The Effect of Fumed Silica Loading on the Thermal Stability of Fluorosilicone Composites Muhammet

Muhammet Iz,이진혁,최명찬,윤유미,강현민,김정완,배종우 한국고무학회 2022 엘라스토머 및 콤포지트 Vol.57 No.4

The effect of fumed silica loading on the thermal stability and mechanical properties of fluorosilicone (FVMQ) rubber was investigated. The distribution of fumed silica inside FVMQ was characterized using scanning electron microscopy, and the thermal stability of composites was evaluated using thermogravimetric analysis and by the changes in mechanical performance during thermo-oxidative aging. The function mechanism of fumed silica was studied by Fourier transform infrared spectroscopy. The results show that with increasing silica content, the crosslink density of composites, the modulus at 100%, and tensile strength also increased, whereas the elongation at break decreased. Furthermore, increasing the silica content of composites increased the initial decomposition temperature (Td) and residual weight of the composite after exposure to nitrogen. In addition, the thermal oxidative aging experiment demonstrated improved aging resistance of the FVMQ composites, including lower change in tensile strength, elongation at break, and modulus at 100%.

Vibration analysis of honeycomb sandwich composites filled with polyurethane foam by Taguchi Method

Muhammet R. Aydin,Ömer Gündoğdu 국제구조공학회 2018 Steel and Composite Structures, An International J Vol.28 No.4

In this study, the effect of polyurethane foam filler, in addition to surface layer thickness and core material thickness, on vibration characteristics of sandwich structures was investigated. The manufacturing process was carried out according to the Taguchi method. The natural frequencies and damping ratios of the produced samples were determined experimentally for fixedfree boundary conditions. In addition, solid models were developed for test samples and their finite element analyses were performed with ANSYS_® to obtain their natural frequencies and mode shapes. An acceptably good agreement was found with the comparison of experimental results with the numerically obtained ones. The most effective parameters on the vibration characteristics of the sandwich structure were determined by the Taguchi method.

터키 대학 한국어문학과 전공생을 위한 한국어 교재 개발 연구

( Muhammet Emre Korkmaz ) 국제한국어교육학회 2018 국제한국어교육학회 학술대회논문집 Vol.2018 No.-

Earthquake response of roller compacted concrete dams including galleries

Muhammet Karabulut,Murat Emre Kartal 국제구조공학회 2019 Structural Engineering and Mechanics, An Int'l Jou Vol.72 No.2

The effect of galleries on the earthquake behavior of dams should be investigated to obtain more realistic results. Therefore, a roller compacted concrete (RCC) dam with and without galleries are examined under ground motion effects. For this purpose, Cine RCC dam constructed in Aydın, Turkey, is selected in applications. The optimal mesh around galleries is investigated to obtain the most realistic results. Two-dimensional finite element models of Cine RCC dam with and without galleries are prepared by using ANSYS software. Empty and full reservoir conditions were taken into account in the time-history analyses. Hydrodynamic effect of the reservoir water was taken into account considering two-dimensional fluid finite elements based on the Lagrangian approach. It is examined that how principle stresses and displacements change by height and during earthquake. The dam-foundation-reservoir interaction was taken into consideration with contact-target element pairs. The displacements and principle stress components obtained from the linear analyses are compared each other for various cases of reservoir water and galleries. According to numerical analyses, the effect of galleries is clear on the response of RCC dam. Besides, hydrodynamic water effect obviously increases the principle stress components and horizontal displacements of the dam.

Modeling of triple concave friction pendulum bearings for seismic isolation of buildings

Muhammet Yurdakul,Sevket Ates 국제구조공학회 2011 Structural Engineering and Mechanics, An Int'l Jou Vol.40 No.3

Seismic isolated building structures are examined in this study. The triple concave friction pendulum (TCFP) is used as a seismic isolation system which is easy to be manufactured and enduring more than traditional seismic isolation systems. In the TCFP, take advantage of weight which pendulum carrying and it’s geometry in order to obtain desirable result of seismic isolation systems. These systems offer advantage to buildings which subject to severe earthquake. This is result of damping force of earthquake by means of their internal constructions, which consists of multiple surfaces. As the combinations of surfaces upon which sliding is occurring change, the stiffness and effective friction change accordingly. Additionally, the mentioned the TCFP is modeled as of a series arrangement of the three single concave friction pendulum (SCFP) bearings. A two dimensional- and eight- story of a building with and without isolation system are used in the time history analysis in order to investigate of the effectiveness of the seismic isolation systems on the buildings. Results are compared with each other to emphasize efficiency of the TCFP as a seismic isolation device against the other friction type isolation system like single and double concave surfaces. The values of the acceleration, floor displacement and isolator displacement obtained from the results by using different types of the isolation bearings are compared each other. As a result, the findings show that the TCFP bearings are more effective devices for isolation of the buildings against severe earthquakes.

Early Outcomes of Sutureless Aortic Valves

Muhammet Onur Hanedan, M.D.,İlker Mataracı, M.D.,Mehmet Ali Yürük, M.D.,Tanıl Özer, M.D.,Ufuk Sayar, M.D.,Ali Kemal Arslan, M.D.,Uğur Ziyrek, M.D.,Murat Yücel, M.D. 대한흉부외과학회 2016 Journal of Chest Surgery (J Chest Surg) Vol.49 No.3

Background: In elderly high-risk surgical patients, sutureless aortic valve replacement (AVR) should be an alternative to standard AVR. The potential advantages of sutureless aortic prostheses include reducing cross-clamping and cardiopulmonary bypass (CPB) time and facilitating minimally invasive surgery and complex cardiac interventions, while maintaining satisfactory hemodynamic outcomes and low rates of paravalvular leakage. The current study reports our single-center experience regarding the early outcomes of sutureless aortic valve implantation. Methods: Between October 2012 and June 2015, 65 patients scheduled for surgical valve replacement with symptomatic aortic valve disease and New York Heart Association function of class II or higher were included to this study. Perceval S (Sorin Biomedica Cardio Srl, Sallugia, Italy) and Edwards Intuity (Edwards Lifesciences, Irvine, CA, USA) valves were used. Results: The mean age of the patients was 71.15±8.60 years. Forty-four patients (67.7%) were female. The average preoperative left ventricular ejection fraction was 56.9±9.93. The CPB time was 96.51±41.27 minutes and the cross-clamping time was 60.85±27.08 minutes. The intubation time was 8.95±4.19 hours, and the intensive care unit and hospital stays were 2.89±1.42 days and 7.86±1.42 days, respectively. The mean quantity of drainage from chest tubes was 407.69±149.28 mL. The hospital mortality rate was 3.1%. A total of five patients (7.69%) died during follow-up. The mean follow-up time was 687.24±24.76 days. The one-year survival rate was over 90%. Conclusion: In the last few years, several models of valvular sutureless bioprostheses have been developed. The present study evaluating the single-center early outcomes of sutureless aortic valve implantation presents the results of an innovative surgical technique, finding that it resulted in appropriate hemodynamic conditions with acceptable ischemic time.

An autonomous system design for mold loading on press brake machines using a camera platform, deep learning, and image processing

Muhammet Üsame Öziç,Mücahid Barstuğan,Atakan Özdamar 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.8

Press brakes are among the most important machines used in sheet metal processing. In these machines, different numbers of molds are used for sheet bending and these molds are placed in the system by an operator. However, this process is slow, errorprone, and dependent on human labor. In this study, a real-time system that automatically detects molds and manipulates a robotic arm was designed using YOLOv4 and image processing. YOLOv4, a deep learning (DL)-based object detection algorithm, was applied to detect the positions, types, and holes of molds. Classical image processing methods were implemented to find the center (X, Y) coordinates of the mold hole. This study shows that the press brake machines currently used in industry can be transformed into smart machines through DL, image processing, camera systems, and robotic arm features.

Comparisons of Elasto-Fiber and Fiber & Bernoulli-Euler reinforced concrete beam-column elements

Muhammet Karaton 국제구조공학회 2014 Structural Engineering and Mechanics, An Int'l Jou Vol.51 No.1

In this study, two beam-column elements based on the Elasto-Fiber element theory for reinforced concrete (RC) element have been developed and compared with each other. The first element is based on Elasto Fiber Approach (EFA) was initially developed for steel structures and this theory was applied for RC element in there and the second element is called as Fiber & Bernoulli-Euler element approach (FBEA). In this element, Cubic Hermitian polynomials are used for obtaining stiffness matrix. The beams or columnselement in both approaches are divided into a sub-element called the segment for obtaining element stiffness matrix. The internal freedoms of this segment are dynamically condensed to the external freedoms at theends of the element by using a dynamic substructure technique. Thus, nonlinear dynamic analysis of high RC building can be obtained within short times. In addition to, external loads of the segment are assumed to be distributed along to element. Therefore, damages can be taken account of along to element and redistributions of the loading for solutions. Bossak-α integration with predicted-corrected method is used for the nonlinear seismic analysis of RC frames. For numerical application, seismic damage analyses for a 4-story frame and an 8-story RC frame with soft-story are obtained to comparisons of RC element according to both approaches. Damages evaluation and propagation in the frame elements are studied and response quantities from obtained both approaches are investigated in the detail.

Changes in the Total Lipid, Neutral Lipid, Phospholipid and Fatty Acid Composition of Phospholipid Fractions during Pastırma Processing, a Dry-Cured Meat Product

Muhammet Irfan Aksu,Mehmet Dogan,Ahmet Necdet Sirkecioglu 한국축산식품학회 2017 한국축산식품학회지 Vol.37 No.1

Pastırma is a dry-cured meat product, produced from whole beef or water buffalo muscles. This study was carried out to investigate the effect of production stages (raw meat, after curing, after 2nd drying and pastırma) on the total lipid, neutral lipid, phospholipid and fatty acid composition of phospholipid fraction of pastırma produced from beef M. Longissimus dorsi muscles. The pH and colour (L*, a* and b*) analyses were also performed in raw meat and pastırma. It was found that pastırma production stages had significant effects (p

Independently generated modules

Muhammet Tamer Kosan,Tufan Özdin 대한수학회 2009 대한수학회보 Vol.46 No.5

A module M over a ring R is said to satisfy (P) if every generating set of M contains an independent generating set. The following results are proved; (1) Let τ = (Tτ , Fτ ) be a hereditary torsion theory such that Tτ ≠ Mod-R. Then every τ-torsionfree R-module satisfies (P) if and only if S = R/τ(R) is a division ring. (2) Let K be a hereditary pre-torsion class of modules. Then every module in K satisfies (P) if and only if either K ={0} or S = R/ Soc_K(R) is a division ring, where Soc_K(R) = ∩{I≤ R_R : R/I ∈ K}. A module M over a ring R is said to satisfy (P) if every generating set of M contains an independent generating set. The following results are proved; (1) Let τ = (Tτ , Fτ ) be a hereditary torsion theory such that Tτ ≠ Mod-R. Then every τ-torsionfree R-module satisfies (P) if and only if S = R/τ(R) is a division ring. (2) Let K be a hereditary pre-torsion class of modules. Then every module in K satisfies (P) if and only if either K ={0} or S = R/ Soc_K(R) is a division ring, where Soc_K(R) = ∩{I≤ R_R : R/I ∈ K}.