The Economics of Cloud Computing

( Ergin Bayrak ),( John P. Conley ),( Simon Wilkie ) 한국경제학회 2011 The Korean Economic Review Vol.27 No.2

Cloud computing brings together several existing technologies including service oriented architecture, distributed grid computing, virtualization, and broadband networking to provide software, infrastructure, and platforms as services. Under the old IT model, companies built their own server farms designed to meet peak demand using bundled hardware and software solutions. This was time consuming, capital intensive and relatively inflexible. Under the cloud computing model, firms can rent as many virtual machines as they need at any given time, and then either design or use off-the-shelf solutions to integrate company-wide data in order to easily distribute access to users both within and outside of the company firewall. This converts fixed capital costs into variable costs, prevents under and over provisioning, and allows minute by minute flexibly. Consumers are also increasingly turning to the cloud for computing service through such applications as Gmail, Pandora, and Facebook. The purpose of this paper is to discuss this new and transformative technology, survey the existing economics literature on the subject, and suggest potential directions for new research.

EMG based neural network and admittance control of an active wrist orthosis

Ergin Kilic 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.12

This study proposes an Electromyography (EMG) based neural network and admittance control strategy for an Active wrist orthosis (AWO) that is mobile, powerful and lightweight in order to avoid the occurrence and/or for the treatment of repetitive strain injuries. The device has an EMG based control strategy so that it can track the contraction of the forearm muscles of interest in real time to assist the device user during the extension and flexion wrist movements. Indeed, time-delayed artificial neural networks were trained offline to predict the forearm muscle forces based on features extracted from raw EMG signals. The predicted force values were used to calculate a reference velocity command by using an admittance model with properly adjusted parameters. A closed loop velocity control system was used to perform the desired wrist motion. Some experimental studies were performed to evaluate the assistive performance of the AWO device with the proposed control system under various disturbance loads. The experimental results show that the activation levels of the forearm muscles were considerably reduced when the AWO device was enabled.

Meta Analysis of Studies about Breast Self Examination between 2000-2009 in Turkey

Ergin, Ayla Berkiten,Sahin, Nevin Hotun,Sahin, Fezan Mutlu,Yaban, Zuleyha Simsek,Acar, Zeynep,Bektas, Hatice Asian Pacific Journal of Cancer Prevention 2012 Asian Pacific journal of cancer prevention Vol.13 No.7

Aim: The aim of this study was to analyze studies in Turkey about self-breast examination and produce conclusive, reliable and detailed basis for future studies. Methods: Studies performed between 2000 and 2009 (until the end of September) were retrieved from databases using breast cancer, breast examination, breast cancer screening and risk factors as key words. Fifty-nine studies were identified and 18 of them (15 journal articles and three theses) were used for the meta-analysis. Results: Married women and women with a family history of breast cancer were found to perform self-breast examination more frequently than single women and women without a family history of breast cancer, respectively (OR=1.02 %CI 0.82-1.63; OR=1.16 %CI 0.82-1.63). According to the health belief model scales, women performing self-breast examination were determined to have 1.7 times higher susceptibility (OR=1.70), 1.34 times higher seriousness perception (OR=1.34), 3.32 times higher health motivation (OR=3.32), 5.21 times more self-efficacy/confidence (OR=5.21) and 2.56 times higher self-breast examination benefit perception (OR=2.56). Conclusion: Nursing care models caused an increase in self-breast examination by women, and thus, it may be useful to organize and evaluate such health-related programs and consider women health perceptions.

Design and Implementation of a Hybrid Fuzzy Logic Controller for a Quadrotor VTOL Vehicle

Bora Erginer,Erdinç Altuğ 제어·로봇·시스템학회 2012 International Journal of Control, Automation, and Vol.10 No.1

Helicopters have generated considerable interest in both the control community due to their complex dynamics, and in military community because of their advantages over regular aerial vehicles. In this paper, we present the modeling and control of a four rotor vertical take-off and landing (VTOL) un-manned air vehicle known as quadrotor aircraft. This model has been generated using Newton-Euler equations. In order to control the helicopter, classical PD (proportional derivative) and Hybrid Fuzzy PD controllers have been designed. Although fuzzy control of various dynamical systems has been presented in literature, application of this technology to quadrotor helicopter control is quite new. A quadrotor helicopter has nonlinear characteristics where classical control methods are not adequate es-pecially when there are time delays, disturbances and nonlinear vehicle dynamics. On the other hand, Fuzzy control is nonlinear and it is thus suitable for nonlinear system control. Matlab Simulink has been used to test, analyze and compare the performance of the controllers in simulations. For the evaluation of the autonomous flight controllers, some experiments were also performed. For this pur-pose, an experimental test stand has been designed and manufactured. This study showed that although, both of the classical PD and the Fuzzy PD controllers can control the system properly, the Fuzzy PD controllers performed slightly better than the classical PD controllers, and have benefits such as better disturbance rejection, ease of building the controllers.

An Analysis of the Potential Relationship between Crowe Type and Lower Extremity Morphology in Patients with Developmental Dysplasia of the Hip

Ömer Naci Ergin,Serkan Bayram,Fikret Berkan Anarat,Mehmet Ekinci,Lezgin Mert,Emre Özmen,I˙rfan Öztürk 대한고관절학회 2020 Hip and Pelvis Vol.32 No.2

Purpose: To test whether Crowe type is related to femoral alignment and leg length discrepancy by evaluating the preoperative lengths and coronal alignment of femurs, pelvic parameters and hip morphology of patients who underwent primary hip arthroplasty due to coxarthrosis secondary to developmental dysplasia of the hip (DDH). Materials and Methods: Medical records of patients with coxarthrosis secondary to DDH who were treated with total hip arthroplasty at Department of Orthopaedics and Traumatology, Istanbul University Faculty of Medicine between 2008 and 2017 were reviewed. The mechanical axis of lower limbs was analyzed; pelvic height and femoral and tibial lengths were measured. All femurs were classified according to the Dorr classification. Results: A total of 97 patients were eligible for analysis and were diagnosed with unilateral DDH (n=51) or bilateral DDH (n=46). In those diagnosed with unilateral DDH, the affected pelvis, femur, and tibia were often shorter than the unaffected side. In those diagnosed with bilateral DDH, femoral and pelvic lengths were unpredictable. In the femoral coronal alignment test, data varied widely but were within normal limits. The difference in the Dorr types of femurs was significant between dysplastic and normal sides of patients with unilateral DDH (P=0.001) but not those with bilateral DDH. Conclusion: Especially in patients with unilateral DDH, pelvic heights and femoral and tibial lengths on the affected side may be shorter compared with unaffected side regardless of the Crowe type. Femoral coronal alignment is unpredictable for both groups. Careful preoperative analyses of femoral coronal alignment and pelvic length are advised.

The influence of the implant-abutment complex on marginal bone and peri-implant conditions: A retrospective study

Tokgoz, Selen Ergin,Bilhan, Hakan The Korean Academy of Prosthodonitics 2021 The Journal of Advanced Prosthodontics Vol.13 No.1

Purpose. The design of the implant-abutment complex is thought to be responsible for marginal bone loss (MBL) and might affect the condition of the peri-implant tissues. This the present study aimed to evaluate the influence of the implant-abutment complex on MBL and the peri-implant tissues in partially edentulous patients treated with dental implants and determine the most advantageous design. Materials and Methods. A total of ninety-one endosseous implants with different designs of implant-abutment complex [tissue level-TL (n = 30), platform switch-PS (n = 18), and platform match-PM (n = 43)] were reviewed for MBL, Probing Pocket Depth (PPD) and Bleeding on Probing (BoP). MBL was calculated for first year of the insertion and the following years. Results. The median MBL for the PM implants (2.66 ± 1.67 mm; n = 43) in the first year was significantly higher than those for the other types (P=.033). The lowest rate of MBL (0.61 ± 0.44 mm; n = 18) was observed with PS implants (P=.000). The position of the crown-abutment border showed a statistically significant influence (P=.019) and a negative correlation (r=-0.395) on MBL. BoP was found significantly higher in PM implants (P=.006). The lowest BoP scores were detected in PS implants, but the difference was not significant (P=.523). The relation between PPD and connection type revealed no statistically significant influence (P>.05). Conclusion. Within the limitations of the present study, it may be concluded that PS implants seem to show better peri-implant soft tissue conditions and cause less MBL.

Effect of biofilm formation, and biocorrosion on denture base fractures

Sahin, Cem,Ergin, Alper,Ayyildiz, Simel,Cosgun, Erdal,Uzun, Gulay The Korean Academy of Prosthodonitics 2013 The Journal of Advanced Prosthodontics Vol.5 No.2

PURPOSE. The aim of this study was to investigate the destructive effects of biofilm formation and/or biocorrosive activity of 6 different oral microorganisms. MATERIALS AND METHODS. Three different heat polymerized acrylic resins (Ivocap Plus, Lucitone 550, QC 20) were used to prepare three different types of samples. Type "A" samples with "V" type notch was used to measure the fracture strength, "B" type to evaluate the surfaces with scanning electron microscopy and "C" type for quantitative biofilm assay. Development and calculation of biofilm covered surfaces on denture base materials were accomplished by SEM and quantitative biofilm assay. According to normality assumptions ANOVA or Kruskal-Wallis was selected for statistical analysis (${\alpha}$=0.05). RESULTS. Significant differences were obtained among the adhesion potential of 6 different microorganisms and there were significant differences among their adhesion onto 3 different denture base materials. Compared to the control groups after contamination with the microorganisms, the three point bending test values of denture base materials decreased significantly (P<.05); microorganisms diffused at least 52% of the denture base surface. The highest median quantitative biofilm value within all the denture base materials was obtained with P. aeruginosa on Lucitone 550. The type of denture base material did not alter the diffusion potential of the microorganisms significantly (P>.05). CONCLUSION. All the tested microorganisms had destructive effect over the structure and composition of the denture base materials.

Morgagni-Stewart-Morel syndrome presenting with neurological symptoms: a case report

( Bünyamin Tosunoğlu ),( Nazlıcan Ergin ),( Nilay Kaya ),( Levent Ertuğrul İnan ) 영남대학교 의과대학 2023 Yeungnam University Journal of Medicine Vol.40 No.3

Morgagni-Stewart-Morel (MSM) syndrome is characterized by the thickening of the frontal bone of the skull (hyperostosis frontalis internal), obesity, neurological symptoms, and hypertrichosis. We present the case of a 76-year-old patient who complained of confusion, extreme irritability, and headache and was diagnosed with MSM based on examination, imaging, and test results.

Morgagni-Stewart-Morel syndrome presenting with neurological symptoms: a case report

( Bünyamin Tosunoğlu ),( Nazlıcan Ergin ),( Nilay Kaya ),( Levent Ertuğrul İnan ) 영남대학교 의과대학 2023 Yeungnam University Journal of Medicine Vol.40 No.4

Morgagni-Stewart-Morel (MSM) syndrome is characterized by the thickening of the frontal bone of the skull (hyperostosis frontalis internal), obesity, neurological symptoms, and hypertrichosis. We present the case of a 76-year-old patient who complained of confusion, extreme irritability, and headache and was diagnosed with MSM based on examination, imaging, and test results.

Employing variable impedance (stiffness/damping) hybrid actuators on lower limb exoskeleton robots for stable and safe walking trajectory tracking

Ozgur Baser,Hasbi Kizilhan,Ergin Kilic 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.6

Compliant actuators are employed in exoskeleton robots instead of stiff actuators for safe human-robot interaction. In parallel with this idea, we previously constructed a biomimetic compliant exoskeleton robot (BioComEx). In this study, to provide more stable and safe trajectory tracking even under disturbances, magneto-rheological (MR) brakes were added to all joints of BioComEx as variable damping actuators and a PID+D controller was proposed. To evaluate the robot and controller, first, BioComEx was hung on a platform and the controller was applied without device user under external forces. This primary test results showed that the proposed design and controller can effectively minimize disturbance effects and consequently reduce trajectory tracking oscillations. In the rest of the study, the similar control experiments were repeated with a user who has unilateral lower limb movement disorders. In these experiments, the movements of the user's healthy leg were detected by force feedback impedance control algorithm and then were used as reference for the impaired leg with walking cycle delay in real time. The secondary test results showed that the variable impedance exoskeleton robot design with PID+D controller can ensure effective walking assistance for the impaired human legs.