• The Journal of Engineering Geology
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• v.26 no.1
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• pp.101-115
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• 2016

We carried out laboratory material tests on two cements (KS-1 ordinary Portland and Class G) with changing W/S (Water/Solid) and the content of fly ash in order to evaluate their physical and mechanical properties. The specimens of KS-1 ordinary Portland cement were prepared with varying W/S (Solid=cement) in weight, while those of Class G cement were prepared with changing the content of fly ash in volume but maintaining W/S (Solid=cement+fly ash). The results of the material tests show that as the W/S in KS-1 ordinary Portland cement and the content of fly ash in Class G cement increase, the properties (density, sonic wave velocity, elastic constants, compressive and tensile strengths, thermal conductivity) decrease, but porosity and specific heat increase. In addition, an increase in confining pressure and in the content of fly ash leads to plastic failure behavior of the cements. The laboratory data were then used in a stability analysis of cement sheath for which an analytical solution for computing the stress distribution induced around a cased, cemented well was employed. The analysis was carried out with varying the injection well parameters such as thickness of casing and cement, injection pressure, dip and dip direction of injection well, and depth of injection well. The analysis results show that cement sheath is stable in the cases of relatively lower injection pressures and inclined and horizontal wells. However, in the other cases, it is damaged by mainly tensile failure.

• Journal of the Korean Recycled Construction Resources Institute
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• v.5 no.3
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• pp.223-229
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• 2017

When concrete is exposed to neutron rays for a long time, the concrete tends to become activated. If activated, it is classified as middle or low level radioactive waste. However, the great amount of the activated concrete is hard to dispose. In this study, low-activation cement was developed for decreasing the activated waste from shielding concrete around nuclear reactor. Furthermore, the manufactured low-activation was analyzed with activation nuclide Eu, Co. The low-activation cement showed great advantage for low-activation with detecting none of Eu and 3.75ppm of Co while ordinary portland cement showed 0.4~0.9ppm of Eu, 5.5~19.8ppm of Co content. As the results of physical properties of the low-activation cement, it is similar to type 1 ordinary portland cement and accords with type 4 low heat portland cement. Meanwhile, as for the chemical properties of the cement, it accords wite type 1 and 4 at the same time.

• Cement Symposium
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• s.37
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• pp.37-46
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• 2010

• Cement Symposium
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• s.40
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• pp.46-54
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• 2013

• Cement Symposium
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• s.39
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• pp.103-110
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• 2012

• Cement Symposium
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• s.39
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• pp.73-82
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• 2012

• Resources Recycling
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• v.27 no.1
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• pp.92-105
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• 2018

The present study was carried out to find a suitable drying method for measuring non-evaporable water contents of various hydraulic inorganic materials. In Part 1 of the paper, the case Ordinary Portland cement is discussed. Various drying methods including vacuum and oven drying, and an ignition, were used for the OPC paste and mortar having different w/c. The sole vacuum drying under room temperature led a fluctuation on measurement of hydration degree, while the sole oven drying also yielded unwanted hydration promotion at the early age. A combination of the vacuum and oven drying was considered as a suitable drying method for the OPC case.

• Cement
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• s.200
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• pp.36-39
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• 2013

포틀랜드 시멘트만이 유일하던 지난 1976년, 제설과정에서 발생하는 부산물인 슬래그(slag)를 재활용한 시멘트를 국내 최초로 생산한 한국C&T(주)는 1985년 무재해 3배 달성업체로 노동부 은탑산업상을 수상한 바 있으며 1986년 증권감독원으로부터 우량기업으로 선정되는 등 양질의 슬래그 시멘트 생산을 통해 연관산업 발전에 이바지해왔다. 신뢰에 기반을 둔 경영과 끊임없는 기술개발을 토대로 2014년 힘찬 도약을 준비해 나가고 있는 한국C&T(주) 김훈석 대표이사를 만났다.

• Journal of the Korean Wood Science and Technology
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• v.12 no.4
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• pp.36-46
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• 1984

In order to investigate the inhibitory index (I) and the effects of hot water extraction treatments and addition of accelerators on the index in hardening of Korean lignocellulosics, portland cement (Type I) and water system, hydration tests were carried out on 8 Korean lignocellulosics, namely, Pinus densiflora, Pinus rigida, Pinus koraiensis, Abies holophylla, Larix leptoiepis, Populus alba-glandulosa, rice husk and rice stalk with or without hot water extraction or chemical additives. The inhibitory index of Pinus densiflora and Pinus rigida found to be suitable under limited conditions for composite without any treatment. With hot water treatment rice husk, Pinus koraiensis, Larix leptolepis, and A hies holophylla were reclassified from not suitable to suitable under limited conditions. Combining hot water extraction with chemical addition of accelerator, calcium chloride of magnesium chloride, Populus alba-glandulosa, Larix leptolepis, and Pinus rigida became highly suitable.

• Resources Recycling
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• v.12 no.5
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• pp.23-28
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• 2003

Converter slag was reduced and modified with the addition of 5~10 weight percent of $SiO_2$, $Al_2O_3$ and $SiO_2+Al_2O_3$. which was water quenched and used as a cement additives. Additive was mixed from 10 to 30 weight percent with ordinary portland cement and made 9 kinds of mixed cement. Compressive strength of mixed cement mortar was tested md compared with com pressive strength of ordinary portland cement mortar. Effect of hydration reaction on the compressive strength of cement mortar was investigated by means of x-ray diffraction and scanning electron microscopy.