Serum and Mucosal Nitric Oxide Levels and Efficacy of Sodium Nitroprussid in Experimentally Induced Acute Sinusitis

Muammer?zt?rk,ErolSelimo?lu,M.FevziPolat,ZekaiErman 연세대학교의과대학 2003 Yonsei medical journal Vol.44 No.3

Increasing the drawing height of conical square cups using anti-lock braking system (ABS)

Muammer Gavas 대한기계학회 2009 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.23 No.11

This paper deals with increasing the drawing height of metal conical square cups with anti-lock braking system (ABS). A novel technique enabling higher drawing height than that achieved in the conventional deep drawing process is introduced, and the principle of the process is explained in this paper. Results of experiments conducted using aluminum alloyed Al-1050 blanks of thickness of 1 mm to draw conical square cups are reported here. Measured drawing load, drawing height and thickness distributions were compared with those obtained from the conventional method. The experimental results showed that higher drawing height of the cup can be achieved by the use of ABS.

Strategic, organizational and operational challenges of product innovation in emerging economies

Muammer Ozer,Mumin Dayan 한국마케팅과학회 2015 마케팅과학연구 Vol.25 No.1

Although there are several studies highlighting the best new product development(NPD) practices of Western firms, we know very little about NPD practices inemerging economies, which are widely expected to play an important role in theworld’s economic growth in the years to come. In particular, we focus here on theUnited Arab Emirates (UAE), which is an important gateway to the Middle East andAfrica. Understanding NPD practices in the UAE will be helpful not only for firms inthe UAE seeking to improve their NPD but also for Western firms interested inengaging in NPD in that region, in order for them to know what to expect from theirpotential partners from the UAE and how to align their NPD practices with those oftheir partners in that region. This paper presents a survey study highlighting majorstrategic, organizational and operational aspects of the NPD practices of firms in theUAE and identifying related challenges.

Real-time hybrid substructuring of a base isolated building considering robust stability and performance analysis

Muammer Avci,Rui M. Botelho,Richard Christenson 국제구조공학회 2020 Smart Structures and Systems, An International Jou Vol.25 No.2

This paper demonstrates a real-time hybrid substructuring (RTHS) shake table test to evaluate the seismic performance of a base isolated building. Since RTHS involves a feedback loop in the test implementation, the frequency dependent magnitude and inherent time delay of the actuator dynamics can introduce inaccuracy and instability. The paper presents a robust stability and performance analysis method for the RTHS test. The robust stability method involves casting the actuator dynamics as a multiplicative uncertainty and applying the small gain theorem to derive the sufficient conditions for robust stability and performance. The attractive feature of this robust stability and performance analysis method is that it accommodates linearized modeled or measured frequency response functions for both the physical substructure and actuator dynamics. Significant experimental research has been conducted on base isolators and dampers toward developing high fidelity numerical models. Shake table testing, where the building superstructure is tested while the isolation layer is numerically modeled, can allow for a range of isolation strategies to be examined for a single shake table experiment. Further, recent concerns in base isolation for long period, long duration earthquakes necessitate adding damping at the isolation layer, which can allow higher frequency energy to be transmitted into the superstructure and can result in damage to structural and nonstructural components that can be difficult to numerically model and accurately predict. As such, physical testing of the superstructure while numerically modeling the isolation layer may be desired. The RTHS approach has been previously proposed for base isolated buildings, however, to date it has not been conducted on a base isolated structure isolated at the ground level and where the isolation layer itself is numerically simulated. This configuration provides multiple challenges in the RTHS stability associated with higher physical substructure frequencies and a low numerical to physical mass ratio. This paper demonstrates a base isolated RTHS test and the robust stability and performance analysis necessary to ensure the stability and accuracy. The tests consist of a scaled idealized 4-story superstructure building model placed directly onto a shake table and the isolation layer simulated in MATLAB/Simulink using a dSpace real-time controller.

The feasibility of ammonia as marine fuel and its application on a medium-size LPG/ammonia carrier

Muammer Akturk,서정관 한국마린엔지니어링학회 2023 한국마린엔지니어링학회지 Vol.47 No.3

The study investigated the feasibility of using ammonia as a marine fuel and its application on a medium-size LPG/ammonia carrier. The study included a comprehensive literature review of existing research on ammonia as a marine fuel and further research on industrial developments in the field to gain insights into the practical challenges and opportunities associated with using ammonia as a marine fuel. The study found that ammonia has several advantages as a marine fuel, including its high energy density, low emis-sions profile, and potential for production from renewable sources. However, there are also significant technical, economic, and safety challenges associated with using ammonia, particularly in the design and operation of marine engines and fuel systems, particularly due to ammonia’s combustion characteristics. The study also demonstrated that the application of ammonia on a medium size LPG/Am-monia carrier is feasible but requires investment and technical expertise. The findings of this study have important implications for the shipping industry's efforts for decarbonization and suggest that ammonia could play a significant role in a carbon-free maritime future. In conclusion, the study provides a comprehensive analysis of the feasibility of ammonia as a marine fuel and highlights its potential application on a medium size LPG/Ammonia carrier.

Chromosomal aberrations in benign prostatic hyperplasia patients

Muammer Altok,Özkan Bağcı,Mehmet Umul,Mustafa Güneş,Mehmet Akyüz,Fatih Uruç,Efkan Uz,Sedat Soyupek 대한비뇨의학회 2016 Investigative and Clinical Urology Vol.57 No.1

Purpose: To investigate the chromosomal changes in patients with benign prostatic hyperplasia (BPH). Materials and Methods: A total of 54 patients diagnosed with clinical BPH underwent transurethral prostate resection to address their primary urological problem. All patients were evaluated by use of a comprehensive medical history and rectal digital examination. The preoperative evaluation also included serum prostate-specific antigen (PSA) measurement and ultrasonographic measurement of prostate volume. Prostate cancer was detected in one patient, who was then excluded from the study. We performed conventional cytogenetic analyses of short-term cultures of 53 peripheral blood samples obtained from the BPH patients. Results: The mean (±standard deviation) age of the 53 patients was 67.8±9.4 years. The mean PSA value of the patients was 5.8±7.0 ng/mL. The mean prostate volume was 53.6±22.9 mL. Chromosomal abnormalities were noted in 5 of the 53 cases (9.4%). Loss of the Y chromosome was the most frequent chromosomal abnormality and was observed in three patients (5.7%). There was no statistically significant relationship among age, PSA, prostate volume, and chromosomal changes. Conclusions: Loss of the Y chromosome was the main chromosomal abnormality found in our study. However, this coexistence did not reach a significant level. Our study concluded that loss of the Y chromosome cannot be considered relevant for the diagnosis of BPH as it is for prostate cancer. Because BPH usually occurs in aging men, loss of the Y chromosome in BPH patients may instead be related to the aging process.

Designing Continuous Proximate Time-Optimal Control System for a Class of Third-Order Systems

Samer Charifa,Muammer Kalyon 보안공학연구지원센터(IJCA) 2011 International Journal of Control and Automation Vol.4 No.2

Control of the flow past a sphere in a turbulent boundary layer using O-ring

Abdulkerim Okbaz,Muammer Ozgoren,Cetin Canpolat,Besir Sahin,Huseyin Akilli 한국풍공학회 2022 Wind and Structures, An International Journal (WAS Vol.35 No.1

This research work presents an experimental study's outcomes to reveal the impact of an O-ring on the flow control over a sphere placed in a turbulent boundary layer. The investigation is performed quantitatively and qualitatively using particle image velocimetry (PIV) and dye visualization. The sphere model having a diamater of 42.5 mm is located in a turbulent boundary layer flow over a smooth plate for gap ratios of 0≤G/D≤1.5 at Reynolds number of 5 × 103 . Flow characteristics, including patterns of instantaneous vorticity, streaklines, time-averaged streamlines, velocity vectors, velocity fluctuations, Reynolds stress correlations, and turbulence kinetic energy (<TKE>), are compared and discussed for a naked sphere and spheres having O-rings. The boundary layer velocity gradient and proximity of the sphere to the flat plate profoundly influence the flow dynamics. At proximity ratios of G/D=0.1 and 0.25, a wall jet is formed between lower side of the sphere and flat plate, and velocity fluctuations increase in regions close to the wall. At G/D=0.25, the jet flow also induces local flow separations on the flat plate. At higher proximity ratios, the velocity gradient of the boundary layer causes asymmetries in the mean flow characteristics and turbulence values in the wake region. It is observed that the O-ring with various placement angles (θ) on the sphere has a considerable alteration in the flow structure and turbulence statistics on the wake. At lower placement angles, where the O-ring is closer to the forward stagnation point of the sphere, the flow control performance of the O-ring is limited; however, its impact on the flow separation becomes pronounced as it is moved away from the forward stagnation point. At G/D=1.50 for O-ring diameters of 4.7 (2 mm) and 7 (3 mm) percent of the sphere diameter, the -ring exhibits remarkable flow control at θ=50° and θ=55° before laminar flow separation occurrence on the sphere surface, respectively. This conclusion is yielded from narrowed wakes and reductions in turbulence statistics compared to the naked sphere model. The O-ring with a diameter of 3 mm and placement angle of 50° exhibits the most effective flow control. It decreases, in sequence, streamwise velocity fluctuations and length of wake recovery region by 45% and 40%, respectively, which can be evaluated as source of decrement in drag force.

Conditions implying continuity of maps

Mehmet Baran,Muammer Kula,Ayhan Erciyes 대한수학회 2009 대한수학회지 Vol.46 No.4

In this paper, we generalize the notions of preserving and strongly preserving maps to arbitrary set based topological categories. Further, we obtain characterizations of each of these concepts as well as interprete analogues and generalizations of theorems of Gerlits at al [20] in the categories of filter and local filter convergence spaces. In this paper, we generalize the notions of preserving and strongly preserving maps to arbitrary set based topological categories. Further, we obtain characterizations of each of these concepts as well as interprete analogues and generalizations of theorems of Gerlits at al [20] in the categories of filter and local filter convergence spaces.

Predictive role of hematologic parameters in testicular torsion

Mustafa Güneş,Mehmet Umul,Muammer Altok,Mehmet Akyuz,Cemal Selcuk İşoğlu,Fatih Uruc,Bekir Aras,Alpaslan Akbaş,Ercan Baş 대한비뇨의학회 2015 Investigative and Clinical Urology Vol.56 No.4

Purpose: To evaluate the predictive role of the neutrophil to lymphocyte ratio (NLR), platelet to lymphocyte ratio (PLR), mean platelet volume (MPV), and platelet count (PLT) in the diagnosis of testicular torsion (TT) and testicular viability following TT. Materials and Methods: We analyzed two study groups in this retrospective study: 75 patients with a diagnosis of TT (group 1) and 56 age-matched healthy subjects (group 2). We performed a complete blood count as a part of the diagnostic procedure, and NLR, PLR, MPV, and PLT values were recorded. We compared the patient and control groups in terms of these parameters. Then, TT patients were divided into two subgroups according to the time elapsed since the onset of symptoms. Subsequently, we evaluated the relationship between the duration of symptoms and these parameters. Results: There were significant differences between groups 1 and 2 in NLR, PLR, and PLT (p<0.001 for all). There was no predictive role of MPV in the diagnosis of TT (p=0.328). We determined significantly high sensitivity and specificity levels for NLR in the prediction of TT diagnosis (84% and 92%, respectively). Furthermore, NLR was significantly related to the duration of symptoms in TT patients (p=0.01). Conclusions: NLR may be a useful parameter in the diagnosis of TT. Furthermore, NLR may be used as a predictive factor for testicular viability following TT.