• Journal of the Microelectronics and Packaging Society
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• v.27 no.4
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• pp.113-117
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• 2020

In this paper, We investigated the effect of heat treatment process using photo-thermal effect in order to improve mechanical properties of nanostructure on polymer films made by nanoimprint process with hybrid resin. Nanostructures which have a low refractive characteristic were fabricated by UV nanoimprint and after that heat treatment was performed using IPL (intense pulsed light) under process condition of 550 V voltage, pulse width 5 ms, frequency 0.5 Hz. The transmittance and mechanical property of fabricated nanostructure films were evaluated to observe changes in the pattern transfer rate and mechanical properties of nanostructures. The transmittance of the nanostructure was measured at 97.6% at 550 nm wavelength. Nanoindentation was performed to identify improved anti-scatch properties. Result was compared by the heat source. In case of post treatment with IPL, hardness was 0.51 GPa and in the case of hotplate was 0.27 GPa, resulting the increase of hardness of 1.8 times. Elastic modulus of IPL treated sample was 5.9GPa and Hotplate treated one was 4GPa, showing the 1.4 time increase.

• Restorative Dentistry and Endodontics
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• v.28 no.1
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• pp.23-33
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• 2003

The purpose of this study was to compare in vitro interfacial relationship of restorations bonded with three self-etching primer adhesives and one self-etching adhesive. Class I cavity preparations were prepared on twenty extracted human molars. Prepared teeth were divided into four groups and restored with four adhesives and composites Clearfil SE $Bond/Clearfil^{TM}$ AP-X (SE), UniFil $Bond/UniFil^{\circledR}$ F (UF), FL $Bond/Filtek^{TM}$ Z 250 (FL) and Prompt $L-Pop/Filtek^{TM}$ Z 250 (LP) After storing in distilled water of room temperature for 24 hours, the specimens were vertically sectioned and decalcified. Morphological patterns between the enamel/dentin and adhesives were observed under SEM. The results of this study were as follows : 1. They showed close adaptation between enamel and SE, UF and FL except for LP. 2. The hybrid layer in dentin was $2{\;}\mu\textrm{m}$ thick in SE, $1.5{\;}\mu\textrm{m}$ thick in UF, and $0.4{\;}\mu\textrm{m}$ in both FL and LP. So, the hybrid layers of SE and UF were slightly thicker than that of FL and LP. 3. The lengths and diameters of resin tags in UF and FL were similar, but those of LP were slightly shorter and slenderer than those of SE. 4. The resin tags were long rod shape in SE, and funnel shape in other groups Within the limitations of this study, it was concluded that self-etching primer adhesives showed close adaptation on enamel. In addition, the thickness of hybrid layer ranged from $0.4-1.5{\;}\mu\textrm{m}$ between adhesives and dentin. The resin tags were long rod or funnel shape, and dimension of them was similar or different among adhesives.

• Restorative Dentistry and Endodontics
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• v.31 no.1
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• pp.20-29
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• 2006

The purpose of this study was to analyze the stress distribution aspect of unrestored and restored combined shape (wedge shape occulusally and saucer shape gingivally) class V cavity, which found frequently in clinical cases. A maxillary second permolar restored with a combined shape class V composite restorations were modeled using the three dimensional finite element method. Static occlusal load of 170 N was applied on lingual incline of buccal cusp at the angle of $45^{\circ}$ with the longitudinal axis of the tooth. And three dimensional finite element analysis was taken by ANSYS (Version 6.0, Swanson Analysis System Co., Houston, U.S.A) program which represent the stress distribution on unrestored and restored cavity wall and margin. The conclusions were as follows. 1. Compared to the unrestored cavity, Von Mises stress at the cementoenamel junction and line angle of the cavity base were reduced and in restored cavity. 2. Von Mises stress at the occlusal and cervical cavity margin and wall were increased in restored cavity in comparison with the unrestored cavity. 3. In the hybrid and hybrid/flowable composite resin restoration, Von Mises stress at the cementoenamel junction and line angle of the cavity base were reduced more than in the flowable restoration. 4. In the hybrid and hybrid/flowable composite resin restoration, Von Mises stress at the occlusal and cervical cavity margin and wall were increased more than in the flowable restoration.

• Restorative Dentistry and Endodontics
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• v.25 no.3
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• pp.313-320
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• 2000

The purpose of this study was to evaluate on the interfacial morphology between dentin and restorative materials. In this in vitro study, the cavity wall restorated with 3 different kinds of tooth colored restorative materials [resin-modified Glass Ionomer cement (Fuji II LC), composite resin (Z-100), compomer (Dyract)]. The thirty extracted human molar teeth without caries and/or restorations are used. The experimental teeth were randomly divided into three groups of ten teeth each. In each group, Wedge shaped cavities (width: 3mm, length: 2mm, depth: 1.5mm) were prepared at the cementoenamel junction on buccal and lingual surfaces. The adhesive of composite resin were mixed with rhodamine B. Primer of composite resin, Prime & Bond 2.1 of Dyract and liquid of Fuji II LC were mixed with fluorescein. In group 1, the cavity wall was treatment with dentin conditioner, and then restorated with Fuji II LC. In group 2, the cavity wall was treatment with Prime & Bond 2.1 and then restorated with Dyract. In group 3, the cavity wall was etching with 10% maleic acid, applied with primer and bonding agent and then restorated with Z-100. The interface between dentin and restorative materials was observed by fluoresence imaging with a confocal laser scanning microscope. The results were as follows : 1. In Glass ionomer group, adaptation of resin modified Glass-ionomer restoration against cavity wall is tight, but the crack formed inside of restoration were observed. 2. In Dyract group, the penetration of resin tag is shorter and the width of hybrid layer is narrower than composite resin group. 3. In Z-100 group, primer penetrated deeply through dentinal tubule. Also bonding agent was penetrated along the primer, but the penetration length is shorter than primer part, and in 3-D image, the resin tag is conical shape and lateral branch is observed.

• Journal of Korean Society of Forest Science
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• v.69 no.1
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• pp.19-27
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• 1985

Introgressive hybridization of Pinus densiflora in Korea was investigated by examining the position of resin ducts in 4,992 trees from 67 populations. Judging that P. densiflora has only external resin ducts, P. thunbergii only medial resin ducts, and any tree which has even one needle with external and medial resin ducts is hybrid, hybrids are found at all populations investigated. As variation in position of resin ducts was found among needles on a tree, the number of needles investigated from a tree affects judgment of the tree's hybridity. Therefore, hybridity seems to be judged by many traits rather than by the single trait, position of resin ducts. Seed production by artificial pollination between P. densiflora and P. thunbergii was very poor, i.e. one full seed from five female flowers or from two mature cones. This poor seed production, in addition to the low hybrid vigor, if any, seems to make the artificial pollination between the two species for mass-production of seeds for planting impractical.

• Journal of the Korean Applied Science and Technology
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• v.31 no.4
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• pp.595-601
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• 2014

The microstructures of NATM were examined by SEM, FT-IR spectra, tensile properties, mole % of [NCO/OH], and particle size analyzer. Growing concerns in the environment-friendly industries have led to the development of solvent-free formulations that can be cured. We had synthesized NATM(New Austria Tunnel Method) resin having the ability to protect stainless steel against corrosion. Comparing with general NATM resin and coatings, this resin that synthesized with polyurethane and epoxy was highly stronger in intensity and longer durability. Hybrid resin was composed of polyols, MDI, epoxy, silicone surfactant, catalyst and crosslink agent, and fillers. Moreover, fillers such as fume silica not only accelerated the curing rate but also improved the physical property as thermal barriers. The rigid segments of synthetic resin in mechanical properties were due to fume silica and the increase the mole% of [NCO/OH] for corrosion protection. In conclusion, the hybrid resin microstructure with crosslink agent and fume silica are good material for thermosetting coating of metal substrates such as stainless steel.

• Macromolecular Research
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• v.11 no.2
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• pp.98-103
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• 2003

The mechanical properties and failure mechanisms of through-the-thickness stitched plain weave glass fabric/polyurethane foam/epoxy composites were studied. Hybrid composites were fabricated using resin infusion process (RIP). Stitched sandwich composite increased drastically the flexural properties as compared with the unstitched fabrics. The breaking of stitching yarns was observed during the flexural test and this failure mode yielded relatively high flexural properties. Composites with stitched sandwich structure improved the mechanical properties with increasing the number of stitching yarns. From this study, it was concluded that proper combination of stitching density and types of stitching fiber is important factor for through-the-thickness stitched composite panels.

• Composites Research
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• v.34 no.2
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• pp.88-95
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• 2021

VARTM (Vacuum-assisted resin transfer molding) process is a low-cost process technology and affiliated with OoA (Out of Autoclave). Besides, it has been widely used in various fields. However, because of its lower quality than the autoclave process, it isn't easy to apply the VARTM process to the aerospace industry, which requires high reliability. The main problem of the VARTM process is the loss of mechanical properties due to the low fiber volume fraction and high void content in comparison to the autoclave. Therefore, many researchers have studied to reduce void and increase fiber volume fraction. This study examines whether the method of controlling atmospheric pressure could increase the fiber volume fraction and reduce void during the resin impregnation process. Reliability evaluation was confirmed by compressive strength test, fiber volume fraction analysis, and optical microscopy. As a result, it was confirmed that increasing the atmospheric pressure step by step in the VARTM process of impregnating the preform with resin effectively increases the fiber volume fraction and reduces void.

• Restorative Dentistry and Endodontics
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• v.21 no.2
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• pp.505-516
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• 1996

The effects of application of dentin desensitizer containing glutaraldehyde (Gluma Desensitizer) and dentin adhesive system (All Bond 2) to the exposed dentin on the intradental nerve activity (INA) and the occluding aspects of dentinal tubules were investigated in cat canine teeth. Single pulp nerve units were dissected from the inferior alveolar nerve and indentified as $A{\delta}$-fiber units. The INAs elicited by 4M NaCl before and after the application of each experimental agent were compared. The morphological changes of exposed dentin surfaces and dentinal tubules in the dentin specimens used to record INAs were observed by SEM. The results obtained were as follows. 1. Eight $A{\delta}$-fiber units (conduction velocity: $8.0{\pm}4.0m$/sec) were identified. 4M NaCl evoked an irregular burst of action potentials which ceased immediately after washing. 2. In 4 $A{\delta}$-fiber units, the change of INA after the application of Gluma Desensitizer was $133.9{\pm}80.7%$ when it was compared with the INA before the application of the same agent. 3. In 4 $A{\delta}$-fiber units, application of All Bond 2 completely abolished the INA induced by 4M NaCl. 4. In specimens applied with Gluma Desensitizer, the formation of hybrid layer as well as the identification of resin penetration and reaction products with proteins in dentinal tubules were not clearly observed in interface between dentin and adhesive resin. In specimens applied with All Bond 2, the gap width of 2-$3{\mu}m$ was formed between exposed dentin and adhesive resin, and the hybrid layer and resin tags were not clearly formed either.

• Restorative Dentistry and Endodontics
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• v.44 no.4
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• pp.45.1-45.10
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• 2019

Objectives: Self-adhesive resin cements contain functional monomers that enable them to adhere to the tooth structure without a separate adhesive or etchant. One of the most stable functional monomers used for chemical bonding to calcium in hydroxyapatite is 10-methacryloyloxydecyl dihydrogen phosphate (10-MDP). The aim of this study was to evaluate the influence of the10-MDP concentration on the bond strength and physical properties of self-adhesive resin cements. Materials and Methods: We used experimental resin cements containing 3 different concentrations of 10-MDP: 3.3 wt% (RC1), 6.6 wt% (RC2), or 9.9 wt% (RC3). The micro-tensile bond strength of each resin cement to dentin and a hybrid resin block (Estenia C&B, Kuraray Noritake Dental) was measured, and the fractured surface morphology was analyzed. Further, the flexural strength of the resin cements was measured using the three-point bending test. The water sorption and solubility of the cements following 30 days of immersion in water were measured. Results: The bond strength of RC2 was significantly higher than that of RC1. There was no significant difference between the bond strength of RC2 and that of RC3. The water sorption of RC3 was higher than that of any other cement. There were no significant differences in the three-point bending strength or water solubility among all three types of cements. Conclusions: Within the limitations of this study, it is suggested that 6.6 wt% 10-MDP showed superior properties than 3.3 wt% or 9.9 wt% 10-MDP in self-adhesive resin cement.