• Proceedings of the Korean Fiber Society Conference
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• 2007.11a
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• pp.13-15
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• 2007

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• Journal of the Korean Wood Science and Technology
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• v.41 no.1
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• pp.64-76
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• 2013

In this study, eco-friendly hybrid composite boards were manufactured from green tea, three kinds of charcoals and wood fiber for developing interior materials to reinforce the strength performances and the functionalities in addition to performances of the green tea-wood fiber hybrid boards. The effects for the kind and the component ratio of raw materials on mechanical properties were investigated. Bending strength performances of hybrid composite boards were highest in the hybrid composite boards composed of green tea, fine charcoal and wood fiber on average. However, the difference caused by the kind of charcoals was not large. These values were was markedly improved than those of green tea - wood fiber hybrid composite boards reported in previous researches. And it was found that the bending strength performance decreased with increasing component ratios of green tea and charcoals. The difference between urea resins used as the binder showed the higher value in hybrid composite boards using $E_1$ grade urea resin than in those using $E_0$ grade urea resin, but the difference between hybrid composite boards manufactured by both resins decreased markedly than the green tea - wood fiber hybrid composite boards reported in previous research. The internal bond strength of hybrid composite boards was in the order of hybrid composite boards with fine charcoal, activated charcoal and black charcoal, and it was found that the hybrid composite boards with fine charcoal had a similar values to control boards composed of only wood fiber.

• Journal of dental hygiene science
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• v.10 no.6
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• pp.445-450
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• 2010

The aim of this study was to evaluate the effect according to the fiber type and combination on the reinforcement of heat-polymerized denture base resin. The heat-polymerized resin(Vertex RS, Dentimax, Netherlands) was used in this study. Glass fiber(GL; ER 270FW, Hankuk Fiber Glass, Korea), polyaromatic polyamide fiber(PA; aramid; Kevlar-49, Dupont, U.S.A.) and ultra high molecular weight polyethylene fiber(PE, polyethylene; P.E, Dong Yang Rope, Korea) were used to reinforce the denture base resin specimens. The final size of test specimen was $64mm{\times}10mm{\times}3.3mm$. The specimens of each group were stored in distilled water at $37^{\circ}C$ for 50 hours before measurement. The flexural strength and flexural modulus were measured by an universal testing machine(Z020, Zwick, Germany) at a crosshead speed of 5 mm/min in a three-point bending mode. In this study, all fibers showed reinforcing effects on denture base resin(p<0.05). In terms of flexural strength and flexural modulus, glass fiber 5.3 vol.% showed most effective reinforcing effect on heat polymerized denture base resin. For flexural modulus, PA/GL was the highest in denture base resin specimen for hybrid FRC using two combination (p<0.05). Glass fiber 5.3 vol.% and PA/GL are considered to be applied effectively in reinforcing the heat polymerized denture base resin.

• Journal of agriculture & life science
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• v.44 no.5
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• pp.1-8
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• 2010

In this study, eco-friendly hybrid composite boards were manufactured from green tea and wood fibers for application as interior materials with various functionalities of green tea and strong strength properties of wood fibers. In this relation, the effect of green tea content on the static bending strength performances of these green tea and wood fibers composite boards were investigated. Static bending strengths of hybrid composite boards were lower than those of control boards and decreased with the increase of green tea content. Also, the strength performances appeared to be somewhat different by resin type used for board manufacture. The hybrid composite boards manufactured from $E_1$ grade urea resin adhesive, which has higher molar ratio of formaldehyde to urea than that of $E_0$ grade one, were 1.08~1.53 times higher in bending modulus of elasticity (MOE) and 1.19~1.82 higher in modulus of rupture (MOR) than that manufactured from $E_0$ grade. And, the differences of MOE and MOR between hybrid composite boards manufactured from $E_0$ grade and $E_0$ grade urea resin adhesive increased with the increase of green tea content. In the case of hybrid composite boards manufactured from $E_1$ grade urea resin adhesive, the MOR was within 0.94~1.03 times the commercial medium density fiberboard. Thus, it was thought that eco-friendly hybrid composite boards with various functionalities and strong strength performances could be manufactured from green tea and wood fibers.

• Proceedings of the KACD Conference
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• 2001.11a
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• pp.586.2-586
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• 2001

The selection of a curing light is a multifactorial decision. While each method of polymerization presents unique clinical benefits, the optimal light-curing technique remains to be determined. The objective of this study was to check the difference of micro hardness and microleakage according to various light intensity (50, 100, 200, 300, 400, 600 ㎽/$\textrm{cm}^2$) and curing time (10, 20, 40 seconds). A3 color of two composite resin, hybrid type DenFil and submicron type Esthet X were tested.(중략)

• Restorative Dentistry and Endodontics
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• v.36 no.6
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• pp.490-497
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• 2011

Objectives: This study examined the effect of the uncured dentin adhesives on the bond interface between the resin inlay and dentin. Materials and Methods: Dentin surface was exposed in 24 extracted human molars and the teeth were assigned to indirect and direct resin restoration group. For indirect resin groups, exposed dentin surfaces were temporized with provisional resin. The provisional restoration was removed after 1 wk and the teeth were divided further into 4 groups which used dentin adhesives (OptiBond FL, Kerr; One-Step, Bisco) with or without light-curing, respectively (Group OB-C, OB-NC, OS-C and OS-NC). Pre-fabricated resin blocks were cemented on the entire surfaces with resin cement. For the direct resin restoration groups, the dentin surfaces were treated with dentin adhesives (Group OB-D and OS-D), followed by restoring composite resin. After 24 hr, the teeth were assigned to microtensile bond strength (${\mu}TBS$) and confocal laser scanning microscopy (CLSM), respectively. Results: The indirect resin restoration groups showed a lower ${\mu}TBS$ than the direct resin restoration groups. The ${\mu}TBS$ values of the light cured dentin adhesive groups were higher than those of the uncured dentin adhesive groups (p < 0.05). CLSM analysis of the light cured dentin adhesive groups revealed definite and homogenous hybrid layers. However, the uncured dentin adhesive groups showed uncertain or even no hybrid layer. Conclusions: Light-curing of the dentin adhesive prior to the application of the cementing material in luting a resin inlay to dentin resulted in definite, homogenous hybrid layer formation, which may improve the bond strength.

• Journal of the Korean Wood Science and Technology
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• v.34 no.2
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• pp.37-45
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• 2006

The viscoelastic properties of blends of melamine-formaldehyde (MF) resin and poly(vinyl acetate) (PVAc) for engineered flooring used on the Korean traditional ONDOL house floor heating system were investigated by dynamic mechanical thermal analysis (DMTA). Because MF resin is a thermosetting adhesive, the effect of MF rein was shown across all thermal behaviors. The addition of PVAc reduced the curing temperature. The DMTA thermogram of MF resin showed that the storage modulus (E') increased as the temperature was further increased as a result of the cross-linking induced by the curing reaction of the resin. The storage modulus (E') of MF resin increased both as a function of increasing temperature and with increasing heating rate. From isothermal DMTA results, peak $T_{tan{\delta}}$ values, maximum value of loss modulus (E") and the rigidities (${\Delta}E$) of MF/PVAc blends at room temperature as a function of open time, peak $T_{tan{\delta}}$ and maximum loss modulus (E") values were found to increase with blend MF content. Moreover, the rigidities of the 70:30 and 50:50 MF/PVAc blends were higher than those of the other blends, especially of 100% PVAc or MF. We concluded that blends the MF/PVAc blend ratios correlate during the adhesion process.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.8
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• pp.149-154
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• 1999

FRMLs(Fiber Reinforced Metal Laminates) is a new type of hybrid materials. FRMLs consists of high strength metal and fiber which are laminated using a structural adhesive bond(epoxy resin). The effect of resin mixture ratios on the fatigue crack propagation behavior and mechanical property of Aramid fiber reinforced aluminum composites was investigated. The epoxy, diglycidylether of bisphenol A(DGEBA) was cured with methylene dianiline(MDA) with or without accelerator(K-54). Eight kinds of resin mixture ratio were tested for the experiment ; five kinds of FRMLs(1))epoxy & curing agent) and three kinds of FRMLs(2)(epoxy & curing agent & accelerator). FRMLs(2) have a more effective characteristics on the fatigue crack propagation behavior and mechanical property than FRMLs(1)

• Composites Research
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• v.30 no.6
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• pp.416-421
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• 2017

The structural adhesive have been manufactured for improvement of bonding process between CFRP and metal. The optimal condition for bonding process were investigated by evaluating the lap shear strength with amount of adhesive and curing time and the surface treatment of the CFRP. To confirm proper adhesion conditions, the fracture sections between CFRP and metal was observed using reflection microscope. Not only the improvement of the adhesion condition was important, but surface treatment on CFRP was also important. The optimal curing temperature was at $180^{\circ}C$ for 20 minutes. The improvement for adhesive property was confirmed After surface treatment on CFRP. The optimal amount of structural adhesive for bonding between CFRP and metal was $1.5{\times}10^{-3}g/mm^2$. Through the optimization of bonding process, the improvement of mechanical property over 10% is confirmed in comparison with existing adhesive.

• Polymer(Korea)
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• v.27 no.1
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• pp.61-68
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• 2003

In this study, we have investigated the preparation of mixed bead and fiber type hybrid ion-exchanger for recovering nickel ion from plating rinse water. There was little dependence of adsorption capacity for nickel ion on the mixing ratio of resin type and fiber type of ion exchangers. However, it increased with increasing the resin content in the mixed bed. It was shown that the data Langmuir and Freundlich's adsorption isotherm model were well fitted to the linear. Affinity between the functional groups in the ion exchanger and nickel ion in the process was confirmed. The pressure drop decreased with increasing the number of stage in the multistage bed, but it increased with increasing the resin content in the mixing bed. The initial breakthrough time in the multistage bed was short due to the increase of number of stage in the continuous process. It was found that the final breakthrough time of the multistage bed was little changed. The breakthrough time decreased with increasing the amount of fibrous ion exchanger in the mixed bed. The maximum adsorption capacities of the mixed and multistage beds were 2.51 meq/g and 2.69 meq/g, respectively. The desorption time for the nickel ion with $1N H_2SO_4$ solution was lower than 10 minutes and the yield of desorption was greater than 98 percent.