• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 추계학술대회 논문집 전기설비전문위원
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• pp.261-262
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• 2008

Damaged glass insulator that is utilized the high-speed railroad in domestic try to find the cause. This paper is investigated on the characteristics of alumina cement as the binder of class insulator. The components of glass insulator ore stub(tin), rod(tin), shed(tempered glass), and alumina cement. If composition of alumina cement is not unified, crack of alumina cement generated. As these results, cracked marks of cement is appeared and composition of alumina cement is not unified. Therefore, it is estimated that main element of long-term degradation is a alumina cement.

• 한국세라믹학회지
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• 제30권4호
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• pp.273-278
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• 1993

Using water vapor (de)sorption isotherm, pore structure analyses were performed for hardened cement pastes by a combination of the "MP-method" for the micropores and the "corrected modelless method" for the wide pores. This work was carried out to investigate the pore structure and to understand the microstructural basis of alumina cement developing much higher strength than Portland cement. Alumina cement shows extremely low microporosity and its wide pores are also composed mainlyof pores with very small radii. And the pore structure analysis results are consistent with the high strength property of alumina cement.y of alumina cement.

• 한국세라믹학회지
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• 제16권3호
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• pp.164-168
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• 1979

In the previous paper, it was reported that formation of desirable calcium alunimate(CA) in clinker was considerably affected by sulfur-contaminated alumina which was prone to form a disadvantageous mineral, $C_4A_3S$. In this study, however, sulphate-free alumina cement was made from sulfur-free alumina refined from alunite and corresponding materials. The major minerals in the clinker were identified by X-ray diffraction patterns as calcium aluminate (CA), calcium dialuminate $(CA_2)$ and dicalcium alumino silicate $(C_2AS)$. The formation of CA was more effective with decreasing contents of silica to 2 per cent or less and sulfur in the refined alumina. Physical properties of prepared alumina cement such as setting time, stability and compressive strength were measured. The values were similar to those of commercial alumina cements.

• 시멘트 심포지엄
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• 29호
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• pp.31-41
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• 2002

• 시멘트 심포지엄
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• 7호
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• pp.15-22
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• 1979

• 한국세라믹학회지
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• 제44권11호
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• pp.633-638
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• 2007

The setting time of alkali activated slag cement tends to be much faster than ordinary Portland cement, and its compressive strength had been higher from the 1 day but became lower than that of the cement on the 28 days. According to the results of the surface observation, weight loss, compressed strength, and erosion depth tests on the sulphuric acid solution. It has been drawn that alkali activated slag cement has a higher sulphate resistance than ordinary Portland cement, and in particular, the alkali activated slag cement added 5 wt% alumina cement has little deterioration on the sulphuric acid solution. The reason why the alkali activated slag cement has higher sulphate resistance than other hardened cement pastes is that it has no $Ca(OH)_2$ reactive to sulphate ion, and there is little $CaSO_4{\cdot}2H_2O$ production causing volume expansion, unlike other pastes. And it is supposed that $Al(OH)_3$ hydrates with high sulphate resistance, which is produced by adding the alumina cement increases the sulfate resistance.

• 한국안전학회지
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• 제26권5호
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• pp.59-64
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• 2011

This paper presents the research results performed to develope the shrinkage-free grout with high early strength. Alumina cement and anhydrite were utilized as the expensive tool to gain the shrinkage-free grout. The compressive strength, length change, and ettringite formation of the grout were investigated with compressive test, length change test, and X-ray diffraction. The more anhydrite was added into the grout, the larger the early expansion of the grout. In addition, the more anhydrite formated the more ettringite. From this study, It was conformed that the grout mixture with shrinkage-free property and high early strength is the mixture with the ratio of alumina cement and anhydrite of 40:60 by weight.

• 시멘트
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• 통권59호
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• pp.26-38
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• 1975

본고는 일본 소야전Cement Co.의 중앙연구소주임연구원으로 있는 Hiroshi Uckikawa 박사가 일본의 Ceramics-Japan지(''74.10)에 기고한 것을 번역한 것으로서 그 내용에 의한 목차는 다음과 같다. 즉 근년에 개발된 새로운 cement로서는 1. 속경성 cement 2) 초속경 cement(jet cement, regulated set cement) 2) Alumina cement 3) 초조강 cement 4) 급경 cement 2. 고강도 cement 3. 내구성 cement 1) 내유산균 cement 2) 내화 cement (1) alumina cement 계 (2) barium, strontium 계 cement (3) 인산 aluminium 계 cement 3) 방사선차폐용 cement 4. 팽창 cement 1) alumine 산, 유산 calcium 수화물의 생성에 의한 것 2) 수산화 calcium의 생성에 의한 것 3) 기타 5. 시공성을 개선한 cement (예: 유정용 cement, 도장용 cement) 등이 있다. 머지 않아 우리나라에서도 cement 품종의 다양화가 필연적인 문제로 대두될 것을 생각하여 본번역문이 다소나마 도움이 되기를 바란다.

• 한국세라믹학회지
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• 제15권4호
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• pp.199-204
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• 1978

In the present investigation, refined alumina obtained from alunite locally available was used as a aluminous source to synthesize monocalcium aluminate $(CA)_3$ the major mineral constituent of alumina cement. The influence of $SiO_2$ and $Fe_2O_3$ contents on the formation of monocalcium aluminate was studied by X-ray diffraction analysis mainly. About 0.8-1.0 of $Al_2O_3/C_3O$ mol ratio and less than 4 percent of $SiO_2$ were desirable for the effective formation of CA. The small amount of alkali and sulphur contents contained in refined alumina from alunite as the impurities were affected to form $C_4A_3S$ and $C_3S_2$, disadvantageous compounds for the alumina cement, therefore the impurities should be restricted in minimum content as possible.

• 한국구조물진단유지관리공학회 논문집
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• 제21권4호
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• pp.124-131
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• 2017

본 연구는 저온환경에서 경화가 가능한 알루미나시멘트 및 아질산염을 사용한 보수용 시멘트 모르타르의 기초성능을 평가하고자 하였다. 이를 위해 국내 건설현장에서 사용되고 있는 보수용 모르타르를 조사 및 선정하였으며, 이를 대상으로 알루미나시멘트, 아질산염을 치환하여 혼입량 조절에 따른 실험평가를 실시하였다. 그 결과, 알루미나시멘트, 아질산염을 보수용 모르타르에 치환하여 사용할 경우 초기 강도발현이 증진되었다. 또한 내화학성이 개선되었고 수축거동이 감소하였으며 동결융해에 대한 저항성이 증대되었다. 알루미나시멘트와 아질산염을 2:1의 비율로 7.5% 치환하여 외부구조물에 시공한 결과 표면상태가 5개월 이상 양호하게 유지되었으며, 실제 외부구조물에 사용성이 우수한 것으로 판단된다.