• Journal of Technologic Dentistry
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• v.30 no.2
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• pp.71-77
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• 2008

Acrylic resin has been widely used for dental care since it requires relatively simple equipment for treatment and less time and cost are needed to make it and, furthermore, proper strength, dimensional stability as well as durability are ensured after treatment. A survey of denture users showed, however, that more than 60% of dentures installed need repair each year, $22{\sim}30%$ of which are due to falling out of teeth. This study is aimed at exploring the means to increase bonding strength of denture by reducing the causes for falling out of teeth during the processing of dentures. For this aim, the bonding strength of dentures was compares and analyzed before and after the glazed surface of teeth contacting denture was eliminated. From the analysis, it was revealed that there was a difference of 4.3MPa in average in bonding strength between 20MPa for the glazed surface not eliminated and 24.3MPa for the glazed surface eliminated.

• Transactions on Electrical and Electronic Materials
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• v.9 no.1
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• pp.33-37
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• 2008

This paper describes the development of a new $5.0{\times}3.2mm$ SAW filter bank which is consist of 12 L, C matching components and 4 SAW bare chips on PCB substrate with CSP technology. We improved the manufacturing cost by removing the ceramic package through direct flip bonding of $LiTaO_3$ SAW bare chip on PCB board after mounting L, C passive element on PCB board. After that we realized the hermitic sealing by laminating the epoxy film. To confirm the confidentiality and durability of the above method, we have obtained the optimum flip bonding & film laminating condition, and figured out material property and structure to secure the durability & moisture proof of PCB board. The newly developed super mini $5.0{\times}3.2mm$ filter bank shows the superior features than those of existing products in confidence, electrical, mechanical characters.

• Journal of Adhesion and Interface
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• v.7 no.4
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• pp.60-64
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• 2006

In modern vehicle construction the search for means of weight reduction, improving durability, increasing comfort and raising body stiffness are issues of priority to the design engineer. The intelligent usage of many materials such as high strength steel, light-alloys and plastics enables a significant vehicle weight reduction to be achieved. The classical joining techniques used in the automobile industry need to be newly-evaluated since they often do not present workable solutions for such mixed-material connections, for example aluminium/steel. Calculation/simulation methods have made progress as a key factor for broader and more cost-effective implementation of structural bonding. This will lead to reduction of spotwelds and accelerate the car development. A special focus of the paper is the use of high strength steel grades. It will be shown that adhesive bonding is a key tool for yielding the potential of advanced high strength steel for low gauging without compromising the stiffness. The latest status of adhesive development has been described. Improvements with physical strength and glass temperature as well as of process relevant properties are shown. Also the situation regarding occupational hygiene is treated, showing that by further spotweld point reduction the emission around the working area can be even lowered against the current praxis. High performing lightweight design cannot longer do without high performing crash durable adhesives.

• Journal of the Microelectronics and Packaging Society
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• v.28 no.2
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• pp.89-94
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• 2021

The mechanical reliability of flexible devices has become a major concern on their commercialization, where the importance of reliable bonding is highlighted. In terms of component materials' properties, it is important to consider thermal damage of polymer substrates that occupy large area of the flexible device. Therefore, room temperature bonding process is highly advantageous for implementing flexible device assemblies with mechanical reliability. Conventional epoxy resins for the bonding still require curing at high temperatures. Even after the curing procedure, the bonding joint loses flexibility and exhibits poor fatigue durability. To solve this problems, low-temperature and adhesive-free bonding are required. In this work, we develop a room temperature bonding process for polymer substrates using carbon nanotube heated by microwave irradiations. After depositing multiple-wall carbon nanotubes (MWNTs) on PET polymer substrates, they are heated locally with by microwave while the entire bonding specimen maintains room temperature and the heating induces mechanical entanglement of CNT-PET. The room temperature bonding was conducted for a PET/CNT/PET specimen at 600 watt of microwave power for 10 seconds. Thickness of the CNT bonding joint was very thin that it obtains flexibility as well. In order to evaluate the mechanical reliability of the joint specimen, we performed lap shear test, three-point bending test, and dynamic bending test, and confirmed excellent joint strength, flexibility, and bending durability from each test.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.2
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• pp.154-163
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• 2013

Adhesive bonding and plastic welding have been widely used to join two plastic materials together. The goal of this paper is to determine a proper joining technology of a pair of flat panel (FP) photobioreactor (PBR) case. The material of the FP PBR case is polycarbonate (PC) plate. Two types of adhesion, including acryl adhesive and two-part epoxy adhesive, as well as two types of plastic welding technology, including ultrasonic welding and thermal welding, are employed for joining of PC plates. In order to influence of the adhesion and welding conditions on the joining characteristics of the PC plates in operational conditions of the FP PBR case, the morphology in the vicinity of the joined region as well as the water and pressure resistance characteristic are investigated. In addition, the variation of the bonding strength of the joined region and deformation behaviors in the vicinity of the joined region according to the adhesion and welding conditions is examined via the lap-shear test. From the results of basic experiments, proper joining technologies are chosen. Using the chosen joining technologies, the FP PBR case are fabricated to perform full-scale durability experiment. The results of the full-scale durability experiment have been shown that the chosen joining technologies can be applicable to fabricate the FP PBR case.

• International Journal of Highway Engineering
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• v.18 no.1
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• pp.43-55
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• 2016

PURPOSES : This study aims to develop a repair material that can enhance pavement performance, inducing rapid traffic opening through early strength development and fast setting time by utilizing MgO-based patching materials for repairing road pavements. METHODS : To consider the applicability of MgO-based patching materials for repairing domestic road pavements, first, strength development and setting time of the materials were evaluated, based on MgO to $KH_2PO_4$ ratio, water to binder ratio, and addition ratio of retarder (Borax), by which the optimal mixture ratio of the developed material was obtained. To validate the performance of the developed material as a repair material, the strength(compressive strength and bonding strength) and durability (freezing, thawing, and chloride ion penetration resistance) was checked through testing, and its applicability was evaluated. RESULTS : The results showed that when an MgO-based patching material was used, the condensation time was reduced by 80%, and the compressive strength was enhanced by approximately 300%, as compared to existing cement-based repair materials. In addition, it was observed that the strength (compressive strength and bonding strength) and durability (freezing and thawing, and chloride ion penetration resistance) showed an excellent performance that satisfied the regulations. CONCLUSIONS : The results imply that an emergent repair/restoration could be covered by a rapid-hardening cement to meet the traffic limitation (i.e. the traffic restriction is only several hours for repair treatment). Furthermore, MgO-based patching materials can improve bonding strength and durability compared to existing repair materials.

• Journal of the Korean Wood Science and Technology
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• v.47 no.1
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• pp.110-123
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• 2019

This work was conducted to examine the relationship between lignin content and the durability of larch (LAR) pellets. LAR sawdust was immersed in tap water (TW), sulfuric acid (AC) and sodium hydroxide (AK) solutions, and then the immersed sawdust was used for pellet fabrication. Klason lignin (KL) content of the immersed LAR, contents of soluble lignin (SL) and monomeric sugars liberated from the immersion of LAR, and durability of LAR pellets were measured. KL content decreased as the concentration of AC and AK solutions increased, but glucose content increased with increase in AC and AK concentration. Durability of wood pellets fabricated using non-immersed LAR sawdust was the highest, followed by those made using TW-, AK- and AC-immersed sawdust. LAR pellets became more durable as the concentration of KL and SL increased, but a significant positive correlation was found only between pellet durability and KL content. Through the fluorescent microscopic observation and SEM-EDX analysis, it was verified that lignin content of non-immersed LAR pellets was higher than that of AC- and AK-immersed LAR pellets. These results suggest that lignin might contribute to an increase in inter-particle bonding in wood pellets.

• Journal of the Korean Academy of Esthetic Dentistry
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• v.22 no.1
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• pp.4-8
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• 2013

This clinical report shows the importance of selecting appropriate materials in fabricating laminate veneer restorations. Such cases should be carefully selected to ensure bonding durability, providing consistently reliable prognosis.

• Restorative Dentistry and Endodontics
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• v.23 no.1
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• pp.413-423
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• 1998

Dental ceramics exhibit excellent esthetic property, compressive strength, chemical durability, biocompatibility and translucency. This study evaluated the shear bond strength of composite resin to the new heat-pressed ceramic material (IPS-Empress System) depending on the surface treatments and bonding agents. The surface treatments were etching with 4.0% hydrofluoric acid, application of silane, and the combination of the two methods. Composite resin was bonded to ceramic with four kinds of dentin bonding agents(All-Bond 2, Heliobond, Scotch bond Multi-purpose and Tenure bonding agents). The ceramic specimen bonded with composite resin was mounted in the testing jig, and the universal testing machine(Zwick 020, Germany) was used to measure the shear bond strength with the cross head speed of 0.5 mm/min. The results obtained were as follows 1. The mean shear bond strength of the specimens of which the ceramic surface was treated with the combination of hydrofluoric acid and silane before bonding composite resin was significantly higher than those of the other surface treatment groups(p<0.05). 2. In the case of All-Bond 2 and Scotchbond Multi-purpose bonding agent group, the surface treatment methods did not influenced significantly on the shear bond(p>0.05). 3. Of the four bonding agents tested, the shear bond strength of Heliobond was significantly lower than those of other bonding agents regardless of the surface treatment methods(p<0.05). 4. The highest shear bond strength($12.55{\pm}1.92$ MPa) was obtained with Scotchbond Multipurpose preceded by the ceramic surface treatment with the combination of 4% hydrofluoric acid and silane.

• Journal of the Korea Institute of Military Science and Technology
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• v.11 no.3
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• pp.123-128
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• 2008

Ti-6Al-4V alloy is a critical strategic metal used in aerospace structure due to the high specific strength, toughness, durability, low density, corrosion resistance. Examples of application of this alloy are airframe structural components, aircraft gas turbine disks and blades. Forming of this alloy is not easy due to its high strength and low formability. However, this alloy shows superplastic properties that allow for large plastic deformation under certain conditions. Combination of superplastic forming and diffusion bonding(SPF/DB) processes of this alloy has been widely used to replace mechanically fastened structures with reduced weight and fabrication costs. In this study, superplastic forming/diffusion bonding technology has been developed for fabricating lightweight sandwich panels with Ti-6Al-4V alloy. The experimental results show the forming of titanium lightweight sandwich structure is successfully performed from 3 and 4 sheets of Ti-6Al-4V.