• Composites Research
• /
• v.35 no.5
• /
• pp.334-339
• /
• 2022

This study suggests the prediction algorithm for transverse permeability, represented the flow resistance during the manufacturing process of composite, of unidirectional continuous fiber reinforced plastics. The cross-sectional shape of representative volume element (RVE) is considered to reflect fiber arrangement. The equivalent length is used as a factor to express the change of resin flow according to fiber arrangement. The permeability prediction algorithm is created by grafting the Electro-Hydraulic analogy and validity is confirmed. The code for permeability prediction was composed by means of MATLAB and Python, flow analysis was performed by using FLUENT. The algorithm was verified as the permeability results obtained through Algorithm and numerical analysis were almost identical to each other, and the calculation time was reduced around 1/450 compared to the numerical analysis.

• Journal of the Korean earth science society
• /
• v.27 no.2
• /
• pp.177-187
• /
• 2006

Due to a lack of reproducibility and visibility of the conventional equipment for westerly wave simulation, it is difficult to have indoor experiments at high school that show the stream of Hadley cell. A modified improvement of the old one improves the problem. The side wall and bottom of the new equipment is made by copper and acrylic resin, respectively, in order to clarify the difference between the water temperature inside and outside of the water tank. The equipment also has a high quality digital record for generating exact analysis of the results. And we also carried out several experiments that relate theoretical and experimental aspection of westerly wave. Temperature Detected Sheet (TDS) in flow visualization unit provides not only visual information of liquid flow, but also clear understanding of the relation between upper and lower wind flow structure. And the liquid stream simulated in indoor experiment using proposed equipment is commensurate with westerly wave in real atmosphere. The efficiency of educational properties of the proposed equipment is verified indirectly by Likert Scales survey of high school teachers.

• Restorative Dentistry and Endodontics
• /
• v.41 no.3
• /
• pp.189-195
• /
• 2016

Objectives: A variety of root canal sealers were recently launched to the market. This study evaluated physicochemical properties, biocompatibility, and sealing ability of a newly launched resin-based sealer (Dia-Proseal, Diadent) compared to the existing root canal sealers (AHplus, Dentsply DeTrey and ADseal, Metabiomed). Materials and Methods: The physicochemical properties of the tested sealers including pH, solubility, dimensional change, and radiopacity were evaluated. Biocompatibility was measured using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. For microleakage test, single-rooted teeth were instrumented, and obturated with gutta-percha and one of the sealers (n = 10). After immersion in 1% methylene blue solution for 2 weeks, the specimens were split longitudinally. Then, the maximum length of staining was measured. Statistical analysis was performed by one-way analysis of variance followed by Tukey test (p = 0.05). Results: Dia-Proseal showed the highest pH value among the tested sealers (p < 0.05). ADseal showed higher dimensional change compared to AHplus and Dia-Proseal (p < 0.05). The solubility values of AHplus and Dia-Proseal were similar, whereas ADseal had the lowest solubility value (p < 0.05). The flow values of sealer in increasing order were AHplus, DiaProseal, and ADseal (p < 0.05). The radiopacity of AHplus was higher than those of ADseal and Dia-Proseal (p < 0.05). The cell viability of the tested materials was statistically similar throughout the experimental period. There were no significant differences in microleakage values among the tested samples. Conclusions: The present study indicates that Dia-Proseal has acceptable physicochemical properties, biocompatibility, and sealing ability.

• Journal of Periodontal and Implant Science
• /
• v.53 no.4
• /
• pp.295-305
• /
• 2023

Purpose: Various methods have been proposed to achieve the nearly complete decontamination of the surface of implants affected by peri-implantitis. We investigated the in vitro debridement efficiency of multiple decontamination methods (Gracey curettes [GC], glycine air-polishing [G-Air], erythritol air-polishing [E-Air] and titanium brushes [TiB]) using a novel spectrophotometric ink-model in 3 different bone defect settings (30°, 60°, and 90°). Methods: Forty-five dental implants were stained with indelible ink and mounted in resin models, which simulated standardised peri-implantitis defects with different bone defect angulations (30°, 60°, and 90°). After each run of instrumentation, the implants were removed from the resin model, and the ink was dissolved in ethanol (97%). A spectrophotometric analysis was performed to detect colour remnants in order to measure the cumulative uncleaned surface area of the implants. Scanning electron microscopy images were taken to assess micromorphological surface changes. Results: Generally, the 60° bone defects were the easiest to debride, and the 30° defects were the most difficult (ink absorption peak: 0.26±0.04 for 60° defects; 0.32±0.06 for 30° defects; 0.27±0.04 for 90° defects). The most effective debridement method was TiB, independently of the bone defect type (TiB vs. GC: P<0.0001; TiB vs. G-Air: P=0.0017; TiB vs. GE-Air: P=0.0007). GE-Air appeared to be the least efficient method for biofilm debridement. Conclusions: T-brushes seem to be a promising decontamination method compared to the other techniques, whereas G-Air was less aggressive on the implant surface. The use of a spectrophotometric model was shown to be a novel but promising assessment method for in vitro ink studies.

• Design & Manufacturing
• /
• v.12 no.2
• /
• pp.22-26
• /
• 2018

In the automotive industry these days, plastic parts have been developed and replaced with plastic parts by maintaining the same function of existing press parts for a variety of reasons. Injection molding plastic parts are subject to molding defects due to various factors, among which the sink marks usually occur in the areas where bosses and ribs are installed. In this study, we analyzed the influence of various factors on the occurrence of sink marks by using the flow analysis of the forming analysis program(Moldflow analysis) using the rib model with the T-shape. Tests have shown that the greatest influence on the sink mark of cosmetic products is the thickness and pressure of the ribs, and the thickness of the basic moulding thickness of the product increases. However, it was considered that the resin temperature and the mold temperature do not greatly affect the occurrence of the sink mark.

• Proceedings of the KACD Conference
• /
• 2008.05a
• /
• pp.246-257
• /
• 2008

The purpose of this study was to investigate the influence of various occlusal loading sites and directions on the stress distribution of the cervical composite resin restorations of maxillary second premolar, using 3 dimensional (3D) finite element (FE) analysis. Extracted maxillary second premolar was scanned serially with Micro-CT (SkyScan1072; SkyScan, Aartselaar, Belgium). The 3D images were processed by 3D-DOCTOR (Able Software Co., Lexington, MA, USA). HyperMesh (Altair Engineering. Inc., Troy, USA) and ANSYS (Swanson Analysis Systems. Inc., Houston, USA) was used to mesh and analyze 3D FE model. Notch shaped cavity was filled with hybrid (Z100, 3M Dental Products, St. Paul, MN, USA) or flowable resin (Tetric Flow, Viva dent Ets., FL-9494-Schaan, Liechtenstein) and each restoration was simulated with adhesive layer thickness ($40{\mu}m$). A static load of 200 N was applied on the three points of the buccal incline of the palatal cusp and oriented in $20^{\circ}$ increments, from vertical (long axis of the tooth) to oblique $40^{\circ}$ direction towards the buccal. The maximum principal stresses in the occlusal and cervical cavosurface margin and vertical section of buccal surfaces of notch-shaped class V cavity were analyzed using ANSYS. As the angle of loading direction increased, tensile stress increased. Loading site had little effect on it. Under same loading condition. Tetric Flow showed relatively lower stress than Z100 overall, except both point angles. Loading direction and the elastic modulus of restorative material seem to be important factor on the cervical restoration.

• Restorative Dentistry and Endodontics
• /
• v.33 no.3
• /
• pp.246-257
• /
• 2008

The purpose of this study was to investigate the influence of various occlusal loading sites and directions on the stress distribution of the cervical composite resin restorations of maxillary second premolar, using 3 dimensional (3D) finite element (FE) analysis. Extracted maxillary second premolar was scanned serially with Micro-CT (SkyScan1072; SkyScan, Aartselaar, Belgium). The 3D images were processed by 3D-DOCTOR (Able Software Co., Lexington, MA, USA). HyperMesh (Altair Engineering, Inc., Troy, USA) and ANSYS (Swanson Analysis Systems, Inc., Houston, USA) was used to mesh and analyze 3D FE model. Notch shaped cavity was filled with hybrid (Z100, 3M Dental Products, St. Paul, MN, USA) or flowable resin (Tetric Flow, Vivadent Ets., FL-9494-Schaan, Liechtenstein) and each restoration was simulated with adhesive layer thickness ($40{\mu}m$). A static load of 200 N was applied on the three points of the buccal incline of the palatal cusp and oriented in $20^{\circ}$ increments, from vertical (long axis of the tooth) to oblique $40^{\circ}$ direction towards the buccal. The maximum principal stresses in the occlusal and cervical cavosurface margin and vertical section of buccal surfaces of notch-shaped class V cavity were analyzed using ANSYS. As the angle of loading direction increased, tensile stress increased. Loading site had little effect on it. Under same loading condition, Tetric Flow showed relatively lower stress than Z100 overall, except both point angles. Loading direction and the elastic modulus of restorative material seem to be important factor on the cervical restoration.

• 한국전산유체공학회:학술대회논문집
• /
• 2011.05a
• /
• pp.96-99
• /
• 2011

Fiber coatings are essential in optical fiber manufacturing, since they provide the protective layers from the surface damages and the adequate fiber strength. Flow and temperature fields of coating liquid in a fiber coating applicator are numerically investigated by using a commercial CFD software. The main focus of this computational study is on the thermal effects by viscous dissipation and the effects of coating supply temperature on the final fiber coating thickness. The numerical results reveal that the thermal effects play a major role in the high-speed optical fiber coating process and give substantial influences on the determination of coating thickness. Changing the supply temperature of coating liquid is found to relieve the radial variation of coating liquid viscosity in the coating die and it can be an effective way to control the fiber coating thickness.

• Tribology and Lubricants
• /
• v.16 no.3
• /
• pp.166-172
• /
• 2000

The friction and wear characteristics of dental composite resins such as Charisma, Elitefil, TPH and Veridonfil were investigated. Furthermore, The surface characteristics examination, the analysis of contents of filler, Victors hardness and fracture toughness measurement of composite resins were preformed. The wear test applied ball to move reciprocationally on flat wear tester at room temperature. Microstructure of surfaces and worn surfaces were observed by SEM. Experimental results indicate that the friction coefficient of TPH was quite low, and the wear resistance of TPH was better than that of Charisma, Elitefil or Veridonfil at the same condition. The main wear mechanism was found to be plastic flow and abrasive wear by failure of filler's bond to the matrix.

• Analytical Science and Technology
• /
• v.15 no.3
• /
• pp.236-242
• /
• 2002

A method was investigated to determine the thickness of coating on steel sheet using rf glow discharge atomic emission spectrometer. The RF gas-jet boosted glow discharge has such salient feature as good pleasure stability and high sputtering efficiency that it was possible to determine the thickness of silicon resin film on zinc electroplated steel. The erosion speed variation is dependent on discharge power, gas flow rate and discharge pressure. therefore determine discharge condition to measure the thickness of coating on steels. The fundamental studies have been carried out to investigate an optimum condition for in-depth analysis and composition of zinc coating on steel. In this study, the calibration curve for thickness determination of silicon resin film was found to be linear in the range of $1000{\sim}3500mg/m^2$ film thickness. The developed rf gas-jet boosted glow discharge was applied to the analysis of zinc coating and silicon resin film on steel made by RIST.