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높은 입체선택성을 나타내는 고리카보네이트의 친핵성 치환반응과 광학활성인 β-Hydroxy Ester의 합성
강석구,박동철,노호식,윤승현,홍덕표 성균관대학교 기초과학연구소 1995 論文集 Vol.46 No.1
The nucleophilic ring opening of the cyclic carbonates of optically active threo-2,3-dihydroxy esters afforded α-substituted β-hydroxy esters with highly regio- and stereoselectivity under mild conditions. The α-substituted β-hydroxy esters were transformed to β-hydroxy esters
콘크리트 표면성능개선에 의한 중성화억제방안에 관한 실험적 연구
강석표,김경덕,이병기,길배수,홍성윤,김무한 대한건축학회 2004 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.24 No.1(구조계)
Penetration of concrete by aggressive materials in solution may cause an undesirable effect on concrete durability, for instance when Ca(OH)₂ is being leached out or an attack by aggressive liquids takes place. In particular, carbonation occurs in concrete because the calcium bearing phases present are easily attacked by carbon dioxide and converted to calcium carbonate from surface of concrete, It has been known that the durability of reinforced concrete structure is concerned with the surface performance of concrete which affects on the carbonation occurred by invasion of CO₂ gas and the corrosion of steel bar occurred by O₂ In this paper, the effects of carbonation resistance by improvement of surface performance for concrete are investigated according to the accelerated carbonation test. It is believed that the carbonation resistance of concrete has been significantly improved by the application of penetrative hardening agent due to the formation of a dense surface.
홍석표,최상구,강석근,이화우 全北大學校 1995 論文集 Vol.39 No.-
Epoxy resins were mixed with asphalt solution in the range of 0 - 60phr for the total components. The blending properties, curing properties, and surface properties for mixtures were investigated experimentally. Compatability of epoxy resins with asphalt were relatively good over mixture temperature 50℃. Interpenetrated polymer networks(IPNs) were partially formed between epoxy resins and asphalt. Increase of hardness was depended on the crosslinking density of epoxy resins and oxidation of asphalt. Defects of coated surface including crater, pinhole, and crack could be improved by adding epoxy resins 20 phr.
조강표,정진택,정명채,김윤석 대한건축학회 2003 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.23 No.2(구조계)
Wind load is evaluated based on Standard Design Loads for Building of AIK(Architectural Institute of Korea), which was obtained from wind-tunnel experiment for an isolated building in open country, actual wind load can be different from the code because of terrain, building geometry, wind direction, separation distance between the buildings. Among them. separation distance is the most important factor. This paper presents the interference factor for sqaue section high-rise building structure, focusing on the separation distance. Interference factor was obtain from the force balance test in a wind tunnel.
김경덕,강석표,홍성윤 대한건축학회 2003 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.23 No.2(구조계)
The natural aggregate will be used up within 10 years due to the great amount of consumption in making of construction materials. Regarding reservation of natural aggregate, the construction waste has to be recycled as one of important constituents of construction materials, typically, concrete. In mortar industry, the demand of fine aggregate is much heavier as industry developed. It is highly essential to think of application study using recycled fine aggregate. In this study, we investigated the effect on basic properties of screeding mortar when recycled fine aggregate is replaced. This study presents document in order to give an applicable guideline for the best use of recycled fine aggregate together with checking properties. We could find that screeding mortar properties is not much influenced by the existence of recycled fine aggregate because particle size distribution is well classified through manufacturing process. As a result, it is considered that application of recycled fine aggregate in dry mortar system is sufficient.
알카리성 부여제 도포에 의한 중성화된 콘크리트의 알카리성 회복성능에 관한 실험적 연구
김무한,권영진,강석표,유재강,이강우 충남대학교 산업기술연구소 2000 산업기술연구논문집 Vol.15 No.1
Concrete is the most commonly used material in construction field and it is the permanent construction material with respect to civil property. But, if concrete loses its alkalinity by CO2 gas, it loses its structural characteristics and results in total collapse in construction field. Therefore. it is needed to be studied the alkali-recovery performance by alkalization agent on carbonated concrete by accelerated carbonation test. In this paper, we investigate recovery performance by impregnating alkalization agent in carbonated concrete, then we evaluate alkali maintenance performance by pH survey in each kinds of finishing materials. The results of this paper can be summarized as follows. 1)Carbonated concrete under pH 10 was recovered its alkalinity to pH 11 at first stage by spreading alkalization agent on its outer surface. 2)After spreading alkalization agent, there is a difference due to types of moreover effect of anti-rust paint and ordinary cement paste were excellent.
증점제를 사용한 고유동콘크리트의 기포조직과 내동해성에 관한 실험적 연구
김무한,권영진,강석표,여동구,김용로,장종호 충남대학교 산업기술연구소 2000 산업기술연구논문집 Vol.15 No.1
Recently, lots of studies for high flowing concrete have been suggested under practical use that it is only a way to solve the confronted problem. However, most studies have been concentrated on the manufacture method and properties of fresh concrete, but there is few studies for the durability of hardened concrete, specially for the freezing and thawing. It is generally known that the frost resistance of concrete is much affected by the air content in concrete and by the air void system. The frost resistance is also believed to vary with the strength of concrete. The purpose of this experimental study is to make a comparison between high flowing concrete using viscosity agent and ordinary concrete about the effect of the viscosity agent, air content and curing method on the frost resistance. As the result of tutus study, the frost resistance have not effect the viscosity agent but effect the different of curing methods.
포러스콘크리트의 기초물성에 미치는 시멘트페이스트의 유동성 및 진동다짐시간의 영향에 관한 실험적 연구
김무한,백용관,최영욱,강석표,김재환,이성일 忠南大學校 産業技術硏究所 2001 산업기술연구논문집 Vol.16 No.2
This study analyzed the influence of paste fluidity and vibration time for fundamental properties of porous concrete. Results of this study were shown as follows: 1) Even if target void ratio is same, void ratio and compressive strength of porous concrete is different according to w/c, paste flow and vibration time. So, In case of target void ratio, we must consider the influence of w/c, past flow and vibration time. 2) Though w/c and vibration time is same, as paste flow increase, all void ratio, continuous void ratio, and compressive strength decrease and difference between upper and lower void ratio increase. 3) Though w/c and paste flow is same, as vibration time increase, all void ratio and continuous void ratio decrease and difference between upper and lower void ratio increase. Also, compressive strength increase by 10 seconds and decease after 10 seconds. 4) As types of superplasticizer is different, all void ratio, continuous void ratio, and compressive strength is different. So, we must give consideration to paste fluidity and vibration time in order that increase of strength of porous concrete and distribution of uniform void.
Effects of red mud and Alkali-Activated Slag Cement on efflorescence in cement mortar
Kang, Suk-Pyo,Kwon, Seung-Jun Elsevier 2017 Construction & building materials Vol.133 No.-
<P><B>Abstract</B></P> <P>Recently AASC (Alkali Activated Slag Cement) is utilized for construction materials in order to reduce environmental load like abundant CO<SUB>2</SUB> emission. Red mud which is a byproduct from Bauxite ores process has a strong alkali component containing 10.0–15.0% of Na<SUB>2</SUB>O, so that it can be used for an alkali activator or retarder for cement hydration. This work presents an evaluation of efflorescence characteristics in cement mortar with AASC and red mud. For the work, OPC (Ordinary Portland Cement) and AASC are used as matrix binder, and varying replacement ratios of red mud (0.0–30%) are prepared. In order to evaluate the efflorescence characteristics in the binders with red mud, analysis of water absorption and porosity are performed. The changing efflorescence areas with weight loss are also measured. The compounds in efflorescence are quantitatively analyzed through various techniques such as EDS, XRD, SEM, TGA, and alkali leaching test. In the work, the accelerated efflorescence mechanism and its characteristics are quantitatively evaluated considering the effects of binder types and red mud replacement ratios.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Quantitative evaluation of red mud effect on efflorescence. </LI> <LI> Various micro observation test results like EDA, XRD, SEM, and TGA. </LI> <LI> The relationship between efflorescence and the results (ion concentration, porosity). </LI> <LI> Verification of efflorescence mechanism through micro observation test. </LI> <LI> Mechanical and durability performance evaluation. </LI> </UL> </P>