• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.11a
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• pp.159-160
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• 2022

The purpose of this study is to evaluate the adhesion in flexure depending on the cement type, polymer type, polymer-cement ratio, and silica fume ratio of the polymer-cement composites(PCCs) for crack repair in RC structures to induce optimal mix proportions. The adhesion in flexure of PCCs for crack repair of RC structure has a significant effect on the polymer type and polymer-cement ratio, and the adhesion in flexure is generally improved with mixing of silica fume as a mixture. The adhesion in flexure according to the type of polymer is slightly higher in the order of SAE, EVA, and SBR, and it is relatively high at the polymer-cement ratio of 60% or 80%. In addition, the adhesion in flexure of PCCs with silica fume ratio of 10% or 20% to the cement weight is higher than that without silica fume. In order to improve the adhesion in flexure of PCCs for repairing cracks in RC structures, the optimal mix design is to properly adjust the cement type, polymer type, polymer-cement ratio, and silica fume ratio.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1993.10a
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• pp.1176-1185
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• 1993

The purpose of this study is to propose a new dynamic model of wheels and agricultural tractors through verification of the existence of " lift resistance " and "perpendicular adhesion" which also can be called " contra-retractive adhesion". The existence of these forces was proved through experiments including the development of a sensor which can measure the forces acting on a wheel accurately. Consequently " perpendicular adhesion ratio" which is defined as the ratio of the perpendicular adhesion to the distributed load was observed to be in the range of 0.05 to 0.3. This means the influence of the " lift resistance " is comparable to that of motion resistance in wheel dynamics. The perpendicular adhesion ratio was observed to decrease logarithmically with the increase of ground contact pressure, and to increase linearly with increase of the travel speed of the wheel . Some examples to express the new dynamic model compared to the conventional dynamics are explained.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.05a
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• pp.200-201
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• 2018

The purpose of this study is to evaluate the adhesion in tension of polymer-modified mortars according to curing conditions. From the test results, the adhesion in tension is seriously affected by type of curing conditions compared with type of polymer dispersions or polymer-cement ratios. The maximum adhesion in tension of EVA-modified mortar with polymer-cement ratio of 20% cured by standard condition is about 1.81 times, the cement mortar cured in water. It is apparent that the adhesion in tension of polymer-modified mortars according to raising of polymer-cement ratio is also much more improved irrespective of type of polymer dispersions and curing conditions.

• Journal of the Korean Society for Railway
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• v.8 no.4
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• pp.367-371
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• 2005

Pile foundations are utilized when soil is so weak that shallow foundations are not suitable or point load is concentrated in small area. Such soil can be formed by the land reclamation works which have extensively been executed along the coastal line of southern and western parts of the Korean Peninsula. The working load at pile is sometimes subjected to not only compression load but also lateral load sad uplift forces. But in most of the practice design, uplift capacity of pile foundation is not considered and estimation of uplift capacity is presumed on the compression skin friction. This study was carried out to determine that the effect of embedment ratio and loading rate on uplift adhesion factor of concrete pile driven in clay. Based on the test results, the critical embedment ratio is about 9. Adhesion factor is constant under the critical embedment ratio, and decreasing over the critical embedment ratio. Also, adhesion factor is increased with the loading rate is increased.

• Journal of the Korean Wood Science and Technology
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• v.45 no.2
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• pp.223-231
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• 2017

This work was conducted to investigate on the effect of urea-formaldehyde (UF) resin viscosity on plywood adhesion. The viscosity of UF resin was controlled either by adjusting the condensation reaction during its synthesis to obtain different target viscosities (100, 200 and 300 mPa.s) at two levels of formaldehyde/urea (F/U) mole ratios (1.0 and 1.2) or by adding different amounts (10, 20 and 30%) of wheat flour into the resins for the manufacture of plywood. When the viscosity of UF resin increased by the condensation reaction, the adhesion strength of plywood bonded with UF resin of 1.2 F/U mole ratio consistently increased, while those bonded with the 1.0 F/U mole ratio resin slightly decreased, suggesting a difference in the adhesion in plywood. However, the adhesion strength of plywood decreased as the viscosity increased by adding wheat flour, regardless of F/U mole ratio. The manipulation of UF resin viscosity by adjusting the condensation reaction was much more efficient than by adding wheat flour in improving the adhesion performance of plywood. These results indicated that a way of controlling the viscosity of UF resin adhesives has a great influence to their adhesion in plywood.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.893-896
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• 2006

This study examined plant adhesion characteristics of the porous concrete that used specially treated granular fertilizer for field application, which was used for the restoration of the marine ecosystem. The results of the experiment showed that nutrient eruption amount, the destruction and dissolution ratio tended to decrease when the coating thickness was increased. The void ratio and compressive strength tended to decrease when the specially treated granular fertilizer mixing ratio was increased. According to these results, the appropriate thickness of coating for cement coated granular fertilizer was 1.0mm. The adhesion ability of marine plant to porous concrete was superior when the cement coated granular fertilizer was mixed. Therefore, the appropriate cement coated granular fertilizer mixing ratio of 20% with a coating thickness of 1.0mm is thought to be a factor when considering the strength of the porous concrete for marine ecosystem restoration and the adhesion characteristics of marine plant.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2017.05a
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• pp.232-233
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• 2017

The purpose of this study is to evaluate the Adhesion in tension of cement mortar according to adding admixtures such as polymer dispersions, blast-furnace slag and fly ash. From the test results, the adhesion in tension is seriously affected by type of polymer compared with polymer-binder ratios and types of admixture. The maximum adhesion in tension of EVA- modified mortar is about 1.46 times, the cement mortar. It is apparent that the adhesion in tension of polymer-modified mortars according to adding two admixtures is much more improved irrespective of polymer-binder ratio.

• Journal of the Korean Wood Science and Technology
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• v.49 no.5
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• pp.453-461
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• 2021

In wood-based composite panels, low-molar ratio (LMR) urea-formaldehyde (UF) resins usually result in reduced formaldehyde emission (FE) at the expense of poor adhesion. However, the FE and adhesion of medium-density fiberboard (MDF) bonded with LMR UF resins were both improved in this study. The modified LMR UF resins with transition metal ion-modified bentonite (TMI-BNT) nanoclay simultaneously improved the FE and adhesion of MDF panels. The modified LMR UF resins with 5% TMI-BNT resulted in a 37.1% FE reduction and 102.6% increase in the internal bonding (IB) strength of MDF panels. Furthermore, thickness swelling and water absorption also significantly decreased to 13.0% and 24.9%, respectively. These results imply that TMI-BNT modification of LMR UF resins could enhance the formation of a three-dimensional network rather than crystalline domains, resulting in improved cohesion.

• Journal of Adhesion and Interface
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• v.2 no.4
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• pp.32-38
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• 2001

Effects of the ratio of rubber composition on covulcanization and ozone resistance were studied in this study. Specimens used in this study were rubber compounds(specimen-A) blended with various ratio of NR, SBR, BR, IIR, and EPDM, unsaturated rubber compounds(specimen-B) with NR/BR/SBR, and saturated rubber compounds(specimen-C) with NR/IIR/EPDM. PAD adhesion specimen was prepared from vulcanizing specimen-A and B, and specimen-A and C, respectively. Using same adhesion specimen, peel strength was measured and tested ozone resistance. In specimen-A, peel strength was higher with increasing NR ratio for NR and BR contained blends. In other specimen-A containing NR and SBR, the peel strength was also increased with increasing SBR ratio. NR/BR/IIR/EPDM rubber compounds had also better adhesion property than NR/SBR/IIR/EPDM compounds. As more unsaturated rubber was blended, the peel strength was higher but ozone resistance was worse. Optimum ratio of unsaturated and saturated rubbers for the peel strength and ozone resistance was 60/40.

• Archives of Pharmacal Research
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• v.26 no.11
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• pp.973-978
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• 2003

A polymeric film composed of Carbopol, Poloxamer and hydroxypropyl methylcellulose was prepared to develop a buccal patch and the effects of composition of the film on adhesion time, swelling ratio, and dissolution of the film were studied. The effects of plasticizers or penetration enhancers on the release of triamcinolone acetonide (TAA) were also studied. The hydrogen bonding between Carbopol and Poloxamer played important role in reducing swelling ratio and dissolution rate of polymer film and increasing adhesion time. The swelling ratio of the composite film was significantly reduced and the adhesion time was increased when compared with Carbopol film. As the ratio of Poloxamer to hydroxypropyl methylcellulose increased from 0/66 to 33/33, the release rate of TAA decreased. However, no further significant decrease of release rate was observed beyond the ratio of 33/33. The release rate of TAA in the polymeric film containing polyethylene glycol 400, a plasticizer, showed the highest release rate followed by triethyl citrate, and castor oil. The release rate of TAA from the polymeric film containing permeation enhancers was slower than that from the control without enhancers. Therefore, these observations indicated that a preparation of a buccal patch is feasible with the polymeric film composed of Cabopol, Poloxamer and hydropropyl methylcellulose.