Predicting the moment capacity of RC slabs with insulation materials exposed to fire by ANN

Hakan Erdem 국제구조공학회 2017 Structural Engineering and Mechanics, An Int'l Jou Vol.64 No.3

Slabs prevent harmful effects of fire that may occur in any floor. However, it is necessary to protect the slabs from fire. Insulation materials may be appropriate to protect reinforced concrete (RC) slab from elevated temperature. In the present study, a model has been developed in artificial neural network (ANN) to predict the moment capacity (Mr) of RC slabs exposed to fire with insulation material. 672 data were obtained for ANN model through author\'s prepared program. Input layer in model consisted of seven input parameters; such as effective depth (d), ratio of d\'/d, thermal conductivity coefficient (kinsulation), insulation materials thickness (Linsulation), reinforcement area (Ast), fire exposure time (texp), and concrete compressive strength (fc). The predicted Mr by ANN was consistent with the obtained Mr by author. It is proposed to ease computational complexity in determining Mr using ANN. The effects of using insulation material on the moment capacity in RC slabs were also investigated. Insulating material with low thermal conductivity has been found to be more effective for durability to high temperature.

Predicting residual moment capacity of thermally insulated RC beams exposed to fire using artificial neural networks

Hakan Erdem 사단법인 한국계산역학회 2017 Computers and Concrete, An International Journal Vol.19 No.6

This paper presents a method using artificial neural networks (ANNs) to predict the residual moment capacity of thermally insulated reinforced concrete (RC) beams exposed to fire. The use of heat resistant insulation material protects concrete beams against the harmful effects of fire. If it is desired to calculate the residual moment capacity of the beams in this state, the determination of the moment capacity of thermally insulated beams exposed to fire involves several consecutive calculations, which is significantly easier when ANNs are used. Beam width, beam effective depth, fire duration, concrete compressive and steel tensile strength, steel area, thermal conductivity of insulation material can influence behavior of RC beams exposed to high temperatures. In this study, a finite difference method was used to calculate the temperature distribution in a cross section of the beam, and temperature distribution, reduction mechanical properties of concrete and reinforcing steel and moment capacity were calculated using existing relations in literature. Data was generated for 336 beams with different beam width (bw), beam account height (h), fire duration (t), mechanical properties of concrete (fcd) and reinforcing steel (fyd), steel area (As), insulation material thermal conductivity (kinsulation). Five input parameters (bw, h, fcd, fyd, As and kinsulation) were used in the ANN to estimate the moment capacity (Mr). The trained model allowed the investigation of the effects on the moment capacity of the insulation material and the results indicated that the use of insulation materials with the smallest value of the thermal conductivities used in calculations is effective in protecting the RC beam against fire.

Femoral Neuropathy in a Patient with Rheumatoid Arthritis

Hakan Genc,Ozlem Balaban,Aynur Karagoz,Hatice Rana Erdem 연세대학교의과대학 2007 Yonsei medical journal Vol.48 No.5

Femoral mononeuropathy (FMN) as an extraarticular finding of rheumatoid arthritis (RA) is a phenomenon which has not been reported previously. We report a 53-year-old female patient with RA, presenting FMN findings during the course of the disease. On examination, right quadriceps and iliopsoas muscles showed grade 3 weakness on the Medical Research Council (MRC) scale. Sensory examination revealed sensory loss in the right medial leg and thigh. Patellar tendon reflex was absent in the right side. A diagnosis of a partial right femoral neuropathy was confirmed using nerve conduction study and electromyography. The probable mechanism of FMN was thought to be vasculitis.

The Role of Tendinitis in Fibromyalgia Syndrome

Hakan Gen?,Meryem Saraco?lu,Burcu Duyur,Hatice Rana Erdem 연세대학교의과대학 2003 Yonsei medical journal Vol.44 No.4

Fibromyalgia Syndrome (FS) is a common disease characterized by diffuse, widespread pain and multiple tender points. The syndrome has been subclassified as primary (PFS) and secondary (SFS) fibromyalgia. The aim of this study was to evaluate the role of common tendinitis (rotator cuff tendinitis, bicipital tendinitis, lateral epicondylitis, De-Quervain's tendinitis and pes anserinus tendinitis) in FS. Twenty female patients with PFS, 20 with SFS and 20 female controls, matched by age and body mass index, participated in the study. Existence of common tendinitis was evaluated with specific examination methods. Right and left rotator cuff tendinitis, pes anserinus tendinitis and left lateral epicondylitis were significantly more common in patients with PFS and SFS than in control subjects. As a result, considering the central hyperexcitability present in the fibromyalgia patients, concomitant pathologies such as tendinitis which lead to shoulder, arm, and leg pain must be evaluated. Follow up and therapy for the disease must be planned according to these factors which are not only probable symptoms of FS, but also leading causes for the occurence and continuity of the pain in this disease.

Full-color computational holographic near-eye display

Hakan Urey,Seyedmahdi Kazempourradi,Erdem Ulusoy 한국정보디스플레이학회 2019 Journal of information display Vol.20 No.2

Near-eye displays (NEDs) are an excellent candidate for the future of augmented reality. Conventional micro-display based NED designs mostly provide stereoscopic 3D experience, which leads to visual discomfort due to vergence-accommodation conflict. Computational holographic near-eye displays (HNEDs) can simultaneously provide wide FOV, retinal resolution, attractive form-factor, and natural depth cues including accommodation. In HNEDs, computer-generated holograms (CGHs) are displayed on a spatial light modulators (SLMs). We propose a CGH computation algorithm that applies to arbitrary paraxial optical architectures; where the SLM illumination beam can be collimated, converging or diverging, and the SLM image as seen by the eye box plane may form at an arbitrary location, and can be virtual or real. Our CGH computation procedure eliminates speckle noise, which is observed in all other laser-based displays, and chromatic aberrations resulting from the light sources and the optics. Our proof-of-concept experiments demonstrate that HNEDs with simple optical architectures can deliver natural 3D images within a wide FOV (70 degrees) at retinal resolution (30 cycles-per-degree), exceeding 4000 resolvable pixels on a line using a printed binary mask. With the advances in SLM technology, HNEDs can realize the ultimate personalized display, meeting the demand of emerging augmented and virtual reality applications.

The presence of MEFV gene mutations in patients with primary osteoarthritis who require surgery

( Sedat Yilmaz ),( Hakan Erdem ),( Servet Tunay ),( Deniz Torun ),( Halil Genc ),( Yusuf Tunca ),( Omer Karadag ),( Ismail Simsek ),( Muhterem Bahce ),( Salih Pay ),( Ayhan Dinc ) 대한내과학회 2013 The Korean Journal of Internal Medicine Vol.28 No.5

Background/Aims: Chronic arthritis of familial Mediterranean fever (FMF) involves weight-bearing joints and can occur in patients without a history of acute attack. Our aim was to investigate a possible causal relationship between FMF and osteoarthritis in a population in which FMF is quite common. Methods: Patients with late stage primary osteoarthritis were enrolled, and five MEFV gene mutations were investigated. The frequency of MEFV gene mutations was compared among patients with osteoarthritis and a previous healthy group from our center. Results: One hundred patients with primary osteoarthritis and 100 healthy controls were studied. The frequency of MEFV gene mutations was significantly lower in the osteoarthritis group (9% vs. 19%). M694V was the most frequent mutation (5%) in the osteoarthritis group, whereas in the control group, E148Q was the most common (16%). In subgroup analyses, the mutation frequency of patients with hip osteoarthritis was not different from that of patients with knee osteoarthritis and controls (7.1%, 9.7%, and 19%, respectively). There were no differences among the three groups with respect to MEFV gene mutations other than E148Q (8.1% vs. 3.6%). E148Q was significantly lower in the osteoarthritis group than in the controls (16% vs. 1%), although the mutations did not differ between patients with knee osteoarthritis and controls. Conclusions: In a population with a high prevalence of MEFV gene mutations, we did not find an increased mutation rate in patients with primary osteoarthritis. Furthermore, we found that some mutations were significantly less frequent in patients with osteoarthritis. Although the number of patients studied was insufficient to claim that E148Q gene mutation protects against osteoarthritis, the potential of this gene merits further investigation.

Reliability of 2 Smartphone Applications for Cobb Angle Measurement in Scoliosis

İsmail Emre Ketenci,Hakan Serhat Yanık,Özgür Erdoğan,Levent Adıyeke,Şevki Erdem 대한정형외과학회 2021 Clinics in Orthopedic Surgery Vol.13 No.1

Background: As mobile technology has evolved, smartphone applications have been used for radiographic angle measurements in daily clinical practice. This study aimed to assess the reliability of 2 smartphone applications (iPinPoint and Cobbmeter) in measuring scoliosis Cobb angles compared with picture archiving and communication system (PACS) tools. Methods: Anteroposterior whole spinal digital radiographs of 50 patients were retrospectively analyzed. Four observers measured Cobb angles of predetermined major structural curves using the tools in the PACS software and 2 smartphone applications. The inter- and intraobserver reliabilty were measured using intraclass correlation coefficients (ICC). Results: Very good interobserver agreement was seen with PACS, iPinPoint, and Cobbmeter measurements (ICC, 0.991, 0.980, and 0.991, respectively). Intraobserver reliability of the 4 observers was also very good for all techniques (ICC > 0.9 for all observers). Conclusions: Both smartphone applications were reliable in measuring scoliosis Cobb angles, with reference to PACS tools. They may be useful when digital or manual mesurement tools are not available.

Intraspinal Anomalies in Individuals with Scheuermann’s Kyphosis: Is the Routine Use of Magnetic Resonance Imaging Necessary for Preoperative Evaluation?

Serdar Demiroz,Ismail Emre Ketenci,Hakan Serhat Yanik,Samet Bayram,Koray Ur,Sevki Erdem 대한척추외과학회 2018 Asian Spine Journal Vol.12 No.4

Study Design: Retrospective study. Purpose: This study aimed to determine the incidence of intraspinal pathologies (ISPs) in individuals with Scheuermann’s kyphosis (SK) and to validate whether the routine use of magnetic resonance imaging (MRI) is necessary for preoperative evaluation. Overview of Literature: There are several studies on the necessity of routine MRI screening and prevalence of ISPs related to different types of scoliosis have been conducted. However, despite the well-established association between ISPs and a higher risk for neurological complications there is no any study on the scientific literature concerning the prevalence of ISPs in patients with SK has been conducted. Methods: The database of the institution was retrospectively reviewed to identify all patients diagnosed with SK who underwent surgery between 2012 and 2015. Patients were excluded from the study if their hospital database records did not include spinal images, which are routinely collected before surgery. The presence or absence of ISPs, as indicated on magnetic resonance images, was evaluated by a radiologist. Results: Of the 138 potential participants, 120 were included in the study. Of these, seven patients (5.8%) had ISPs, and all the cases involved syringomyelia. None of the seven patients with ISPs required additional neurosurgical procedures before corrective surgery. No complications were reported during the perioperative period, and none of the patients developed postoperative neurological deficits. Conclusions: According to this study, the incidence rate of ISPs in patients with SK was 5.8%, and we recommend that all patients with SK should be evaluated using MRI of the spine before corrective surgery.

Properties of Synchronous Versus Metachronous Bilateral Breast Carcinoma with Long Time Follow Up

Eliyatkin, Nuket,Zengel, Baha,Yagci, Ayse,Comut, Erdem,Postaci, Hakan,Uslu, Adam,Aktas, Safiye Asian Pacific Journal of Cancer Prevention 2015 Asian Pacific journal of cancer prevention Vol.16 No.12

Background: Breast cancer is the most common cancer type among women with increasing incidence rates, improved prognosis and survival. According to the localization of the tumor, breast cancer is designated as unilateral (UBC) or bilateral (BBC). BBC can be classified as synchronous (SBBC) or metachronous (MBBC) based on the time interval between the diagnosis of the first and the secondary tumors. According to the guideline of WHO 2012, BBC is generally defined as SBBC when contralateral breast carcinoma is diagnosed within 3 months. The aim of this study was to compare the characteristics and patterns of metastasis of BBC patients with UBC. Materials and Methods: A cohort of 768 patients with breast cancer treated at the Turkish Ministry of Health-Izmir Bozyaka Research and Training Hospital between 1976 and 2012 were studied. Survival analysis was performed comparing UBC and BBC patients. In addition, evaluations were performed in patients with SBBC and MBBC sub-groups. We used a 3-months interval to distinguish metachronous from synchronous. Results: When clinical and histopathological parameters were statistically evaluated, ER status, event-free and overall survival were found to be significant between UBC and BBC patients. In comparison of SBBC and MBBC patients, age, histological type of tumor, event-free and overall survival were found to be significant. Conclusions: BBC cases were found to show worse prognosis than UBC cases. Among BBC, SBBC had the worst prognosis based on overall survival rates.

The dynamic instability of FG orthotropic conical shells within the SDT

Abdullah H. Sofiyev,Zihni Zerin,Bilender P. Allahverdiev,David Hui,Ferruh Turan,Hakan Erdem 국제구조공학회 2017 Steel and Composite Structures, An International J Vol.25 No.5

The dynamic instability of truncated conical shells subjected to dynamic axial load within first order shear deformation theory (FSDT) is examined. The conical shell is made from functionally graded (FG) orthotropic material. In the formulation of problem a dynamic version of Donnell's shell theory is used. The equations are converted to a Mathieu-Hill type differential equation employing Galerkin’s method. The boundaries of main instability zones are found applying the method proposed by Bolotin. To verify these results, the results of other studies in the literature were compared. The influences of material gradient, orthotropy, as well as changing the geometric dimensions on the borders of the main areas of the instability are investigated.