Green supplier selection with Edas and Vikor methods in the electricity industry

For years, businesses have polluted nature with toxic liquid, solid and gaseous wastes and have not considered the damage they have caused to the earth. The point of view of the importance and observation of nature came to the fore by gaining importance in the 90s. With this point of view, our age approaches nature with a different sensitivity, allowing businesses to progress in an industrial sense. Today, businesses reveal their primary purposes with this point of view. In this way, businesses operating in different fields support producing environmentally friendly end products. At the same time, they come to the fore with green practices by preserving the balance of nature at every step of the product life cycle. Making the produced paper reusable by paper enterprises and producing with environmental sensitivity by plastic production enterprises are studies in this field and are very important applications today. Apart from these sectors, many businesses carry out production with an environmentally friendly approach and reflect this understanding in all production processes. Choosing the right green supplier is essential in enterprises' environmentally friendly production perspective. Consumers also have this nature-friendly view and the legal plans made are also turning businesses towards the green supply chain approach. The aim of minimizing the dangers that can be given to nature increases the efficiency of the management activities of the green supply chain. Targeting environmental approaches in green supply chain management takes it to an important point. Businesses that adopt this approach; set a wide range of targets and present them to their suppliers to optimize their progress in the suppliers they own. Thus, businesses have eco-friendly suppliers that can leave their competitors behind. This issue is at the forefront of the work that many businesses see as a priority. The development and implementation of these studies can put businesses in difficulties in terms of cost. One of the challenging processes is determining the best among these studies and implementing it. At the same time, lack of information, failure to achieve the desired targets in the studies, and the infrastructure problems of the enterprises can create some problems. In today's conditions, businesses have more than one supplier, and they must choose the best one with the greenest approach. This situation raises supplier selection/decision-making problems for businesses, which contain many uncertainties. It becomes even more critical that decision-makers make their decisions objectively and accurately, especially if the number of criteria and alternatives is high. In this case, multi-criteria decision-making methods make it possible to evaluate with a scientific and systematic approach in case of multiple alternatives and criteria. Due to this feature, it is widely used in green supplier selection problems. Multi-criteria decisionmaking techniques enable us to overcome the inadequacy of quantitative information. At the same time, these techniques are robust in representing the ideas of experts in their fields. In this context, these techniques can handle profit and environmental criteria together in green supplier problems and offer a competitive advantage for businesses. RoHS analysis is currently used in the enterprise, the subject of this study, where the green supplier selection study is carried out. With the RoHS analysis, the company chooses a green supplier. With this analysis technique, mercury, cadmium, lead, and chromium values are compared and analyzed with the required standard measurement values, and green supplier selection is made. The critical part, the basis for supplier selection, is the bolts used in the automatic fuses produced in the enterprise where the study is carried out. In the study carried out in this context, EDAS and VIKOR methods, which are multi-criteria decision-making techniques, were handled separately. The best green supplier was selected for the enterprise, and its consistency with RoHS analysis was examined. For this purpose, firstly, the opinion of the experts in the enterprise obtained from the literature, compliance quality, green product design, green purchasing, and green production criteria were determined. EDAS and VIKOR techniques, which are multi-criteria decision-making techniques, have been preferred because they are influential in decision-making under uncertainty and provide a quick solution to complex problems with an objective approach. The study used RoHS analysis to test the validity of green supplier selection. EDAS and VIKOR techniques, which are one of the multi-criteria decision making techniques, are the most effective in decision making under uncertainty. These techniques capture very complex problems quickly by filtering the appropriate step. Multi-criteria decision-making is defined as the decision-making process in which the purpose is evaluated for each option simultaneously in the decision-making process. The biggest difficulty in this process is that an option achieves the optimum benefit in terms of one criterion and cannot achieve the same (same) benefit in terms of another criterion. It expresses a point of view based on the selection of the option in which all the criteria provide maximum benefit. Multi-Criteria Decision Making (MCDM) deals with the decision-making process influenced by many criteria. Multi-criteria decision making; Multi-objective decision making is divided into two groups consisting of multi-quality decision making. The two groups are generally considered in the same sense. Whether the decision space is continuous or discrete is the determining factor in these two groups. Problems in which the number of options are infinite become multi-objective decision making problems. An example of this is mathematical programming. Although multi-criteria decision-making methods have multiple and different structures, some aspects are common. Alternatives, criteria, incomparable units of measure, criterion weights, decision matrix constitute the common aspects of multi-criteria decision making methods In multi-criteria decision making methods, criteria are weighted. Different decisions are made by weighting the criteria. In multi-criteria decision-making methods, weight assignments should be made according to the criteria. It is a very rare event that all criteria are evaluated with exactly the same measurement units in the decision-making problem. The comparison of criteria for non-identical unit values is called the normalization process . In the literature, criteria weighting methods are considered subjectively and objectively. Delphi is shown as an example of subjective methods. Objective methods, on the other hand, can be described as Entropy Weighting Method, Importance Determination of Criteria by Correlation between Criteria method or multi-objective programming technique as models. In subjective methods, while the evaluation criteria xxiii are weighted according to the choices of the decision makers; In objective methods, weighting is done according to real data. The common feature of all the methods is based on the weighting process by using both the judgments of the decision makers and the numerical information simultaneously. Multi-criteria decision making problems are expressed in matrix form. In this matrix, alternatives, decision criteria, weights of decision criteria are considered as the element of the matrix that expresses the success of the alternative. there are . Multi-criteria decision making methods are based on determining the optimum choice and grouping the alternatives There are many methods used in multi-criteria decision making in the literature. Many methods have different features according to their structure. The methods used in multi-criteria decision making are grouped as deterministic, stochastic and fuzzy methods. Grouping process is done according to the type of data and the number of decision makers, as single decision maker techniques and multiple decision maker techniques . The main methods used in multi-criteria decision making; Weighted Product Models can be arranged as Analytical Hierarchy Process (AHP), Electre, Topsis, Promethee. The Analytical Hierarchy Process (AHP) is a multi-criteria decision-making technique developed through Saaty. The steps of the AHP method are defining the problem, structuring the hierarchical order, creating binary comparison matrices for the criteria, determining the importance levels of the criteria, measuring the consistency, determining the importance levels of the alternatives according to each of the criteria, and determining the percent importance of the alternatives . The VIKOR method is a multi-criteria decision-making technique that obtains the optimum ranking of options by utilizing criterion weights obtained by AHP or other methods under agreed conditions. VIKOR, one of the multi-criteria decision-making methods, aims to optimize multi-criteria decision systems and to provide maximum group benefit. This method is a multi-criteria decision making method that uses each value of the alternatives to achieve the most appropriate ranking. The VIKOR technique aims to get closer to the optimum solution . It is used quite frequently in many fields. The VIKOR method is mostly used in robot selection, water resources planning, material selection and risk assessment . Many methods have been developed to solve business problems. Solutions to single-objective decision making problems are developed with linear and non-linear programming and integer programming. Linear programming is the most widely used method. While it is the method applied to solve the problems of the enterprises; The result it produces may not produce the desired result with the production method. In the economic process, inputs and outputs may conflict with indivisibility problems. Integer programming solves this division. Integer linear programming model is a mathematical programming designed on the basis that all parameters take non-negative integer values. In integer linear programming, some or all of the variables take integer values . There are some differences between linear programming model and integer programming. In linear programming, decision parameters are required to be zero or greater than zero. In integer programming, it is required that the decision variables take a large integer value equal to zero. Choosing the right supplier has an important place for businesses. With the right supplier selection, businesses can find the opportunity to achieve successful service quality. Production in companies consists of many rings. Another part of this ring is suppliers. At this point, it reveals how influential the selection of suppliers is. In particular, the fact that businesses can provide good quality service to their customers, improve their process processes, reduce the raw material used in production and production costs, is achieved by choosing the right supplier. Supplier companies that are not selected optimally increase the process processes of the enterprises and cause an increase in the time to respond to customer expectations. In addition, wrong supplier selection creates serious financial losses for businesses. A correct supplier must comply with the management principles of the enterprise. Suppliers who are in constant communication with the enterprises respond to the problems of the enterprises in a very short time. A consistent management structure of the suppliers and at the same time their technology capacities must be developed. RoHS analysis is currently used in the enterprise where this study is carried out. With the RoHS analysis, the appropriate green supplier is selected on behalf of the enterprise. At the same time, with this analysis technique; The mercury, cadmium, lead, chromium values are compared and analyzed with the standard measurement values, and the green supplier is selected. In the study, testing the validity of green supplier selection was aimed with different techniques. For this purpose, firstly the opinion of the experts in the enterprise and obtained from the literature; compliance quality, green product design, green purchasing, green production criteria were determined. EDAS and VIKOR methods, which are multi-criteria decision-making techniques, were handled separately and the optimum green supplier was selected for the enterprise and its consistency with RoHS analysis was examined.