• Journal of Periodontal and Implant Science
• /
• v.45 no.5
• /
• pp.169-177
• /
• 2015

Purpose: Despite the high success rates of endosseous dental implants, their placement is restricted according to the height and volume of bone available. The use of short or mini dental implants could be one way to overcome this limitation. Thus, this study aimed to compare standard, short, and mini dental implants with regard to associated clinical parameters and peri-implant crevicular fluid (PICF) levels of cathepsin-K (CTSK), RANK ligand (RANKL), and osteoprotegerin (OPG), after prosthodontic loading. Methods: A total of 78 non-submerged implants (Euroteknika, $Aesthetica^{+2}$, Sallanches, France) were installed in 30 subjects (13 male, 17 female; range, 26-62 years) who visited the clinic of the Periodontology Department, Faculty of Dentistry, Selcuk University. Sampling and measurements were performed on the loading date (baseline) and 2, 14, and 90 days after loading. Assessment of the peri-implant status for the implant sites was performed using the pocket probing depth (PPD), modified plaque index, modified gingival index, modified sulcular bleeding index, and radiographic signs of bone loss. PICF samples collected from each implant were evaluated for CTSK, RANKL, and OPG levels using the ELISA method. Keratinized tissue and marginal bone loss (MBL) were also noted. Results: Clinical parameters statistically significantly increased in each group but did not show statistical differences between groups without PPD. Although implant groups showed a higher MBL in the upper jaw, only the standard dental group demonstrated a statistically significant difference. At 90 days, the OPG:sRANKL ratio and total amounts of CTSK for each group did not differ from baseline. Conclusions: Within the limitations of this study, both short and mini dental implants were achieving the same outcomes as the standard dental implants in the early period after loading.

• Journal of Animal Environmental Science
• /
• v.4 no.2
• /
• pp.167-174
• /
• 1998

It is known that the anaerobic fermentation of organic matter (OM) is divided into 2 phases, acidogenic phase in which OM is digested into volatile fatty acid (VFA), and methanogenic phase where the produced VFA is converted to CH4 and CO2. In a natural fermenting procedure, these 2 phases occur at the same time. However the total production of end products (methane) may be limited if these 2 phases occur at the same time. This is believed to be due to the difference in growth rate, substrate-utilizing efficiency and favorable environment for each microbes (acidogens and methanogens), involved in each phase. It is therefore suggested for the maximum recycling of organic waste (such as animal waste) through providing 2 different steps in fermenting procedure, acidogenic phase and methanogenic phase, in each case the activity of involved microbes can be maintained at the maximum level. The results obtained from these experiments are summarized as follows : The loading rates of swine waste were made through 2.5, 5 and 10 gVS / l / d to identify its acidogenic fermenting character in this study. The VFA yield was maximized at 10 gVS / l / d of loading rate. On the basis of this study was executed to identify the optimum HRT of 1, 2 and 4 days at 10 gVS / l / d of loading rate in acidogenic phase. The maximum VFA yield was obtained at 1 days of HRT.

• The Journal of Advanced Prosthodontics
• /
• v.11 no.3
• /
• pp.169-178
• /
• 2019

PURPOSE. While dental implants have displayed high success rates, poor mechanical fixation is a common complication, and their biomechanical response to occlusal loading remains poorly understood. This study aimed to develop and validate a computational model of a natural first premolar and a dental implant with matching crown morphology, and quantify their mechanical response to loading at the occlusal surface. MATERIALS AND METHODS. A finite-element model of the stomatognathic system comprising the mandible, first premolar and periodontal ligament (PDL) was developed based on a natural human tooth, and a model of a dental implant of identical occlusal geometry was also created. Occlusal loading was simulated using point forces applied at seven landmarks on each crown. Model predictions were validated using strain gauge measurements acquired during loading of matched physical models of the tooth and implant assemblies. RESULTS. For the natural tooth, the maximum vonMises stress (6.4 MPa) and maximal principal strains at the mandible ($1.8m{\varepsilon}$, $-1.7m{\varepsilon}$) were lower than those observed at the prosthetic tooth (12.5 MPa, $3.2m{\varepsilon}$, and $-4.4m{\varepsilon}$, respectively). As occlusal load was applied more bucally relative to the tooth central axis, stress and strain magnitudes increased. CONCLUSION. Occlusal loading of the natural tooth results in lower stress-strain magnitudes in the underlying alveolar bone than those associated with a dental implant of matched occlusal anatomy. The PDL may function to mitigate axial and bending stress intensities resulting from off-centered occlusal loads. The findings may be useful in dental implant design, restoration material selection, and surgical planning.

• Computers and Concrete
• /
• v.29 no.6
• /
• pp.375-391
• /
• 2022

This paper examined the impact of the cross-sectional structure on the structural results under different loading conditions of reinforced concrete (RC) members' management limited in Carbon Fiber Reinforced Polymers (CFRP). The mechanical properties of CFRC was investigated, then, totally 32 samples were examined. Test parameters included the cross-sectional shape as square, rectangular and circular with two various aspect rates and loading statues. The loading involved concentrated loading, eccentric loading with a ratio of 0.46 to 0.6 and pure bending. The results of the test revealed that the CFRP increased ductility and load during concentrated processing. A cross sectional shape from 23 to 44 percent was increased in load capacity and from 250 to 350 percent increase in axial deformation in rectangular and circular sections respectively, affecting greatly the accomplishment of load capacity and ductility of the concentrated members. Two Artificial Intelligence Models as Extreme Learning Machine (ELM) and Particle Swarm Optimization (PSO) were used to estimating the tensile and flexural strength of specimen. On the basis of the performance from RMSE and RSQR, C-Shape CFRC was greater tensile and flexural strength than any other FRP composite design. Because of the mechanical anchorage into the matrix, C-shaped CFRCC was noted to have greater fiber-matrix interfacial adhesive strength. However, with the increase of the aspect ratio and fiber volume fraction, the compressive strength of CFRCC was reduced. This possibly was due to the fact that during the blending of each fiber, the volume of air input was increased. In addition, by adding silica fumed to composites, the tensile and flexural strength of CFRCC is greatly improved.

• Journal of Korea Society of Industrial Information Systems
• /
• v.28 no.6
• /
• pp.83-90
• /
• 2023

In a reefer container, temperature deviation occurs between the front of the loading part with the refrigerator and the rear of the loading part with the container door due to the external environment. In particular, this temperature deviation in the transport of fresh cargo has a great influence on the freshness of the cargo. In this study, we propose a method to minimize the temperature deviation by partially shielding the T-Floor to reduce the temperature deviation and evaluating the effect of the T-Floor shielding rate on the temperature change of the reefer container loading part. The subject of the experiment was a 40 feet smart reefer container, and the T-Floor shielding rates were set to 0%, 50%, 60%, 70%, and 80%. As a result of the experiment, it occurred differently in the temperature deviation of the reefer container loading part according to the shielding rate, and it was confirmed that the temperature deviation was the most uniform when the shielding rate was 60%. By minimizing the temperature deviation of the loading part, it is possible to prevent corruption and cold damage of cargo during transportation of fresh cargo by using the smart reefer container.

• Journal of Korean Society on Water Environment
• /
• v.16 no.4
• /
• pp.523-532
• /
• 2000

The purpose of this study was to investigate the effects of the hydraulic retention time (HRT) and organic loading rate (OLR) on microbial characteristics and treatment efficiency in sewage treatment using aerated submerged biological filter (ASBF) reactor. This reactor combines biodegradation of organic substrates by fixed biomass with a physical separation of biomass by filtration in a single reactor. Both simulated wastewater and domestic wastewater were used as feed solutions. The experimental conditions were a temperature of 17 to $27^{\circ}C$, a hydraulic retention time of 1 to 9hr, an organic loading rate of 0.47 to $3.84kg\;BOD/m^3{\cdot}day$ in ASBF reactor. This equipment could obtain a stable effluent quality in spite of high variation of influent loading rate. Total biomass concentration. biofilm thickness and biofilm mass increased an exponential function according to the increasing OLR. The relationships between water content and biofilm density were in inverse proportion. The percentage of backwash water to influent flow was almost 9%. The separation efficiency of biomass was the percentage of 91 to 92 in ASBF reactor. The sludge production rates in feed solutions of simulated wastewater and domestic wastewater were 0.14~0.26 kg VSS/kg BODrem, 0.43~0.48 kg VSS/kg BODrem, respectively.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.30 no.7 s.250
• /
• pp.826-832
• /
• 2006

For the improvement of safety and endurance in welded steel structure, it is needed to consider welding residual stress distribution and rolling directional characteristics of materials. In this study, it was investigated experimentally about characteristics of fatigue crack propagation according to welding residual stress and rolling in FCAW(flux cored arc welding) butt-jointed steel plates. SS400 steel plates of 3mm thickness were selected and tested for this study. When the angles between tensile loading direction and rolling direction in welded materials are increased from $0^{\circ}\;to\;90^{\circ}$, their fatigue crack propagation rates are increased. These results are same as predicted increments of fatigue crack propagation rate when stress ratio is increased from 0 to 0.5. When the angles of rolling direction and welding direction to tensile loading direction are $0^{\circ}\;and\;90^{\circ}$ respectively, fatigue crack propagation rate in welded material is lowest.

• Journal of environmental and Sanitary engineering
• /
• v.10 no.3
• /
• pp.67-77
• /
• 1995

This study was performed for minimization of excessive biofilm effects at the high strength organic wastewater treatment. As a results of biofilm attachment experiment using piggery wastewater, aggravation of water quality due to excessive biofilm showed after 15 days of operating times.4 excessive biofilm phase, the equivalent biofilm thickness and VSS contents per unit aura were observed in the range of 1,100 to $1,200{\mu}m$ and 2.5 to 3.0mg $VSS/cm^{2}$, respectively. In the aerobic fixed biofilm reactor/anoxic fixed biofilm reactor(AFBR/ANFBR) process with endogenous respiration phase, the BOD removal efficiency was obtained more than 90 percentage at the surface loading rate and volumetric loading rate of the AFBR maintained less than 17 g $BOD/m^{2}{\cdot}$day and 1.7kg $BOD/m^{3}{\cdot}$day, respectively. The removal efficiency of TKN and $NH_{3}$-N at the loading rates below 5.60g $NH_{3}-N/m^{2}{\cdot}day$ and 0.56kg $NH_{3}-N/m^{3}{\cdot}$day were above 76 percentage and 82 percentage, respectively. In order to reduced sludge production rate and aggravation of water quality, endogenous respiration phase was accepted at first AFBR reactor. As a results of this operating condition, sludge production was minimized and removal efficiency was maintained stability.

• Journal of the Korean Geotechnical Society
• /
• v.16 no.1
• /
• pp.99-106
• /
• 2000

The main advantage of incremental loading consolidation test is the simplicity of equipments that can be used. However, it is known that the incremental loading test has several deficiencies including long testing time, non-uniform stress state, high and variable rates of strain, very soft clay and problem of back pressure saturation. Due to these drawbacks, various testing methods including constant rate of strain consolidation test(CRS) were developed. In this paper, CRS consolidation test was performed with three different strain rate. The results were verified by the modified CRS theory of Wissa et al.(1971). And then the results obtained from the CRS consolidation tests were compared with those from incremental loading test and direct permeability test.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.10 no.1
• /
• pp.71-80
• /
• 1990

The fracture characteristics of concrete under various rates of loading are investigated. The static and dynamic fracture energies of concrete are determined and the size-dependency of fracture energy is clarified from the present study. To this end, a series of experiments were conducted. The maximum failure loads, fracture energies and nominal failure stresses were calculated from those test results. It is found that the fracture energies are increased with the increase of loading rate. The fracture energy values were also greatly influenced with the size of the specimen. The size-dependent prediction eguations for the static and dynamic fracture energies of concrete are proposed in the present study. The present paper provides useful data for the dynamic fracture analysis of concrete structures.