• Geomechanics and Engineering
• /
• 제12권5호
• /
• pp.771-783
• /
• 2017

Using a transparent fracture replica with aperture size and water-cement ratio (w/c), the factors affecting the penetration behavior of rock grouting were investigated through laboratory experiments. In addition, the waterproof efficiency was estimated by the reduction of water outflow through the fractures after the grout curing process. Penetration behavior shows that grout penetration patterns present similarly radial forms in all experimental cases; however, velocity of grout penetration showed clear differences according to the aperture sizes and water-cement ratio. It can be seen that the waterproof efficiency increased as the aperture size and w/c decreased. During grout injection or curing processes, air bubbles formed and bleeding occurred, both of which affected the waterproof ability of the grouting. These two phenomena can significantly prevent the successful performance of rock grouting in field-scale underground spaces, especially at deep depth conditions. Our research can provide a foundation for improving and optimizing the innovative techniques of rock grouting.

• 대한치과보철학회지
• /
• 제34권4호
• /
• pp.816-822
• /
• 1996

The purpose of this study was to determine whether there was any difference in the mean porosity of denture base resin cured by microwave energy, when the liquid monomers of denture resin(K-33 : methyl methacrylate for conventional water bath curing or Acron MC : special monomer for microwave curing) and/or the thicknesses of denture base($5{\times}10{\times}60mm\;or\;10{\times}10{\times}60mm$) were varied. The mean porosities of k-33 specimens cured in water bath with two different thicknesses were used as control. The results were as follows : 1. Regardless of specimen thickness, Acron MC cured by microwave energy showed the least mean porosity, followed by K-33 cured by water bath heat, and K-33 cured by microwave energy showed the highest level of mean porosity(P<0.05). 2. In both K-33 and Acron MC cured by microwave energy the mean porosities of 5mm thickness groups were lower than those of 10mm thickness groups(P<0.05). But no significant difference was found in mean porosity between 5mm thickness and 10mm thickness of water bath heat cured groups made of K-33(P>0.05).

• 한국건축시공학회:학술대회논문집
• /
• 한국건축시공학회 2014년도 춘계 학술논문 발표대회
• /
• pp.100-101
• /
• 2014

The global warming because of the CO₂ emission and solution about this emerge as the international enviroment problem. Particularly, it is the absolutely it is needed for reducing the CO₂ in the cement industry and harmful material actual condition. And the construction of home and abroad and material manufacturers tries for the technology development for the carbon dioxide and harmful material reduction which the portland cement in manufacture is usually emitted along with the increase of concerns about the environment-friendly concrete and panel. Therefore, in this research, the compressive strength of the inorganic binder and flexural strength tries to be measured in order to draw the inappropriate high temperature cure time of the ternary system inorganic binder using the blast furnace slag, red mud, silica fumewhich is the industrial byproduct with the cement substitute material, and etc.

• 한국세라믹학회지
• /
• 제27권3호
• /
• pp.437-443
• /
• 1990

The resistivity of cement paste and mortar for freezing and thawing was investigated for densifying the structure of cement paste and mortor, slag, diatomaceous earth and fly ash as blending materials and superplasticizer were used, and air entraining agent was added to absorb the volume expansion by freezing and thawing reaction. And then the specimens were subjected to freeze-thaw in water. When both of air entraining agent and superplasticizer as additives were mixed to specimens, their freeze-thaw resistance was enhanced by the air entraining effect and the water reduction effect. When 4% of slag were added to cement, freeze-thaw resistance was especially excellent. In addition, it was found that the specimens with blending materials were more influenced by curing periods than those without admixture. It is assumed that the curing periods contribute to exibit the potential hydraulicity and pozzolanic reactivity of blending materials and to densify their texture.

• 콘크리트학회논문집
• /
• 제12권4호
• /
• pp.41-48
• /
• 2000

This study is to investigate for the frost resistance of high-strength concrete using finely ground granulated blast-furnace slag with experimental parameters, such as water/binder ratio, replacement proportion of granulated blast-furnace slag, air content and methods of curing. The high-strength concrete using granulated blast-furnace slag is effective to resist frost and decrease scaling. The more increasable replacement proportion of granulated blast-furnace slag is, the better the effect is. The high-strength concrete using granulated blast-furnace slag needs hydrating adequately to prevent deterioration by drying in the early curing period. The micro structure of high-strength concrete, increased to the pore number with diameter of 0.03~0.1mm, is changed by using granulated blast-furnace slag, but is presented differently according to water/binder ration and replacement proportion of granulated blast-furnace slag.

• Journal of Biosystems Engineering
• /
• 제32권2호
• /
• pp.115-120
• /
• 2007

The adhesive performance of marine mussel extract was compared with that of the commercial medical adhesives for fastening biotissue (SIS) bandages. Joints bonded with mussel extract showed stronger strength than those bonded with other commercial adhesives. The bonding strength was much improved when the moisture in the Joint was reduced using superporous hydrogel regardless of curing time under humid condition ($37^{\circ}C$ and 91% relative humidity). Water inflow into the SIS joint seemed to degrade the performance of mussel extracts adhesive especially for the joints of short period of curing time. The strength of SIS joints coated with surgical sealant was well maintained after being exposed to water inflow.

• Carbon letters
• /
• 제1권2호
• /
• pp.82-86
• /
• 2000

The present research was undertaken to evaluate the possibility of water purification filter with activated carbon fibers (ACFs) using a very low cost precursor consisting of phenolic resin coated on glass fibers. The simplified procedure involving coating, curing and activation and a very low cost glass fiber as a raw material were adopted in order to reduce manufacturing cost. The breakthrough curves of the manufactured ACFs and the commercial activated carbon (AC, Calgon F-200) were investigated in the initial concentration range from 19 to 49 ppm for benzene, toluene and ethylbenzene. From breakthrough profiles, the manufactured ACFs had significantly faster adsorption kinetics than the AC. Especially the benzene breakthrough curves, the manufactured ACF (13 g of ACF with 32% of carbon on the glass) was over the limited level (5 ppb) after flowing of 32 l at initial concentration of 15 ppm, while the commercial AC was shown about 3 ppm in initial adsorption.

• 한국농공학회논문집
• /
• 제50권4호
• /
• pp.27-37
• /
• 2008

It is most serious problem which is various occurs from the agricultural concrete structure and off shore concrete structure the problem which it comes to think is deterioration of the concrete which is caused with the corrosion of the reinforcing steel which is caused by with permeation of the water and the sea water. Specially the off shore concrete structure has been deteriorated by the steel reinforcement corrosion. The latex modified concrete(LMC) was adds latex in the plain concrete as the latex has increase the durability of concrete. This study were accomplished to the estimate the diffusion coefficient of LMC, and the time dependent constants of diffusion. The average chloride diffusion coefficient was estimated. Also, the average chloride diffusion coefficient was compared with diffusion coefficient test results of 28 curing days. The test results indicated that the average chloride diffusion coefficient could closely estimate the test results of the diffusion coefficient test results of 28 curing days.

• 대한소아치과학회지
• /
• 제32권2호
• /
• pp.284-292
• /
• 2005

본 연구에서는 치과용 복합레진의 중합률에 영향을 미치는 다양한 광원인 할로겐, 플라즈마, LED를 사용하여 임상에서 사용하는 여러 치면열구전색제들을 중합 시, 이로부터 용리되는 미반응 모노머들을 확인하고 정량화하고자 하였다. 5가지의 광중합형 치면열구전색제를 각각의 광원에 따라 중합한 시편을 제작하여 3차 증류수에 넣은 후 바로 용리시킨 액을 0시간으로 하고 $37^{\circ}C$ 항온수조에서 10분, 1시간, 12시간, 24시간 보관한 후 각각의 용리액을 고성능 액체 크로마토그래피를 이용하여 미반응 모노머의 정성 및 정량 분석을 시행하였고, 다음과 같은 결과를 얻었다. 1. 표준 모노머들의 분리시간은 BPA 2.3분, TEGDMA 3.2분, UDMA 5.6분, Bis-GMA 6.5분, Bis-DMA 10.4분이었다. 2. 모든 치면열구전색제에서 TEGDMA를 제외한 어떠한 모노머들도 용리되지 않았다. 3. 저장 12시간까지 대부분의 TEGDMA가 용리되었으며, 이후부터는 그 양이 현저히 줄어드는 양상을 보였다. 4. 최소권장중합 시간인 할로겐 20초, 플라즈마 3초, LED 10초 중합 시 TEGDMA의 용리량은 할로겐, LED, 플라즈마 순으로 적었다. 5. 모든 중합기에서 Pit & Fissure $Sealant^{TM}$의 용리량이 가장 적었으며, 할로겐 중합시 $Helioseal^{(R)}$ F가, 플라즈마 아크중합 시 $Concise^{TM}$가, LED 중합 시 $Teethmate^{(R)}$ F-1이 가장 많은 용리량을 보였다.

• Restorative Dentistry and Endodontics
• /
• 제18권1호
• /
• pp.215-226
• /
• 1993

Color stability of tooth colored restorative resins is an important factor, particularly in anterior teeth restoration. The purpose of this study was to evaluate the color stability and opacity change of several light curing composite resins. Specimens of eight composite resins(Prisma AP. H., Brilliant Enamel, Charisma, Durafil, Helio Progress, Herculite XR, P-50 and Silux Plus) were divided into two groups : In Group 1, the specimens were polymerized by visible light curing unit for 60 seconds on both sides and in Group 2, the post-cured specimens were heat tempered by light/heat curing unit for 45 units(about 18 min.). All specimens were stored in distilled water at $60^{\circ}C$ for 30 days. The color characteristics($L^*,a^*,b^*$) and opacity of the specimens before and after immersion were measured by spectrocolorimetry and the total color difference(${\Delta}E^*$) and opacity change (${\Delta}Y%$) were computed. The results obtained were as follows : 1. SP and APH in both groups, DF, HP and HXR in Group 1 showed ${\Delta}E^*$-value above 2.0. 2. DF, HP, SP and HXR in Group 1 showed higher ${\Delta}E^*$-value than in Group 2, but the others had no significant difference. 3. The opacity of CH and HXR in Group 1, and of CH and BE in Group 2 decreased after immersion, while that of the others increased. 4. Opacity change of BE, P50 and HXR was significantly different between Group 1 and 2. These results suggest that color change in the post-cure heat tempered specimens by light/heat curing unit was smaller than that of the specimens polymerized by visible light curing unit. No clinically detectable opacity changes were noted for any materials in either goup.