Fakülteler / Faculties
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Item Improving The Quality Of Micro Holes Drilled With A Current Detection Plasma Arc Device(JOURNAL OF THE BRAZILIAN SOCIETY OF MECHANICAL SCIENCES AND ENGINEERING, 2024-10) Ic, Yusuf Tansel; Kocum, Cengiz; Atalay, Kumru Didem; Serdaroglu, Dilek Cokeliler; Akar, Gurel; Polat, Isil Yanki; Samsun, Berk; Caliskan, Sevde; Atmaca, Dicle Naz; Karayalcin, SerkanToday, microholes play a crucial role in many sectors. Microholes are used in fields such as aerospace, computer systems, and electronic and mechanical industries. In this paper, we improve the performance of the current sensing plasma arc device to create holes within the same diameter, appropriate delamination, and surface quality. In addition, we aim to improve the processing quality of the current sensing plasma arc device, which drills holes from the micron level to the millimeter level and creates microstructures on hard, durable, and inert materials such as glass and quartz. Additionally, we presented a multiobjective optimization model to reach the optimal factor levels to obtain the minimum hole diameter with minimum delamination. For this objective, we propose a design of an experiment-integrated goal programming model in this study. The optimal levels are 90 Watt, 18 Hz, 2.73 ms, and 11.6 cm for the parameter values Power, Frequency, Lead time, and Distance between the probes, respectively, to reach the optimal diameter (183 mu m) and delamination values (1.025).Item Goodness-of-fit and Randomness Tests for the Sun's Emissions True Random Number Generator(2014) Tanyer, Suleyman Gokhun; Atalay, Kumru Didem; Inam, Sitki Cagdas; 0000-0003-0820-9186; I-5023-2013; JHU-3888-2023Random number generators ( RNGs) are one of the key tools necessary for statistical analysis and optimization methods such as Monte Carlo, particle swarm optimization ( PSO) and the genetic algorithm. Various pseudo and true RNGs are available today, and they provide sufficient randomness. Unfortunately, they generate data that do not always represent the required distribution accurately, especially when the data length is small. This could possibly threaten the 'repeatability' of an academic study. A novel true RNG ( TRNG) using the method of uniform sampling ( MUS) is recently proposed. In this work, the Sun's RF emissions MUS-TRNG is comparatively tested with well known pseudo and true RNGs. It is observed that both randomness and very high goodness-of-fit qualities are possible.Item Multi-Criteria Usability Evaluation of Electronic Devices in a Fuzzy Environment(2014) Atalay, Kumru Didem; Eraslan, Ergun; https://orcid.org/0000-0002-9021-3565; https://orcid.org/0000-0002-5667-0391; AAE-7165-2019The user-oriented design is the most important competition issue in today's market. In recent years, user-oriented design (i.e., usability) has become expected, particularly in electronic devices. Usability considers high user satisfaction in conjunction with user performance. Usability of electronic products is essential for high customer satisfaction as well as product life cycles in companies. Therefore, MP3 players were selected among the electronic products. Designing usable MP3 players is extremely important for users who have close interaction with them. In this study, MP3 players of different types and sizes were selected and their usability evaluated. The usability criteria used in the MP3 players' evaluation were divided into two major categories: performance and emotional expectations. The alternatives were ranked with fuzzy multi-criteria decision-making methods, namely, Fuzzy TOPSIS (FTOPSIS), Fuzzy Analytic Hierarchy Process (FAHP), and Fuzzy Axiomatic Design Theory (FADT), and the results were compared. Although the same decision matrices and data obtained from semantic differential experiment were used for all fuzzy multi-criteria decision-making methods, it is shown that different rankings were obtained. (c) 2012 Wiley Periodicals, Inc.Item A Hybrid Algorithm Based on Fuzzy Linear Regression Analysis by Quadratic Programming for Time Estimation: An Experimental Study in Manufacturing Industry(2015) Atalay, Kumru Didem; Eraslan, Ergun; Cinar, M. Oya; 0000-0002-5667-0391; AAE-7165-2019In time studies, estimation of the standard times with direct or indirect measurement methods is particularly difficult in companies having complex production schedules or ones employing an inexperienced workforce. Such companies require new and specific time measurement procedures. In this study, a new time estimation algorithm based on fuzzy linear regression analysis (FLRA) by quadratic programming (QP) is proposed for specific manufacturing systems. In our study, data is provided by one of the biggest casting and machining companies in Europe. The database includes items that have similar production processes. A fuzzy linear regression model is built by using the previously measured standard times of a product family. The model developed is used for estimating the standard times of the remaining products. FLRA based on QP approach facilitates integration of the central tendency of least squares and possible properties of fuzzy regression. The main factors that directly impact standard times are determined and used for the estimation of the fuzzy standard times. Through utilization of sum of squares error (SSE) and index of confidence (IC), the important factors in the model are identified. The use of QP makes it possible to reconcile the minimization of the deviation of central tendency and the spreads of membership functions in a simultaneous manner. In this study, the efficiency of the proposed algorithms in casting companies is authenticated. Besides, it is seen that this estimation procedure could be implemented easily for various sectors using the relevant algorithms. (C) 2014 The Society of Manufacturing Engineers. Published by Elsevier Ltd. All rights reserved.Item Working Posture Analysis in Fuzzy Environment and Ergonomic Work Station Design Recommendations(2015) Can, Gulin Feryal; Atalay, Kumru Didem; Eraslan, Ergun; 0000-0002-5667-0391; AAE-7165-2019Realization of ergonomic design applications in working environments, makes it possible to preserve the health of employees, provide them working comfort and increase productivity. Therefore ergonomic work station design has an outstanding position in work places. In this study, an investigation was made on work stations in a metal accessor producer, which were found to be inappropriate from point of view of design considerations as a result of an ergonomic condition analysis. Inappropriate designs force workers to repetitively assume dangerous postures. As a result production process slows down and workers experience a feeling of increasing tiredness. Postures of workers were analyzed by The Fuzzy Rapid Entire Body Assessment (BREBA) developed by inserting triangular fuzzy scale to Rapid Entire Body Assessment (REBA). The BREBA method determines the level of risk in whole body caused by postures while prevents potential information loss and allows obtaining more accurate results in a fuzzy environment. In the said working place, 688 posture photographs belonging to four work stations (heat treatment, primary press, secondary press and transportation station) were examined. The consequent assessment suggested that; leg, upper arm and wrist in heat treatment, leg, wrist and torso in pres station, torso and arm were found to be the most enforced body sections. The results pointed out that 52,03% of postures displayed in production process introduced medium level risk and improvements were suggested.Item Randomness Tests For The Method Of Unıform Sampling Quasi-Random Number Generator (MUS-QRNG)(2014) Atalay, Kumru Didem; Tanyer, Suleyman Gokhun; https://orcid.org/0000-0001-9506-2391; I-5023-2013Random number generation is still an important research field in many scientific applications today. Cryptography, Monte Carlo simulations and commertial applications all rely on reference random data. Randomness tests and basic statistics share the same history. Randomness can be summarized as the unpredictability of future samples of a random number generator even in the presence of known all past values. Various randomness tests are developed and due to their individual contributions, usually a battery of tests are applied to verify a random number generator. In signal processing however, the error of a specific observed sample set to a given distribution could be much more important when it is used as the input for a system model. Recently, this distance of finite samples set to a given distribution is studied and a quantitative measure for quality is proposed Multi run computations like Monte Carlo simulations, often rely on accurate statistical data for high repetibility. Otherwise when the data is not accurate, the results could often rely on the source of random data generator. Many runs are often required to gain a confidence in the presence of those variances. In this work, recently proposed quasi-random number generator utilizing method of uniform sampling NUS) is tested using standard goodness-of-fitness tests. MUS-QRNG numbers are shown to have exact statistics and also their randomness test results are observed to be similar to well known reference generator of Matlab. MUS-QRNG is proposed for high quality random data generation.Item Analysis of True Random Number Generation Method Utilizing FM Radio Signals(2015) Tanyer, Suleyman Gokhun; Inam, Sitki Cagdas; Atalay, Kumru Didem; 0000-0001-9506-2391; 0000-0003-0820-9186; I-5023-2013Random number generator (RNG)'s utilize some source of entropy. Various RNGs; pseudo, quasi and true RNGs provide observed samples for given distributions which are necessary in statistical signal processing and simulations applications. True random number generators generally utilize the last insignificant bit of observed samples obtained from a source of entropy. In this work, samples obtained from an FM broadcasting are examined. Least significant bit is used to generate 16 bits observed samples. Randomness and goodness-of-fit test results are compared with the raw samples. It is shown that it is possible to generate true random numbers of sufficient merits using FM signals even when the band is occupied with broadcasting signals.Item A New Hybrid Intuitionistic Approach for New Product Selection(2018) Atalay, Kumru Didem; Can, Gulin FeryalThis paper proposes a new hybrid approach for multi-criteria decision-making problems combining intuitionistic fuzzy analytic hierarchy process and intuitionistic fuzzy multi-objective optimization by ratio analysis. Analytic hierarchy process has an inherent ability for handling intangible problems and implements a simple scale to represent evaluations in the structure of pairwise comparisons. Multi-objective optimization by ratio analysis optimizes the solution of a problem having two or more conflicting objectives, taking into account certain constraints. In real-life decision problems, evaluations of decision makers related to performance of alternatives and criteria weights can be expressed by linguistic terms comprising vagueness and uncertainty. These uncertain, vague and hesitant judgments of decision makers can be described more comprehensively by using intuitionistic fuzzy set theory. The proposed approach is a powerful tool for dealing with information which consists of hesitancy and vagueness. An illustrative example related to new product selection for a company is also presented to demonstrate the implementation of the approach.Item Assessment of Mental Workload and Academic Motivation in Medical Students(2016) Atalay, Kumru Didem; Can, Gulin Feryal; Erdem, Saban Remzi; Muderrisoglu, Ibrahim Haldun; https://orcid.org/0000-0002-7537-2170; 27183939; AAJ-2370-2021Objectives: To investigate the level of correlation and direction of linearity between academic motivation and subjective workload. Method: The study was conducted at Baskent University School of Medicine, Ankara, Turkey, from December 2013 to February 2014, and comprised Phase 5 Phase 6 medical students. Subjective workload level was determined by using National Aeronautics and Space Administration Task Load Index scale that was adapted to Turkish. Academic motivation values were obtained with the help of Academic Motivation Scale university form. SPSS 17 was used for statistical analysis. Results: Of the total 105 subjects, 65(62%) students were in Phase 5 and 40(38%) were in Phase 6. Of the Phase 5 students, 18(27.7%) were boys and 47(72.3%) were girls, while of the Phase 6 students, 16(40%) were boys and 24(60%) were girls. There were significant differences in Phase 5 and Phase 6 students for mental effort (p= 0.00) and physical effort (p= 0.00). The highest correlation in Phase 5 was between mental effort and intrinsic motivation (r= 0.343). For Phase 6, highest correlation was between effort and amotivation (r= -0.375). Conclusion: Subjective workload affected academic motivation in medical students.Item Quality Improvement Strategies of Highway Bus Service Based On A Fuzzy Quality Function Deployment Approach(2016) Kurtulmusoglu, Feride Bahar; Pakdil, Fatma; Atalay, Kumru Didem; A-7058-2017
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