• Journal of the Korean Society for Marine Environment & Energy
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• v.12 no.1
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• pp.55-59
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• 2009

As one of the methods for recycling the FRP from the small and medium waste ships, separation of roving layer from the mat has some merits in a sense of the recycling energy and the environmental effects. Similar characteristics, however, between the roving and the mat even with different ratio of the resin and the glass and the thickness of the roving, much thinner than the mat, make the mechanically automatic differentiation difficult. In this study spectrochemical differentiation between the two layers has been made using (1) boiling concentrated sulfuric acid which can dissolve the resin in the FRP layer, (2) methanol and isopropanol solution saturated with KOH which can dissolve the glass, or (3) hydrogen fluoride(HF) solution which can reacts with $SiO_2$ fragments of the glass. Furthermore coloring water-soluble dye following the HF treatment makes the roving layer more distinguishable photo-physically.

• Applied Biological Chemistry
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• v.40 no.6
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• pp.583-587
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• 1997

The MeOH extracts obtained from the tuber of Ipomoea batatas Lam. were solvent-fractionated with EtOAc, n-BuOH, and $H_2O$, respectively. From EtOAc fraction four different compounds were isolated through the repeated silica gel column chromatographies. From not only the results of NMR and MS data but also the adaptation of hydrolysis, methylation, and acetylation, the chemical structures of compounds were elucidated as resin glycoside, simonin I, ${\beta}-sitosterol$, and two kinds of unsaturated fatty acids.

• Applied Chemistry for Engineering
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• v.10 no.2
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• pp.218-224
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• 1999

Continuous ion exchange characteristics of the synthetic coolant contained Ni, Co and Ag ions of low concentration in acidic-oxidizing conditions have been studied to suggest the guideline for the optimum operation of mixed-bed demincralizer during the shutdown period of a pressurized water reactor (PWR). In the effect of the form of cation resins on the removal capacity of metal ions, the performance of a $H^+$-form resin was about 6% higher than that of a $Li^+$-form resin. Mixed-bed of cation and anion resins in comparison with nonmixed-bed of them, had no affected on the removal capacity of metal ions but very slightly increased the slope of breakthrough curves of metal ions. In the effect related to acidic-oxidizing conditions of the coolant, the addition of boric acid very slightly decreased the slope of breakthrough curves of metal ions, while the addition of hydrogen peroxide slightly decreased the removal capacity of metal ions.

• The Journal of Advanced Prosthodontics
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• v.8 no.4
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• pp.251-258
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• 2016

PURPOSE. This study was undertaken to investigate whether use of an adhesive penetration enhancer, dimethyl sulfoxide (DMSO), improves bond stability of fiber posts to root dentin using two two-step etch-and-rinse resin cements. MATERIALS AND METHODS. Forty human maxillary central incisor roots were randomly divided into 4 groups after endodontic treatment and post space preparation, based on the fiber post/cement used with and without DMSO pretreatment. Acid-etched root dentin was treated with 5% DMSO aqueous solution for 60 seconds or with distilled water (control) prior to the application of Excite DSC/Variolink II or One-Step Plus/Duolink for post cementation. After micro-slicing the bonded root dentin, push-out bond strength (P-OBS) test was performed immediately or after 1-year of water storage in each group. Data were analyzed using three-way ANOVA and Student's t-test (${\alpha}$=.05). RESULTS. A significant effect of time, DMSO treatment, and treatment${\times}$time interaction were observed (P<.001). DMSO did not affect immediate bonding of the two cements. Aging significantly reduced P-OBS in control groups (P<.001), while in DMSO-treated groups, no difference in P-OBS was observed after aging (P>.05). CONCLUSION. DMSO-wet bonding might be a beneficial method in preserving the stability of resin-dentin bond strength over time when fiber post is cemented with the tested etch-and-rinse adhesive cements.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.4
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• pp.388-394
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• 2008

For purpose of anti-static film remaining unchanged in the condition of $160^{\circ}C$, organic solvent, acid and base solution $0.01\sim0.03{\mu}m$ particles of Sb doped tin oxide(ATO) were grafted by 3-Glycidyloxypropyltrimethoxysilane(GPTS) for improving interfere bonding force between ATO and epoxy resin. The particles were dispersed in 2-methoxyethanol with YD-I28(Bisphenol A type epoxy resin, Kukdo chemical) and 1-imidazole as hardener. The anti-static solutions were coated on PI film as thickness of $0.1{\mu}m$. Surface resistivity of anti-static film containing conductive polymer became $10^{12}\Omega/\Box$ after 32 hours in $160^{\circ}C$. The surface resistivity of ATO grafted by GPTS / Epoxy coating layer remained as $10^{7.6}\Omega/\Box$ in $160^{\circ}C$ for 7 days. ATO grafted by GPTS / Epoxy coating layer coated on PI film was dipped in acetone for 7 days. The surface resistivity remained unchanged as $10^{7.6}\Omega/\Box$. The anti-static layer dipped in water solutions containing each KOH 10 wt % and $H_2SO_4$ 2 wt% was ultra-sonicated for 10 minutes per once until 30th. The surface resistance of anti-static layer containing ATO grafted by GPTS remained unchanged.

• Journal of the Korean Chemical Society
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• v.27 no.5
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• pp.345-352
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• 1983

Using a column of macrorecticular gel beads impregnated with alcohol solution of diphenylcarbarzide (DPC), the enrichment of Cr(Ⅵ) ion in 0.1M sulfuric acid was investigated. The column performance was compared with respect to the types of solid support such as Amberlite XAD and Diaion HP. Diaion HP-20 was found to be most suitable for this purpose. The break through point was increased when increasing the amount of DPC absorbed in the resin and the concentrated sample solution showed higher break through capacity than the dilute one. The extraction of Cr(Ⅵ) was not affected by the presence of 100 ppm Fe(Ⅲ) which amounted to ten times of 10 ppm Cr(Ⅵ) and the presence of other metal ions which amounted to 100 times of 10 ppm Cr(Ⅵ). Because the used gel particles were effectively regenerated with methanol, they were able to be used repeatedly.

• Korean Journal of Materials Research
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• v.23 no.1
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• pp.24-30
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• 2013

Today, the modification of carbon foam for high performance remains a major issue in the environment and energy industries. One promising way to solve this problem is the optimization of the pore structure for desired properties as well as for efficient performance. In this study, using a sol-gel process followed by carbonization in an inert atmosphere, hollow spherical carbon foam was prepared using resorcinol and formaldehyde precursors catalyzed by 4-aminobenzoic acid; the effect of carbonization temperature and re-immersion treatment on the pore structure and characteristics of the hollow spherical carbon foam was investigated. As the carbonization temperature increased, the porosity and average pore diameter were found to decrease but the compression strength and electrical conductivity dramatically increased in the temperature range of this study ($700^{\circ}C$ to $850^{\circ}C$). The significant differences of X-ray diffraction patterns obtained from the carbon foams carbonized under different temperatures implied that the degree of crystallinity greatly affects the characteristics of the carbon form. Also, the number of re-impregnations of carbon form in the resorcinol-formaldehyde resin was varied from 1 to 10 times, followed by re-carbonization at $800^{\circ}C$ for 2 hours under argon gas flow. As the number of re-immersion treatments increased, the porosity decreased while the compression strength improved by about four times when re-impregnation was repeated 10 times. These results imply the possibility of customizing the characteristics of carbon foam by controlling the carbonization and re-immersion conditions.

• Restorative Dentistry and Endodontics
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• v.37 no.1
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• pp.41-49
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• 2012

Objectives: The internal adaptation of composite restorations with or without resin modified glass ionomer cement (RMGIC) was analyzed non-destructively using Microcomputed tomography (micro-CT). Materials and Methods: Thirty intact human teeth were used. The specimens were divided into 3 groups. In the control group, the cavities were etched with 10% phosphoric acid for 15 sec. Composite resin was filled into the cavity without adhesive. In group 1, light cured glass ionomer cement (GIC, Fuji II LC, GC) was applied as a base. The cavities were then etched, bonded, light cured and filled with composites. In group 2, the cavities were then etched, bonded, light cured and filled with composites without base application. They were immersed in a 25% silver nitrate solution. Micro-CT was performed before and after mechanical loading. One-way ANOVA with Duncan analysis was used to compare the internal adaptation between the groups before or after loading. A paired t-test was used to compare internal adaptation before and after mechanical loading. All statistical inferences were made within the 95% confidence interval. Results: The silver nitrate solution successfully penetrated into the dentinal tubules from the pulp spaces, and infiltrated into the gap between restoration and pulpal floor. Group 2 showed a lower adaptation than the control group and group 1 (p < 0.05). There was no significant difference between the control group and group 1. For all groups, there was a significant difference between before and after mechanical loading (p < 0.05). Conclusions: The internal adaptation before and after loading was better when composites were bonded to tooth using adhesive than composites based with RMGIC.

• Journal of the Korean Society for Marine Environment & Energy
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• v.13 no.1
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• pp.43-46
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• 2010

As one of the methods for recycling the FRP used for the small and medium-sized waste ships, separation of the roving layer from the mat has some merit in a sense of the recycling energy and the environmental effects. Similar characteristics between the roving and the mat make the mechanically automatic differentiation difficult. They, however, contain different ratio of the resin and the glass and the thickness. In this study photo physical differentiation between the two layers has been made using (1) boiling concentrated sulfuric acid which can dissolve the resin in the FRP layer and (2) hydrogen fluoride(HF) solution which can reacts with $SiO_2$ fragments of the glass. Furthermore coloring the FRP sample with water-soluble dye following the HF treatment makes the roving layer more distinguishable photophysically. The implementation of HF treatment has been successfully tested in this study.

• Restorative Dentistry and Endodontics
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• v.20 no.2
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• pp.832-838
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• 1995

The purpose of this study was to evaluate the amount of marginal microleakage of 2 light curable GI cements(Fuji II LC & VariGlass), which contain some resin components. 4 volunteers kept on acrylic resin plates, which contained dentin disks with cavities filled with test materials for 2 weeks. The time when polishing was done(5 minutes and 24 hours after filling) and the use of protective agents were varied, so 8 groups with each 6 specimens were tested. After having specimens(disks with cavities filled with materials) penetrated with 1% Methylene Blue solution, specimens were stored in 40% nitric acid solution for 4 days to extract adsorbed dye material. Supernatants of centrifuged samples were diluted 5 times and Spectrophotometer was used to determine the degree of absorption. Dye concentration was calculated through the pre-obtained Linear Regression Curve. The results were as follows. 1. The best result was seen in groups (PF24, PV24) which were protected and polished 24 hours later and the opposite phenomenon was seen in groups(NF24, NV24) which were held without protection and polished 24 hours later. Groups polished S minutes later showed moderate leakage pattern. 2. Groups polished 5 minutes later showed similar leakage amount irrespective of using of protective agent. But statistically insignificant lower values were seen in VariGlass than in Fuji II LC groups, So It was considered that VariGlass may be more resistant to early moisture attack than Fuji II LC. 3. In groups polished 24 hours later, there was no significant difference between materials but was definitely significant difference according to the use of protective agent. If the cement in which polishing will be done 24 hours later, Protective agent should be used to cover the surface.