• International Journal of Oral Biology
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• v.46 no.4
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• pp.184-189
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• 2021

When luting indirect restorations with dual-cure resin cement (DCRC), excess cement can be easily removed by performing tack cure of DCRC for a few seconds. The purpose of this study was to evaluate whether different tack cure times affect polymerization shrinkage (PS) of the selected DCRC. One dual-cure resin cement (G-CEM LinkAce, GC) was used for measuring PS in light-cure (LC group), self-cure (SC group), and two tack-cure modes. In the first tack-cure subgroup, tack cure was performed for 1, 2, 3, and 5 seconds, followed by light cure after 2 minutes of remnant removal time in each case (TC-LC groups). In the other tack-cure subgroup, tack cure was performed for the same lengths of time, but followed by self-cure in each case (TC-SC groups). PS was measured by a modified bonded disc method for 1,800 seconds. One-way analysis of variance followed by Duncan's post hoc test was used to determine any statistically significant differences among the test groups (α = 0.05). When the DCRC was self-cured after tack cure, PS was significantly lower than when it was only self-cured (p < 0.05); however, tack cure time did not affect PS (p > 0.05). When the DCRC was light-cured, PS was not affected by tack cure or tack cure time (p > 0.05). Therefore, tack cure within 5 seconds did not negatively affect the final PS when the DCRC was light-cured after cement remnant removal.

• Advances in environmental research
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• v.6 no.4
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• pp.301-315
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• 2017

An Amberlite XAD-4 resin impregnated with di(2-ethylhexyl)phosphoric acid was prepared and its adsorption-desorption behaviors with Sr(II) ions under various conditions was examined. The resin was characterized by fourier transform infrared and thermal analysis techniques. The effects contact time, temperature, pH, interfering ions and eluants were studied. Results showed that adsorption of Sr (II) well fitted with pseudo-second-order kinetic model. The equilibrium adsorption data of Sr (II) on the impregnated resin were analyzed by Jossens, Weber-van Vliet, Redlich-Peterson and Fritz-Schlunder models to find out desirable equilibrium condition. Among them, the Fritz-Schlunder model best fitted to the experimental data. The maximum sorption capacity of impregnated resin amounted to 0.45 mg/ g at pH 8.0 and $20^{\circ}C$.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 1999.11b
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• pp.61-69
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• 1999

Contaminants such as fatty acids, triglycerides, resin acids and foam collected from a high yield sulfite weak liquor storage tank lowered the water surface tension and reduced inter-fibre bonding but also tended to benefit sheet opacity. Some common wet end additives such as defoamers and dispersants gave similar results. Lignosulfonate and naphthalene sulfonate showed little if any negative effect on both surface tension and sheet strength properties. Among the natural wood extractives. fatty acids were identified to be most detrimental followed by triglycerides and then resin acids. In order to alleviate the detrimental impact of these contaminants, membrane separation, air floatation and ozone treatment were carried out on paper machine white water samples. The effect of these treatments on removal of fatty and resin acids was quantified by a GC-Mass analysis. Reverse osmosis with a 1000 molecular weight cut off membrane failed to totally reject fatty and resin acids, but markedly reduced losses of sheet properties due to contaminants. Ozone treatment resulted in a significant increase of the surface tension and air floatation was considered to be a practical and useful method for removing fatty and resin acids from the machine white water.

• Journal of Environmental Science International
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• v.18 no.6
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• pp.645-654
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• 2009

Lab-scale Electrodialysis(ED) system with different membranes combined with before or after pyroma process were carried out to remove nitrate from two pickling acid wastewater containing high concentrations of $NO_3\;^-$(${\approx}$150,000 mg/L) and F($({\approx}$ 160,000 mg/L) and some heavy metals(Fe, Ti, and Cr). The ED system before Pyroma process(Sample A) was not successful in $NO_3\;^-$ removal due to cation membrane fouling by the heavy metals, whereas, in the ED system after Pyroma process(Sample B), about 98% of nitrate was removed because of relatively low $NO_3\;^-$ concentration (about 30,000 mg/L) and no heavy metals. Mono-selective membranes(CIMS/ACS) in ED system have no selectivity for nitrate compared to divalent-selective membranes(CMX/AMX). The operation time for nitrate removal time decreased with increasing the applied voltage from 10V to 15V with no difference in the nitrate removal rate between both voltages. Nitrate adsorption of a strong-base anion exchange resin of $Cl\;^-$ type was also conducted. The Freundlich model($R^2$ > 0.996) was fitted better than Langmuir mode($R^2$ > 0.984) to the adsorption data. The maximum adsorption capacity ($Q^0$) was 492 mg/g for Sample A and 111 mg/g for Sample B due to the difference in initial nitrate concentrations between the two wastewater samples. In the regeneration of ion exchange resins, the nitrate removal rate in the pickling acid wastewater decreased as the adsorption step was repeated because certain amount of adsorbed $NO_3\;^-$ remained in the resins in spite of several desorption steps for regeneration. In conclusion, the optimum system configuration to treat pickling acid wastewater from stainless-steel industry is the multi-processes of the Pyroma-Electrodialysis-Ion exchange.

• Applied Chemistry for Engineering
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• v.27 no.6
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• pp.633-638
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• 2016

In this study, we used three kinds of commercially available cation, anion, and mixed-ion exchange resins to separate radioactive ions from a polluted water containing Cs, I, and other radioactive ions. The experiment was conducted at a room temperature with a batch method, and a comparative analysis on the decontamination ability of each resin for the removal of Cs and I was performed by using different quantities of resins. The concentration was analyzed using ion chromatography and the ion exchange resin product from company D showed an overall high ion exchange ability. However, for most of the experiments when the amount of ion exchange resin was decreased, the decontamination ability of the resins against mass increased. When the mass of company D's cation exchange resin was small, the ion exchange ability against Cs and I ions were measured as 0.199 and 0.344 meq/g, respectively. When the mixed ion exchange resin was used, the ion exchange ability against I ions was measured as 0.33 meq/g. All in all, company D's ion exchange resins exhibited a relatively higher ion exchange ability particularly against I ions than that of other companies' exchange ions.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.6
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• pp.96-102
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• 2000

The finishing process for dies and molds is an important process because it has influence on final quality of products. And it is difficult to automatize finishing process so that the process has depended on expert's skill until now. However, recently a study on development of die automatic finishing machine has been progressed, and actually this machine is applied to fabrication of die. But the research about tooling system is not enough and finishing tool must have high machining efficiency and adaptability of curved surface. So, this study investigated the application of conductive elastic tool which is composed of metal-resin bonded pellet and elastic backing material. The metal-resin bonded pellet is used to finish the surface by conventional mechanical grinding or electro-chemial grinding method. And elastic backing material is used to follow the curved surface. So conductive elastic tool has long lifetime, uniform removal rate and adaptability of curved surface.

• Journal of the Korean Society of Clothing and Textiles
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• v.2 no.1
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• pp.125-131
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• 1978

This study was intended to clarify (1) the release of free formaldehyde (2) transfer of free formaldehyde to the contacted fabrics during storing, and (3) the removal effect of free formaldehyde by washing from resin finished fabrics. The results of this study were as follow; 1. The decrease rate of free formaldehyde content in fabrics was higher during storing in open air, poly bag, and glass tube in descending order and the content of free formaldehyde in fabrics was decreased in glyoxal resin finished but, increased in Melamine M-3 resin finished when the fabrics was stored in polybag and in glass tube. 2. Increased amount of formaldehyde transfer to contacted fabrics was noted with Melamine M-3 resin finished than that of glyoxal resin finished. Increased amount of formaldehyde transfer as well as more free formaldehyde were noted in cotton fabrics than in polyester/ cotton blend. 3. The effect of removing free formaldehyde from the fabrics was better in case of solid alkaline soap, synthetic alkaline powdered detergents, neutral detergents in descending order. The romoval of free formaldehyde was marked after the 1st washing and almost no increase in free formaldehyde was found after three times of washing. 4. After first washing, the content of formaldehyde in Melamine M-3 resin finished fabrics increased more rapidly than that of glyoxal resin finished fabrics in condition of closed storing.

• Restorative Dentistry and Endodontics
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• v.39 no.4
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• pp.265-269
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• 2014

Objectives: To evaluate the effect of different ultrasonic tip designs on intraradicular post removal. Materials and Methods: The crowns of forty human canine teeth were removed, and after biomechanical preparation and filling, the roots were embedded in acrylic resin blocks. The post spaces were made, and root canal molding was performed with self-cured acrylic resin. After casting (Cu-Al), the posts were cemented with zinc phosphate cement. The specimens were randomly separated into 4 groups (n = 10), as follows: G1 - no ultrasonic vibration (control); G2 - ultrasonic vibration using an elongated cylindrical-shaped and active rounded tip; G3 - ultrasonic vibration with a flattened convex and linear active tip; G4 - ultrasonic vibration with active semicircular tapered tip. Ultrasonic vibration was applied for 15 seconds on each post surface and tensile test was performed in a Universal Testing Machine (Instron 4444 - 1 mm/min). Results: G4 presented the highest mean values, however, with no statistically significant difference in comparison to G3 (p > 0.05). G2 presented the lowest mean values with statistically significant difference to G3 and G4 (p < 0.05). Conclusions: Ultrasonic vibration with elongated cylindrical-shaped and active rounded tip was most effective in reducing force required for intraradicular post removal.

• Journal of the korean academy of Pediatric Dentistry
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• v.30 no.4
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• pp.581-592
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• 2003

The aim of this study was to evaluate the effect of chemo-mechanical caries removal system($Carisolv^{TM}$, Medi Team, Sweden) for resin adhesion to carious primary and permanent dentin compared with conventional drilling method. The buccal surface of 92 primary molars and 92 permanent molars were used. Exposed dentins were occurred artificial caries. 32 tooth of primary molars and 32 tooth of permanent molars were prepared to observe treated dentin surface with $Carisolv^{TM}$ and conventional drilling method by SEM. Other tooth were prepared to measure resin-dentin shear bonding strength according to caries removal methods and dentin adhesive system. Two adhesive systems and a composite resin were used; single bonding agent(Scotchbond Multi-Purpose Plus, 3M) and self-etching bonding system(Prompt L-pop, 3M ESPE), and a composite resin (Z-250, 3M). The results were as follows : 1. The removal effect of carious dentin on $Carisolv^{TM}$ was stronger on the primary dentin than that to permanent dentin, and dentin surface became rougher with treated $Carisolv^{TM}$ than drilling method. 2. Acid-etched dentin surfaces were showed smoothening without smear layer. 3. In specimen applied single bonding system hybrid layer and adhesive layer were $2-4{\mu}m$ and $10-15{\mu}m$ in thickness, whereas self-etching bonding system were showed only thin hybrid layer($1-2{\mu}m$). 4. The shear bonding strength of group applied single bonding agent was higher than that applied self-etching priming system(P<0.05). 5. The shear bonding strength of group applied $Carisolv^{TM}$ and self-etching priming system were slightly higher than that applied conventional drilling method and self-etching priming system(P>0.05).

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2006.11a
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• pp.133-134
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• 2006