Case Reports : Splenic infarction as a complication of celiac artery thromboembolism: an unusual cause of abdominal pain

( Volkan Genc ),( Omer Arda Cetinkaya ),( Ilgaz Kayilioglu ),( Ahmet Serdar Karaca ),( Gokhan Cipe ),( Ali Ekrem Unal ) 대한내과학회 2011 대한내과학회지 Vol.81 No.5

Splenic infarction is a relatively uncommon diagnosis and this clinical presentation can mimic other causes of acute abdominal pain. Cardiologic and hematologic disorders are common reasons for this entity. There have been a few series and single case reports of splenic infarction published in peer-reviewed medical journals. We report a 53-year-old patient who had splenic infarction caused by celiac artery thromboembolism. The importance of this case, without any etiological predisposing factors, is that this kind of clinical situation should be considered in the differential diagnosis of abdominal pain.

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.

GAUSSIAN PROCESS REGRESSION FEEDFORWARD CONTROLLER FOR DIESEL ENGINE AIRPATH

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.

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.

Effect of layer thickness and print orientation on strength of 3D printed and adhesively bonded single lap joints

Volkan Kovan,Gurkan Altan,Eyup Sabri Topal 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.5

Three-dimensional printing is the common name given to various techniques used to manufacture different objects. Fused deposition technique is a commonly used additive manufacturing technology in prototyping and production. Fused deposition modelling systems are limited in terms of shape and size of parts. Printing parts with less support material, for parts too large to print in a single operation or for parts with fine details, sectioning and adhesively bonding is the solution for manufacturing. According to adhesion theory, the strength of adhesively bonding between three-dimensional printed parts is affected by surface roughness. Effects of layer thickness and print orientation on adhesion strength of parts manufactured with three-dimensional printing were experimentally studied. As a result of the study, it was found that the edgewise orientation had the highest bonding strength in lower layer thicknesses, while flatwise orientation had the highest bonding strength in higher layer thicknesses.

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.

DIESEL ENGINE AIRPATH CONTROLLER VIA DATA DRIVEN DISTURBANCE OBSERVER

Volkan Aran,Mustafa Unel 한국자동차공학회 2020 International journal of automotive technology Vol.21 No.4

This study presents a novel data driven disturbance observer design method and its integration with a recursive controller developed for diesel engine airpath control problem. Mass Air Flow (MAF) and Manifold Absolute Pressure (MAP) are identified with Multi-Input Single-Output NFIR models using experimental data. Heavy-duty diesel engine airpath with variable geometry turbine (VGT) and exhaust gas recirculation (EGR) valve is the main focus of the paper. Presented data driven disturbance observer and controller are implemented to a serial production level engine embedded software. The proposed controllers are compared with the available commercial controllers in dynamometer test cycles. Better overall performance is achieved with respect to the commercial controllers using proposed easy-to-tune controllers.

Analysis of Marine Traffic Feature for Safety Assessment at Southern Entrance of the Istanbul Strait-I

Volkan Aydogdu,박진수,Yavuz Keceli,박영수 한국항해항만학회 2008 한국항해항만학회지 Vol.32 No.7

The Istanbul Strait is one of the important waterways in the world. And its southern entrance has a highly congested local traffic. Till now there are several studies regarding how the Istanbul Strait is dangerous to navigate and how those dangers can be mitigated. But there is no study regarding local traffic which is posing great collision risk. In a certain traffic area, marine traffic safety assessment parameters are traffic volume, frequency of collision avoidance maneuver, traffic density, traffic flow and potential encounter. In this paper local traffic volume, traffic flow and potential encounter number of local traffic vessels and possibility of collision are investigated in order to find degree of danger at the southern entrance of the Istanbul Strait. Finally by utilizing those, risky areas are determined for southern entrance of the Istanbul Strait. Results have been compared to a previous study regarding risk analysis at congested areas of the Istanbul Strait (Aydogdu, 2006) and consistency of the results were presented. The Istanbul Strait is one of the important waterways in the world. And its southern entrance has a highly congested local traffic. Till now there are several studies regarding how the Istanbul Strait is dangerous to navigate and how those dangers can be mitigated. But there is no study regarding local traffic which is posing great collision risk. In a certain traffic area, marine traffic safety assessment parameters are traffic volume, frequency of collision avoidance maneuver, traffic density, traffic flow and potential encounter. In this paper local traffic volume, traffic flow and potential encounter number of local traffic vessels and possibility of collision are investigated in order to find degree of danger at the southern entrance of the Istanbul Strait. Finally by utilizing those, risky areas are determined for southern entrance of the Istanbul Strait. Results have been compared to a previous study regarding risk analysis at congested areas of the Istanbul Strait (Aydogdu, 2006) and consistency of the results were presented.

Questionnaire Survey on the Risk Perception in the Istanbul Strait

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

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

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(ASRT) 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.