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Publication Metadata only A novel fuzzy TOPSIS method using emerging interval-valued spherical fuzzy sets(2019-06-03) Kahraman, Cengiz; GÜNDOĞDU, FATMA KUTLUAll the extensions of ordinary fuzzy sets with three-dimensional membership functions such as intuitionistic fuzzy sets, second type intuitionistic fuzzy sets (or Pythagorean fuzzy sets) and neutrosophic sets aim at defining the judgments of decision makers/ experts with a more detailed description. As a new extension of intuitionistic fuzzy sets of second type, the emerging spherical fuzzy sets (SFS) have been proposed by Kutlu Gundogdu and Kahraman (2019b). In spherical fuzzy sets, the sum of membership, non-membership and hesitancy degrees must satisfy the condition0 <= mu(2) + v(2) + pi(2) <= 1 in which these parameters are assigned independently. SFS is an integration of Pythagorean fuzzy sets and neutrosophic sets. In this paper, novel interval-valued spherical fuzzy sets are introduced with their score and accuracy functions; arithmetic and aggregation operations such as interval-valued spherical fuzzy weighted arithmetic mean operator and interval-valued spherical fuzzy geometric mean operator. Later, interval-valued spherical fuzzy sets are employed in developing the extension of TOPSIS under fuzziness. Then, we use the proposed interval-valued spherical fuzzy TOPSIS method in solving a multiple criteria selection problem among 3D printers to verify the developed approach and to demonstrate its practicality and effectiveness. A comparative analysis with single-valued spherical TOPSIS is also performed.Publication Metadata only Yöneylem Araştırması ve Endüstri Mühendisliği 32 Ulusal Kongresi(2012) Tarhan, İbrahim Ethem; 114926Publication Metadata only Bir Tekstil Firması için AHP ve Bulanık TOPSIS Metodlarıyla Süreç Yönetimi Yazılım Seçimi(2018-06) Gergin, Zeynep; Semiz, Neslihan; Güneş, Buse; Şen, Arda Yiğit; Demirok Dönmez, Nurcan; Algül, Duygu; 141772Günümüz perakende şirketleri süreçlerinin yönetimi için kullanacakları yazılımın seçiminde birçok farklı kriterle karşı karşıya kalabilmektedir. Uygun yazılımın seçimi, süreç yöneticilerin karşılaştıkları, birden fazla faktörün yanında, farklı karar vericilerin de bir araya gelmesini gerektiren çok kriterli bir karar verme problemidir. Bu çalışmada, tekstil sektöründe faaliyet gösteren bir perakende satış firmasına süreç yönetimi yazılımı seçilmesi problemi ele alınmıştır. Firmanın süreç yönetimi departmanında kullanılan ve tüm süreç akışlarını kapsamayan mevcut yazılımdaki ana problem, diğer yazılımlarla iletişimsizliktir. Bu çalışma ile, süreçleri tek bir sistemde birleştiren yazılımın seçilmesiyle operasyonlarda zaman kaybını azaltmak amaçlanmaktadır. Böylece, tüm departmanlarda istatistiklerin gerçek zamanlı analizi için birleşik ve tek bir raporlama sistemi olacak ve tüm departmanlarda daha iyi bir işbirliği sağlanacaktır. Çalışmamız kapsamında, Analitik Hiyerarşi Süreci (AHP) ve Bulanık TOPSIS yaklaşımlarının kademeli kullanımı ile tasarlanan bir çok kriterli karar verme metodolojisi sunulmuştur. îlk aşamada, AHP uygulaması ile yedi karar vericiden alman ikili karşılaştırmalar neticesinde, karar vermede etkili kriterlerin bütünleşik önem dereceleri belirlenmiştir, ikinci aşamada, Bulanık TOPSIS yöntemi uygulanmış, alternatif yazılımlar için, her bir karar kriteri bağlamında, farklı karar vericilerin niceliksel ve niteliksel verilerden oluşan değerlendirmeleri analiz edilerek firma için en uygun yazılım belirlenmiştir.Publication Metadata only The Effect of Seed Value Choice in an Incomplete Fuzzy Preference Relations Guided by Social Influence(Springer International Publishing, 2022) ÇİÇEKLİ, SEVRA; Gürbüz, TuncayNowadays, there is an enormous increase in alternatives almost in every area with the development of technology. Thus, it has become harder for a single decision maker (DM) to completely evaluate each alternative for a problem on hand. In group decision making (GDM) problems, each DM has a different effect on the final decision because of their background. Also, it has been observed that DM's judgments are affected by those of other DMs in the group. This is defined as social influence (SI). Social Influence Network (SIN) is useful especially when there is incomplete preference information. In this paper, a proposed model has been used to demonstrate the effect of seed value choice in completion process of missing fuzzy information given by DMs.Publication Metadata only Cross Mark Coordinate Determination and Automatic Registration for Offset Printing(2018-08) Kasapoğlu, N. Gökhan; Gergin, Zeynep; Gençyılmaz, Mehmet Güneş; Torbalı, Ayşe Bilge; YÜKSEKTEPE, FADİME ÜNEY; GÜNDOĞDU, FATMA KUTLU; 141772; 30141; 108243; 273471Offset printing is the method for producing commercialized printed media as newspapers and magazines. There are various factors contributing to the overall print quality such as; paper, ink pigment penetration, ink water balance, hygiene of environment, air temperature and humidity. Moreover, quality control is still operator dependent process where the operator is responsible for the visual checks of the printed material. One of the major checks applied is the correct registration of the plates in order to have a sharp image. The misregistration check may require more than one iterations creating setup time variation. Consequently, this highly time consuming setup takes considerable amount of time, especially in low circulation amounts. In this study a novel method called Cross Mark Coordinate Determination and Automatic Registration (CMCDR) is proposed for setup time reduction. CMCDR is based on x and y intensity profiles of registration marks and applied in a printing shop for automatic registration. For this purpose a traditional registration cross for overlapped color components (CMYK) as well as one registration cross for each individual color component is used to determine misclassification error. Using x and y intensity profiles of individual color component to determine misregistration errors and corrections of misregistrations are reduced with only one iteration.Publication Metadata only Data Mining Approach for Quality Control Process Improvement(2019-09) Gergin, Zeynep; Buldanlı, B.Berk; Şahin, Turabi; Elçi, Lütfi; Ekinci, Mert; YÜKSEKTEPE, FADİME ÜNEY; 141772While striving for serving high quality products, companies are also struggling for cost efficiency. In other words, today’s competitive business environment entails the fact that the economic benefits of the company must be considered together with the product requirements to be met for customer satisfaction. Hence, companies must focus both on improving their ongoing process and establishing cost efficiency. To accomplish this success, they are trying various ways, and data science and data mining tools are the latest solutions that the companies are using in this digital transformation era. With this motivation, this research is conducted in one of the leading bus manufacturers in the automotive industry for improving the cost efficiency of quality control processes with the application of data mining methods. The company has decided to make optimization in the current routes of test drives. Currently, the busses are sent to various routes for validation after the quality control processes. The company supports this project for identifying optimum route assignments in order to minimize test-drives distances, and consequently decrease the related costs. The study starts with the collection of data from the quality control records. Then, it continues with pre-processing and analysis of data to understanding the quality control (QC) process and failure modes. After that, data are processed on WEKA data mining software, for understanding and inspecting the patterns and relationships between route requirements and specific error codes. Finally, the appropriate classification algorithm is selected. After the application of appropriate data mining algorithm, rules are set for route characteristics, and assignments are done between routes and QC error codes. Optimization of routes is done by considering the minimization of distance that is completed on test drives. The comparative results display 18.11% decrease in fuel consumption after the optimization of the routes with the rules set. A decision support app is also developed on android studio, which can be used by the company for faster route assignment decisions.Publication Embargo The electrical modulus and other dielectric properties by the impedance spectroscopy of LaCrO3 and LaCr0.90Ir0.10O3 perovskites(Royal Soc Chemistry, Thomas Graham House, Science Park, Milton Rd, Cambridge Cb4 0Wf, Cambs, England, 2018) Coşkun, Merve; Coşkun, Fatih Mehmet; Durmuş, Zehra; Çağlar, Müjdat; Turut, Abdulmecit; POLAT, ÖZGÜR; 110485; 48508; 108339; 21994; 3726We have prepared LaCrO3 (LCO) and 10% Ir doped LCO samples by the solid state reaction method and studied the electrical modulus and the other dielectric properties of the samples by means of the impedance spectroscopy in the -100 degrees C to 100 degrees C range, with steps of 20 degrees C. It has been clearly observed that the dielectric properties change due to Ir doping. The absolute dielectric constant value of Ir doped LCO has decreased and this reduction was attributed to decreasing Cr6+ ions which may play a vital role in space charge polarization and charge hopping. A plateau region appeared in the temperature-dependent real electrical modulus M' versus f curves of the pure LCO sample while almost no plateau region is visible in the Ir doped LCO sample. The temperature-dependent imaginary modulus M" versus f curves has two peaks at each temperature; one of the peaks is at low frequency and the other at the high frequency region, which shifts through higher frequency region with increasing temperature. This originates from free charge accumulation at the interface with the increase of the temperature. Furthermore, it has been seen that the Ir doped LCO sample has higher impedance and resistance values than the undoped LCO sample at the same frequency and temperature. This phenomenon was attributed to doped Ir ions behaving like a donor in LCO because LCO is a p-type compound. Moreover, the activation energy values of 0.224 eV and 0.208 eV for LCO and of 0.161 eV and 0.265 eV for the Ir doped LCO have been obtained from the slopes of the rho(dc) vs. (kT)(-1) curves, respectively. Also the activation energies were calculated from the slopes of the f(ma)x vs. (kT)(-1) curves and the obtained results from low frequency region were in good agreement with rho(dc) vs. (kT)(-1) ones.Publication Metadata only Lean Manufacturing Implementations for Process Improvement in a Company Operating in FMCG Sector(Springer, Cham, 2018-09) Emir, Oğuz; Karataş, Samet; Ay, Eren; Özker, Hümra; Gergin, Zeynep; 141772In order to survive in the global contest, enterprises have to increase their productivity via better use of their production resources. Hence, companies increasingly implementing lean management principles, which help them generate value and satisfy the requirements of their customers, through the elimination of non-value adding activities and pursuing continuous improvement in the processes. This study is an example of a process improvement that is applied to one of the fmcg company in Turkey. The project is implemented in packaging lines of Perfetti Van Melle Turkey, which is a global company, engaged in confectionery production and distribution, operating in more than 150 countries. The Turkey plant has been implementing various waste reduction practices for three years, and this project has been initiated to support the design of the packaging zone of the production system, considering the total seven wastes of lean management; namely overproduction, overprocessing, inventory, defects, transportation, motion, and waiting. It is desired to improve the performance of the packaging lines in order to keep up with the growing competition and fulfil the rapidly rising demands. The study begins by observing processes of packaging lines. The scope is determined by examining utilization rates, general line efficiency (GLE) and operational efficiency (OE). Then, selected lines are analyzed using value stream mapping (VSM) for waste identification, and statistical process control methods are implemented for improvements. The main objective is to increase the line efficiency rates that are calculated based on production quantities and scheduled time parameters. Improvement opportunities are proposed with future state VSMs by utilizing appropriate lean manufacturing techniques. Furthermore, a simulation study using ARENA Software is performed to evaluate proposed enhancements and to compare the alternative implementation scenarios.Publication Metadata only Spherical Fuzzy Sets and Decision Making Applications(2019-07) Kahraman, Cengiz; GÜNDOĞDU, FATMA KUTLU; 273471; 9178The extensions of ordinary Fizzy sets such as intuitionistic Fizzy sets (IFS). Pythagorean frizzy sets (PFS). and neutrosophic sets (NS), whose mem bership Emotions are based on three dimensions, aim to describe expert's judg ments more informatively and explicitly. Introduction of generalized three di mensional spherical Fizzy sets (STS) including some essential differences from the other frizzy sets is presented in the literature with their arithmetic, aggrega tion. and defrizzfication operations [S]. This study summarizes the previously in troduced spherical frizzy sets and as an application spherical frizzy CODAS method will be applied to the warehouse location selection problem.Publication Metadata only The r-interdiction selective multi-depot vehicle routing problem(WILEY, 111 RIVER ST, HOBOKEN 07030-5774, NJ USA, 2020) Sadati, Mir Ehsan Hesam; Aksen, Deniz; Aras, Necati; 40308; 21097The protection of critical facilities has been attracting increasing attention in the past two decades. Critical facilities involve physical assets such as bridges, railways, power plants, hospitals, and transportation hubs among others. In this study we introduce a bilevel optimization problem for the determination of the most critical depots in a vehicle routing context. The problem is modeled as an attacker-defender game (Stackelberg game) from the perspective of an adversary agent (the attacker) who aims to inflict maximum disruption on a routing network. We refer to this problem as the r-interdiction selective multi-depot vehicle routing problem (RI-SMDVRP). The attacker is the decision maker in the upper level problem (ULP) who chooses r depots to interdict with certainty. The defender is the decision maker in the lower level problem (LLP) who optimizes the vehicle routes in the wake of the attack. The defender has to satisfy all customer demand either using the remaining depots or through outsourcing to a third party logistics service provider. The ULP is solved through exhaustive enumeration, which is viable when the cardinality of interdictions does not exceed five among nine depots. For the LLP we implement a tabu search heuristic adapted to the selective multi-depot VRP. Our results are obtained on a set of RI-SMDVRP instances synthetically constructed from standard MDVRP test instances.