Alev Taskin
Yildiz Technical University, Industrial Engineering, Faculty Member
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A manufacturing supply chain is a network of suppliers, factories, subcontractors, warehouses, distribution centers and retailers, through which raw materials are acquired, transformed, produced and delivered to the end customers. Many... more
A manufacturing supply chain is a network of suppliers, factories, subcontractors, warehouses, distribution centers and retailers, through which raw materials are acquired, transformed, produced and delivered to the end customers. Many methods have been suggested over the years for supply chain evaluation of any organization. This study discusses the supply chain performance criteria for efficient supply chain performance evaluation in chemical industry on the basis of Balanced Scorecard's (BSC) four perspectives: finance, customer, internal business process, and learning and growth. The balanced scorecard developed in this paper provides a useful guidance in evaluation and measuring of SCM in a balanced way.
As the technology improves and widens, the companies change. Especially to be competitive in the market, the companies should renew themselves. In past, managers thought that if they had produced something they could sell it in the... more
As the technology improves and widens, the companies change. Especially to be competitive in the market, the companies should renew themselves. In past, managers thought that if they had produced something they could sell it in the market, but now this is impossible. There are too many rivals in the market. For this reason, companies should control their inventories and they should arrange their supply chain mangement activities according to their inventories. Also companies should force their suppliers to deliver in time, at the highest quality and in minimum price. In such a competitive market, the customers should be satisfied and inventories should be effectively managed. So, inventory management and optimization is very important in supply chain management. Supply chain inventory management (SCIM) is an integrated approach for planning and control of inventory, throughout the entire network of cooperating organizations from the source of supply to the end user. SCIM is focused ...
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Measuring customer satisfaction in service businesses is very important in terms of both increasing service quality and meeting customer expectations. Up-to-date and comprehensive quality of service measurement techniques provide... more
Measuring customer satisfaction in service businesses is very important in terms of both increasing service quality and meeting customer expectations. Up-to-date and comprehensive quality of service measurement techniques provide important information to the companies about the way customers perceive the quality and their service quality expectations. It is critical to measure the service quality for airline transportation, which is becoming more popular compared to other types of transportation and therefore increasing competition. In order to compete in the market and improve their service quality, companies should know their customers well and make improvements by analysing their expectations correctly. In this context, the SERVQUAL method is one of the frequently preferred and effective tools in service quality measurement. However, it is not possible to deal with the effects of radical changes such as the development and transformations of technology, events and trends under the influence of the world with the conventional SERVQUAL method. For this purpose, the traditional method consisting of five dimensions has been extended to nine dimensions by adding four more dimensions, namely Environment, Pandemic, Digital Technology and Information Systems. While it is possible to perform a more detailed service quality measurement with the proposed method, companies are provided with an effective and up-to-date tool to determine which dimensions are more important. In this study after structuring main dimensions and its inner levels hierarchically, Modified Delphi method is applied to a group of experts and the main criteria are evaluated with Best Worst Method and sub-criteria are evaluated with Interval-Valued Neutrosophic AHP method. After subjecting the criteria, whose importance are determined, to sensitivity analysis, the results obtained are evaluated in terms of airline transportation and recommendations are presented. In addition to the extended approach it proposes, this study is the most detailed research on airline service quality as far as we know.
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This study introduces a forecasting model to help design an effective blood supply chain mechanism for tackling the COVID-19 pandemic. In doing so, first, the number of people recovered from COVID-19 is forecasted using the Artificial... more
This study introduces a forecasting model to help design an effective blood supply chain mechanism for tackling the COVID-19 pandemic. In doing so, first, the number of people recovered from COVID-19 is forecasted using the Artificial Neural Networks (ANNs) to determine potential donors for convalescent (immune) plasma (CIP) treatment of COVID-19. This is performed explicitly to show the applicability of ANNs in forecasting the daily number of patients recovered from COVID-19. Second, the ANNs-based approach is further applied to the data from Italy to confirm its robustness in other geographical contexts. Finally, to evaluate its forecasting accuracy, the proposed Multi-Layer Perceptron (MLP) approach is compared with other traditional models, including Autoregressive Integrated Moving Average (ARIMA), Long Short-term Memory (LSTM), and Nonlinear Autoregressive Network with Exogenous Inputs (NARX). Compared to the ARIMA, LSTM, and NARX, the MLP-based model is found to perform better in forecasting the number of people recovered from COVID-19. Overall, the findings suggest that the proposed model is robust and can be widely applied in other parts of the world in forecasting the patients recovered from COVID-19.
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Abstract Service quality is one of the most important factors that increase the use of public transportation, especially in metropolitan cities such as Istanbul. When evaluating service quality in public transportation systems, one of the... more
Abstract Service quality is one of the most important factors that increase the use of public transportation, especially in metropolitan cities such as Istanbul. When evaluating service quality in public transportation systems, one of the most important factors is customer satisfaction. The increase in service quality increases the usage of public transport system utilization and it helps to solve many problems such as traffic congestion, air and noise pollution and energy consumption. For this purpose, the SERVQUAL model is extended with two new criteria related to Industry 4.0 and the pandemic to understand and evaluate the service quality of public transport systems. New criteria added into the SERVQUAL model and a novel P-SERVQUAL 4.0 (Pandemic SERVQUAL 4.0) model is presented. The novel service quality evaluation model is constructed as a three level hierarchical structure to evaluate public transport systems during the pandemic. Then, the evaluation model is modeled as a multi criteria decision making problem and a novel AHP (Analytic Hierarchy Process) integrated WASPAS (Weighted Aggregated Sum Product Assessment) under interval valued intuitionistic fuzzy (IVIF) environment methodology is employed. A real case application to evaluate Istanbul public transport systems is presented in this study. The proposed novel model is applied to evaluate the most used public transportation alternatives such as IETT Bus, Metrobus, Tram, Metro and Marmaray, in Istanbul. By the application of P-SERVQUAL 4.0 model; as a result of this study, Marmaray is determined as the best alternative. The proposed methodology can be used by public or private organizations to improve their strategies and operations to adapt Industry 4.0 and prevent the spread of SARS-CoV-2 (COVID-19). Also, the main limitations and the practical and managerial implications of the study are included in the conclusions.
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There is no defined methodological approach that would rank the quality goals of a process in uncertain environments, which is one of the basic problems in process management. In this paper, the considered problem is stated as a... more
There is no defined methodological approach that would rank the quality goals of a process in uncertain environments, which is one of the basic problems in process management. In this paper, the considered problem is stated as a multi-criteria decision problem. The criteria present performances which are defined by the knowledge and experience of the decision makers. The fuzzy rating weights of each pair of the considered criteria and uncertain criteria values for the defined quality goals are described by linguistic expressions which are ...
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... Alev TAŞKIN Yıldız Teknik Üniversitesi Ali Fuat GÜNERİ Yıldız Teknik Üniversitesi Özet ... organizasyonun kendi iç yapısındaki güçlü ve zayıf yönlerin analiz edilmesini sağlarken; aynı zamanda, organizasyonun diğer organizasyonlar... more
... Alev TAŞKIN Yıldız Teknik Üniversitesi Ali Fuat GÜNERİ Yıldız Teknik Üniversitesi Özet ... organizasyonun kendi iç yapısındaki güçlü ve zayıf yönlerin analiz edilmesini sağlarken; aynı zamanda, organizasyonun diğer organizasyonlar karşısındaki durumunu tespit etmeye yarar. ...
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Abstract Many governments decided to cancel face‐to‐face teaching and learning activities in schools and universities. They replaced them with online teaching and distance learning activities to prevent the spread of Coronavirus disease... more
Abstract Many governments decided to cancel face‐to‐face teaching and learning activities in schools and universities. They replaced them with online teaching and distance learning activities to prevent the spread of Coronavirus disease 2019 (COVID‐19). Due to this sudden change, students experienced some anthropometric, environmental, and psychosocial difficulties at home during the distance learning process. This study focuses on determining the importance of anthropometric, environmental, and psychosocial factors in the distance learning process during the COVID‐19 pandemic. This study presents main factors and their subfactors affecting ergonomic conditions of university students during distance learning. A novel distance learning ergonomics checklist is proposed based on the Occupational Safety and Health Administration checklists. The data are collected via a questionnaire filled by 100 university students who attend the Ergonomics course online. Then, the integrated methodology includes Voting Analytic Hierarchy Process integrated Pythagorean Fuzzy Technique for Order Preference by Similarity to An Ideal Solution method is adopted to prioritize the factors determined. Thirty‐nine different subfactors are evaluated under five titles, and the most important factors are determined using the proposed methodology. With the results achieved, it is seen that the suggested checklist and proposed methodology can be used by public and private education organizations as a guide for improving their distance learning strategies.
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Supply chain operations reference (SCOR) is a combined benchmarking, business process reengineering, and best practices, and it also references a model that is intended to be an industry standard. SCOR model is one of the best models to... more
Supply chain operations reference (SCOR) is a combined benchmarking, business process reengineering, and best practices, and it also references a model that is intended to be an industry standard. SCOR model is one of the best models to describe supply chain activities in operations management for research and practice alike. There are radical changes in the structure of supply chains as well as developing technology in today’s information age. The purpose of this paper is to extend the SCOR model with new metrics related to Industry 4.0 and digitalization to understand and evaluate the performance of supply chains. New metrics added to the SCOR model and a novel SCOR 4.0 model is proposed. The novel performance evaluation model is structured as a three-level hierarchical structure to evaluate the supply chain. This problem is handled as a multi-criteria decision-making problem. This study uses the hybrid Best worst method and Pythagorean fuzzy AHP method to determine the weights of...
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Managing the distribution of goods is a vital operation for many companies. A successful distribution system requires an effective distribution strategy selection and optimum route planning at the right time and minimum cost. Furthermore,... more
Managing the distribution of goods is a vital operation for many companies. A successful distribution system requires an effective distribution strategy selection and optimum route planning at the right time and minimum cost. Furthermore, customer’s demand and location can vary from order to order. In this situation, a mixed delivery system is a good solution for it and allows the use of different strategies together to decrease delivery costs. Although the “distribution strategy selection” is a critical issue for companies, there are only a few studies that focus on the mixed delivery network problem. There is a need to propose an efficient solution for the mixed delivery problem to guide researchers and practitioners. This paper develops a new “modified” savings-based genetic algorithm which is named “distribution strategy selection and vehicle routing hybrid algorithm (DSSVRHA).” Our new algorithm aims to contribute to the literature a new hybrid solution to solve a mixed deliver...
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Researchers work on facility location problems in different structures and solve them by developing different models over the years. In this study, we focus on the automated teller machine (ATM) site selection problem for a public bank in... more
Researchers work on facility location problems in different structures and solve them by developing different models over the years. In this study, we focus on the automated teller machine (ATM) site selection problem for a public bank in İstanbul. Twenty-five districts, which are located at the European side of İstanbul, are designated as ATM candidate districts. The balanced scorecard (BSC) model is modified to determine the criteria according to the literature review and experts’ judgments for this problem. Internal, Customer, and Financial perspectives of the traditional BSC model are used as the main criteria and an external perspective is considered as the fourth criterion for modified balanced scorecard. The experts’ criteria evaluations are gained and consolidated by the Modified Delphi Method. The criteria weights are determined by the Pythagorean Fuzzy-AHP method using the final pairwise comparison results obtained from the Modified Delphi Method. Subsequently, the Pythago...
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<p>Nowadays small, medium and severe disasters are threatening our world. One of the important role players in alleviating these traits are humanitarian relief... more
<p>Nowadays small, medium and severe disasters are threatening our world. One of the important role players in alleviating these traits are humanitarian relief supply chains. The increasing number of disasters in our planet earth urges the humanitarian relief supply chains to focus on the assurance of safety of the victims. In order for this to occur, these supply chains should work effectively and efficiently. This can be possible through considerable evaluation of their supply chain performance. In this paper a literature review on supply chain performance evaluation in general and humanitarian relief supply chain performance in particular is presented. Previously conducted researches from the year 2000 until the present time have been reviewed. The works were categorized according to writers, publication year, publishing journal, technique utilized and objective intended. Then an analysis was made on humanitarian relief supply chain literature with respect to the publishing journals and the research technique applied. The result shows that humanitarian relief supply chain evaluation is almost an untouched area which needs further study. Recent supply chain management techniques can be applied for the improved performance of these supply chains. Based on this result, Supply Chain Operations Reference (SCOR), Fuzzy Logic System, and Artificial Neural Networks are found to be the areas which need further study.</p>
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Page 1. Multi-echelon inventory management in supply chains with uncertain demand and lead times: literature review from an operational research perspective A Taskin Gümüs* and A Fuat Güneri Department of Industrial Engineering ...
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This paper aims to decide on the number of facilities and their locations, procurement for pre and post-disaster, and allocation to mitigate the effects of large-scale emergencies. A two-stage stochastic mixed integer programming model is... more
This paper aims to decide on the number of facilities and their locations, procurement for pre and post-disaster, and allocation to mitigate the effects of large-scale emergencies. A two-stage stochastic mixed integer programming model is proposed that combines facility location- prepositioning, decisions on pre-stocking levels for emergency supplies, and allocation of located distribution centers (DCs) to affected locations and distribution of those supplies to several demand locations after large-scale emergencies with uncertainty in demand. Also, the use of the model is demonstrated through a case study for prepositioning of supplies in probable large-scale emergencies in the eastern and southeastern Anatolian sides of Turkey. The results provide a framework for relief organizations to determine the location and number of DCs in different settings, by using the proposed model considering the main parameters, as; capacity of facilities, probability of being affected for each deman...
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In this study finite scheduling and artificial neural networks are applied for finite capacity planning. Utilisation of artificial neural networks on solving finite scheduling problems is examined. Also a model is developed by using multi... more
In this study finite scheduling and artificial neural networks are applied for finite capacity planning. Utilisation of artificial neural networks on solving finite scheduling problems is examined. Also a model is developed by using multi layer perceptron (MLP) networks ...
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Alev Taskin Gumus is a Research Assistant in the Department of Industrial Engineering at Yildiz Technical University. Dr. Taskin Gumus received her MSc. Degree in Industrial Engineering from Yildiz Technical University, in 2003, MBA... more
Alev Taskin Gumus is a Research Assistant in the Department of Industrial Engineering at Yildiz Technical University. Dr. Taskin Gumus received her MSc. Degree in Industrial Engineering from Yildiz Technical University, in 2003, MBA degree from Istanbul Technical University, in ...
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ABSTRACT Third-party logistics (3PL) service provider selection for a strategic alliance is not an easy decision, and is constantly associated with uncertainty and complexity. For this reason, in this study, a hybrid fuzzy multi-criteria... more
ABSTRACT Third-party logistics (3PL) service provider selection for a strategic alliance is not an easy decision, and is constantly associated with uncertainty and complexity. For this reason, in this study, a hybrid fuzzy multi-criteria decision-making methodology is proposed to provide a systematic decision support tool for 3PL provider evaluation, especially for 3PL transportation provider. The proposed evaluation methodology consists of several steps. First, the strategic goal and sub-attributes are identified for 3PL service provider evaluation. After constructing the hierarchy, Buckley’s fuzzy-analytical hierarchy process (AHP) extension algorithm is used to determine the evaluation criteria weights. Then, by using fuzzy-AHP results as input weights, the fuzzy-Technique for Order Preference by Similarity to Ideal Solution technique is conducted in order to identify the most suitable third-party providers. Finally, a real-life case study in a confectionary company is presented to demonstrate the potential use of the methodology and a sensitivity analysis is performed to analyse the hybrid methodology proposed here. In the conclusion of the study, future recommendations are presented.
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Disaster and humanitarian logistics are one of the most important subjects for a country to take care about. It is possible to increase the performance of humanitarian relief logistics management processes by several planning and... more
Disaster and humanitarian logistics are one of the most important subjects for a country to take care about. It is possible to increase the performance of humanitarian relief logistics management processes by several planning and prevention activities. This paper's main contribution is identifying and then evaluating the success factors which are critical for effective management of humanitarian relief logistics operations. Therefore, an effective method that combines type-2 fuzzy sets, which provide additional degrees of freedom to present the uncertainty and the fuzziness of the real world, and analytic hierarchy process, is proposed to sustain a realistic evaluation. It is aimed that, the proposed method will be used by governmental and non-governmental organizations to improve their HRLM activities and strategies.
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ABSTRACT Multi criteria decision making (MCDM) is a discipline of operations research which has widely studied by researchers and practitioners. It deals with evaluating and ranking alternatives from the best to the worst under... more
ABSTRACT Multi criteria decision making (MCDM) is a discipline of operations research which has widely studied by researchers and practitioners. It deals with evaluating and ranking alternatives from the best to the worst under conflicting criteria with respect to decision maker(s) preferences. Since, many real-world systems include uncertainty and vagueness in information, MCDM uses fuzzy sets. In recent years, as an extension of the traditional fuzzy sets concept, type-2 fuzzy sets are preferred to have the capability of handling more uncertainty, and hence, to produce more accurate and robust results, MCDM approaches based on interval type-2 fuzzy sets (IT2FSs) have been published in various subjects. This paper reviews 82 different papers using various MCDM approaches based on IT2FSs which are classified into 35 categories. All papers with respect to single and hybrid approaches are discussed, pointing out their real applications or empirical results and limitations. Furthermore, the papers are statistically analyzed to show new trends within the context of IT2FSs. This systematic and comprehensive review study provides an insight for researchers on interval type-2 fuzzy MCDM in terms of showing current state and potential areas to be focused in the future .
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ABSTRACT This paper provides a hierarchical customer satisfaction framework to measure rail transit lines’ performances in Istanbul. The problems related to rail transit line systems are addressed via customer satisfaction surveys. Then,... more
ABSTRACT This paper provides a hierarchical customer satisfaction framework to measure rail transit lines’ performances in Istanbul. The problems related to rail transit line systems are addressed via customer satisfaction surveys. Then, a framework is proposed combining statistical analysis, fuzzy analytic hierarchy process, trapezoidal fuzzy sets and Choquet integral to evaluate customer satisfaction levels. Next, the criteria need to be improved are determined and specific recommendations to enhance the operation for specific lines are suggested. The proposed framework provides directions for the future investments and it also can be used at a more macroscopic level to determine the operational deficiencies. Furthermore, it can be generalized and applied to complex decision making problems that include uncertain and subjective data or vague information.
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ABSTRACT In this paper, the problems of public transportation customers in Istanbul are addressed and their satisfaction levels are evaluated by using customer satisfaction survey and statistical analysis. A novel interval type-2 fuzzy... more
ABSTRACT In this paper, the problems of public transportation customers in Istanbul are addressed and their satisfaction levels are evaluated by using customer satisfaction survey and statistical analysis. A novel interval type-2 fuzzy MCDM method is proposed based on TOPS'S and GRA, to evaluate and improve customer satisfaction in Istanbul public transportation. Then, the criteria need to be improved are determined and different improvement suggestions are made for all public transportation firms. (c) 2013 Elsevier Ltd. All rights reserved.
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ABSTRACT Rail transit is one of the most important public transportation types, especially in big and crowded cities. Therefore, getting a high customer satisfaction level is an essential task for municipalities and governments. For this... more
ABSTRACT Rail transit is one of the most important public transportation types, especially in big and crowded cities. Therefore, getting a high customer satisfaction level is an essential task for municipalities and governments. For this purpose, a survey is conducted to question the attributes related to rail transit network (metros, trams, light rail and funicular) in Istanbul. In this study, we present a novel framework which integrates statistical analysis, SERVQUAL, interval type-2 fuzzy sets and VIKOR to evaluate customer satisfaction level for the rail transit network of Istanbul. Level of crowdedness and density in the train, air-conditioning system of trains' interior, noise level and vibration during the journey, and phone services are determined as the attributes need improvements. On the other hand, different improvement strategies are suggested for the rail transit network. The proposed approach provides directions for the future investments and can be generalized and applied to complex decision making problems encounter inexact, indefinite and subjective data or uncertain information.
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In this paper, supply chain structure and it's key elements are emphasized, and a case in electronics industry about business process redesign in supply chains is presented. In this case, the services and business processes of an... more
In this paper, supply chain structure and it's key elements are emphasized, and a case in electronics industry about business process redesign in supply chains is presented. In this case, the services and business processes of an electronics manufacturing service provider are examined, and these are assessed again to define the sections need to be improved.
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The thermal stability of the Schottky barrier height 0268-1242/13/7/020/img11 of Cr-Ni-Co alloy Schottky contacts on an MBE n-GaAs substrate has been investigated using current-voltage (I-V) and capacitance-voltage... more
The thermal stability of the Schottky barrier height 0268-1242/13/7/020/img11 of Cr-Ni-Co alloy Schottky contacts on an MBE n-GaAs substrate has been investigated using current-voltage (I-V) and capacitance-voltage (0268-1242/13/7/020/img12-V) techniques after thermal annealing for 5 min in an 0268-1242/13/7/020/img13 atmosphere at several temperatures in the 200-0268-1242/13/7/020/img14C range. It has been found that the value of 0268-1242/13/7/020/img11 (0.83 or 0.84 eV) remains
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... companies adapted the ERP processes along with business process reengineering and best ... MK, Godla, J. (1999), "Critical issues affecting an ERP implementation", Information Systems ... Boykin, RF (2001), "Enterprise... more
... companies adapted the ERP processes along with business process reengineering and best ... MK, Godla, J. (1999), "Critical issues affecting an ERP implementation", Information Systems ... Boykin, RF (2001), "Enterprise resource planning software: a solution to the return material ...
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Kanbans play an important role in the information and material flows in a JIT production system. The traditional kanban system with a fixed number of cards does not work satisfactorily in an unstable environment. In the flexible... more
Kanbans play an important role in the information and material flows in a JIT production system. The traditional kanban system with a fixed number of cards does not work satisfactorily in an unstable environment. In the flexible kanban-type pull control mechanism the number of kanbans is allowed to change with respect to the inventory and backorder level. Based on the