Research of Sustainable Supplier Selection Problem Using Fuzzy Inference Systems
Turgut Hacıvelioğulları, Nurullah UmarusmanThe concept of sustainability, emerged against the concerns about environmental degradation and social inequality, has led the public and private sectors to follow sustainability policies and practices. Therefore, businesses have started to select their suppliers by evaluating them based on the sustainability criteria such as market conditions, government policies, business objectives, and geographical location. In sustainable supply chain management, possible problems can be overcome by creating a balance between economic, environmental, and social dimensions through supplier selection. Using the Mamdani-type Fuzzy Inference Systems, a new model in the on-board equipment sector has been proposed to solve the sustainable supplier selection problem of a company. The sustainability level and performance level of suppliers were simultaneously calculated based on the same rules in the proposed model. Later, the business suppliers were ranked according to the sustainability and performance levels of the suppliers. It has been determined that there are different priority rankings among the same criteria for sustainability and performance levels by using the rules in the proposed model.
Bulanık Çıkarım Sistemleri Kullanılarak Sürdürülebilir Tedarikçi Seçim Probleminin İncelenmesi
Turgut Hacıvelioğulları, Nurullah UmarusmanÇevresel bozulma ve sosyal eşitsizlikle ilgili kaygılara karşı ortaya çıkan sürdürülebilirlik kavramı kamu ve özel sektörü sürdürülebilirlik politikalarını ve uygulamalarını takip etmeye yönlendirmiştir. Dolayısıyla bu sektörlerdeki işletmeler tedarikçilerini sürdürülebilirlik kriterlerine göre değerlendirerek seçimi gerçekleştirmeye başlamıştır. Bu seçim sürecinde piyasa şartları, devlet politikaları, işletmenin hedefleri ve coğrafi konumu farklı kriterler kullanılabilmektedir. Sürdürülebilir kalkınmanın ekonomik, çevresel ve sosyal boyutlarının tedarik zinciri yönetimine entegrasyonuyla gelişen sürdürülebilir tedarik zinciri yönetiminde tedarikçi seçimiyle bu boyutlar arasındaki denge oluşturularak muhtemel sorunları üstesinden gelinebilir. Bu çalışmada araç üstü ekipman sektöründe faaliyet gösteren bir işletmenin sürdürülebilir tedarikçi seçim problemi Bulanık Çıkarım Sistemlerinin Mamdani-tipi Bulanık Çıkarım Sistem yaklaşımı kullanılarak yeni bir model önerilmiştir. Önerilen modelde tedarikçilerin sürdürülebilirlik düzeyi ve performans düzeyi aynı kurallara bağlı olarak eş zamanlı olarak hesaplanmıştır. Daha sonra tedarikçilerin sürdürülebilirlik ve performans düzeylerine göre işletme tedarikçiler sıralaması yapılmıştır. Ayrıca önerilen modeldeki kurallar kullanılarak sürdürülebilirlik ve performans düzeyleri için aynı kriterler arasında farklı öncelik sıralamasının olduğu belirlenmiştir.
The industrial revolution brought about a transition from human-based production to machine-based production, and with this development coal became the primary energy source. The invention of the internal combustion engine enabled the use of electricity and fossil fuels, resulting in rapidly developing industrialization. Increasing production activities with developing technology that have led to development moves based on economic growth and consumption has been encouraged. However, the industrialization process has revealed environmental degradation on a global scale, causing concerns about meeting the needs of future generations.
These concerns have made it difficult to develop an attitude of using scarce resources more rationally and in the long term. Activities related to the management/protection of limited resources and alternative sustainable development studies have also entered the agenda of the United Nations, independent organizations, and world leaders. Although the concept of sustainability was first expressed in the 20th century, it has inspired philosophical thoughts and applications in civilizations throughout the human history. The concept of sustainability has influenced people’s thoughts and lifestyles and has been useful in dealing with current problems. Although the origin of this concept dates back to the 1700s, it is possible to come across sustainability practices that overlap with the way of life by improving economic and social welfare without harming nature in Ancient Egypt, Ancient China, Rome, Maya, Aztec, Seljuk, and Ottoman civilizations.
The idea of sustainability comes from the concept of sustainable development. This idea essentially refers to the integration of three dimensions of sustainability, environmental, social, and economic dimensions, into business practices. By defining each dimension, it will ensure that appropriate activities are put forward to achieve or approach sustainability in daily life. The way to operationalize these three dimensions is through TBL; a concept developed by Elkington (1998) that addresses and balances the dimensions of sustainability from a microeconomic perspective. The emergence of the TBL concept has aroused great interest by changing the perspective of businesses toward sustainability. Businesses have been effective in environmental and social priority issues of sustainable development, such as reducing environmental damage and employee well-being. It is important for businesses that aim for sustainability to adopt and implement this process to their own staff and other members in the chain. Knowing which application, the supply chain concept will increase the success in understanding and implementing sustainable supply chain management. Sustainable supply chain management is an environmental and social extension of traditional supply chain management.
Sustainable supply chain management ensures coordination between members in the chain and manages the flow of materials and information. In this process, it is especially important to select suppliers that can best implement the three dimensions of sustainability. The determination of criteria is the objective of the business to manage the supplier selection process. Additionally, it is important to determine the method that will solve the problem. Therefore, businesses should determine the criteria and methods that can achieve their goals to the extent that they are aware of their goals and responsibilities. Different criteria may arise in traditional supplier selection and evaluation due to geography, location, different development levels of countries, and sectoral differences. However, price, quality, delivery time, and payment period have become important criteria in the selection process. Although the economic dimension is at the forefront in traditional supplier selection, the inclusion of social and environmental factors has made sustainable supplier selection vitally important.
The simultaneous evaluation of the performance and sustainability of suppliers of a company operating in the on-vehicle equipment sector according to the three dimensions of TBL was carried out using the proposed BÇS model. For the proposed model, first the main criteria used in the sustainable supplier selection literature were determined, and then it was asked to define additional criteria suitable for business goals. A Deputy General Manager of Business Administration determined the criteria of “product price,” “quality,” “delivery time,” and “payment period” for the economic dimension of TBL; the criteria of “improvable supplier” for the social dimension; and “renewable energy and green production” for the environmental dimension. Among these, “improvable supplier” was defined by the business decision maker. According to this criterion, the supplier must be open to development and innovation, and must develop, improve, renew itself, and create conditions that will ensure high standards by adopting the support activities provided by the business such as training, finance, and information. How the improvable supplier treats its own suppliers, customers, competitors, nature, and environment is also included. It is also important to be able to adapt to the business culture of the focal company. Accordingly, the supplier can be developed from a certain level or from scratch. Although, the improvable supplier criterion has not been mentioned in previous studies, it is possible that it covers all three dimensions of sustainability as a concept. The improvable supplier will contribute to the fulfillment and continuity of economic, social, and environmental criteria with correct training. This will positively affect the supply chain and create added value. Moreover, according to this criterion, the supplier that can be considered is required to be the best employer certified business.
After determining the operating criteria, a new model was proposed to solve the operational problem using the Mamdani-type Fuzzy Inference System. For the proposed model, membership functions were created using linguistic ranges, triangular and trapezoidal type fuzzy numbers, and performance and sustainability level outputs. Later, seventy-eight rules, used simultaneously for both outputs, were created by the Deputy General Manager of Business Administration. Based on these rules, the scores of the business suppliers were entered into the proposed model and the performance level and sustainability level scores for each supplier were determined with the suppliers being ranked. Further, 3D graphics were created for each output depending on two-input criteria, and a priority order was made between the input criteria within the framework of the rules. In the proposed model, the result was achieved with the help of rules created based on the same inputs and two outputs. This demonstrates the difference of the proposed model from other models developed for multi-output supplier selection. Plus, the model proposed can be developed as a modular FIS, as in Carrera and Mayorga (2008) and Amindoust et al. (2012), and it may be a guide for subsequent studies.
