• The Journal of Korean Academy of Prosthodontics
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• v.48 no.1
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• pp.8-15
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• 2010

Purpose: The purpose of this study was to evaluate the effect of various methods of dentin bonding agent application and air abrasion pretreatment on microtensile bond strength between dentin and resin, using a self-etching adhesive system. Material and methods: Thirty freshly extracted human molars were obtained and divided into 6 groups of 5 teeth. A 2-step self etching adhesive system (Clearfil SE Bond) was used for all groups. The control specimens were prepared using a direct immediate bonding technique. The delayed dentin sealing specimens were prepared using an indirect approach without dentin prebonding. The immediate dentin sealing specimens were prepared using dentin prebonding immediately following preparation. Immediate dentin sealing teeth and delayed dentin sealing teeth had provisional restorations using Fermit for two weeks. Then all specimens of each group were divided into two groups of three, depending on air abrasion pretreatment. Composite "crowns" were incrementally built on and specimens were stored in water for 24 hours. All teeth were prepared for a microtensile bond strength test. Bond strength data were analyzed with a one-way ANOVA test, and post hoc comparison was done using the Scheffe's test. Results: The mean microtensile bond strengths of all groups were not statistically different from each other. Conclusion: When preparing teeth for indirect restorations, IDS and DDS with Clearfil SE bond, have no difference on the microtensile bond strength between dentin and resin. Air abrasion pretreatment did not affect the microtensile bond strength when using IDS and DDS with Clearfil SE bond.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.10
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• pp.4197-4201
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• 2014

Minor trauma to the uterine cervix is supposed to induce local immunity to prevent cervical lesions caused by human papillomavirus (HPV) infection. This study aimed to investigate the local cervical immunity in women with low grade squamous intraepithelial lesion (LSIL) and effects of abrasion after cryosurgery or Pap smear. One hundred women with LSIL and known results of HPV detection were recruited. HPV positive women were randomly divided according to abrasion into cryotherapy and Pap smear observation groups. Cervical tissues and cervico-vaginal lavage (CVL) were collected at 6 and 12 months after allocation. The levels of cytokines at first recruitment were compared with cytokine levels at 6 months after abrasions. The mRNA of IFN-${\gamma}$, TNF-${\alpha}$ and IL-10 in cervical tissues and these cytokines secreted in CVL were determined using real time PCR and ELISA, respectively. Anti-HPV16 IgG and IgA antibodies in CVL were assessed by western blotting. At first recruitment of women with LSIL (100 cases), IL-10 mRNA and cytokine in HPV positive group (60 cases) was significantly higher than negative group (40 cases). IFN-${\gamma}$ and TNF-${\alpha}$ mRNA level in both groups were comparable but their secretions in CVL were significantly increased in HPV negative group. After abrasion for 6 months in HPV-positive women, all mRNA and secreted cytokines were changed, but no significant difference was observed between cryotherapy and observation groups. When individuals were compared between first recruitment and after abrasion for 6 months, IFN-${\gamma}$ mRNA and anti-HPV16 L1 IgA antibodies were significantly increased in the cryotherapy group. The results suggest that modulation of local cervical immunities by abrasion might promote different effects in clearance of HPV-related cytological abnormalities.

• Journal of dental hygiene science
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• v.18 no.3
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• pp.164-171
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• 2018

To improve the oral health status of Korean people, it is necessary to encourage proper oral hygiene management habits, such as toothbrushing, through appropriate health promotion techniques. Therefore, the purpose of this study was to evaluate the removal of plaque and tooth abrasion using ultra-soft (filament 0.11~0.12 mm) and soft toothbrushes for toothbrushing. The plaque removal was performed using a dentiform and Arti-spray, and the Patient Hygiene Performance (PHP) index was calculated as the sum total score divided by the total number of surfaces. In the abrasivity experiment, according to the number of brushings, a micro Vickers hardness tester was used, and a sample in the range of 280~380 Vickers hardness number was selected. The number of toothbrushing stroke were 1,800 (2 months), 5,400 (6 months), 10,800 (12 months), and 21,600 (24 months). The tooth abrasion was measured using a scanning electron microscope. Statistical analysis was performed using IBM SPSS Statistics 22.0 and a p-value <0.05 was considered significant. According to the results, there was no statistically significant difference in the degree of plaque removal between ultra-soft and soft toothbrushes. The difference in tooth abrasion between before and after toothbrushing was found to be greater with the soft toothbrushes than with the ultra-soft toothbrushes. Therefore, the ultra-soft toothbrush not only lowers tooth damage by reducing tooth abrasion, but also shows a similar ability to remove plaque as soft toothbrushes.

• Elastomers and Composites
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• v.46 no.1
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• pp.70-77
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• 2011

A new piece of test equipment, the slurry wear tester (SWT), was proposed in this study to evaluate the wear behavior of rubber vulcanizate in environmental contact with slurry. Natural rubber (NR) and chloroprene rubber (CR) were chosen as the basic matrices to test the slurry wear. The fluids used to fill the chamber of the SWT were 35% HCl and NaCl solution. The Akron abrasion test was used for comparison with SWT. According to the results of the Akron abrasion test, CR vulcanizate abraded more rapidly than NR vulcanizate under same test condition. It was found that the hysteresis of rubber was key factor contribute to the wear behavior. However, the slurry wear rate of the NR and CR vulcanizates did not change significantly, even with changes in the concentration of acid and the immersion time in both HCl and NaCl solutions; the fluid decreased the friction between the abrasive paper and the specimen. It also reduced the heat generated from repeated deformation and wear debris at the surface of the SWT's abrasion arm. Thus, these phenomena affected the wear behavior of rubber vulcanizate and caused different results in the conventional Akron abrasion test. This outcome could have resulted in an incorrect analysis if the slurry wear behavior of the rubber vulcanizate was estimated by the conventional abrasion tests, which are operated under dry conditions.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.1069-1077
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• 2008

The railway abrasion measurement system have to satisfy two conditions to increase the measurement accuracy as follows. The laser region which is projected on the rail have to be extracted without the geometrical distortion. The mapping of the acquired laser region data on the rail profile have to be processed exactly. But, the conventional railway abrasion measurement system is deeply effected by the foreign substance( dust, rainwater, and so on ) on the railway or the sensitive response characteristic of the laser to the external measurement circumstance, and then the measurement errors arise from above factors. When the laser region is projected on the rail extracts from the acquired image, the interference of the light with the same frequency as the laser system occurs the serious problems. In the process of the mapping between the railway profile and the extracted laser region, the measurement accuracy is very highly effected by the geometrical distortion and the abnormal variation. In this Paper, we propose the novel method to increase the accuracy of the railway abrasion measurement dramatically. we designed and manufactured the high precision and fast image processing board with DSP Core and FPGA to measure the railway abrasion. The image processing board has the capability that the image of 1024X1280 from camera can be processed with the speed of 480 frame/sec. And, we apply the image processing algorithm base on the wavelet to extract the laser region is projected on the rail exactly. Finally, we developed high precision railway abrasion measurement system with the error range less than +/-0.5mm by which 2D image data is covered 3D data and mapped on the rail profile using the camera model and the perspective transform.

• Journal of the Korean Graphic Arts Communication Society
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• v.20 no.1
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• pp.54-64
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• 2002

For the efficient work of map printing and quality improvement, we experimented on abrasion-resistance and beam-endurance of 5 kinds of map papers (offset paper, art paper, domestic map paper, foreign map paper, and Tyvek paper). The results obtained that imported and domestic map paper were superior to the others in endurance-proof.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1994.10a
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• pp.67-72
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• 1994

Tool test was conducted to investigate the were process of only flank face TiN coated HSS tool in interrupted cutting for variuos cutting speeds and feed rates. Flank wear was caused by microchipping at the cutting edge. At high cutting speed, the which was formed as a result of diffusion and abrasion lowered cutting edge and influenced flank were. Flank wear due to chipping was little influenced by cutting speed.

• The Journal of Advanced Prosthodontics
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• v.9 no.2
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• pp.130-137
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• 2017

PURPOSE. The purpose of this study was to evaluate the effect of nano-structured alumina surface coating on shear bond strength between Y-TZP ceramic and various dual-cured resin cements. MATERIALS AND METHODS. A total of 90 disk-shaped zirconia specimens (HASS CO., Gangneung, Korea) were divided into three groups by surface treatment method: (1) airborne particle abrasion, (2) tribochemicalsilica coating, and (3) nano-structured alumina coating. Each group was categorized into three subgroups of ten specimens and bonded with three different types of dual-cured resin cements. After thermocycling, shear bond strength was measured and failure modes were observed through FE-SEM. Two-way ANOVA and the Tukey's HSD test were performed to determine the effects of surface treatment method and type of cement on bond strength (P<.05). To confirm the correlation of surface treatment and failure mode, the Chi-square test was used. RESULTS. Groups treated with the nano-structured alumina coating showed significantly higher shear bond strength compared to other groups treated with airborne particle abrasion or tribochemical silica coating. Clearfil SA Luting showed a significantly higher shear bond strength compared to RelyX ARC and RelyX Unicem. The cohesive failure mode was observed to be dominant in the groups treated with nano-structured alumina coating, while the adhesive failure mode was prevalent in the groups treated with either airborne particle abrasion or tribochemical silica coating. CONCLUSION. Nano-structured alumina coating is an effective zirconia surface treatment method for enhancing the bond strength between Y-TZP ceramic and various dual-cured resin cements.

• Journal of the Korean Society of Clothing and Textiles
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• v.11 no.3 s.25
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• pp.57-65
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• 1987

The purpose of this study was to investigate the optimum treatment [condition for the Durable press finish of viscose rayon fabrics. Three types of commercial N-methylol crosslinking agents were applied to the fabric utilizing the pad-dry-cure technique. Changes in physical properties were evaluated for the various resin and catalyst concentrations. For DMU, the effect of different catalysts, $MgCl_2$ and $NH_4Cl$, were also compared. DMU treated fabrics showed in crease recovery angle, tensile strength and tearing strength but drastic decrease in abrasion resistance. DMDHEU and MDMDHEU treated fabrics were similar in most physical properties. However, DMDHEU treated fabrics were better in crease recovery angle and stiffness, and MDMDHEU treated fabrics were better in tensile strength, tearing strength and abrasion resistance. For a given resin system, crease recovery angle, tensile strength and stiffness increased with a increase in resin concentration. Tearing strength showed very little change, while abrasion resistance was decreased significantly as the crease recovery angle was increased. For the treatment of DMU, $MgCl_2$ catalyst was much better than $NH_4Cl$ in all physical properties. When $NH_4Cl$ catalyst was used, strength reduction and discoloration were observed. As the catalyst concentration increased, crease recovery angle, stiffness were increased. Tensile strength and tearing strength were increcased than control but at high catalyst concentration, the strength were decreased and abrasion resistance was significantly lowered. DMDHEU and MDMDHEU were more sensitive to catalyst concentrations than DMU.

• Proceedings of the Korean Society for Rock Mechanics Conference
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• 2006.09a
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• pp.59-79
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• 2006

The successful execution of shield tunnelling depends on the cutting ability of cutter. So the selection of shape, size and material of cutter according to geology condition is important work. Since shield tunnelling method was first invented in 1881, the cutting tool for rock has been developed owing to various experiments and researches, the study for soil, however, is insufficient. This paper introduces the shield tunnelling that will be carried out on weathered rock section (920m) of Seoul Subway Line 7 Extension C703. The shape and the material of cutter are discussed required for execution without replacement of cutter tool as well as for advance of excavation efficiency. In addition the estimation method of cutter abrasion in case of excavation on weathered soil is proposed and verified. Specially, the coefficient of abrasion for different soil and cutter is proposed by means of investigation into construction example of foreign country.