• Journal of the Korea Concrete Institute
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• v.20 no.5
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• pp.593-600
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• 2008

In this study, to analyze the correlation between hydration heat and autogenous shrinkage of high strength concrete at an early age, hydration heating velocity and autogenous shrinking velocity as quantitative coefficients which represent the main properties of hydration heat and autogenous shrinkage were proposed. Two coefficients were calculated by statistical analysis and were equal with the regression coefficient. The complemented semi-adiabatic temperature rise test as test method to evaluate the hydration heat and autogenous shrinkage of concrete were proposed. In results of proposed test and analysis method, it was possible that early age properties of hydration heat and autogenous shrinkage of concrete were expressed numerically, and autogenous shrinkage was represented by equation with coefficients of hydration heat.

• Resources Recycling
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• v.24 no.1
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• pp.12-20
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• 2015

In this study, change of hydration property with contents and type of gypsum in ternary natural hydraulic lime containing blast furnace slag and gypsum was investigated. Anhydrite, hemihydrate and dihydrate were added 3 % and 10 %, respectively in natural hydraulic lime adding blast furnace slag 20 %. Hydration and physical behavior due to solubility and reactivity of different types of gypsum were analyzed in early hydration. As a result of analysis of hydration properties, in all samples, hydrates such as ettringite and C-S-H were produced in early hydration, and amount of hydrates with increase of hydration time was increased. In the case of compressive strength, when contents of gypsum are 3 %, it was higher compressive strength than other specimens. At hydration 28 days, for addition of anhydrite and hemihydrate, compressive strength was more than adding dihydrate.

• Polymer(Korea)
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• v.33 no.5
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• pp.441-445
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• 2009

In order to develop an intelligent delivery system for cosmetic active agents (e.g., arbutin, ascorbic acid, and adenosine), pH-responsive P(MAA-co-PEGMA) hydrogel particles having an average size of approx. $2{\mu}m$ and spherical shape were synthesized via dispersion photopolymerization. There was a drastic change in the swelling ratio of P (MAA-co-PEGMA) hydro gels at a pH 5, which is the $pK_a$ of the hydrogel. To determine the factors that have an effect on the loading of cosmetic active agents into the hydrogel, the loading efficiency of the active agents was investigated at various MAA and EG compositions of the hydrogel and the loading pH conditions. When the MAA contents in the hydrogel decreased, the loading efficiency of the active agents increased. In loading experiments with different pH conditions, the active agents showed higher loading efficiency into the hydrogel at the pH where the hydrogel was at the swollen state than at the pH where the electrostatic repulsion was minimized.

• Applied Chemistry for Engineering
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• v.10 no.8
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• pp.1124-1128
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• 1999

In this study the effect of organic additive, triethanolamine(TEA), and temperature change of accelerator for shotcrete was studied. Then the amount of accelerator, temperature and W/C were experimentally investigated. Effects of hydration time and hydration heat of concrete on organic additive amount were analysed by DSC, SEM and XRD. We found that the hydration heat was increased and hydration time was decreased with TEA(<5 wt %). The order of hydration rate of potassium accelerator was PA < PC-3 < PC-5 < PC-8.

• Journal of the Korean Ceramic Society
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• v.38 no.8
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• pp.732-739
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• 2001

산업부산자원으로부터 유입되는 중금속이 시멘트 수화반응에 미치는 영향에 대하여 연구하였다. 출발물질은 순수시약을 사용하여 $C_3$S와 $C_2$S 조성으로 배합하고 여기에 Zn, Cu, Cr의 중금속 산화물을 1000ppm, 2000ppm, 3000ppm 첨가하여 150$0^{\circ}C$에서 1시간 소결하여 중금속의 고용분배, 결정구조, 용출상태 그리고 수화열을 관찰하였다. 중금속중 Zn는 $C_3$S와 간극질에 집중 고용되고 Cu는 간극물질에 집중 고용되며 Cr은 $C_3$S와 $C_2$S에 집중 고용되었다. 광학현미경 및 XRD 관찰결과 중금속 함량별로 $C_3$S와 $C_2$S의 결정상에는 큰 영향이 없는 것으로 나타났다. 그리고 7일간 수화시 Zn는 40~50%, Cu와 Cr은 전량 용출되었다. Conduction calorimeter 분석결과 중금속 함량별 변화에도 $C_3$S와 $C_2$S 수화열에는 차이가 없었다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2011.07a
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• pp.4-5
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• 2011

수화는 몸 동작 또는 손가락의 움직임을 통하여 상호 커뮤니케이션을 하는 하나의 언어이며, 이 언어의 디지탈 미디어로의 소통을 위해서는 동작을 하나의 의미 있는 단어, 음절로의 표현이 가능해야 한다. 여기서는 몸 동작, 팔 다리의 움직임 보다는 손가락의 움직임에 초점을 맞추어 지문자 인식에 필요한 센서 시스템에 대하여 고찰한다. 우선 연속적인 지문자, 지숫자의 입력을 인식하기 위해서는 각 문자 절음 인식이 가장 중요한 문제가 된다. 절음 위치를 인식하는 것은 현재 입력된 패턴과 다음 패턴을 구분지어 각각 다른 지문자 혹은 지숫자로 인식할 수 있게 하는 기반이 된다. 손가락 구부러짐의 구분 및 인식을 위한 방법의 개발을 위해, 언어별 수화의 특징 분석을 토대로 다양한 적용 가능한 센서를 탐색하고 수화 장갑을 위한 원천기술을 개발, 수화 장갑 프로토타입을 제작하였다.

• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.315-316
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• 2009

In this study, latent heat material was used to reduce hydration heating velocity of high-strength mass concrete. And the properties of hydration heat and autogenous shrinkage, and the relationship between hydration heat and autogenous shrinkage of high-strength mass concrete were numerically investigated.

• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.385-386
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• 2009

The temperature crack of concrete structure is caused by the phenomenon which the concrete volume is restricted in the inside or outside part due th the temperature variations induced by the hydration heat of cement. And mass concrete structures are weak in temperature crack. This study performed the hydration heat analysis of Seongdeok dam to analyze the hydration heat according to different interval of placement.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2017.11a
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• pp.172-173
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• 2017

본 논문에서는 지상파 방송사업자의 장애인방송 편성비율 목표치 만족여부를 검증하기 위한 상시 수화방송 모니터링 기술을 제안한다. 이를 위해서 방송프로그램 안내정보와 방송 시그널링 정보를 기반으로 채널별로 방송스트림을 저장하는 수집장치의 구조와 기능에 대해서 설명하고, 수집장치를 통해서 획득된 방송스트림에서 수화방송 서비스 유무를 판단하기 위한 분석방법을 제안한다. 마지막으로, 수화방송 모니터링 기술을 이용한 분석 결과를 기술한다. 향후, 전국의 지역별/채널별 장애인방송(자막방송, 화면해설방송, 수화방송) 상시 모니터링 시스템 구축을 통해 장애인방송 활성화에 기여하고자 한다.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.249-252
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• 2008

In recent large-scale structures, as mass concrete type structure is frequently applied to the building, temperature crack due to hydration heat needs to be considered. Since a volume change is internally or externally restricted in a mold after placing concrete, temperature crack of mass concrete takes place. By this reason, the reduction method to control this crack is required. In this study, low heat mixture and hydration heat difference is used to execute the analysis of hydration heat, considering the changes of heat transfer coefficient according to curing conditions and block placement of mass concrete. For the analytical modelling, original portland cement and concrete of low heat mixture are placed in the upper and lower payer, respectively. A convection boundary condition is fixed because mass concrete of block placement is characterized by the difference of mold form and curing condition. Through the analysis results considering the changes of low heat mixture, block placement, and heat transfer coefficient, we check out the temperature and stress distribution and analyze the temperature crack reduction effect.