Earthquake performance of FRP retrofitting of short columns around band-type windows

Kocak, Ali Techno-Press 2015 Structural Engineering and Mechanics, An Int'l Jou Vol.53 No.1

Due to design codes and regulations and the variety of building plans in Turkey, it is very often seen that band-type windows are left for ventilation and lightening of the basements of buildings which are used for various purposes such as workplaces and storage. Therefore when the necessary support measures cannot be given, short columns are subjected to very high shear forces and so damage occurs. One of the precautions to avoid the damage of short column mechanisms in buildings where band-type windows are in the basement is to strengthen the short columns with fiber reinforced polymer (FRP). In this study, the effect of the FRP retrofitting process of the short columns around band-windowed structures, which are found especially in basement areas, is analyzed in accordance with Turkish Seismic Code 2007 (TSC 2007). Three different models which are bare frame, frame with short columns and retrofitted short columns with FRP, are created and analyzed according to TSC 2007 performance analysis methods to understand the effects of band windows in basements and the effect of FRP retrofitting.

The effect of short columns on the performance of existing buildings

Kocak, Ali Techno-Press 2013 Structural Engineering and Mechanics, An Int'l Jou Vol.46 No.4

In this study, the seismic performance of a residential building which was damaged in the 1992 Erzincan (Turkey) Earthquake (Ms = 6.8) is performed. Damages on columns due to short columns are estimated analytically implementing the shear hinges and results are compared with the observed damages on the building after the earthquake. In seismic performance evaluation, a deformation based approach is adopted, whereby the structural behavior under external and seismic loads is evaluated. Furthermore, the effects of short columns formed by band windows in basement floors are investigated analytically. The sizes of band windows are parametrically changed in order to understand the effects of short columns on overall building behavior.

Predicting the compressive strength of cement mortars containing FA and SF by MLPNN

Yilmaz Kocak,Eyyup Gulbandilar,Muammer Akcay 사단법인 한국계산역학회 2015 Computers and Concrete, An International Journal Vol.15 No.5

In this study, a multi-layer perceptron neural network (MLPNN) prediction model for compressive strength of the cement mortars has been developed. For purpose of constructing this model, 8 different mixes with 240 specimens of the 2, 7, 28, 56 and 90 days compressive strength experimental results of cement mortars containing fly ash (FA), silica fume (SF) and FA+SF used in training and testing for MLPNN system was gathered from the standard cement tests. The data used in the MLPNN model are arranged in a format of four input parameters that cover the FA, SF, FA+SF and age of samples and an output parameter which is compressive strength of cement mortars. In the model, the training and testing results have shown that MLPNN system has strong potential as a feasible tool for predicting 2, 7, 28, 56 and 90 days compressive strength of cement mortars.

Wear Characterization of Reinforced Polyurethane Composites Produced via Vacuum Casting

Sait Kocak,Yavuz Kaplan 한국고분자학회 2021 폴리머 Vol.45 No.6

In recent years, research relating to polyurethane has been growing because of the lightness, low cost, and favorable mechanical properties of this material. The increased usage areas of polyurethane in tribological systems make it very important to determine its wear behavior. This study focuses on the wear characterization of polyurethane composites reinforced with glass fiber, SiC, and Al₂O₃. The wear tests were carried out using a pin-on-disc test apparatus against an abrasive counter-face at different applied loads (5 and 10 N). Scanning electron microscopy was used to observe the damage on the worn surfaces. The wear experiments clearly demonstrated that the reinforcement materials significantly affected the tribological properties of the polyurethane composites. In addition, it was observed that particle reinforcement was more effective than fiber reinforcement under experimental conditions. Consequently, polyurethane with glass fiber, SiC, and Al₂O₃ fillers would be a suitable candidate for use in tribological applications.

Effect of the PC, diatomite and zeolite on the performance of concrete composites

Yilmaz Kocak,Muhsin Savas 사단법인 한국계산역학회 2016 Computers and Concrete, An International Journal Vol.17 No.6

This study has been carried out to investigate the effect of the surface properties of Portland cement, diatomite and zeolite on the performance of concrete composites. In this context, to describe the materials used in this study and determine the properties of them, chemical, physical, mineralogical, molecular, thermal, and zeta potential analysis have been applied. In the study, reference (Portland cement), 10%–20% diatomite, 10%–20% zeolite, 5+5%–10+10% diatomite and zeolite were substituted for Portland cement, a total of 7 different cements were obtained. Ultrasonic pulse velocity, capillary water absorption and compressive strength tests were performed on the hardened concrete specimens. Hardened concrete tests have been done on seven different types of concrete, for 28, 56 and 90 days. As a result of experiments it has been identified that both the zeolite and diatomite substitution has a positive effect on the performance of concrete.

Is FDG -PET-CT A Valuable Tool in Prediction of Persistent Disease in Head and Neck Cancer

Uzel, Esengul Kocak,Ekmekcioglu, Ozgul,Elicin, Olgun,Halac, Metin,Uzel, Omer Erol Asian Pacific Journal of Cancer Prevention 2013 Asian Pacific journal of cancer prevention Vol.14 No.8

Objectives: To evaluate accuracy of FDG-PET CT in prediction of persistent disease in head and neck cancer cases and to determine prognostic value of metabolic tumor response. Materials and Methods: Between 2009 and 2011, 46 patients with squamous cell carcinoma of head and neck receiving PET-CT were treated with definitive radiotherapy, with or without chemotherapy. There were 29 nasopharyngeal, 11 hypopharyngeal, 3 oropharyngeal and 3 laryngeal cancer patients, with a median age of 50.5 years (range 16-84), 32 males and 14 females. All patients were evaluated with PET-CT median 3-5 months (2.4-9.4) after completion of radiotherapy. Results: After a median 20 months of follow up, complete metabolic response was observed in 63% of patients. Suspicious residual uptake was present in 10.9% and residual metabolic uptake in 26.0% of patients. The overall sensitivity, specificity, positive predictive value and negative predictive value of FDG-PET-CT for detection of residual disease was 91% and 81%, 64% and 96% respectively. Two year LRC was 95% in complete responders while it was 34% in non-complete responders. Conclusions: FDG PET CT is a valuable tool for assessment of treatment response, especially in patients at high risk of local recurrence, and also as an indicator of prognosis. Definitely more precise criteria are required for assessment of response, there being no clear cut uptake value indicating residual disease. Futhermore, repair processes of normal tissue may consume glucose which appear as increased uptake in control FDG PET CT.

Intravitreal Dexamethasone Implantation in Intravitreal Bevacizumab Treatment-Resistant Pseudophakic Cystoid Macular Edema

AYSE GUL KOCAK ALTINTAS,Cagri Ilhan 대한안과학회 2019 Korean Journal of Ophthalmology Vol.33 No.3

Purpose: To evaluate the changes in visual acuity (VA) and central macular thickness (CMT) after intravitrealdexamethasone (IVD) implantation in intravitreal bevacizumab (IVB) treatment-resistant cases with pseudophakiccystoid macular edema (PCME). Methods: This study included 10 PCME cases who underwent uneventful phacoemulsification and intraocularlens implantation with similar methods and six PCME cases referred to our hospital for treatment oflow VA after cataract surgery. Due to the persistence of PCME, both topical steroid and anti-inflammatorymedication were administered first, followed by IVB injection. IVD implantation was performed for all IVBtreatment-resistant cases. VA and CMT values were compared before and at three months after the first IVDimplantation. Results: The mean VA values before and at 3 months after the first IVD implantation were 0.69 ± 0.19 logarithmof the minimum angle of resolution (logMAR) (1.50 to 0.10 logMAR) and 0.26 ± 0.07 logMAR (1.00 to 0.00logMAR), respectively (p < 0.001). The mean CMT was 476.13 ± 135.13 mm (314 to 750 mm) and 294.06 ±15.26 mm (222 to 480 mm), respectively (p < 0.001). The mean number of implanted IVD was 1.44 ± 0.89 (1to 4) and the mean follow-up time was 7.4 ± 4.6 months (6 to 24 months). After IVD implantation therapy, themean VA and CMT values were 0.19 ± 0.05 logMAR (0.70 to 0.00 logMAR) and 268.38 ± 31.35 mm (217 to351 mm), respectively. Conclusions: To the best of our knowledge, this is the first report to show the efficacy of IVD implantationeven after repeated IVB injections in treatment-resistant PCME. IVD implantation is both a safe and effectivemethod for decreasing PCME after both uneventful and complicated cataract surgery.

Risk for Malignant and Borderline Ovarian Neoplasms Following Basic Preoperative Evaluation by Ultrasonography, Ca125 Level and Age

Karadag, Burak,Kocak, M.,Kayikcioglu, F.,Ercan, F.,Dilbaz, B.,Kose, M.F.,Haberal, A. Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.19

Objective: To verify the basic preoperative evaluation in the discrimination between benign and malignant adnexal masses in our clinical practice. Materials and Methods: Data were collected on the records of 636 women with adnexal masses who had undergone surgery either by open or endoscopic approaches. Those with obvious signs of malignancy, any history of cancer, emergency surgeries without basic evaluation were excluded. The preoperative features by age, ultrasound and serum Ca125 level were compared with final histopathological diagnosis at the four departments of the institution. These are the general gynecology (Group 1: exploratory laparotomy), the gynecologic endoscopy (Group 2: laparoscopy and adnexectomy), the gynecological oncology (Group 3: staging laparotomy) and the gynecologic endocrinology and infertility (Group 4: laparoscopy and cystectomy). Results: There were simple and complex cyst rates of 22.3% and 77.2%, respectively. There were 86.3% benign, 4.1% (n:20) borderline ovarian tumor (BOT) and 6.4% (n:48) malignant lesions. There were 3 BOT and 9 ovarian cancers in Group 1 and one BOT and two ovarian cancer in the Group 2. During the surgery, 15 BOT (75%) and 37 ovarian cancer (77%) were detected in the Group 3, only one BOT was encountered in the Group 4. The risk of rate of unsuspected borderline or focally invasive ovarian cancer significantly increased by age, size, complex morphology and Ca125 (95% CI, OR=2.72, OR=6.60, OR=6.66 and OR=4.69, respectively). Conclusions: Basic preoperative evaluation by comprehensive ultrasound imaging combined with age and Ca125 level has proved highly accurate for prediction of unexpected malignancies. Neither novel markers nor new imaging techniques provide better information that allow clinicians to assess the feasibility of the planned surgery; consequently, the risk of inadvertent cyst rupture during laparoscopy may be significantly decreased in selected cases.

New metal connectors developed to improve the shear strength of stone masonry walls

Karabork, Turan,Kocak, Yilmaz Techno-Press 2014 Structural Engineering and Mechanics, An Int'l Jou Vol.50 No.1

Stone masonry structures are widely used around the world, but they deteriorate easily, due to low shear strength capacity. Many techniques have been developed to increase the shear strength of stone masonry constructions. The aim of this experimental study was to investigate the performance of stone masonry walls strengthened by metal connectors as an alternative shear reinforcement technique. For this purpose, three new metal connector (clamp) types were developed. The shear strength of the walls was improved by applying these clamps to stone masonry walls. Ten stone masonry walls were structurally tested in diagonal compression. Various parameters regarding the in-plane behavior of strengthening stone masonry walls, including shear strength, failure modes, maximum drift, ductility, and shear modulus, were investigated. Experimentally obtained shear strengths were confirmed by empirical equations. The results of the study suggest that the new clamps developed for the study effectively increased the levels of shear strength and ductility of masonry constructions.

Cost Saving Strategy and Wellness Programs Featuring Decision Tree, Utility and Analytical Hierarchy Analysis

James Powers,Mehmet C. Kocakü,lâ,h People&Global Business Association 2015 Global Business and Finance Review Vol.20 No.2

Paying for healthcare is a challenge for employers and employees alike. As companies strive to find ways to reduce costs, comprehensive wellness programs are one way to control rising health care premiums. Healthy employees require less medical attention and are they less costly to insure. Cost savings are measured uantitatively and qualitatively. Here we are going try to make clear in analysis that positive financial returns on investment in a wellness center facility are possible. The exploration will also demonstrate decisions that go beyond ROI. To gain insight into probable outcomes, decision tree methods, Bayes’ Theorem, utility analysis, and analytical hierarchy process methods are used. Analysis from multiple perspectives, using various approaches, may result in to help decision makers more informed decision. Wellness programs increase productivity, reduce absenteeism, and create a happier work environment. Taking care of employees and encouraging wellness in our companies is the right thing to do and increase profitability