• International Journal of Computer Science & Network Security
• /
• v.22 no.10
• /
• pp.97-106
• /
• 2022

Objective. Nanotechnology is spreading among all areas of life, from everyday devices to medicine. The concept of nanotechnology argues that not only can new physical and chemical properties of materials be discovered, but also the new potential of nanostructures when reduced to the nanoscale. The growing interest in the application of nanomaterials in dentistry contributes to the proliferation of the range of nanomaterials used by specialists. The purpose of this review of information sources was to analyze the prospects for the use of nanomaterials in dentistry. Methods. We used the bibliographic semantic method of research, for which we analyzed electronic databases of primary literature sources Scopus, Web of Science, Research Gate, PubMed, MDPI, and MedLine. English-language scientific articles published after 2017 were taken into consideration. Results. According to the results of a search study among modern information primary sources, nanotechnology improves the preventive properties of oral care products, improves the structural-mechanical and aesthetic properties of composite mixtures for dentistry, overcomes the problems of the clinical application of dental implants. Despite the prospects of nanotechnology applications in medicine in general and dentistry in particular, the existing economic and technological problems require a thorough solution for further implementation of nanostructures. Scientific novelty. For the first time, the analysis of modern trends in the application of nanotechnology in dentistry is carried out and the peculiarities of materials are highlighted, the problems and prospects of nanostructures implementation in modern dental implantology are given, physical, chemical, mechanical, and antibacterial properties of nanomaterials are evaluated. The effect of nanomaterials on the microbial adhesion of the tooth or implant surface is described. Practical significance. The presented publication can become a scientific basis for the solution of urgent problems hindering the introduction of nanotechnology into dental practice. Conclusions. Thus, the use of nanostructures opens up great opportunities for the treatment of a wide range of diseases, not only of dental nature but also in medicine in general.

• Journal of the Korean Society of Industry Convergence
• /
• v.25 no.6_2
• /
• pp.1111-1117
• /
• 2022

Recently, interest in the circular economy has emerged in the industry. As a result, interest in Re-manufacturing, which makes old equipment similar to new products, is growing. In the machine tool industry with many aging equipment, the Re-manufacturing industry is essential, and among them, research on the performance improvement of gear type oil pumps was conducted. The purpose was to achieve the target performance of flow rate and volume efficiency by changing the shape of the gear pump housing clearance and inlet/outlet, and Computational Fluid Analysis and Central Composite Design were conducted using ANSYS CFX 2022 R2 and MINITAB®. The level of each determined factor was determined. 20 design points were derived, and the Flow Rate at each design point was calculated, and the Theoretical Flow Rate was calculated to obtain Volumetric Efficiency. The optimal design point was obtained when the Flow Rate was 140 lpm and the Volumetric Efficiency was maximum, the optimal design point was obtained when both were maximum, and the Surface Plot for each factor was obtained to identify the tendency.

• Journal of the Semiconductor & Display Technology
• /
• v.21 no.1
• /
• pp.79-84
• /
• 2022

As various flexible display products are released, the demand for high-performance colorless and transparent polyimide (CPI) film is continuously increasing. The primary purpose of this study is to establish a systematic procedure for optimizing the optical performance of CPI films by applying the response surface method. After selecting three key factors (monomer type, stirring time for varnish synthesis, and maximum temperature of vacuum furnace for film production) affecting optical performance based on experiences and references, CPI films were manufactured according to the experimental sequence designed by the central composite design, and then the yellowness index (YI) and optical transmittance (Tr) of the films were measured. When producing a CPI film by pouring varnish into a petri dish, the change in optical properties according to thickness should be considered, and there was a meaningful linear relationship between YI and Tr. The species of monomer and the maximum temperature were the critical factors that had an influence on YI and Tr, respectively. It is expected that the procedure proposed in this study can serve as a starting point for CPI film optimization studies considering the other factors that were not considered and responses such as thermal properties.

• Steel and Composite Structures
• /
• v.46 no.4
• /
• pp.471-483
• /
• 2023

This paper presents an analytical hyperbolic theory based on the refined shear deformation theory for mechanical stability analysis of the simply supported advanced composites plates (exponentially, sigmoidal and power-law graded) under triangular, trapezoidal and uniform uniaxial and biaxial loading. The developed model ensures the boundary condition of the zero transverse stresses at the top and bottom surfaces without using the correction factor as first order shear deformation theory. The mathematical formulation of displacement contains only four unknowns in which the transverse deflection is divided to shear and bending components. The current study includes the effect of the geometric imperfection of the material. The modeling of the micro-void presence in the structure is based on the both true and apparent density formulas in which the porosity will be dense in the mid-plane and zero in the upper and lower surfaces (free surface) according to a logarithmic function. The analytical solutions of the uniaxial and biaxial critical buckling load are determined by solving the differential equilibrium equations of the system with the help of the Navier's method. The correctness and the effectiveness of the proposed HyRPT is confirmed by comparing the results with those found in the open literature which shows the high performance of this model to predict the stability characteristics of the FG structures employed in various fields. Several parametric analyses are performed to extract the most influenced parameters on the mechanical stability of this type of advanced composites plates.

• Journal of the Korean Geotechnical Society
• /
• v.25 no.11
• /
• pp.117-130
• /
• 2009

In this paper, a series of laboratory chamber tests were carried out to evaluate the applicability of a porous concrete pile fabricated with recycled aggregates (RAPP) for the soft ground improvement. While performing the laboratory chamber tests for the RAPP, the surface settlement, excess pore pressure and vertical stress distribution with time were compared with those of SCP provided by You (2003) under the same experimental condition. In addition, the experimental results were compared with the numerical simulation using ABAQUS in this study. The results show that the settlement reduction is significantly enhanced due to the stress-sharing mechanism between the RAPP and soil formation by stress concentration on the RAPP. Furthermore, the comparison of consolidation rate shows that the RAPP can accelerate consolidation as well, which behaves as a vertical drain.

• Composites Research
• /
• v.22 no.3
• /
• pp.1-8
• /
• 2009

In this paper, we present the results of experimental and analytical investigations on the structural behavior of GFRP pipes used in the water supply pipeline system. Cross-section of the pipe is consisted with two GFRP tubes and polymer mortar between the tubes. Due to the advantages such as light-weight, corrosion resistance, smooth surface, flexibility, etc., use of GFRP pipe in the water supply pipeline system is ever increasing trend. Therefore, more optimized structural design methodology should be developed. In the investigation, we conducted theoretical and analytical studies on the load versus radial deformation characteristics of GFRP pipes. In addition, ring stiffness test is also performed. Test results are compared with theoretical and analytical results and it was found that the results are agreed well within 5% of radial deformation. Finally, it was also found that the GFRP pipes used in the water supply pipeline system are strong enough to satisfy the industrial requirements.

• Composites Research
• /
• v.21 no.1
• /
• pp.40-45
• /
• 2008

Rubber hose assembly for automotive hydraulic brake during operation is subject to combined stresses of cyclic pressure, cyclic bending and torsion as well as thermal load. The rubber hose is composed of ethylene-propylene diene monomer(EPDM) rubber layers reinforced by polyvinyl acetate(PVA) braided fabrics. A durability tester with loading rigs for inducing the above cyclic stresses was used to investigate failure mechanisms in the rubber hose assembly. Failure examination was performed at every 100 thousands cycles of bending and torsion. Hose samples were sectioned with a diamond-wheel cutter and then polished. The polished surface was observed by optical microscope and scanning electron microscope (SEM). Some interfacial delamination with a length of about 1mm along the interface between EPDM rubber and PVA fabrics was shown at the test cycles of 400,000. The delamination induced some cracking into the outer rubber skin layer to leading the final rupture of the hose.

• Nuclear Engineering and Technology
• /
• v.55 no.5
• /
• pp.1519-1526
• /
• 2023

For the first time Aluminium-BariumeZinc oxide nanocomposite (ZABONC) was synthesized by solution combustion method where calcination was carried out at low temperatures (600℃) to study the electromagnetic (EM) (X/γ) radiation shielding properties. Further for characterization purpose standard techniques like PXRD, SEM, UV-VISIBLE, FTIR were used to find phase purity, functional groups, surface morphology, and to do structural analysis and energy band gap determination. The PXRD pattern shows (hkl) planes corresponding to spinel cubic phase of ZnAl₂O4, cubic Ba(NO₃)₂, α and γ phase of Al₂O₃ which clearly confirms the formation of complex nano composite. From SEM histogram mean size of nano particles was calculated and is in the order of 17 nm. Wood and Tauc's relation direct energy band gap calculation gives energy gap of 2.9 eV. In addition, EM (X/γ) shielding properties were measured and compared with the theoretical ones using standard procedures (NaI (Tl) detector and multi channel analyzer MCA). For energy above 356 keV the measured shielding parameters agree well with the theory, while below this value slight deviation is observed, due to the influence of atomic/crystallite size of the ZABONC. Hence synthesized ZABONC can be used as a shielding material in EM (X/γ) radiation shielding.

• Computers and Concrete
• /
• v.29 no.2
• /
• pp.107-115
• /
• 2022

With the improvements in computer technologies, utilization of image processing techniques has increased in many areas (such as medicine, defence industry, other industries etc.) Many different image processing techniques are used for surface analysis, detection of manufacturing defects, and determination of physical and mechanical characteristics of composite materials. In this study, cementitious composites were obtained by addition of Grounded Granulated Blast-Furnace Slag (GGBFS), Styrene Butadiene polymer (SBR), and Grounded Granulated Blast-Furnace Slag and Styrene Butadiene polymer together (GGBFS+SBR). Expanded Polystyrene (EPS) beads were added to these cementitious composites in different ratios (20%, 40% and 60%). The mechanical and physical characteristics of the composites were determined, and homogeneity indexes of the composites were determined by image processing techniques to determine EPS distribution forms in them. Physical and mechanical characteristics of the produced samples were obtained by applying consistency, density, water absorption, compressive strength (7 and 28 days), flexural strength (7 and 28 days) and tensile splitting strength (7 and 28 days) tests on them. Also, visual examination by using digital microscope, and image analysis by using image processing techniques with open source coded ImageJ program were performed. As a result of the study, it is determined that GGBFS and SBR addition strengthens the adhesion sites formed as it increases the adhesion power of the mixture and helps to get rid of the segregation problem caused by EPS. As a result of the image processing analysis it is demonstrated that GGBFS and SBR addition has positive contribution on homogeneity index.

• The Bulletin of The Korean Astronomical Society
• /
• v.44 no.2
• /
• pp.51.1-51.1
• /
• 2019

At the commissioning phase of KVN from 2009 to 2013, single-dish survey and monitoring observations were performed toward about 1000 evolved stars and about 60 relatively strong SiO and H2O maser sources respectively. Based on these single-dish results and VLBI feasibility test observations at K/Q/W/D bands in 2014, KVN Key Science Project (KSP) has started from 2015 and will be completed in 2019 as KSP phase I. Here we present the overview of observational studies on evolved stars using KVN. In KSP phase I, we have focused on nine KSP sources which show a successful astrometrically registered maps of SiO and H2O masers using the source frequency phase referencing method. We aim at investigating the spatial structure and dynamical effect from 43/42/86/129 GHz SiO to 22 GHz H2O maser regions associated with a stellar pulsation and development of asymmetry in circumstellar envelopes. Using the combined network KaVA (KVN+Japanese VLBI network VERA), KaVA Large Program titled on "Expanded Study on Stellar Masers: ESTEMA Phase I" was performed from 2015 to 2016. Based on ESTEMA Phase I, EAVN Large Program titled on "EAVN Synthesis of Stellar Maser Animations: ESTEMA Phase II" was also performed from 2018. The ESTEMA II project aims to publish composite animations of circumstellar H2O and SiO masers, which taken from up to 6 long-period variable stars with a variety of the pulsation periods (333-1000 days). The animations will exhibit the three-dimensional kinematics of the maser gas clumps with complexity caused by stellar pulsation-driven shock waves and anisotropy of clump ejections from the stellar surface. Adding three EAVN telescopes (Tianma 65m, Nanshan 26m and NRO 45m telescopes) with KaVA always secures the high quality of the maser image frames through the monitoring program.