• Proceedings of the Korean Fiber Society Conference
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• 1997.10a
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• pp.270-274
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• 1997

• Cement Symposium
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• s.48
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• pp.6-9
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• 2021

• Journal of the Korea Institute of Building Construction
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• v.16 no.4
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• pp.321-329
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• 2016

The use of ternary blended cement consisting of Portland cement, granulated blast-furnace slag (GGBFS) and fly ash has been on the rise to improve marine concrete structure's resistance to chloride attack. Therefore, this study attempted to investigate changes in chloride attack resistibility of concrete through NT Build 492-based chloride migration experiments and test of concrete's ability to resist chloride ion penetration under ASTM C 1202(KS F 2271) when 1.5-2.0% of alkali-sulfate activator (modified alkali sulfate type) was added to the ternary blended cement mixtures (40% ordinary Portland cement + 40% GGBFS + 20% fly ash). Then, the results found the followings: Even though the slump for the plain concrete slightly declined depending on the use of the alkali-sulfate activator, compressive strength from day 2 to day 7 improved by 17-42%. In addition, the coefficient from non-steady-state migration experiments for the plain concrete measured at day 28 decreased by 36-56% depending on the use of alkali-sulfate. Furthermore, total charge passed according to the test for electrical indication of concrete's ability to resist chloride ion penetration decreased by 33-62% at day 7 and by 31-48% at day 28. As confirmed in previous studies, reactivity in the GGBFS and fly ash improved because of alkali activation. As a result, concrete strength increased due to reduced total porosity.

• Journal of the Korean Chemical Society
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• v.30 no.4
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• pp.359-368
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• 1986

Solvent extraction equilibria of alkali metal cation with crown ether (DC18C6, DC24C8) and HDEHP have been studied. The extraction equilibrium constants increase in the order of, in the DC18C6 system, $Na^+, and in the DC24C8 system, $Rb^+. The species extracted to organic phase are $M_1(crown ether)_1\;(HDEHP)_1$. The magnitude of extraction equilibrium constant is determined by the distribution ratio of crown ether between organic and aqueous phase, and stability constant of crown ether-alkali metal complex.

• Textile Coloration and Finishing
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• v.10 no.4
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• pp.24-29
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• 1998

11종류의 cellulose에 고착된 vinylsulfone(VS)계 반응성 염료(F-type)의 알칼리 가수분해 거동과 염료와 섬유의 결합 안정성을 cellophane film을 이용한 film권층법에 의하여 조사하였다. F-type은 알칼리욕에서 분해되어 VS type을 생성하고 VS type은 가수분해에 의해 hydroxyethylsulfone(Hy)을 생성하거나 cellulose와 재결합하여 F-type을 생성하였다. F-type은 알칼리 처리에 의해 cellulose의 수산기의 위치에 기인하는 bimodal 가수분해 거동(fast and slow hydrolysis)을 나타내었다. Orange 7과 Yellow 17는 cellulose와의 반응성이 높고 F-type의 초기 분해속도가 빠르며 일반적으로 fast 가수분해속도가 slow 가수분해 속도보다 약 5배정도 큼을 알 수 있었다. 또한 조사된 대부분의 염료의 경우 slow 가수분해 속도는 거의 유사함을 알 수 있었다.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.97.1-97.1
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• 2011

저온에서 양이온 고분자막을 사용하는 고분자 연료전지의 경우 뛰어난 성능과 다양한 응용분야로 인해 많은 연구와 실증이 이루어지고 있지만 공기극에서의 느린 산소 환원반응으로 인해 백금과 같은 귀금속의 사용이 불가피하고 백금의 제한된 매장량과 높은 가격으로 인해 상용화가 늦어지고 있다. 그래서 많은 연구자들이 합금 촉매 또는 비귀금속 촉매를 이용한 전극 개발에 집중하고 있다. 알칼리 분위기에서 저가의 전이 금속들이 백금과 비슷한 활성을 보이고 고체 음이온 교환막이 개발됨에 따라 최근 알칼리 연료전지가 다시금 큰 주목을 받고 있다. 그러나 고분자 연료전지와는 달리 아직 촉매나 전해질막, 이오노머의 특성 및 메커니즘에 관해 별로 알려진 것이 없다. 본 연구에서는 직접 개발한 세공충진막 형태의 탄화수소계의 음이온 교환막과 비귀금속 공기극 촉매를 이용하여 막전극접합체(MEA)를 개발하였고 촉매 및 이오노머 함량과 같은 전극 조성, 막전극접합체의 제조 및 체결, 가습이나 가스조성 등의 단위전지 운전조건과 같은 다양한 변수에 대해에 최적 조건을 도출하고자 하였다. 공기극 촉매는 Cu-Fe/C를 이용한 상용 촉매를 이용하였고 이오노머의 경우는 탄화수소계의 상용 제품을 사용하였으며 음이온 교환막에 전극층을 형성하기 위해서는 스프레이 공정을 이용하였다. 단위전지를 통해 성능을 확인하였고 임피던스 및 CV를 통해 전기화학적인 특성을 규명하였다. 조건의 최적화를 통해 상당한 성능 향상을 이루었으나 추가적인 성능 향상 및 내구성 확보 등에 대해 계속적인 실험을 진행할 예정이다.

• Proceedings of the Korean Fiber Society Conference
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• 1991.06b
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• pp.46-46
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• 1991

• KOREAN JOURNAL OF CROP SCIENCE
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• v.53 no.2
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• pp.203-216
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• 2008

This study was conducted to provide the fundamental data based on the analysis of phsyco-chemical characteristics of domestic aroma rice and foreign aroma rice for breeding of aroma rice. The average amylose content of domestic aroma rice and widely cultured domestic traditional rice were 18.1% and 19.0% respectively. The Indica and the Japonica types were 25.6% and 25.0%. In the domestic rice of Tongil and Japonica type, the average protein content were 7.6% and 6.4% respectively. And the average protein content of foreign Indica and Japonica type were 7.6% and 7.0% respectively. And the average protein content of widely cultured domestic traditional rice was 5.6%. The Japonica type of rice shown a low protein content compared with Indica type of rice, and the foreign Indica types of rice exhibited a wide range of protein contents. The average alkali digestive value (ADV) of Tongil type of the domestic aroma rice was about 5.0 and the value of Japonica type was about 6.0. The average ADV of foreign Indica and Japonica type were 4.3 and 5.1 respectively. Also the average ADV of widely cultured domestic aroma rice was about 6.0. The foreign aroma rice were distributed a variable range of ADV value and lower than the both domestic aroma rice and widely cultivated domestic rice. In the whole aspect of the amylogram, the highest viscosity, the lowest viscosity and the last viscosity of the total resources, in domestic aroma rice were clearly lower with the next order, Japonica type of foreign aroma rice, Indica type of foreign aroma rice, Japonica type of domestic aroma rice, widely cultured domestic traditional rice, and Tongil type of domestic aroma rice. It shown the difference aspect of amylograms according to the eco-type of the domestic and foreign aroma and the general rice, and it was distinguishable in difference of the aspect of the amylogram of the endosperm of rice as non-glutinous rice, waxy rice, and middle-waxy rice.

• Journal of the Korea Concrete Institute
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• v.19 no.5
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• pp.577-584
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• 2007

The effect of steel microfibers (SMF) on alkali-silica reaction (ASR) was investigated using two types of reactive aggregates, crushed opal and a pyrex rod of constant diameter. Cracks are less visible in the SMF mortars compared with the unreinforced mortars. Due to crack growth resistance behavior in SMF mortar specimens, the strength loss is eliminated and the ASR products remained well confined within the ASR site. The expansion and the ASR products were characterized by microprobe analysis and inductively coupled plasma (ICP) spectroscopy. The confinement due to SMF resulted in a higher Na and Si ion concentration of the ASR liquid extracted from the reaction site. The higher concentration reduced the ASR rate and resulted in a lower reactivity of the reactive pyrex rods in SMF mortars.

• Journal of the Korean Recycled Construction Resources Institute
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• v.5 no.1
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• pp.29-36
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• 2017

The purpose of this study is to investigate experimentally the effect of types of alkali-activators and curing conditions on the compressive and tensile behavior of fiber-reinforced cementless composites. Two types of alkali-activators and two curing conditions were determined and density test, compressive strength test, and uniaxial tension test were performed. Test results showed that the cementless composite with sodium silicate showed higher performance in terms of strength, tensile strain capacity, and toughness than that with calcium hydroxide and sodium carbonate. The effect of curing conditions depends on the types of alkali-activators.