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      • KCI등재

        Questionnaire Survey on the Risk Perception in the Istanbul Strait

        Volkan,Aydogdu,Cemil,Yurtoren,Serdar,Kum,박진수 한국항해항만학회 2010 한국항해항만학회지 Vol.34 No.7

        '스콜라' 이용 시 소속기관이 구독 중이 아닌 경우, 오후 4시부터 익일 오전 7시까지 원문보기가 가능합니다.

        There are enormous challenges in the Istanbul Strait- one of the most important, congested and narrow waterways in the world – from the view point of risk determination and risk mitigation for the local traffic. Previously several traffic parameters such as; traffic volume for local vessels, traffic flow and potential encounters of local traffic, in addition to the possibility of collision, were investigated in order to determine the degree of dangers in the southern entrance of the Istanbul Strait. Furthermore, risky zones were also determined in this waterway. On the basis of the results of those, a group of expert was surveyed. These experts were pilots, Vessel Traffic Services Operators (VTS-O), Local Traffic Vessel Captains and Master Mariners who had several experience of navigation through the Istanbul Strait. In order to assess experts perceptions of danger and to propose further studies based on this survey. The questionnaire was analyzed by using SPSS (Statistical Package for the Social Sciences) program version 13.0. Finally, some differences and/or shares on risk perceptions of expert in the Istanbul Strait are considered

      • KCI등재

        Multiple renal arteries challenge in laparoscopic donor nephrectomy

        Volkan,Genc,Ahmet,Serdar,Karaca,Erkinbek,Orozakunov,Atil,Cakmak,Yusuf,Sevim,Evren,Ustuner,Derya,Oztuna,Selcuk,Mevlut,Hazinedaroglu 대한외과학회 2011 Annals of Surgical Treatment and Research Vol.80 No.4

        Purpose: Living donor kidneys with multiple arteries are routinely procured laparoscopically. We aim to present our experience with laparoscopic donor nephrectomy (LDN) and to compare the graft function and outcome between cases with single versus multiple arteries. Methods: We compared the demographic data, operation time, warm ischemia time, rejection rate, and graft function between LDN kidneys with single artery and those with multiple arteries. Results: Seventy-three cases with 1 renal artery (group LDN-1), 8 cases with 2 renal arteries (group LDN-2) and 5 cases with 3 or more renal arteries (group LDN-3) were included in the study. The mean operative time was significantly higher in groups LDN-2 (100.3 ± 9.5 minutes) and LDN-3 (120.6 ± 10.3 minutes) compared to group LDN-1 (75.7 ± 10 minutes, P < 0.001). Similar results were detected with respect to the warm ischemia time. There were no statistically significant differences related to graft function and outcome among these groups. Conclusion: Multiple renal arteries present a special challenge in both donor nephrectomy and renal transplantation. However, laparoscopic procurement of a kidney with multiple renal arteries, regardless of the number, is reliable and has no significant impact on the graft outcome.

      • KCI등재SCOPUS


        Volkan,Aran,Mustafa,Unel 한국자동차공학회 2018 International journal of automotive technology Vol.19 No.4

        Gaussian Process Regression (GPR) provides emerging modeling opportunities for diesel engine control. Recent serial production hardwares increase online calculation capabilities of the engine control units. This paper presents a GPR modeling for feedforward part of the diesel engine airpath controller. A variable geotmetry turbine (VGT) and an exhaust gas recirculation (EGR) valve outer loop controllers are developed. The GPR feedforward models are trained with a series of mapping data with physically related inputs instead of speed and torque utilized in conventional control schemes. A physical model-free and calibratable controller structure is proposed for hardware flexibility. Furthermore, a discrete time sliding mode controller (SMC) is utilized as a feedback controller. Feedforward modeling and the subsequent airpath controller (SMC+GPR) are implemented on the physical diesel engine model and the performance of the proposed controller is compared with a conventional PID controller with table based feedforward.


        Vibration and buckling of laminated beams by a multi-layer finite element model

        Volkan,Kahya,Muhittin,Turan 국제구조공학회 2018 Steel and Composite Structures, An International J Vol.28 No.4

        This paper presents a multi-layer finite element for buckling and free vibration analyses of laminated beams based on a higher-order layer-wise theory. An N-layer beam element with (9<i>N</i> + 7) degrees-of-freedom is proposed for analyses. Delamination and slip between the layers are not allowed. Element matrices for the single- and multi-layer beam elements are derived by Lagrange's equations. Buckling loads and natural frequencies are calculated for different end conditions and lamina stacking. Comparisons are made to show the accuracy of proposed element.

      • KCI등재
      • Introduction Of Istanbul VTS and Local Traffic Control Center

        Volkan,Aydogdu 한국항해항만학회 2008 한국항해항만학회 학술대회논문집 Vol.2008 No.추계

        '스콜라' 이용 시 소속기관이 구독 중이 아닌 경우, 오후 4시부터 익일 오전 7시까지 원문보기가 가능합니다.

        Istanbul Strait is one of the difficult and congested water ways in the world. Number of transit vessel is increasing day by day. Last year over than 55,000 vessels passed through Istanbul Strait and over than 2100 local vessel running at the southern entrance of the strait. VTS has been established in order to provide navigational assistance and minimize risks due to difficult navigational characteristic of strait and congested marine traffic in 2003. In the Istanbul Strait VTS system consist from 5 sectors which are controlled by different operators. AIS Class-A is compulsory for all the vessels which are navigating at international waters and over than 300 grt. AIS is highly effective and useful tool for VTS and AIS device has been used effectively in the Strait, since the establishment of VTS. But local vessels were not using AIS device and local vessel traffic one of the problem in the strait due to high number of ship movement. Turkish Government wanted to control local vessels same as transit vessel and supported AIS Class-B research and development. Finally, AIS Class-B device and local traffic control center established. In this presentation Istanbul Strait VTS, Local Traffic Control Center and AIS Class-B device will be introduced.

      • KCI등재SCOPUS

        Evaluation of Overactive Bladder in Male Antidepressant Users: A Prospective Study

        Volkan,Solmaz,Sebahattin,Albayrak,Arslan,Tekatas,Dürdane,Aksoy,Yusuf,Gençten,Sema,İnanır,Fikret,Erdemir 대한배뇨장애요실금학회 2017 International Neurourology Journal Vol.21 No.1

        Purpose: In this study, we investigated overactive bladder (OAB) functions in male patients who used antidepressant drugs (ADs) that were previously examined in female patients, based on conflicting data in literature regarding the effects of AD on OAB and the differences between male and female urinary system physiologies (anatomical and hormonal). Methods: The study included 202 male patients (a control group of 90 healthy subjects, and an experimental group of 112 patients taking ADs for different disorders). All the patients completed the overactive bladder-validated 8 (OAB-V8) questionnaire, the International Consultation on Incontinence Questionnaire-Short Form (ICIQ-SF), and the Beck Depression Inventory (BDS). Results: The OAB-V8, ICIQ-SF, and BDS scores for the antidepressant users were significantly higher than those of the control group. The highest prevalence of OAB symptoms was observed in patients taking venlafaxine (68.2%), and the lowest prevalence was in patients taking sertraline (28.0%). Moreover, the frequency of OAB between the antidepressant groups was statistically significant. The univariate logistic regression analyses showed a significant relationship between the presence of OAB, antidepressant usage, BDS score, and the age of a patient. In the multivariate logistic regression analyses, the association between the presence of OAB and antidepressant usage was statistically significant. Conclusions: The present study showed that the incidence of OAB and the severity of OAB symptoms increased in males using antidepressants for various disorders. This may have been due to unique pharmacological effects, on a molecular or individual level, of serotonin-norepinephrine reuptake inhibitors.

      • KCI등재

        A CNN-LSTM neural network for recognition of puffing in smoking episodes using wearable sensors

        Volkan,Y.,Senyurek,Masudul,H.,Imtiaz,Prajakta,Belsare,Stephen,Tiffany,Edward,Sazonov 대한의용생체공학회 2020 Biomedical Engineering Letters (BMEL) Vol.10 No.2

        A detailed assessment of smoking behavior under free-living conditions is a key challenge for health behavior research. Anumber of methods using wearable sensors and puff topography devices have been developed for smoking and individualpuff detection. In this paper, we propose a novel algorithm for automatic detection of puff s in smoking episodes by using acombination of Respiratory Inductance Plethysmography and Inertial Measurement Unit sensors. The detection of puff s wasperformed by using a deep network containing convolutional and recurrent neural networks. Convolutional neural networks(CNN) were utilized to automate feature learning from raw sensor streams. Long Short Term Memory (LSTM) network layerswere utilized to obtain the temporal dynamics of sensor signals and classify sequence of time segmented sensor streams. Anevaluation was performed by using a large, challenging dataset containing 467 smoking events from 40 participants underfree-living conditions. The proposed approach achieved an F1-score of 78% in leave-one-subject-out cross-validation. Theresults suggest that CNN-LSTM based neural network architecture suffi ciently detect puffi ng episodes in free-living condition. The proposed model be used as a detection tool for smoking cessation programs and scientifi c research.

      • KCI등재

        Piceatannol Mediated Modulation of Oxidative Stress and Regeneration in the Liver of Endotoxemic Mice

        Volkan,Kilic 한국식품영양과학회 2019 Journal of medicinal food Vol.22 No.6

        Liver plays a pivotal role in host defense mechanisms related to endotoxemia. However, liver dysfunction often occurs in early sepsis. This study investigated the hepatoprotective potential of natural stilbenoid piceatannol (PIC) in lipopolysaccharide (LPS)-induced endotoxemic mice. Swiss Albino mice were divided into four groups: Control (C), LPS administrated (LPS), PIC administrated (PIC), and LPS administrated/PIC preadministrated (LPS+PIC) animals. PIC was administrated intraperitoneally (i.p.) at the dose of 4 mg/kg/day during 7 days. Endotoxemia was induced with a single i.p. administration of LPS at the dose of 4 mg/kg. Superoxide dismutase (SOD), catalase (CAT) and lipid peroxidation (LP) levels, light microscopic pathology, and genotoxicity were investigated. Proliferating cell nuclear antigen and SQSTM1/p62 immunofluorescence were measured. PIC preadministration restored SOD activity, reduced LP and genotoxicity. However, moderate level of oxidative stress (OS) had been progressed in PIC preadministrated animals depending upon prolonged autophagic response and selective degradation of CAT. Positive OS stimulated liver regeneration by upregulating oval cells' and downregulating hepatocytes' proliferation and resulted in the maintanence of hepatic tissue integrity in PIC preadministrated animals. These results suggested that PIC may be a useful hepatoprotective agent in LPS-induced endotoxemia as a modulator of OS and genotoxicity, as an inducer of autophagy, and as a promoter of liver regeneration.


        Shear-deformable finite element for free vibrations of laminated composite beams with arbitrary lay-up

        Volkan,Kahya,Sebahat,Karaca,Thuc,P.,Vo 국제구조공학회 2019 Steel and Composite Structures, An International J Vol.33 No.4

        A shear-deformable finite element model (FEM) with five nodes and thirteen degrees of freedom (DOFs) for free vibrations of laminated composite beams with arbitrary lay-up is presented. This model can be capable of considering the elastic couplings among the extensional, bending and torsional deformations, and the Poisson's effect. Lagrange's principle is employed in derivation of the equations of motion, and thus the element matrices are obtained. Comparisons of the present element's results with those in experiment, available literature and the 3D finite element analysis software (ANSYS®) are made to show its accuracy. Some further results are given as referencing for the future studies in vibrations of laminated composite beamst.

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