• The Journal of Korean Academy of Prosthodontics
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• v.51 no.1
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• pp.27-32
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• 2013

Purpose: The aims of this study were to evaluate the effect of a resin coating on the shear bond strength of indirect composite restoration bonded to dentin with a self adhesive resin cement and to compare the shear bond strength with that of a conventional resin cement. Materials and methods: The occlusal enamels of thirty six extracted noncarious human molars were removed until the dentin flat surfaces of the teeth were exposed. Then, they were divided into 3 groups. The dentin surfaces of group 1 and 3 were left without any conditioning, while the dentin surfaces of group 2 were resin-coated with Clearfil SE bond and a flowable resin composite, Metafil Flo. After all specimens were temporized for 24 hours, indirect composite resin blocks fabricated by Tescera were bonded to dentins by Unicem for group 1 and 2, and by Panavia F for group 3. After 48 hours of water storage, shear bond strengths were measured. The data was analyzed with one-way analysis of variance and multiple comparison test (Tukey method). Results: The shear bond strengths of Unicem applied to resin coated dentin surfaces were significantly higher than those of Unicem and Panavia F used to uncoated dentin surfaces (P<.0001). Conclusion: Application of a resin coating to the dentin surface significantly improved the shear bonding strength of a self adhesive resin cement in indirect restoration.

• Journal of the Korean Wood Science and Technology
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• v.45 no.4
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• pp.409-418
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• 2017

This work attempted to manufacture glued-laminated timber (Glulam) bonded with melamine-urea-formaldehyde (MUF) resin adhesives at various melamine contents from 20% to 50% under high frequency (HF) heating for a very short time. Two preparation methods were employed to prepare MUF resin adhesives with different melamine contents: one-batch method of synthesizing MUF resins in a single batch, and two-batch method of mixing urea-formaldehyde (UF) resin with melamine-formaldehyde (MF) resin that had been synthesized separately. As the melamine content increased, the gelation time and peak temperature of MUF resins decreased. The adhesion performance of plywood showed that the one-batch MUF resin adhesive with 50% melamine content only satisfied the standard requirement of water resistance. Thus, the one-batch MUF resin adhesive with 50% melamine content was applied for bonding wood lamina from four softwood species such as Japanese larch, Korean red pine, Korean pine and Japanese cedar to manufacture Glulam under HF heating. All Glulam samples bonded with the one-batch MUF resin adhesives with 50% melamine content except those from Korean Red Pine satisfied the requirement in water soaking or boiling water delamination test as an exterior grade Glulam. The presence of rosin in Korean Red Pine was believed to be responsible for its poor adhesion. These results showed that the one-batch MUF resin adhesives with 50% melamine content provided acceptable water resistance with exterior grade Glulam manufactured under HF heating.

• Journal of Korean Association for Spatial Structures
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• v.20 no.2
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• pp.39-49
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• 2020

In this study, we will develop a hybrid cross-sectional shape of steel inserted type glued-laminated timber that can improve the strength of structural glued-laminated timber and maximize the ductility by using steel plate with excellent tensile and deformation ability. A total of three specimens were fabricated and the flexural performance test was carried out to evaluate the structural performance of the steel inserted type glued-laminated timber. In order to compare the effect of steel inserted glued-laminated timber, one structural glued-laminated timber test specimen composed of pure wood was manufactured. In addition, in order to evaluate the adhesion performance of the steel inserted, one each of a screw joint test specimen and a polyurethane joint test specimen was prepared. As a result, all the specimens showed the initial crack in the finger joint near the force point. This has been shown to be a cause of crack diffusion and strength degradation. The use of finger joints in the maximum moment section is considered to affect the strength and ductility of the glued-laminated timber beam. Polyurethane-adhesive steel inserted glued-laminated timber showed fully-composite behavior with little horizontal separation between the steel plate and glued-laminated timber until the maximum load was reached. This method has been shown to exhibit sufficient retention bending performance.

• Restorative Dentistry and Endodontics
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• v.29 no.1
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• pp.66-72
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• 2004

All-in-one adhesives were recently developed for reducing the technique sensitivity and chair time, but lots of concerns were made on bondability, longevity, and microleakage. The object of this study was to evaluate microleakage and marginal quality of all-in-one adhesives using electrochemical method and SEM analysis quantitatively. After making Class V cavities, they were bulk filled with Heliomolar(#A1 after surface treatment with three adhesives: Adper Prompt (Group A), One up bond F (Group O), Xeno III (Group X) Electrical conductivity (microamphere, ${\mu}A$) was checked two times: before and after cavity filling. Percentage of leaky margin was estimated from SEM image (${\times}1,000$). The data were statistically analysed: ANOVA and Paired T test for electrical conductivity, Kruskal-Wallis and Mann-Whitney test for marginal quality, Spearman s rho test for checking of relationships between 2 methods. The result were as follows: 1. There was no difference in microleakage between adhesive systems and every specimen showed some of microleakage after filling. 2. Microleakage was reduced about 70% with composite resin filling. 3. Marginal quality was the best in group A. decreasing among groups in the following order: group O, followed by group X. There were significant differences between group A and group X (p=0.015), and between group 0 and group X (p=0.019). 4. There was no relationship between the microleakage measured by electrochemical method and marginal quality measured by SEM analysis. Within the results of this study, there was no difference in microleakage among groups by electrical conductivity. However, significant difference in marginal quality was seen among groups. It was believed that these dissimilar results might be induced because of their own characteristics. Analysis of microleakage needs various methods for accuracy.

• Analytical Science and Technology
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• v.24 no.4
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• pp.290-297
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• 2011

In present, evaluation method for car cabin air quality has been developed in ISO, China, Japan. Also The management standard for new produced car has been applied since 1, July, 2010. To manage car cabin air quality, It is important to evaluate VOC emitted from interior material. In this study, complete component of door trim armrest was evaluated in accordance with ISO 12219-5, cut component was evaluated in accordance with ISO 12219-3. The vapour gas was collected with stainless tube packed with Tenax TA and analyzed with TD-GC/MS. It was confirmed that emission rate of each compounds was difficult in each evaluation method. As a result, to evaluating each components composing door trim armrest, main sources of emitting VOCs in door trim armrest were PP substrate and adhesive.

• Journal of the Korean Wood Science and Technology
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• v.35 no.5
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• pp.58-66
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• 2007

The objective of this research was to develop environment-friendly adhesives for face fancy veneer bonding of engineered flooring. Urea-formaldehyde (UF)-tannin and melamine-formaldehyde (MF)/PVAc hybrid resin were used to replace UF resin in the formaldehyde-based resin system in order to reduce formaldehyde and volatile organic compound (VOC) emissions from the adhesives used between plywoods and fancy veneers. Wattle tannin powder (5 wt%) was added to UF resin and PVAc (30 wt%) to MF resin. These adhesive systems showed better bonding than commercial UF resin with a similar level of wood penetration. The initial adhesion strength was sufficient to be maintained within the optimum initial tack range. The standard formaldehyde emission test (desiccator method) and VOC analyzer were used to determine the formaldehyde and VOC emissions from engineered flooring bonded with commercial UF resin, UF-tannin and MF/PVAc hybrid resin. By desiccator method, the formaldehyde emission level of UF resin showed the highest but was reduced by replacing with UF-tannin and MF/PVAc hybrid resin. MF/PVAc hybrid satisfied the $E_1$ grade (below $1.5mg/{\ell}$). VOC emission results by VOC analyzer were similar with the formaldehyde emission results. TVOC emission was in the following order: UF > UF-tannin > MF/PVAc hybrid resin.

• The Journal of Advanced Prosthodontics
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• v.9 no.5
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• pp.350-357
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• 2017

PURPOSE. The object of the present study was to evaluate the shear bonding strength of composite to PEKK by applying several methods of surface treatment associated with various bonding materials. MATERIALS AND METHODS. One hundred and fifty PEKK specimens were assigned randomly to fifteen groups (n = 10) with the combination of three different surface treatments (95% sulfuric acid etching, airborne abrasion with $50{\mu}m$ alumina, and airborne abrasion with $110{\mu}m$ silica-coating alumina) and five different bonding materials (Luxatemp Glaze & Bond, Visio.link, All-Bond Universal, Single Bond Universal, and Monobond Plus with Heliobond). After surface treatment, surface roughness and contact angles were examined. Topography modifications after surface treatment were assessed with scanning electron microscopy. Resin composite was mounted on each specimen and then subjected to shear bond strength (SBS) test. SBS data were analyzed statistically using two-way ANOVA, and post-hoc Tukey's test (P<.05). RESULTS. Regardless of bonding materials, mechanical surface treatment groups yielded significantly higher shear bonding strength values than chemical surface treatment groups. Unlike other adhesives, MDP and silane containing self-etching universal adhesive (Single Bond Universal) showed an effective shear bonding strength regardless of surface treatment method. CONCLUSION. Mechanical surface treatment behaves better in terms of PEKK bonding. In addition, self-etching universal adhesive (Single Bond Universal) can be an alternative bonding material to PEKK irrespective of surface treatment method.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.05a
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• pp.177-180
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• 2004

In this study, we report a novel encapsulation method for longevity of an organic thin-film transistor (OTFT) using pentaceneby means of an adhesive multiplayerincluded Al film. For encapsulation of OTFTs, the Al film adhered onto the OTFT in a dry nitrogen atmosphere using a proper adhesive. A lifetime, which was defined as the time necessary to reduce mobility to 2% of initial mobility value, was observed from the typical $I_{D-VD}$ characteristics of the field-effect transistor (FET). The initial field effect mobility ${\mu}$ was measured to be $2.0{\times}10^{-1}\;cm^2/Vs$. The characterization was maintained for long times in air. No substantial degeneration occurred. The performance and the stability are probably due to the encapsulation effect.

• Journal of the Korean Society for Advanced Composite Structures
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• v.2 no.2
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• pp.7-12
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• 2011

Presently, composite method for steel and concrete is often used the stud. Steel properties of composite column could be changed by increasing of welding. The changed properties is possibly to cause local-buckling. Composite column had a large effect by slip instead of pull-out force in comparison composite girder. Improvement of adhesive force had effect by contact area rather than height of stud in composite column. This paper proposed new type of stud and analyzed performance through experimental study. This method would be effect steel structure with curvature.

• Fire Science and Engineering
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• v.30 no.3
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• pp.67-72
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• 2016

The development of flame retardants aims to prevent the spread of fire and reduce the casualties caused by flammable and toxic gases generated during the combustion of building materials used in the interiors of multi-use facilities. Flame material application provides flame resistance to a silica sol in an organic-inorganic hybrid material by flame retardant adhesive or coating by producing a sol-gel method. The conventional flame retardant materials, non-flame retardant material is applied with Halogen freeway. In particular, the basic physical properties of conventional adhesive coating improves the heat resistance, enhances the durability fire and heat, and expands the halogen free flame retardant of building materials.