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Tahir Gonen,Salih Yazicioglu,Bahar Demirel 대한토목학회 2015 KSCE Journal of Civil Engineering Vol.19 No.3
The main objective of this experimental study is to determine which of the effective parameter among ultrasonic pulse velocity,compressive strength, capillary water absorption and porosity during freezing and thawing on concrete produced with mineraladmixtures. The specimens were exposed to 25, 50, 75 and 100 freezing-thawing cycles after 28 curing days. The results showed thatamong the measured parameters, capillary water absorption was the most affected parameter from freeze-thaw cycles.
Crack detection in folded plates with back-propagated artificial neural network
Oguzhan Das,Can Gonenli,Duygu Bagci Das 국제구조공학회 2023 Steel and Composite Structures, An International J Vol.46 No.3
Localizing damages is an essential task to monitor the health of the structures since they may not be able to operate anymore. Among the damage detection techniques, non-destructive methods are considerably more preferred than destructive methods since damage can be located without affecting the structural integrity. However, these methods have several drawbacks in terms of detecting abilities, time consumption, cost, and hardware or software requirements. Employing artificial intelligence techniques could overcome such issues and could provide a powerful damage detection model if the technique is utilized correctly. In this study, the crack localization in flat and folded plate structures has been conducted by employing a Backpropagated Artificial Neural Network (BPANN). For this purpose, cracks with 18 different dimensions in thin, flat, and folded structures having 150 , 300 , 450 , and 600 folding angle have been modeled and subjected to free vibration analysis by employing the Classical Plate Theory with Finite Element Method. A Four-nodded quadrilateral element having six degrees of freedom has been considered to represent those structures mathematically. The first ten natural frequencies have been obtained regarding healthy and cracked structures. To localize the crack, the ratios of the frequencies of the cracked flat and folded structures to those of healthy ones have been taken into account. Those ratios have been given to BPANN as the input variables, while the crack locations have been considered as the output variables. A total of 500 crack locations have been regarded within the dataset obtained from the results of the free vibration analysis. To build the best intelligent model, a feature search has been conducted for BAPNN regarding activation function, the number of hidden layers, and the number of hidden neurons. Regarding the analysis results, it is concluded that the BPANN is able to localize the cracks with an average accuracy of 95.12%.
Pinar Oztas,Meltem Onder,Sevim Gonen,Murat Orhan Oztas,Oguz Soylemezoglu 연세대학교의과대학 2004 Yonsei medical journal Vol.45 No.SUP
The Human Leukocyte Antigen (HLA) typing of large groups of patients with various autoimmune diseases has demonstrated that some HLA alleles occur at higher frequencies in specific diseases than in the general population. Chronic urticaria has been shown to have an autoimmune basis by a previous study which found an association between chronic urticaria and specific HLA groups. We investigated the HLA subtypes of Turkish chronic urticaria patients. For this purpose 42 Turkish patients with chronic urticaria and 115 healthy controls were typed for HLA-DR and DQ by PCR-SSP (Polymerase Chain Reaction Sequence Specific Primers) low resolution DNA technique. We found an increased frequency of DR4 (42.9%, p=0.01) in chronic urticaria patients in comparison with that in healthy controls. This study supports the hypothesis that HLA alleles may be involved in the pathogenesis of chronic urticaria and that they appear to be directly involved in the initiation of the immune response.
Effect of Fly Ash and Silica Fume on Compressive Strength, Sorptivity and Carbonation of SCC
Kazim Turk,Mehmet Karatas,Tahir Gonen 대한토목학회 2013 KSCE JOURNAL OF CIVIL ENGINEERING Vol.17 No.1
In this paper, ASTM C 618 Class F Fly Ash (FA) at 25%, 30%, 35% and 40% and Silica Fume (SF) at 5%, 10%, 15% and 20%replacement of Portland Cement (PC) CEM I 42.5 in SCC was used to evaluate the effect of types and quantity of powder additions on compressive strength and permeations properties of SCC. To this end, eight types of SCC were designed, in comparison with Vibrated Traditional Concrete (VTC). The results indicated that SCC specimens with SF15 had the highest compressive strength with 73.87 MPa for 130 days. The sorptivity values of SCC specimens with FA and SF were lower than those of VTC specimens regardless of type and quantity of powder additions. On the other hand, the carbonation resistance of VTC was higher than that of SCC specimens containing both SF and FA for all accelerated carbonation periods. Consequently, it can be said that type and quantity of powder additions had an important effect on the correlation among the compressive strength and permeation properties of SCC.
Free vibration and buckling analyses of curved plate frames using finite element method
Oguzhan Das,Hasan Ozturk,Can Gonenli 국제구조공학회 2023 Structural Engineering and Mechanics, An Int'l Jou Vol.86 No.6
This study investigates the free vibration and buckling analyses of isotropic curved plate structures fixed at all ends. The Kirchhoff-Love Plate Theory (KLPT) and Finite Element Method (FEM) are employed to model the curved structure. In order to perform the finite element analysis, a four-node quadrilateral element with 5 degrees of freedom (DOF) at each node is utilized. Additionally, the drilling effect (θz) is considered as minimal to satisfy the DOF of the structure. Lagrange's equation of motion is used in order to obtain the first ten natural frequencies and the critical buckling values of the structure. The effects of various radii of curvatures and aspect ratio on the natural frequency and critical buckling load values for the single-bay and twobay curved frames are investigated within this scope. A computer code based on finite element analysis is developed to perform free vibration and buckling analysis of curved plate frames. The natural frequency and critical buckling load values of the present study are compared with ANSYS R18.2 results. It has been concluded that the results of the present study are in good agreement with ANSYS results for different radii of curvatures and aspect ratio values of both single-bay and two-bay structures.
Finite element vibration analysis of laminated composite parabolic thick plate frames
Oguzhan Das,Hasan Ozturk,Can Gonenli 국제구조공학회 2020 Steel and Composite Structures, An International J Vol.35 No.1
In this study, free vibration analysis of laminated composite parabolic thick plate frames by using finite element method is introduced. Governing equations of an eigenvalue problem are obtained from First Order Shear Deformation Theory (FSDT). Finite element method is employed to obtain natural frequency values from the governing differential equations. The frames consist of two flat square plates and one singly curved plate. Parameters like radii of curvature, aspect ratio, ply orientation and boundary conditions are investigated to understand their effect on dynamic behavior of such a structure. In addition, multi-bay structures of such geometry with different stacking order are also taken into account. The composite frame structures are also modeled and simulated via ANSYS to verify the accuracy of the present study.
The effects of ozone therapy as an adjunct to the surgical treatment of peri-implantitis
Sila Cagri Isler,Berrin Unsal,Fatma Soysal,Gonen Ozcan,Elif Peker,Inci Rana Karaca 대한치주과학회 2018 Journal of Periodontal & Implant Science Vol.48 No.3
Purpose: The decontamination procedure is a challenging aspect of surgical regenerative therapy (SRT) of peri-implantitis that affects its success. The purpose of the present study was to determine the impact of additional topical gaseous ozone therapy on the decontamination of implant surfaces in SRT of peri-implantitis. Methods: A total of 41 patients (22 males, 19 females; mean age, 53.55±8.98 years) with moderate or advanced peri-implantitis were randomly allocated to the test group (ozone group) with the use of sterile saline with additional ozone therapy or the control group with sterile saline alone for decontamination of the implant surfaces in SRT of peri-implantitis. Clinical and radiographic outcomes were evaluated over a period of 12 months. Results: At the 12-month follow-up, the plaque and gingival index values were significantly better in the ozone group (P<0.05). Probing depth decreased from 6.27±1.42 mm and 5.73±1.11 mm at baseline to 2.75±0.7 mm and 3.34±0.85 mm at the end of the 12-month observation period in the ozone and control groups, respectively. Similarly, the clinical attachment level values changed from 6.39±1.23 mm and 5.89±1.23 mm at baseline to 3.23±1.24 mm and 3.91±1.36 mm at the 12-month follow-up in the ozone and control groups, respectively. According to the radiographic evidence, the defect fill between baseline and 12 months postoperatively was 2.32±1.28 mm in the ozone group and 1.17±0.77 mm in the control group, which was a statistically significant between-group difference (P<0.05). Conclusions: Implant surface decontamination with the additional use of ozone therapy in SRT of peri-implantitis showed clinically and radiographically significant. Trial registry at ClinicalTrials.gov, NCT03018795.