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• 2017

For diseases that are difficult to detect by conventional imaging techniques, the development of a diagnostic method that allows sensors to be inserted into the human body to aid the diagnosis of local spots of the target tissue, is highly desirable. In particular, it is extremely difficult to determine whether vulnerable plaque can later develop into atherosclerosis using only imaging techniques. However, vulnerable plaques are expected to have slightly different mechanical properties than healthy tissue. In this study, we aim to develop a piezoelectric cantilever-type sensor that can be inserted into the human body and can detect the local mechanical properties of the target tissue. A piezoelectric polymer composite based on $BaTiO_3$ nanoparticles was optimized for fabrication of a piezoelectric cantilever. Next, a micro-cone tip was fabricated at the end of the piezoelectric cantilever by thermal drawing. Finally, stiffness of biological tissue samples was measured with the piezoelectric cantilever sensor for verifying its functionality.

• Journal of the Korea Concrete Institute
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• v.23 no.3
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• pp.347-352
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• 2011

When concrete is worked in cold weather, the methods of using hot air, water and aggregate heating, accelerators are used to prevent early frosting and to improve early strength. But these methods raise problems such as implementation difficulty, high cost, and energy losses. Among the available cold weathering methods, accelerator method is the most economical but with the drawbacks of rapid setting and insufficient workability in the initial hydration stage. Therefore, the tablet method usually used for pharmaceutical field was applied to the accelerator method to compare the controlled reaction time of the new and old accelerator method. Based on the test results, physical and mechanical properties of concrete were tested and the possibility of delaying initial reactions to increase the total reaction time was evaluated. The results showed that when both accelerators and tablet were used, setting-time decreased. Physical properties of concrete were optimal for tablet 0.5% and 1.0%. Also, accelerator 0.5%, tablet 0.5% and 1.0% showed good early strengths.

• Magazine of the Korea Concrete Institute
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• v.10 no.3
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• pp.13-22
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• 1998

• 레미콘
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• no.7 s.48
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• pp.46-55
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• 1996

본고는 한국레미콘공업협회에서 실시한 '96 일본레미콘산업시찰시(96.4.1 ~ 4.7) 일본생콘크리트 중앙기술연구소에서 제공한 자료이다.

• The Bulletin of The Korean Astronomical Society
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• v.21
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• pp.8.1-8.1
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• 1996

• JOURNAL OF ELECTRICAL WORLD
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• s.422
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• pp.76-81
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• 2012

'미션 중심 강소형 조직' 조기 안착, '국민 감동' 기술 개발 성과와 '국가 미래 먹거리' 창출이 소리없이 강한 김호용 원장이 내건 화두이자 KERI의 최종 지향 목표점이다.