Ayağ, Zeki

Ayağ, Zeki

Name Variants

Ayağ, Zeki
Z.,Ayağ
Z. Ayağ
Zeki, Ayağ
Ayag, Zeki
Z.,Ayag
Z. Ayag
Zeki, Ayag
Ayağ,Z.
Zeki Ayağ

Job Title

Prof. Dr.

Email Address

Zekıa@khas.edu.tr

Full item page

Scholarly Output

44

Articles

31

Citation Count

0

Supervised Theses

5 Scholarly Output Search Results

Now showing 1 - 10 of 44

Minimizing the Defect Rate Using Six Sigma Dmaic Method; a Case Study in Supsan A.ş.
(Kadir Has Üniversitesi, 2016) Aslan, Nazmiye Yağmur; Ayağ, Zeki
Today manufacturing industries are highly impacted by the fast changing economic conditions. In this scenario, manufacturing industries become face to face with global competition due to globalization. The major problems of these industries are declining profit margin, customer demand for high quality product and product variety. Therefore so many organizations, especially in manufacturing sector, understand the importance of quality. Companies try to implement various strategies and innovations for enhancing their producing process. A very powerful philosophy in this area is Six Sigma. The aim of Six Sigma is to reduce cost, waste and increase productivity to produce high-quality products. So this study is applied to improve the quality of the manufactured valves, reduce the manufacturing waste and increase the yield of the manufacturing process by applying the Six Sigma methodology. Also comparison analysis is made between approaches as DMAIC, Jidoka, Value Stream Tranformation, Kaizen. In result of the analysis DMAIC is chosen for this project. DMAIC approach is a business strategy help to improve business profitability and efficiency of operations to meet customer needs and expectations. In this search discusses the quality and productivity improvement in an manufacturing enterprise which is called SUPSAN. And this search deals with an application of Six Sigma DMAIC methodology in SUPSAN to improve quality performance, to identify root causes of failure in Stellite Coating Process which is found with help of DMAIC tools. Several tools are used to identify root causes and situation analysed with help of Pareto Charts, FMEA, SIPOC, C&E Diagram. In improve phase Process Capability Analysis and Implementation Plan are made. Also improvement solutions are applied. Then with the help of tools as Control Charts, SPC Analysis results tracked, documented and controlled.In SUPSAN, the appliation of Six Sigma DMAIC methodology resulted in a reduction in the defect rate from 4.34% to 2%.
Citation Count: 4
An Intelligent Approach for the Evaluation of Transformers in a Power Distribution Project
(IOS Press BV, 2020) Samanlıoğlu, Funda; Ayağ, Zeki
In this study, a hybrid approach is presented for the evaluation and selection of transformers in a power distribution project. Ranking transformers and selecting the best among alternatives is a complex multiple criteria decision making (MCDM) problem with various possibly conflicting quantitative and qualitative criteria. In this research, two hesitant fuzzy MCDM methods; hesitant fuzzy Analytic Hierarchy Process (hesitant F-AHP) and hesitant fuzzy Preference Ranking Organization Method for Enriching Evaluations II (hesitant F-PROMETHEE II) are combined to evaluate and rank transformers. In the hesitant fuzzy AHP-PROMETHEE II, hesitant F-AHP is implemented to determine criteria weights and hesitant F-PROMETHEE II is applied to rank transformer alternatives, utilizing obtained criteria weights. An illustrative example is presented to demonstrate the effectiveness and applicability of the proposed approach. In the example, five transformers are evaluated based on twelve criteria by three decision makers (DMs) and best alternative is selected. For comparison analysis, integration of hesitant F-AHP and hesitant fuzzy Technique for Order Preference by Similarity to Ideal Solution (hesitant F-TOPSIS) is used and results are compared.
Citation Count: 87
An Analytic Network Process-Based Approach To Concept Evaluation in a New Product Development Environment
(Taylor & Francis, 2007) Ayağ, Zeki; Özdemir, Rifat Gürcan
Selecting the best product concept is one of the most critical tasks in a new product development (NPD) environment. Making decisions at this stage becomes very difficult due to imprecise and uncertain product requirements. So the evaluation process of determining the most satisfying conceptual design has been a very vital issue for companies to survive in fast-growing markets for a long time. Therefore most companies have used various methods to successfully carry out this difficult and time-consuming process. Of these methods an analytic hierarchy process (AHP) has been widely used in multiple-criteria decision-making problems (i.e. concept selection equipment evaluation). In this study however we use an analytic network process (ANP) a more general form of AHP due to the fact that AHP cannot accommodate the variety of interactions dependencies and feedback between higher and lower level elements. Briefly in this paper an ANP-based approach is presented to evaluate a set of conceptual design alternatives in order to reach to the best concept satisfying the needs and expectations of both customers and company. In addition a numerical example is presented to illustrate the proposed approach.
Citation Count: 15
A Combined Fuzzy Ahp-Simulation Approach To Cad Software Selection
(Taylor & Francis Ltd, 2010) Ayağ, Zeki
In this paper a combined approach where the fuzzy analytic hierarchy process (AHP) and simulation come together is presented to select the best computer-aided design (CAD) software out of the available options in the market. The fuzzy AHP is used due to the vagueness and uncertainty of the judgements of a decision maker(s) because the crisp pair-wise comparison in the conventional AHP seems to be insufficient and imprecise to capture the right judgements of the decision maker(s). In this study first the fuzzy AHP is used to reduce a possible number of alternatives for the CAD system to an acceptable level for further study simulation analysis. Secondly a simulation generator as an integrated part of the fuzzy AHP is used to try the remaining alternatives on the generated model of a real-life product organisation in which the final alternative will be used. The results of simulation experiments are obtained and then evaluated to reach to the ultimate CAD alternative.
Citation Count: 0
An Intelligent Approach To Cam Software Selection
(IEEE, 2012) Ayağ, Zeki
In this paper an intelligent approach is presented to help the companies select most suitable CAM software for their current and future needs. For this purpose fuzzy AHP method is used to carry out CAM selection process more effectively easily and applicable for a company. Shortly the objectives of the research are
Citation Count: 0
A Network Model for the Location-Routing Decisions of a Logistics Company
(Institute of Industrial Engineers, 2012) Sama, Funda; Yücekaya, Ahmet; Ayağ, Zeki
In this paper, part of the logistics network of one of the leading logistics companies in Turkey is analyzed. Data related to the candidate warehouse locations, supplies and demands of customers are collected. A network model is developed in order to reconfigure the logistics network. The aim of the mathematical model is to help decision makers decide on the locations of warehouses, as well as routing products from suppliers to the distribution center; from distribution center to warehouses; and finally from warehouses to customers. The mathematical model is solved optimally with LINGO solver, and the comparison of the current network with the optimal solution revealed that the overall operating costs can be reduced by approximately 7%.
Citation Count: 1
Achieving Sustainability in Solar Energy Firms in Turkey Through Adopting Lean Principles
(Mdpi, 2022) Aldewachi, Bilal; Ayag, Zeki
Lean principles and sustainability are considered important terms in business. Solar firms are witnessing great competition to fulfill energy requirements, suffering from a huge amount of waste, negatively affecting the sustainability dimensions. Thus, the aim of the study is to build a framework for solar energy firms to achieve sustainability through adopting lean principles, which will help to fix many problems as waste and costs. The method included reviewing the literature to explore the founding of the relation between the two terms, and using a questionnaire that was directed to the responsible people in Turkish solar energy firms. The results of the survey were analyzed to: (1) Find out what the responsible people think about the two terms lean and sustainability; (2) Measure the probable relationship between lean principles and sustainability dimensions by applying a linear regression test; (3) Use the results of point number two to build the framework. The result showed there was a high level of relative importance about the two terms from the point of view of managers and experts in solar firms. In addition, the study found a relationship between adopting pull and flow principles of lean, and achieving economic and social dimensions of sustainability, this finding is represented in a framework.
Citation Count: 14
An Intelligent Approach for the Evaluation of Innovation Projects
(IOS Press, 2020) Samanlıoğlu, Funda; Ayağ, Zeki
In this study, an intelligent approach is presented for the evaluation and selection of innovation projects. Selecting the best innovation project is a complicated multiple criteria decision making (MCDM) problem with several potentially competing quantitative and qualitative criteria. In this paper, two hesitant fuzzy MCDM methods; hesitant fuzzy Analytic Hierarchy Process (hesitant F-AHP) and hesitant fuzzy VIsekriterijumska optimizacija i KOmpromisno Resenje (hesitant F-VIKOR) are integrated to evaluate and rank innovation projects. In the hesitant fuzzy AHP-VIKOR, hesitant F-AHP is used to find fuzzy evaluation criteria weights and hesitant F-VIKOR is implemented to rank innovation project alternatives. A numerical example is given where five innovation projects are evaluated based on nine criteria by three decision makers.
Citation Count: 10
A Fuzzy Anp-Based Gra Approach To Evaluate Erp Packages
(IGI Global, 2019) Ayağ, Zeki; Yücekaya, Ahmet
One of the major problems that most companies face with during the implementation of an ERP system is to determine the best satisfying ERP software based on their needs and expectations. Because an improperly selected ERP software might lead to time loss and increased costs and in the long run a loss of market share. Therefore the ERP evaluation process for companies becomes to a vital point. On the other hand evaluating ERP software alternatives under a set of criteria leads us to a multiple-criteria decision making (MCDM) problem and needs to use proper MCDM methods. In the current literature a number of the MCDM methods have been proposed to solve these kinds of problems both of which are the analytic network process (ANP) of Saaty and grey relational analysis (GRA) which has been widely used in solving MCDM selection problems in various fields. Moreover in this article the authors used the fuzzy extension of the ANP method to reflect the uncertainty and ambiguity of decision maker(s) into problem in order to reach more reliable solution. As the fuzzy ANP method was used to calculate the priority weights of the evaluation criteria the GRA method with fuzzy interval-values was employed to rank a set of the possible ERP software alternatives. The proposed approach was also validated in a case study to show its applicability to potential readers and practitioners. Copyright © 2019 IGI Global. Copying or distributing in print or electronic forms without written permission of IGI Global is prohibited.
Building a Framework for Adopting Lean Principles To Achieve Sustainability in Solar Energy Firms: Turkiye as a Case Study
(Kadir Has Üniversitesi, 2022) Aldewachi, Bilal; Zeki Ayağ
The two terms lean, and sustainability have become one of the most important terms in the field of business because of their role in developing the work in line with increasing profits on the one hand and taking into account the future on the other. Solar energy firms are witnessing great competition to meet energy requirements and suffering from a huge amount of waste, which negatively affects in achieving sustainability. Hence, this study aims to build a framework for solar energy firms to achieve sustainability dimensions through adopting lean principles. The framework will help to solve problems that the solar energy sector is facing. The method in the study included reviewing the literature to examine the founding of the relation between lean and sustainability and using a questionnaire that was directed to the responsible people in Turkish solar energy companies. The results of the survey were analyzed to (1) Discover what the people in charge in solar energy firms think about lean and sustainability; (2) Measure the possible relationship between lean principles and sustainability dimensions by applying a linear regression and non-linear regression test; (3) Using the results of the second point to build the framework. The final results indicated a high level of the relative importance of the two terms from the perspective of the people in charge in the solar energy firms. Besides, the study found a relationship between adopting the two principles of lean, pull, and flow and achieving economic, social resources, and technology dimensions of sustainability; this finding is represented in a framework.