• International Journal of Highway Engineering
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• v.9 no.2 s.32
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• pp.129-140
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• 2007

A major purpose of this study is to develop a drainage system that can quickly drain water penetrated into pavement layers to mitigate pot holes which is one of the major distress types in bridge deck pavements. This system can be established by applying a thin drainage layer between waterproof and pavement layers. The most important elements for this system are the performance of waterproof layer and construction technique for the thin drainage layer. The porous asphalt mix with the maximum aggregate size of 10mm is first developed based on the porous asphalt mix design guide proposed by NCAT, and various physical and mechanical tests are performed to confirm that the porous mix satisfies all the specification requirements. In addition, a series of laboratory tests including low-temperature bending and bonding strength tests for the MMA(Methyl Methacrylate) type of waterproofing material. It is observed from the tests that the MMA material satisfies all the specification requirements. To evaluate the Reld performance of the drainage system, a field study has been conducted on a relatively small size bridge. The QC/QA tests are conducted on the both waterproofing and pavement materials. It has been found that the drainage system works well to drain the water penetrated into the pavement layers.

• The Journal of Korean Academy of Prosthodontics
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• v.39 no.4
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• pp.351-365
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• 2001

For accurate impression taking, accurate impression material, solid individual tray, and bond strength between impression materials and resin tray are important factors. The purpose of this study was to evaluate tensile bond strength of rubber impression materials to various tray resin materials. This study tested the time dependent tensile bond strength between commercial brands or poly ether, polysulfide, additional silicone impression materials and commercial brands of self curing tray resin. light activited tray resin when applying adhesive Resin specimens were made with 20mm in diameter, 2mm in thickness. 1 made total 360 specimens, 10 per each group and the tensile bond strength was measured by using the Instron($M100EC^{(R)}$, Mecmesin Co., England). The results were as follows ; Comparisons of various impression materials. 1. In case of Impregum $F^{(R)}$, the bond strength of tray resin was decreased in order of SR $Ivolen^{(R)}$, Ostron $100^{(R)}$ Instant tray $mix^{(R)}$, $Lightplast^{(R)}$. All groups excluding Ostron $100^{(R)}$, Instant tray $mix^{(R)}$ are significant difference (p<0.05). Drying time after applying adhesive, the tensile bond strength of tray resin was insignificantly decreased in order of 10 min drying time group. 1 min drying time group. 5 min drying time group. 2. In case of Permlastic $regular^{(R)}$ the bond strength of tray resin was insignificantly decreased in order of Ostron $100^{(R)}$. SR $Ivolen^{(R)}$, Instant tray $mix^{(R)}$ $Lightplast^{(R)}$. About drying time after applying adhesive, the tensile bond strength of tray resin was significantly decreased in order of 5 min drying time group, 10 min drying time group, 1 min drying time group(p<0.05). 3. In case of Exaflex $regular^{(R)}$. the bond strength of tray resin was decreased in order of $Lightplast^{(R)}$, SR $Ivolen^{(R)}$, Instant tray $mix^{(R)}$, Ostron $100^{(R)}$. $Lightplast^{(R)}$ was significant difference(p<0.05). About drying time after applying adhesive, the tensile bond strength of tray resin was decreased in order of 5 min drying time group, 10 min drying time group, 1 min drying time group(p<0.05). Especially 5 min ding time group was significant difference(p<0.05). According to the results of this study, we can see the greatest tensile bond strength when using Impregrm $F^{(R)}$ and Permlastic $regular^{(R)}$ with self curing tray resin, when using Exaflex $regular^{(R)}$ with light activated tray resin In my opinion, adhesive should be dried more than 5 min before impression taking to achieve the greatest tensile bond strength.

• Restorative Dentistry and Endodontics
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• v.27 no.3
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• pp.299-309
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• 2002

The purposes of this study were to evaluate the microtensile bond strength of one-step adhesives accord ing to various dentin surface treatments and to observe the interface between resin(Z-100$^{TM}$) and dentin under SEM. In this study forty-five non-caries extracted human molars and three adhesive systems were used ; AlI-Bond 2(AB), One-Up Bond F(OU), AQ-Bond(AQ). ; In Group 1, 2, 3, AB was used and tooth surfaces were treated by smearing(S), ultrasonic cleansing(US), etching(E) respectively. In Group 4. 5, 6, One-Up Bond F was used and tooth surfaces were also treated as the same way above. In Groups 7, 8, 9, AQ Bond was used and tooth surfaces wet$.$e treated as the same way. Each specimen was prepared for microtensile bond testing, and were stored for 24hrs in 37$^{\circ}C$ distilled water. After that, microtensile bond strength for each specimen was measured. Specimens were fabricated to examine the failure patterns of interface between resin and dentin and observed under the SEM. The results were as follows ; 1. The results(mean$\pm$SD) of microtensile test were group 1, 25.69$\pm$4.31MPa; group 2, 40.93$\pm$10.94MPa; group 3, 47.65$\pm$8.85MPa； group 4, 35.98$\pm$9.14MPa； group 5, 39.66$\pm$8.45MPa; group 6, 43.26$\pm$13.01MPa; group 7, 25.07$\pm$4.2MPa；group 8, 30.4$\pm$4.74MPa；group 9, 33.61$\pm$7.88MPa. 2. One-Up Bond F was showed the highest value of 36.98$\pm$9.14MPa in dentin surface treatment with smearing, and there were significant differences to the other groups (p<0.05). 3. All-Bond 2 was showed the highest value of 40.93$\pm$10.94MPa in dentin surface treatment with ultra-sonic cleansing, but was no significant difference to One-Up Bond F(p>0.05) 4. All-Bond 2 was showed the highest value of 47.65$\pm$8.85MPa in dentin surface treatment with etch ing(10%phosphoric acid), and there were significant differences to the other groups(p<0.05). 5. All-Bond 2 was showed the highest value of 47.65$\pm$8.85MPa in dentin surface treatment according to manufacture's directions. but was no significant difference to One-Up Bond F(p>0.05). 6. AQ Bond was skewed the lowest microtensile bond strength with various dentin surface treatment, and the were significant differences to the other groups(p<0.05).

• Journal of the Microelectronics and Packaging Society
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• v.29 no.2
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• pp.113-119
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• 2022

In order to improve the mechanical reliability of next-generation electronic devices including flexible, wearable devices, a high level of mechanical reliability is required at various flexible joints. Organic adhesive materials such as epoxy for bonding existing polymer substrates inevitably have an increase in the thickness of the joint and involve problems of thermodynamic damage due to repeated deformation and high temperature hardening. Therefore, it is required to develop a low-temperature bonding process to minimize the thickness of the joint and prevent thermal damage for flexible bonding. This study developed flexible laser transmission welding (f-LTW) that allows bonding of flexible substrates with flexibility, robustness, and low thermal damage. Carbon nanotube (CNT) is thin-film coated on a flexible substrate to reduce the thickness of the joint, and a local melt bonding process on the surface of a polymer substrate by heating a CNT dispersion beam laser has been developed. The laser process conditions were constructed to minimize the thermal damage of the substrate and the mechanism of forming a CNT junction with the polymer substrate. In addition, lap shear adhesion test, peel test, and repeated bending experiment were conducted to evaluate the strength and flexibility of the flexible bonding joint.

• Korean Journal of Heritage: History & Science
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• v.46 no.3
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• pp.212-228
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• 2013

Stone cultural heritages are repaired by the use of metal stiffeners. The problem is that this type of repair has been based on the experience of workers without specific guidelines and has caused various problems. This is to suggest the structural reinforcement and behavioral characteristics of metal rods to minimize the secondary damage of materials and have the specimens tested and verified to establish the guidelines on how to insert metal stiffeners. When only epoxy resin is applied to the cut surface, only 70% of the properties of the parent material are regenerated and it is required to structurally reinforce the metal stiffener for the remaining 30%. The metal rod is under the structural behavior after the brittle failure of stone material and the structural behavior does not occur when the metal stiffener is below 0.251%. When it accounts for over 0.5%, it achieves structural reinforcement, but causes secondary damage of parent materials. The appropriate ratio of metal stiffener for the stone material with the strength of $1,500kgf/cm^2$, therefore, should be between 0.283% and 0.377% of the cross section of attached surface to achieve reversible fracture and ductility behavior. In addition, it is more effective to position the stiffeners at close intervals to achieve the peak stress of metal rod against bending load and inserting the stiffener into the upper secions is not structurally supportive, but would rather cause damage of the parent material. Thus, most stiffeners should be inserted into the lower part and some into the central part to work as a stable tensile material under the load stress. The dispersion effect of metal rods was influenced by the area of reinforcing rods and unrelated to their diameter. However, it ensures stability under the load stress to increase the number of stiffeners considering the cross section adhered when working on large-scale structures. The development length is engineered based upon the diameter of stiffener using the following formula: $l_d=\frac{a_tf_y}{u{\Sigma}_0}$. Also, helically-threaded reinforcing rods should be used to perform the behaviors as a structural material.