• Proceedings of the Korean Society of Crop Science Conference
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• 2023.04a
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• pp.185-185
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• 2023

• Journal of Periodontal and Implant Science
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• v.34 no.1
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• pp.1-17
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• 2004

It is improtant that performing prophylaxis procedure on an infected implant surface in order to treat peri-implantitis should not change the surface roughness and composition, so that the surface can be recovered to almost same condition as initial implant surface. This thesis, therefore, studied an effect of various oral hygiene instrument on implant surface. A surface roughness measurement instrument and an infection electron microscope were used to observe a change on surface. The purpose of this study was to obtain a clinical guidelines during implant care and peri-implantitis treatment. The result were as follows 1. Ra values (surface roughness value) at experimental group 1, group 2, and group 5 were increased significantly as compared with comparison group(p<0.05). 2. When compared experimental group 1 with each experimental groups at which prohylaxis procedure was performed, mean values of Ra at experimental group 2, group 3, group 6, and group 7 were decreased significantly(p<0.05). 3. Mean value of Ra was lowest at experimental group 2, and highest at experimental group 2, and highest at experimental group 5. 4. Analysis of SEM showed that was significant surface change at experimental group 2, group 3, group 4, group 5, and group 6 as compared with comparison group(X1000). 5. Analysis fo EDX showed that a quantity of Ti on surface for experimental group 6 was very similar to that for comparison group. In conclusion, air-powder abrasive and citric acid, plastic instrument are safe methods to use for performing prophylaxis procedure on implant care or for cleaning and sterilization process on treatment of peri-implantitis, based on the result that those method did not affect implant surface roughness and Ti composition.

• Journal of the Korean Society of Industry Convergence
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• v.27 no.5
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• pp.1167-1174
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• 2024

The purpose of this study was to evaluate the effects of various layer thicknesses and build angles on the flexural strength and surface roughness of repaired 3D-printed denture base resin. 3D-printed bar-shaped specimens with a 45° bevel were fabricated according to layer thickness(50 ㎛ and 100 ㎛) and build angle(0-degree, 45-degree, and 90-degree). Denture relining resin was applied to the 2 mm repair area Flexural strength was measured by a three-point bending test using a universal testing machine, and surface roughness(Ra) and surface topography were observed using a digital optical microscope at ×500 magnification. Statistical significance was analyzed using two-way ANOVA, one-way ANOVA, and Games-Howell post hoc(α = .05). Except for the 90-degree group, the group with a layer thickness of 100 ㎛ showed better flexural strength values than the group with a layer thickness of 50 ㎛(p < .05). Additionally, within the same layer thickness, the 45-degree group showed the lowest flexural strength value. The Ra values of the 0-degree and 90-degree groups, where the build angle was 45° to the layer orientation, were higher at 100 ㎛ than at 5 0 ㎛ layer thickness(p < .05), and the Ra value of the 45-degree group, where the build angle was parallel to the layer orientation, was lower than those of other build angles(p < .05). Layer thickness and build angle significantly affected the surface roughness of 3D-printed denture base resin, and the surface roughness was confirmed to be closely related to the bonding strength with denture relining resin.

• Korean Journal of Materials Research
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• v.30 no.7
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• pp.327-332
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• 2020

Laser induced surface activation (LISA) technology requires refined selection of process variables to fabricate conductive microcircuits on a general polymer material. Among the process variables, laser mode is one of the crucial factors to make a reliable conductor pattern. Here we compare the continuous wave (CW) laser mode with the pulse wave (PW) laser mode through determination of the surface roughness and circuit accuracy. In the CW laser mode, the surface roughness is pronounced during the implementation of the conductive circuit, which results in uneven plating. In the PW laser mode, the surface is relatively smooth and uniform, and the formed conductive circuit layer has few defects with excellent adhesion to the polymer material. As a result of a change of laser mode from CW to PW, the value of Ra of the polymer material decreases from 0.6 ㎛ to 0.2 ㎛; the value of Ra after the plating process decreases from 0.8 ㎛ to 0.4 ㎛, and a tight bonding force between the polymer source material and the conductive copper plating layer is achieved. In conclusion, this study shows that the PW laser process yields an excellent conductive circuit on a polymeric material.

• Korean Journal of Applied Biomechanics
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• v.31 no.4
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• pp.270-275
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• 2021

Objective: The purpose of this study was to evaluate 16 muscles activity according to three exercise intensity when performing Deadlift and Upright row. Method: To accomplish the purpose of the study, subjects (n=10) were performed Electromyography (EMG) measurement for 16 different muscles. The experimental movements were Deadlift and Upright row, measured five times for each intensity (40%, 60%, 80%) of 1RM. This study normalized the EMG values through RVC for comparative analysis. Results: The results were summarized as follows: As a result of Deadlift, there was significant difference in the mean EMG value according to the exercise intensity in all muscles except RA, PM and BB (p<.05). As a result of Upright row, There was significant difference in the mean EMG value according to the exercise intensity in all muscles except BF, TA, GN, RA and UT (p<.05). Conclusion: This study allowed us to know the activities of major muscles according to the exercise intensity for 16 different muscles when performing Deadlift and Upright row.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.20 no.3
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• pp.297-306
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• 2022

The acoustic emission (AE) is proposed as a feasible method for the real-time monitoring of the structural damage evolution in concrete materials that are typically used in the storage of nuclear wastes. However, the characteristics of AE signals emitted from concrete structures subjected to various environmental conditions are poorly identified. Therefore, this study examines the AE characteristics of the concrete structures during uniaxial compression, where the storage temperature and immersion conditions of the concrete specimens varied from 15℃ to 75℃ and from completely dry to water-immersion, respectively. Compared with the dry specimens, the water-immersed specimens exhibited significantly reduced uniaxial compressive strengths by approximately 26%, total AE energy by approximately 90%, and max RA value by approximately 70%. As the treatment temperature increased, the strength and AE parameters, such as AE count, AE energy, and RA value, of the dry specimens increased; however, the temperature effect was only minimal for the immersed specimens. This study suggests that the AE technique can capture the mechanical damage evolution of concrete materials, but their AE characteristics can vary with respect to the storage conditions.

• Journal of Korean society of Dental Hygiene
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• v.21 no.6
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• pp.703-710
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• 2021

Objectives: The purpose of this study was to confirm the influence of commercially available carbonated water on denture resin by confirming the changes in the denture surface and adhesion of bacteria. Methods: Carbonated water available in the domestic market was used on specimens made of prosthetic resins. The top four products with respect to sales performance was deposited for 30 min, 24 h, and 48 h over the study groups and over one control group. The surface roughness was measured. Candida albicans was inoculated and cultured over these dentures at 37℃ on the study groups of 1 h, 24 h, and 48 h, and the number of colonies formed was measured. Results: As a result of comparing the surface roughness between groups by immersion time, the difference between groups was confirmed at 48 hours. The Trevi group showed a larger Rz than the Samdasoo group. As a result of comparing the surface roughness by time in each group, statistical significance was shown in the Ra value of the Seagram and the Rz value of the Chojung sparkling water (p<0.05). The Ra value of the Seagram was higher for 48 h than for 30 min, and the Rz value of the Chojung sparkling water was higher at 48 h than at 30 min (p<0.05). Candida albicans concentration increased over the course of immersion. Conclusions: It was confirmed that longer the specimen of the denture resin was immersed in carbonated water, more the surface roughness was affected and higher the number of attached bacteria.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.33 no.6
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• pp.435-442
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• 2009

Three-dimensional heat transfer characteristics for natural convection flows are numerically investigated in the doubly-inclined cubical-cavity according to the variation of a newly defined orientation angle �� of the hot wall surface from horizontal plane at moderate Rayleigh numbers. Numerical simulations of laminar flows are conducted in the range of Rayleigh numbers($10^4{\leq}Ra{\leq}10^5$) and $0^{\circ}{\leq}{\alpha}90^{circ}$ with a solution code(PowerCFD) employing unstructured cell-centered method. Comparisons of the average Nusselt number at the cold face are made with benchmark solutions and experimental results found in the literature. It is found that the average Nusselt number at the cold wall has a maximum value around the specified orientation ${\alpha}$ at each Rayleigh number. Special attention is also paid to three-dimensional thermal characteristics in natural convection according to new orientation angles at Ra��= $1{\times}10^5$, in order to investigate a new additional heat transfer characteristic found in the range of above Ra = $6{\times}10^4$.

• Nuclear Engineering and Technology
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• v.55 no.5
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• pp.1757-1762
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• 2023

Radiological hazards from external exposure of naturally occurring radioactive materials (NORM) scales residues, generated during the extraction process of oil and gas production in southern Algeria, are evaluated. The activity concentrations of ²²⁶Ra, ²³²Th, and ⁴⁰K were measured using high-purity gamma-ray spectrometry (GeHP). Mean activity concentration of ²²⁶Ra, ²³²Th and ⁴⁰K, found in scale samples are 4082 ± 41, 1060 ± 38 and 568 ± 36 Bq kg^-1, respectively. Radiological hazard parameters, such as radium equivalent (Ra_eq), external and internal hazard indices (H_ex, H_in), and gamma index (I_γ) are also evaluated. All hazard parameter values were greater than the permissible and recommended limits and the average annual effective dose value exceeded the dose constraint (0.3 mSv y^-1). However, for occasionally exposed workers, the dose rate of 0.65 ± 0.02 mSv y^-1 is lower than recommended limit of 1 mSv y^-1 for public.

• The Journal of Korean Academy of Prosthodontics
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• v.34 no.2
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• pp.246-265
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• 1996

After adjusting glazed surface of laminate veneer porcelain by reduction in the clinical procedure, an additional polishing procedure is required to smoothen the roughened surface by reduction, as it is difficult to glaze it again in the furnace. In this study, four kinds of laminate veneer porcelain were ground with diamond points as done in the clinical procedure. The adjusted porcelain surface was polished with Durawhite stone, Ceramiste points, Exa cerapol, Porcelain polishing wheel, Diamond polishing paste. The degree of surface roughness was evaluated with SEM and profilometer at each step, The self glazed surface and the glazed surface with glazing powder were compared with the polished surface and surface roughness of four kinds of laminate veneer porcelain according to the polishing method and step were obserbed. The following results were obtained : 1. There was no difference in the average surface roughness Ra value and the surface roughness obserbed under SEM according to the polishing methods and steps used, among the four kinds of laminate veneer porcelain including Colorlogic, Exelco, Vintage, and Vitadur alpha product. 2. Due to porosities, the surface in the course of polishing by polishing instruments was rougher than the glazed surface, evaluated with a SEM. 3. Insta-Glaze diamond polishing paste has no statistical difference with self glazed group 1, although it has a lower value in average surface roughness Ra value. 4. Group 2 which was glazed with galzing powder was lowest in view of SEM, but it revealed higher surface roughness Ra value than group 1, the glazed surface and group 8, polished by diamond polishing paste, due to surface waveness. 5. Proper surface smoothness could not be in the surface roughness analysis of SEM and profilometer by Shofu laminate polishing kit composed of Diamond point, Durawhite stone and Ceramiste points. Based on the results of this study, the following conclusions can be drawn. We obtain low surface roughness than glazed surface by polishing instruments, but not perfect results clinically. In order to obtain a perfect clinical result or a surface smoothness comparable to glazed porcelain there is a need for further improvement of porcelain materials, condensa-tion techniques, polishing instruments and polishing methods. Furthermore card should be taken not to breakdown the glazed surface during the clinical and laboratory procedure.