• Journal of the Korea Concrete Institute
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• v.13 no.2
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• pp.123-129
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• 2001

Pozzolan is to improve the strength and the durability of concrete as a result of the pozzolanic reaction, Broadly speaking, pozzolanic materials can be artificial materials, such as slica fume and fly ash, and natural material, such as rice husk ash, clay, volcanic ash, clayish pozzolan. Hwangtoh is a mineral which belongs to a group of matakaolin, especially halloysite, and the main elements is SiO$_2$, Al$_2$O$_3$, Fe$_2$O$_3$. The purpose of this study is to examine the application of Hwangtoh for the concrete admixtures, the composition of this study is shown as follows. Chapter I is analysis for properties of concrete as the kinds of admixture, and Chapter H is analysis for properties of concrete as the replacement ratio of activated Hwangtoh. As a result of this study, Hwangtoh is found to have high practical use as pozzolanic material, and the pertinent range of replacement ratios of Hwangtoh on cement are 10∼20 %.

• Journal of the Korean Magnetics Society
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• v.24 no.6
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• pp.197-201
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• 2014

As the importance of rare metal is increasing globally, Japan introduced the concept of Strategic Elements in 2004, and started Strategic Elements Project in 2007. The Goal of this project run by MEXT (Ministry of Education, Culture, Sports, Science and Technology) is to develop high-function materials and components that do not use rare or harmful elements by studying the role and characteristics of the elements that compose materials and components and decide their functions and characteristics. In September 2010, Japanese coast guard arrested a Chinese fishing boat near Senkaku Islands (Diaoyudao Islands by China), which escalated to the territory issue and eventually a big diplomatic and economic conflict. In order to put pressure on Japanese Government, China used an economic option, which is the ban of rare earth export to Japan. This incident doubled Japan's motivation to develop Strategic Elements and put more efforts into this Project. MEXT set the following three research areas in February 2012: Study of alternative materials using sufficient and harmless elements, Study of applications for the high-functions of Strategic Elements, Study of practical design for components using Strategic Elements. Through a course of gathering the opinion of professionals, MEXT settled down with the following 4 research and study areas for the Strategic Elements Project in June 2012. 1. Magnetic materials to replace Dy, Nd. 2. Catalyst/Battery materials to replace Pt, Rh/Li, Co. 3. Electronic materials to replace In, Ta. 4. Structural materials to replace Nb, Mo. This paper deals with the first area and reviews the results of the research and study as of now.

• Land and Housing Review
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• v.3 no.3
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• pp.287-297
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• 2012

To develop 80MPa-high strength concrete with ternary cement used in OPC, blast-furnance slag, and fly ash, mixing ratio of blast-furnace slag and fly ash was evaluated in material characteristics before and after hardening of the high strength concrete. According to the evaluated results of material characteristics before and after hardening of the high strength concrete, the flowability and long-term compressive strength increase up to 30% mixing ratio of blast-furnace slag and fly ash. Also, it is superior to characteristics of length change and neutralization due to the use of mineral admixture when compared in test sample mixed with OPC. The evaluated results show that material characteristics of the high strength concrete was the most outstanding performance at blast-furnace slag of 25% and fly ash of 15%. The result of this study will be useful for the development of high strength concrete as a substitute of costly silica fume in the near future.

• Environmental and Resource Economics Review
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• v.23 no.1
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• pp.91-132
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• 2014

We investigate the effect of ICT capital on the demands for labor and energy in manufacturing and electricity gas water industries of Korea, US, and UK. Assuming ICT capital, non-ICT capital, labor, electricity, fuel, and material as input factors for manufacturing and ICT capital, non-ICT capital, labor and energy material as input factors for electricity gas water industry, we estimate the Morishima elasticities of substitution. Considering the relative price changes of input factors, ICT capital has substituted labor in manufacturing and electricity water gas industries of the three countries. ICT capital has substituted both electricity and fuel in US and UK manufacturing. Although ICT capital has substituted electricity and fuel each other in Korean manufacturing, ICT capital is unlikely to decrease the demands for electricity and fuel when considering their relative price changes. ICT capital has substituted energy material in electricity gas water industries of the three countries.

• 기계와재료
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• v.5 no.1 s.15
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• pp.58-66
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• 1993

• 기계와재료
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• v.2 no.2 s.4
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• pp.20-31
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• 1990

• 기계와재료
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• v.1 no.2 s.2
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• pp.135-141
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• 1989

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.1126-1127
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• 2015

최근 환경오염 문제가 대두되면서 친환경 재료로 만들어진 제품에 대한 연구가 진행되고 있다. 그러나 일반적으로 친환경재료는 기존의 재료보다 성능이 낮거나 비싼 가격 때문에 대체하기가 쉽지 않다. 세노스피어는 화력발전소에서 생성되는 부산물중 하나로 기존 재료에 첨가되는 충전재와 유사한 성분으로 구성되어 있으며, 가벼운 것이 특징이다. 본 논문에서는 화력발전소로부터 발생되는 부산물을 절연재료의 충전재로써 활용하는 방안에 대하여 연구하였다. 에폭시수지에 세노스피어 0~100[wt%]와 실리카 0~40[wt%]를 각각 첨가하여 온도변화에 따른 AC 절연파괴강도 및 유리전이온도, 열팽창율을 시험하였다. 절연파괴 실험 결과 세노스피어/에폭시 복합재료는 실리카/에폭시 복합재료에 비하여 높은 성능을 보여주었으며, 유리전이온도와 열팽창계수는 비슷하거나 좋은 성능을 보여주었다. 따라서 세노스피어는 기존에 사용되고 있는 충전재를 대체할 수 있다고 사료된다.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2014.11a
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• pp.151-151
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• 2014

최근 Touch Screen, OLED, Display, 등과 같은 분야에서 투명전도체 재료를 이용한 연구가 활발히 진행되고 있다. 투명전도체의 재료 중 가장 대표적인 물질은 ITO(Indium tin oxide)가 있지만 ITO는 제한된 매장량과 가격 상승 등의 이유로 이를 대체하기 위한 재료 개발이 필요하다. 본 연구에서는 ITO를 대체할 수 있는 나노섬유전기방사 공정을 통해서 100nm 이하의 직경을 가진 고정횡비 Ni 나노섬유를 만들 수 있다.

• Journal of Korea Foresty Energy
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• v.18 no.1
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• pp.37-45
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• 1999

The greenhouse effect becomes the most serious environmental problem due to excessive emission of carbon dioxide. This effect is aggravated with the deforestation, particularly cleaning of tropical forest for agricultural use. As trees sequester carbon dioxide from atmosphere, forest and forest products play an important role in the use and reduction of carbon dioxide. Wood and wood products require far less energy than the alternatives such as steel, aluminium and concrete for production. Considering high probability of increasing costs in the use of fossil fuel, the relatively low energy requirement for wood processing to very important. Also wood and wood products perform as a long-term storage of carbon. Wood is therefore an environmentally desirable resource. Recently, many alternatives have been introduced for industrial use. In selecting resources, many aspects should be taken into consideration. Wood and wood products have less harmful effects on the environment than the alternatives. We should utilize wood and wood products more efficiently, which should be provided based on the sustainable forest management.