• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2008년도 추계 학술발표회 제20권2호
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• pp.489-492
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• 2008

물/결합재비가 0.4이면서 5%의 실리카퓸이 혼입된 3가지 매스콘크리트 배합과 실리카퓸이 혼입되지 않은 1가지 매스콘크리트 배합에 대해 단열온도상승실험과 자기수축실험을 실시하여 실리카퓸이 매스콘크리트의 수화발열특성과 자기수축에 미치는 영향을 규명하고, 그 결과를 통해 실리카퓸의 매스콘크리트에 대한 적용 가능성을 검토하였다. 실험결과, 매스콘크리트 배합의 경우에는 실리카퓸을 혼입하여도 수화반응속도가 거의 증가하지 않으면서 최종단열온도상승량이 5$^{\circ}$C 정도 감소하는 것으로 나타났으며, 콘크리트의 극한자기수축량은 실리카퓸의 혼입여부에 상관없이 거의 동일한 것으로 나타났다. 따라서 실무에서 매스콘크리트 구조물의 시공에 실리카퓸을 적용하면 내구성뿐만 아니라 수화열 균열제어에도 이점이 있을 것으로 판단된다.

• 대한토목학회논문집
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• 제26권4A호
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• pp.787-794
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• 2006

고성능 콘크리트는 물-결합재비를 작게 하고, 단위결합재량을 다량으로 사용하므로 콘크리트의 수화열 및 자기수축이 증대되는 경향이 있다. 본 연구에서는 고성능 콘크리트의 수축저감 기술을 구축하는 연구의 일환으로 팽창재와 수축저감제 사용이 고성능 콘크리트의 수축특성에 미치는 영향을 검토하였다. 그 결과, 팽창쟁와 수축저감제는 고성능 콘크리트의 수축을 저감시키는 데 효과가 뛰어나며, 특히 팽창재와 수축저감제를 조합하여 사용할 경우, 각각 단독으로 사용하는 경우보다는 수축 저감 효과가 큰 것으로 확인되었다. 또한 시공성, 강도 및 수축특성을 종합적으로 고려하여 팽창재 5.0%와 수축저감제 1.0%의 조합이 적정배합으로 분석되었다.

• 한국세라믹학회지
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• 제44권2호
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• pp.79-83
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• 2007

To fabricate a thick, porous yttria-stabilized zirconia without cracking and warping, a method for the simultaneous control of the porosity and shrinkage was designed. As a pore former, a potato starch was used. For the control of shrinkage the oxidation of Al metal particles was used. For the sintering of the above powder mixtures, a partial sintering technique was used at $1300^{\circ}C$ for 10 min in air. Upon adding the additives, high open porosity above 53% and a low shrinkage level were obtained. As a result cracking and warping of the sintered body were deterred. This outcome most likely resulted from the compensation of sintering shrinkage due to the volume expansion caused by oxidation of the Al metal particles during heat-treatment.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1997년도 가을 학술발표회 논문집
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• pp.183-188
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• 1997

From a viewpoint of construction cost and preserving management of pavement, a policy of domestic pavement was gradually spreaded concrete pavement rather than asphalt. But the use of concrete with ordinary portland cement has shortages, such as dry-shrinkage, low flexural strength, etc. In order to overcome these problems, the concrete pavement using CSA expansive additive (Non-Shrinkage Cement) was studied and carried out the fie이 application. As the results, we find out Non-Shrinkage Cement that was distinguished in short-term construction by increasing flexural strength, shrinkage compensating and low-heat evaluation compared with OPC concrete.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2017년도 춘계 학술논문 발표대회
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• pp.216-217
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• 2017

Slag cement or ternary blended cement is mainly used for non-structural lean concrete for the purpose of foundation work or protection of the waterproof layer on the roof of buildings. However, such non-structural lean concrete has a lot of drying shrinkage cracks, which makes it difficult to maintain the quality of the structure. Therefore, in this study, the compressive strength and the drying shrinkage of ternary blended cement(blended of portland cement, blast furnace slag, fly ash from combined heat and power Plant) for non-structural lean concrete were examined. As a result, it was confirmed that this non-structural lean concrete reduced drying shrinkage compared to the conventional ternary blended cement using fly ash from power plant.

• 대한치과보철학회지
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• 제39권6호
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• pp.709-734
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• 2001

The aims of this experiment were to investigate the strain and temperature changes simultaneously within autopolymerzing acrylic resin specimens. A computerized data acquisition system with an electrical resistance strain gauge and a thermocouple was used over time periods up to 180 minutes. The overall strain kinetics, the effects of stress relaxation and additional heat supply during the polymerization were evaluated. Stone mold replicas with an inner butt-joint rectangular cavity ($40.0{\times}25.0mm$, 5.0mm in depth) were duplicated from a brass master mold. A strain gauge (AE-11-S50N-120-EC, CAS Inc., Korea) and a thermocouple were installed within the cavity, which had been connected to a personal computer and a precision signal conditioning amplifier (DA1600 Dynamic Strain Amplifier, CAS Inc., Korea) so that real-time recordings of both polymerization-induced strain and temperature changes were performed. After each of fresh resin mixture was poured into the mold replica, data recording was done up to 180 minutes with three-second interval. Each of two poly(methyl methacrylate) products (Duralay, Vertex) and a vinyl ethyl methacrylate product (Snap) was examined repeatedly ten times. Additionally, removal procedures were done after 15, 30 and 60 minutes from the start of mixing to evaluate the effect of stress relaxation after deflasking. Six specimens for each of nine conditions were examined. After removal from the mold, the specimen continued bench-curing up to 180 minutes. Using a waterbath (Hanau Junior Curing Unit, Model No.76-0, Teledyne Hanau, New York, U.S.A.) with its temperature control maintained at $50^{\circ}C$, heat-soaking procedures with two different durations (15 and 45 minutes) were done to evaluate the effect of additional heat supply on the strain and temperature changes within the specimen during the polymerization. Five specimens for each of six conditions were examined. Within the parameters of this study the following results were drawn: 1. The mean shrinkage strains reached $-3095{\mu}{\epsilon},\;-1796{\mu}{\epsilon}$ and $-2959{\mu}{\epsilon}$ for Duralay, Snap and Vertex, respectively. The mean maximum temperature rise reached $56.7^{\circ}C,\;41.3^{\circ}C$ and $56.1^{\circ}C$ for Duralay, Snap, and Vertex, respectively. A vinyl ethyl methacrylate product (Snap) showed significantly less polymerization shrinkage strain (p<0.01) and significantly lower maximum temperature rise (p<0.01) than the other two poly(methyl methacrylate) products (Duralay, Vertex). 2. Mean maximum shrinkage rate for each resin was calculated to $-31.8{\mu}{\epsilon}/sec,\;-15.9{\mu}{\epsilon}/sec$ and $-31.8{\mu}{\epsilon}/sec$ for Duralay, Snap and Vertex, respectively. Snap showed significantly lower maximum shrinkage rate than Duralay and Vertex (p<0.01). 3. From the second experiment, some expansion was observed immediately after removal of specimen from the mold, and the amount of expansion increased as the removal time was delayed. For each removal time, Snap showed significantly less strain changes than the other two poly(methyl methacrylate) products (p<0.05). 4. During the external heat supply for the resins, higher maximum temperature rises were found. Meanwhile, the maximum shrinkage rates were not different from those of room temperature polymerizations. 5. From the third experiment, the external heat supply for the resins during polymerization could temporarily decrease or even reverse shrinkage strains of each material. But, shrinkage re-occurred in the linear nature after completion of heat supply. 6. Linear thermal expansion coefficients obtained from the end of heat supply continuing for an additional 5 minutes, showed that Snap exhibited significantly lower values than the other two poly(methyl methacrylate) products (p<0.01). Moreover, little difference was found between the mean linear thermal expansion coefficients obtained from two different heating durations (p>0.05).

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2018년도 춘계 학술논문 발표대회
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• pp.277-278
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• 2018

Improvement of insulation performance of buildings is a major part. Adiabatic method The adiabatic method minimizes the heat loss of the building. External insulation uses insulation to prevent fire. Ambient air hazards are less prone to fire. When a fire occurs, a phenolic pattern is formed and bond strength with the wall increases. EPS insulation and phenol foam were used to compare external heat transfer and external heat transfer. The heat transfer properties of phenolic foam and styrofoam were evaluated as follows. In the mortar and styrofoam structure, the problem of styrofoam reaching the burning point occurred before the collapse of the mortar, and the phenol foam had a problem in that when the direct fire was continued on the phenol foam. The characteristics of continuous infiltration appeared. In the case of mortar and phenol foam + styrofoam, the heat penetrated into the interior due to the shrinkage due to the shrinkage of the carbon screen on the phenol foam. However, when reinforced with glass mesh on the outer surface, And to reduce infiltration.

• 한국지반공학회논문집
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• 제19권6호
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• pp.127-149
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• 2003

본 교량은 교축방향에 대해 사각 60도인 90m 3경간 연속 완전 일체식 교대교량이다. 이 교량의 상부슬래브 콘크리트 타설후, 7일간의 콘크리트 양생에 따른 H말뚝의 수평거동을 알아보기 위하여, H말뚝 축방향으로 매설형 경사계와 변형률계를 설치하여 계측을 실시하였다. 이때 계측 결과를 수화열 및 건조수축 전용프로그램인 HACOM의 해석결과와 H말뚝의 횡방향 비선형 p-y 모델해석 거동에 비교하였다. 그 결과에 의하면, 실측한 H말뚝의 수평변위는 상부슬래브 콘크리트가 양생함에 따라 발생하는 수화열과 건조수축에 영향을 받았고, 그 크기는 각각 2.2mm, 1.4mm이었다. 말뚝 축방항 수평변위의 변곡점은 교대 기초저면에서 1.3m 위치에서 발생하였다. 이는 이 교량의 교대말뚝은 말뚝머리 고정조건으로 거동하는 것이 아니라 이와 매우 유사한 거동을 보였다. 그리고 실측한 말뚝의 휨응력 거동은 말뚝머리 회전구속과 같은 거동을 보이지 않고, 연직방향의 하중전이와 같은 거동을 나타내었다. 또한 교대말뚝의 비선형 p-y 모델해석으로 구한 최대휨응력 증분량의 크기는 약 300(kgf/$\textrm{km}^2$)이었고, 교대말뚝의 계측기 부착위치와는 무관하게 실측한 값보다 약 2배 크게 발생하였다. 그리고 말뚝의 비선형 p-y 모델해석에서 말뚝의 수평하중, 최대수평 변위, 최대휨응력, 최대휨모멘트는 콘크리트 양생시간에 따라 모두 선형적인 거동을 보였다.

• Elastomers and Composites
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• 제53권3호
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• pp.136-140
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• 2018

In this study, research was conducted into the manufacture of thermally expandable microspheres for automotive underbody coatings and applications in industry. In particular, the relationship between heat resistance and the ratio of crosslinking agents and initiators in the manufacture of the thermally expandable microspheres was investigated. We focused on the results with various cross-linking agents; our aim was to make the walls of the microspheres thicker to solve the problem of reductions in size caused by shrinkage when the microspheres are heated to $T_m$ ($T_{max}$). We observed the sectional thickness and surface of the samples with thicker walls. The thick thermally expandable microspheres showed reduced shrinkage and excellent stability in spite of prolonged exposure to heat.

• 대한치과보철학회지
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• 제30권3호
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• pp.401-410
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• 1992

The purpose of this study was to investigate the dimensional changes and surface morphology of dentures processed by various polymerization conditions. The measurements were done by taking radiograph and using vernier calipers and each specimen was observed on scanning electron microscope. Results obtained were as follows. 1. The difference of dimensional stability was not recognized between various polymerization conditions(heat-cured resin, pour-type resin, microwave-cured resin, and injection molding resin). 2. There were expansion and shrinkage in the occlusal dimension, shrinkage in the frontal dimension, and expansion in the lateral dimension. 3. Scanning electron microscope pictures of heat-cured resin showed dense and regular surface morphology. 4. Microwave-cured resin surface appeared more regular and smooth than pour-type resin but less dense and more irregular than heat-cured resin. 5. Scanning electron microscope pictures of pour-type resin with the lowest dimensional change showed the most irregular surface morphology.