Climate Change Impact Assessment on Han River Long Term Runoff in South Korea Based on RCP Climate Change Scenario

The 2007 World Economic Forum (WEF) referred to climate change as the overriding problem we face. Concerns have been raised about how global warming would accelerate future climate change and its consequences. Many climate change studies expect the possible occurrence of extreme high temperature, increase in heavy rains and strong typhoons in the near future. Currently, climate change scenarios are used to prepare an appropriate plan for these phenomena under climate change. The main purpose of this paper is to suggest and evaluate an operational method of assessing the potential impact of climate change on hydrologic components and water resources at the regional scale. Future runoff was simulated using high resolution Regional Circulation Model (RCM) (12.5 × 12.5 km) Representative Concentration Pathway (RCP) scenario operated by the Korea Meteorological Administration (KMA) and a semi-distribution model or SLURP (Semi-distributed Land Use-based Runoff Process). The study was carried out on the Han River including its nine dams. The study found that runoff characteristics, especially annual distribution, could change. The discharge in July tends to decrease while runoff can increase in August and September. The flow duration curve was estimated and compared with observed data and simulated daily runoff data for Paldang-dam to evaluate the effect of climate change. The analysis of the flow duration curve shows that the mean average low flow increased while the average wet and normal flow decreased under the climate change scenario

Improving shear bond strength of temporary crown and fixed dental prosthesis resins by surface treatments

This article is published with open access at Springerlink.comThis study evaluated the effect of surface treatments on the bond strength of repaired temporary resins. One-hundred flat-surfaced cylindrical specimens (Ø 7 mm × 12 mm) of each temporary resin (2 bis-acryl resins and 2 polymethyl-methacrylates) were prepared. The specimens were randomly divided into 10 groups (n = 10), according to the types of surface treatments: untreated, adhesive treated, silanated, silane + adhesive treated, hydrofluoric acid etched, laser treated, sandblasted, sandblasting + adhesive treated, sandblasting + silanated, and tribochemical silica coating + silanated. Each resin material of the same brand with cylindrical shape (Ø 3 mm × 3 mm) was polymerized onto the resin surfaces, and specimens were stored for 24 h in distilled water. The shear bond strengths were measured and failure modes were examined. All data were analyzed with a one-way ANOVA and multiple comparison Scheffé post hoc test (α = 0.05). For bis-acryl resins, the highest shear bond strength was observed in sandblasted group and the lowest was observed in the control group. Results show that the repair bond strength was improved for bis-acryl resin by 23 % than that of the control group due to the increase in surface roughness by sandblasting. However, chemical treatment did not improve repair bond strength. The surface treatment of bis-acryl resins with sandblasting seems to be promising for the improvement of repair bond strength.OAIID:oai:osos.snu.ac.kr:snu2015-01/102/2008003883/12ADJUST_YN:NEMP_ID:A078517DEPT_CD:861CITE_RATE:2.371FILENAME:j mater sci 201510 51(3) 1463-75.pdfDEPT_NM:치의학과SCOPUS_YN:YCONFIRM:

Effect of sandblasting and various metal primers on the shear bond strength of resin cement to Y-TZP ceramic

OBJECTIVES: This study was designed to evaluate the effect of sandblasting and metal primers on the shear bond strength of three commercial resin cements to Yttria-Tetragonl Zirconia Polycrystal (Y-TZP) ceramics. METHODS: One hundred and twenty Y-TZP ceramic cylinders (Ø7 mm x 12 mm) were embedded in polytetrafluoroethylene (PTFE) molds using PMMA. The specimens were divided randomly into 12 groups (n=10), according to the surface treatments (control; sandblast-only; metal primer-only; sandblast+metal primer) and metal primer-resin cements (Alloy primer - Panavia F 2.0, V-primer - Superbond C&B, Metaltite - M bond) rendered. The mixed resin cements were placed onto the treated zirconia surfaces in cylindrical shape (Ø3 mm x 3 mm) using PTFE molds. All specimens were thermocycled (5 and 55 degrees C, 5000 cycles) and subjected to shear bond strength test by a universal testing machine with a crosshead speed of 0.5 mm/min. All data were statistically analyzed using two-way ANOVA and multiple comparison Scheffé test (alpha=0.05), and SEM images of the fractured areas were used to evaluate the fracture mode. RESULTS: In Panavia F 2.0, the bond strength of the specimens treated with sandblasting and metal primer (Alloy primer) was significantly higher than those of the other subgroups. In Superbond C&B and M bond, sandblasting significantly increased the shear bond strength, but the effect of metal primers (V-primer and Metaltite) was not significant and there was disordinal interaction. SIGNIFICANCE: Metal primers are not always effective for bonding between Y-TZP ceramics and resin cements. Even though a metal primer is not enough to be used alone, combined application with sandblasting seems to be an appropriate pretreatment for improving the bond strength of resin cement to Y-TZP ceramics, especially in Panavia F 2.0.This study was supported by the research grant No. 03-2009-0017 from the Seoul National University Dental Hospital Research Fund

Effects of surface treatments on the translucency, opalescence, and surface texture of dental monolithic zirconia ceramics

Statement of problem. Surface polishing or glazing may increase the appearance of depth of monolithic zirconia restorations. Purpose. The purpose of this in vitro study was to investigate the effects of surface treatments on the translucency, opalescence, and surface texture of dental monolithic zirconia ceramics. Material and methods. Forty-five monolithic zirconia specimens (16.3x16.4x2.0 mm) were divided into groups I to V, according to the number of colorings each received. Each group was then divided into 3 subgroups (n=3) according to the surface treatment: N=no treatment; P=polished; and G=glazed. ClElab color coordinates were obtained relative to D65 on a reflection spectrophotometer. The translucency parameter (TP) and opalescence parameter (OP) were calculated. One specimen per subgroups I and V was selected for evaluation of surface roughness (Ra) and was examined with scanning electron microscopy (SEM). Data were analyzed with 2-way ANOVA and pairwise comparisons (alpha=.05). Statistical powers were verified to evaluate results (alpha=.05). Results. The interaction effects of surface treatments combined with the number of colorings were significant for TP, OP, and Ra (P<.001), as follows: Ra=partial eta squared [eta(2)(P)]=.928; OP eta(2)(P)=.184; and TP eta(2)(P):=.144. No significant differences between TP were found among surface treatments in most groups (P>.05), whereas glazing significantly decreased OP and Ra in most groups. SEM images demonstrated that surface treatments affected the surface texture of monolithic zirconia ceramics. Conclusions. Surface treatments combined with coloring strongly affect the surface texture of dental monolithic zirconia ceramics.N

Relationship Between Non-Point Source Pollution and Korean Green Factor

In determining the relationship between the rational event mean concentration (REMC) which is a volume-weighted mean of event mean concentrations (EMCs) as a non-point source (NPS) pollution indicator and the green factor (GF) as a low impact development (LID) land use planning indicator, we constructed at runoff database containing 1483 rainfall events collected from 107 different experimental catchments from 19 references in Korea. The collected data showed that EMCs were not correlated with storm factors whereas they showed significant differences according to the land use types. The calculated REMCs for BOD, COD, TSS, TN, and TP showed negative correlations with the GFs. However, even though the GFs of the agricultural area were concentrated in values of 80 like the green areas, the REMCs for TSS, TN, and TP were especially high. There were few differences in REMC runoff characteristics according to the GFs such as recreational facilities areas in suburbs and highways and trunk roads that connect to major roads between major cities. Except for those areas, the REMCs for BOD and COD were significantly related to the GFs. The REMCs for BOD and COD decreased when the rate of natural green area increased. On the other hand, some of the REMCs for TSS, TN, and TP were still high where the catchments encountered mixed land use patterns, especially public facility areas with bare ground and artificial grassland areas. The GF could therefore be used as a major planning indicator when establishing land use planning aimed at sustainable development with NPS management in urban areas if the weighted GF values will be improved

The effect of preparation order on the crystal structure of yttria-stabilized tetragonal zirconia polycrystal and the shear bond strength of dental resin cements

Objectives. The purpose of this study was to evaluate the effect of preparation order on the crystal structure of yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) and the shear bond strength of dental resin cements. Methods. One-hundred fifty pre-sintered Y-TZP cylinders (Ø 9mm×13.5mm) were prepared and divided into three groups (control group, SBS group and SAS group). Specimens in control group were not treated. Specimens in SBS group were sandblasted and then densely sintered, and specimens in SAS group were sintered in advance, and then sandblasted. The specimens were analyzed by X-ray diffractometry, confocal laser scanning microscopy and Energy dispersive X-ray spectroscopy before and after sandblasting. All specimenswere embedded in polytetrafluoroethylene (PTFE) molds using PMMA and each group was divided into five subgroups. The mixed resin cements (Clearfil SA luting cement, Zirconite, Superbond C&B, Rely-X Unicem, and Multilink) were placed onto the Y-TZP surfaces using PTFE molds with Ø 3mm×3mm, followed by storage in distilled water at 37 ◦C for 24 h, and thermocycling (5000 cycles at 5 ◦C and 55 ◦C with a 30 s dwelling time). All specimens were tested for the shear bond strengths with a universal testing machine, and fractured surfaces were evaluated by SEM. Statistical analysis was performed using one-way ANOVA and Scheffé comparison with ˛ = .05. Results. Sandblasting of the zirconia significantly increased shear bond strength of resin cements, but the preparation order had no significant influence on the shear bond strength in both test groups. In SEM observation, the natures of the surface faceting of the zirconia grains were totally different between SBS and SAS groups. SBS group exhibited less monoclinic structures than SAS group. Significance. Sandblasting of pre-sintered Y-TZP and then sinteringmay induce favorable proportion of tetragonal structures. This might have positive effect on the clinical performance of zirconia restorations. © 2011 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.This study was supported by the research grant No. 03- 2009-0017 from the Seoul National University Dental Hospital Research Fund. The Y-TZP ceramic materials (Rainbow, Dentium, Seoul, Korea) used in this study were generously supplied by their manufacturers.

A randomized clinical 1-year trial comparing two types of non-submerged dental implants

Objectives: This study compared the implant stability and clinical outcomes obtained with two types of non-submerged dental implants that have different thread designs and surface treatments. Materials and methods: A randomized clinical trial with 1 year of follow-up was performed on 56 participants with 75 implants (control group, 36 implants in 28 subjects; experimental group, 39 implants in 28 subjects). The experimental group received the Osstem SSII Implant system; the control group received the Standard Straumann ® Dental Implant System. The diameter and length of the fixture were uniform at 4.1 mm and 10 mm and all the implants restored the unilateral loss of one or two molars from the mandible. To compare implant stability, the peak insertion torque, implant stability quotient (ISQ), and periotest value (PTV) were evaluated during surgery, and at 4 and 10 weeks after surgery. To compare marginal bone loss, standard periapical radiographs were obtained during surgery, and at 10 weeks and 1 year after surgery. Results: This study showed statistically significant differences between the two groups in peak insertion torque (P=0.009) and ISQ (P=0.003) but not in PTV (P=0.097) at surgery. In contrast, there was no statistically significant difference in the pattern of change of ISQ during the 10 weeks after surgery (P=0.339). For marginal bone loss, no significant difference was observed between the control and the experimental groups before functional loading (P=0.624), but after 1 year of follow-up, a borderline difference was observed (P=0.048). Conclusion: The success rate after 1 year of follow-up was 100% for both implant system despite the presence of a significant difference in implant stability during surgery. There was a borderline difference in marginal bone loss after 1 year of follow-up.This study was supported by the Korea Health R&D Project, Ministry of Health & Welfare, Korea, A062480

Effects of airborne-particle abrasion protocol choice on the surface characteristics of monolithic zirconia materials and the shear bond strength of resin cement

The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).This study evaluated the effect of several airborne-particle abrasion protocols on the surface characteristics of monolithic zirconia and of protocol choice on the shear bond strength of resin cement. 375 bar-shaped (45×4×3 mm3) and 500 disk-shaped (Ø9×1 mm2) monolithic zirconia specimens were divided into 25 groups. All specimens were abraded with one of three different sizes of alumina particles (25, 50 or 125 μm), two different pressures (2 or 4 bar), two distinct application times (10 or 20 s) and two distinct incidence angles (45° or 90°). The bar-shaped specimens were used for 3-point bending test; Weibull parameters were calculated and transformed monoclinic phase (XM), surface characteristics were examined. The disk-shaped specimens were used to determine the shear bond strength of resin cement before and after thermocycling. All data were analyzed using 4-way ANOVA and a multiple comparison Scheffé test (α=.05). The particle size, pressure and time significantly affected the flexural strength, while the incidence angle was insignificant. The XM and surface roughness were proportional to the size, pressure, time and incidence angle. The Raman spectrum analysis showed a higher proportion of the monoclinic phase as the depth of the specimen was closer to the abraded surface. In bonding with resin cement, the highest shear bond strength after thermocycling was obtained by the abrasion with 50 μm particles at 4 bar for 20 s, regardless of incidence angle. Surface treatment of monolithic zirconia with 50 μm particle at 4 bar for 20 s at either 45° or 90° incidence angles is recommended.OAIID:oai:osos.snu.ac.kr:snu2016-01/102/2008003883/1ADJUST_YN:NEMP_ID:A078517DEPT_CD:861CITE_RATE:2.605FILENAME:ceram int 201601 42(1) 1552-62.pdfDEPT_NM:치의학과SCOPUS_YN:YCONFIRM: