11979 FACTA UNIVERSITATIS Series: Mechanical Engineering https://doi.org/10.22190/FUME230614026B © 2020 by University of Niš, Serbia | Creative Commons License: CC BY-NC-ND Original scientific paper APPLICATION OF THE DIBR II – ROUGH MABAC DECISION-MAKING MODEL FOR RANKING METHODS AND TECHNIQUES OF LEAN ORGANIZATION SYSTEMS MANAGEMENT IN THE PROCESS OF TECHNICAL MAINTENANCE Darko Božanić1, Igor Epler1, Adis Puška2, Sanjib Biswas3, Dragan Marinković4,5, Stefan Koprivica5 1Military Academy, University of Defence in Belgrade, Belgrade, Serbia 2Department of Public Safety, Government of Brčko District of Bosnia and Herzegovina, Brčko, Bosnia and Herzegovina 3Decision Science & Operations Management Area, Calcutta Business School, Diamond Harbour Road, West Bengal, India 4Faculty of Mechanical Engineering, University of Niš, Niš, Serbia 5TU Berlin, Department of Structural Analysis, Berlin, Germany 6Faculty of Construction Management, Union - Nikola Tesla University, Belgrade, Serbia Abstract. This paper presents a multi-criteria decision-making model based on the application of two methods, DIBR II and MABAC. The DIBR II method was used to define weight coefficients. The MABAC method was used to rank alternatives, and it was applied in a rough environment. Four experts were engaged in defining the criteria and alternatives as well as in the relation of criteria. The model was applied for ranking the methods and techniques of Lean organization systems management in the maintenance of technical systems of special purposes. At the end of the application was conducted a sensitivity analysis which proved the stability of the obtained results. Key words: Defining Interrelationships Between Ranked criteria II (DIBR II), Multi- Attributive Border Approximation area Comparison (MABAC), Rough number, Lean concept Received: June 14, 2023 / Accepted August 11, 2023 Corresponding author: Darko Božanić Military Academy, University of Defence in Belgrade, Veljka Lukica Kurjaka 33, 11040, Belgrade, Serbia E-mail: darko.bozanic@va.mod.gov.rs 2 D. BOŽANIĆ, I. EPLER, A. PUŠKA, S. BISWAS, D. MARINKOVIĆ, S. KOPRIVICA 1. INTRODUCTION By analyzing basic technological process of technical maintenance (TM) of special purpose technical systems (SPTS) in a real maintenance workshop in the Army of Serbia, and its documentation which often lacks the data related to the organization of the process itself, time gaps were observed between the planned (normed) times of TM cycle of SPTS and the realized times of the SPTS technical maintenance cycle [1]. The periods of time in which SPTS wait for operation (considering administration and logistics) are generally not recorded in the workshop documentation, which makes it difficult to discuss about with the purpose of their reduction or total elimination. Many SPTS TM processes are not controlled, causing constant losses in the execution of TM on SPTS. Existing technological TM documentation for the most of the SPTS is “poor” regarding maintenance process management. For that reason, preparing computer data for software information system is very difficult as it relies only on currently available information from the TM technological process. Obviously, under such circumstances the management of SPTS TM processes must be fundamentally changed, primarily in terms of intensifying research and development of practical methods and techniques based on new concepts of maintenance, which are applied and constantly improved by leading companies in the neighborhood and in the world [2]. However, this is easier said than done. There are many difficulties in the management of TM of SPTS, and the most frequent and influential are as follows: poor quality and reliability of input data primarily contained in technological documentation; complexity of the maintenance system (CoM) of SPTS; many years of lack of investment in the management of TM, lack of exchange of work technologies, knowledge and innovations and inadequate training of top management for TM of SPTS to make them able to recognize and decide what is necessary and important to change in the maintenance management of SPTS so as to minimize losses. By eliminating negative effects of the mentioned factors, based on Lean organization systems management, current state of the work process and organization of TM of SPTS would probably change qualitatively. Qualitative changes would be reflected in [3]: - shortening of SPTS TM cycle, - optimal use of available capacities (spatial, human, material), - reduction of costs per every maintained SPTS (increasing efficiency) and - increased effectiveness of the TM process of SPTS. However, the application of all methods and techniques of Lean organization systems management requires significant investments. Considering this, a model for evaluation and ranking of the methods and techniques of Lean concept was developed. Depending on available resources, these methods and techniques (alternatives) would be applied in practice, primarily the first-ranked ones, and when available resources allow, the other alternatives. Previous research in the field of organization systems management [4,5] have proven positive effects of applying the Lean concept [6,7] in terms of the reduction of resources, both human and material, respectively increasing effectiveness and efficiency. There are indications that the application of the methods and tools of Lean organization systems management [8,9] can contribute to the improvement of current situation considering CoM of SPTS. The problem of applying Lean organization systems management has been Application of the DIBR II – rough MABAC Decision-Making Model for Ranking... 3 discussed in several studies. In the following text, a part of the published research is analyzed. Tamanna and Rahman [10], based on the data of periods of operations until failure, criticality and consequences of failure of key equipment for maintenance of SIMGA1 shipyard, wanted to analyze and select the optimal ship maintenance strategy with the goal of increasing the reliability and availability of the maintenance equipment and tools, reducing operating and production costs and increasing the shipyard's competitiveness. They observed the opportunity for improvement of shipyard maintenance in the application of Lean management tools. By using the AHP method, it was made a selection of the most effective Lean tools out of ten available. Singha Mahapatra and Shenoy [11] indicate the constant need of organizations for maintenance and services providing the elimination of activities and processes that do not contribute to the creation of new value for the customer or user, respectively, to the reduction of the price of the product or service. The authors state that the most managers of maintenance systems practically apply the tools of Lean management in different ways, because these proved satisfactory improvements in a relatively short period of use. Through their study, the authors strive to improve the methodology of selecting and applying Lean tools by identifying unique factors consisting the basis for evaluation of the existing rationality of maintenance in any maintenance organization, and which are the basis for measuring improvements after the application of Lean tools in a specific organization. Bhebhe and Zincume [12] analyzing systematically broad literature and applying general scientific method of deduction concluded that correctly dimensioned, constructed, properly exploited transport network with qualified managers was the key of economic power of every state. Based on the same data sources, they claimed that the most countries improved their economies by investing in transportation sector by identifying unnecessary costs generators, respectively, the losses within the maintenance function in transport companies. Observed cost generators were eliminated or reduced by systematic selection and application of Lean management tools that had already given the best results in the similar systems around the world. The paper provides guidelines for the improvement of overall condition by reducing unnecessary costs within transportation systems maintenance department, but also points out the opportunities for adjustment of application methods and its dynamics taking into account the specificities of as many transport companies as possible. Korchagin et al. [13] state that nowadays aircraft manufacturers around the world encounter the need and possibility for improvement of position and competitiveness of the aircraft manufacturing industry after the sale of the aircrafts. They quote that for hitting this goal the crucial thing is the improvement of the aircraft maintenance organization within all the phases of its lifespan by using the concepts such as Lean and Industry 4.0. In this paper was performed the integration of Lean management and Industry 4.0 approaches, for the purpose of aircrafts maintenance, their modeling and simulation of their joint impact on the improvement of aircraft maintenance in the AniLogic simulation system. The results of the simulation showed that the simultaneous use of Lean management tools and Industry 4.0 from the beginning of the aircraft exploiting life in aviation industry would provide good results which would reflect in the aircraft maintenance efficiency increase, through the identification of bottlenecks in the process 4 D. BOŽANIĆ, I. EPLER, A. PUŠKA, S. BISWAS, D. MARINKOVIĆ, S. KOPRIVICA and making the right decisions in the direction of constant management of the maintenance process quality. Dragone et al. [14] in their paper emphasize that during the lifetime of the residential and commercial buildings are not carried out all the necessary maintenance activities often, which can cause serious damage and accidents. They consider that the maintenance of facilities is essential for the effectiveness of their utility value, as well as for the safety of the facilities. Traditional concepts of building maintenance management became ineffective over time, and do not provide good results because these are not oriented towards the processes and increasingly complex users’ demands and of the objects of work themselves – buildings. The authors deem that Lean maintenance management, with its principles and methods, can provide good solutions, applicable in the practice of facility maintenance. One of the most important parts of any decision-making process is the selection of the methods to be used [15-18]. Of course, additional dilemmas in these processes arise when choosing a possible way to modify standard methods, and for the purpose of better treatment of uncertainty in the decision-making process [19-22]. Through the analysis of the available studies, and taking into account the nature of the problem, two methods of multi-criteria decision-making were used in this research. The first method is Defining Interrelationships between Ranked criteria II (DIBR II), which is used for obtaining weight coefficients of criteria. This method is shown through the process of group decision-making. The DIBR II method is presented only in the study by [23] and it has not been used so far for solving complex decision-making problems. However, the simplicity that this method provides in communication with experts, as well as the simple mathematical model, recommended this method for solving the mentioned problem. The second method used in ranking of alternatives is MABAC, which proved as a very reliable one in up to date conducted researches. Considering the values, which were assigned to the alternatives at the beginning of the decision-making process when these were evaluated according to the criteria, the MABAC method was applied in a rough environment. Rough numbers were combined with decision-making methods in a large number of studies. Badi and Abdulshahed [24] used rough numbers to modify the AHP method, while in the study by [25] was presented the combination of rough numbers with DEMATEL method. Qi et al. [26] combine rough numbers with VIKOR method, Song et al. [27] with TOPSIS method, and Arsić et al. [28] with MAIRCA method. Rough numbers are commonly used in combination with fuzzy numbers, as in the studies by [29- 31]. The MABAC method is modified in literature by using rough numbers in multiple studies as [32-36]. Through the analysis up so far, two main contributions of this paper stand out. The first one is the application of the DIBR method in multi-criteria group decision-making, and for the first time as a part of the process of solving a real problem. The second contribution of the paper is related to the solving of a case study, respectively, the problem of ranking the methods and techniques of Lean concept in order to improve the management of the work process and the organization of the TM of SPTS in the Army of Serbia. The paper consists of several parts. In the second part the applied methods are described. Through the third part, that is, the case study, the definition and calculation of Application of the DIBR II – rough MABAC Decision-Making Model for Ranking... 5 the weight coefficients of the criteria and the ranking of alternative solutions are carried out. The fourth part deals with sensitivity analysis, and at the end of the paper is provided the conclusion of this research. 2. DESCRIPTION OF THE APPLIED METHODS This section describes the methods of DIBR II rough MABAC model. The phases and steps of the model are presented in the Fig. 1. Phase 1: Defining the criteria and calculation of weight coefficients of criteria using DIBR II method Step 1. Definition of criteria Step 2. Ranking criteria by their importance/weight Step 3. Defining significance ratio between criteria Step 4. Calculation of the relation of the most significant criterion with other criteria Step 5. Calculation of the value of the most significant criterion Step 6. Calculation of weight coefficients of other criteria Step 7. Evaluation of quality of defined significance of the adjacent criteria Step 8. Aggregation of weight coefficients of criteria for each expert Phase 2: Identification and ranking of alternatives using rough MABAC method Step 1. Forming of initial decision-making matrix Step 2. Normalization of the elements of the initial decision-making matrix Step 3. The calculation of the elements of the weighted matrix Step 4. Defining border approximation area matrix Step 5. Calculation of the matrix elements for alternatives distance from the BAA Step 6. Ranking of alternatives Step 7. Converting a rough number into the crisp value Phase 3: Sensitivity analysis through the changes of weight coefficients of criteria Fig. 1 DIBR II – rough MABAC model As it can be observed from the Fig. 1, the model has three phases, where the criteria and their weight coefficients are defined first. Next, in the second phase of the model, the selection of the best alternative is made and at the end, it is checked the sensitivity of the model. 2.1 Defining Interrelationships Between Ranked Criteria II Method The DIBR II method is developed by Božanić and Pamučar [23]. The method was developed for defining weight coefficients of criteria and consists of eight steps presented below. Step 1. Definition of criteria. As a part of the first step, a set of criteria is defined C={C1, C2,...Cn}, based on which the alternative solutions are ranked. Step 2. Ranking criteria by their importance/weight. All the criteria in the set C are ranked from the most to the least significant. For simple presentation of the method, the set of criteria is defined so that the criterion 1C is the most significant, while the criterion Cn is the least significant, respectively, it is defined as follows C1>C2>C3>...>Cn. Step 3. Defining significance ratio between criteria. 6 D. BOŽANIĆ, I. EPLER, A. PUŠKA, S. BISWAS, D. MARINKOVIĆ, S. KOPRIVICA Step 3.1. Defining significance ratio between adjacent criteria. For each two adjacent criteria, their significance ratio is defined (ηj,j+1 where  , 1 1,2 2,3 3,4 1,, , ,...,j j n n      ). Thus, for example, for the comparison of the criteria C1 and C2 the significance ratio η1,2 is defined. For this significance ratio it is valid that ηj,j+1≥1. The value ηj,j+1 shows how much more significant the criterion Cj is than the criterion Cj+1. According to everything stated, the following relations are defined through this step: 11 2 1,2 1,2 2 : :1 w w w w     (1) 22 3 2,3 2,3 3 : :1 w w w w     (2) ... 1 1 1, 1,: :1 n n n n n n n n w w w w       (3) Step 3.2. Defining significance relations between the most and the least significant criteria. In this step, the following relation is defined: 11 1, 1,: :1n n n n w w w w     (4) This relation has the role of the control factor in evaluating the quality of the defined significance of the adjacent criteria. Step 4. Calculation of the relation of the most significant criterion with other criteria. Based on Eqs. (1-3), the value of the second and the other lower in range criteria is presented through the most significant criterion, as follows: - Based on Eq. (1), the value of the weight coefficient 2w is obtained: 12 1,2 w w   (5) - Based on Eqs. (2) and (5), the value of the weight coefficient 3w is obtained: 2 13 2,3 1,2 2,3 w w w       (6) - Based on Eq. (3), the value of the weight coefficient nw is obtained: 1 1,2 2,3 1,... n n n w w         (7) Step 5. Calculation of the value of the most significant criterion. If it is as follows: Application of the DIBR II – rough MABAC Decision-Making Model for Ranking... 7 1 1 n j j w   (8) upon applying Eqs. (5-8), the result yields: 1 1 11 1,2 1,2 2,3 1,2 2,3 1, ... 1 ... n n w w w w                 (9) From Eq. (9), the value of the weight coefficient of the most significant criterion is obtained as: 1 1,2 1,2 2,3 1,2 2,3 1, 1 1 1 1 1 ... ... n n w                 (10) Step 6. Calculation of weight coefficients of other criteria. Applying Eqs. (5-7), the remaining weight coefficients of criteria, w2, w3,…,wn, are obtained. Step 7. Evaluation of quality of defined significance of the adjacent criteria. The relations of significance of the adjacent criteria need to be checked, to avoid as much as possible subjectivity of the decision makers. Step 7.1. Evaluation of quality of defined significance values. The evaluation of quality of defined significance values is made based on the relation of the significance of the most and the least significant criterion (η1,n). The value of the least significant criterion can be obtained from Eq. (4): 1 1, k n n w w   (11) where k nw presents the control weight coefficient of the criterion Cn. The values wn and k nw should be approximately equal. If their deviation amounts to 10% approximately, it can be concluded that the relations of significance of the adjacent criteria are defined with quality, and vice versa. Checking of the deviation is done by applying the expression: 1 n n k n w d w   (12) where dn presents the value of the deviation of the weight coefficients of the criterion Cn. If the condition 0 ≤ dn ≤ 0.1 is met, then the evaluations of the significance relations of the adjacent criteria are defined with quality, i.e. these meet the requirements. If dn > 0.1, it is necessary to define new relations between the criteria. However, since the research is usually an extensive process engaging significant resources, an additional step can be applied in order to find an error. In such cases, Step 7.2 is applied. Step 7.2. Additional evaluation of quality of the defined significance of the adjacent criteria. Before returning to defining relations of significance of the adjacent criteria, it is 8 D. BOŽANIĆ, I. EPLER, A. PUŠKA, S. BISWAS, D. MARINKOVIĆ, S. KOPRIVICA possible to make additional quality control. For this purpose, the step from Step 7.1 is repeated, in which the relations between the criteria Cn-1 and Cn-2 are defined. For this procedure, it is necessary for the decision-maker to define new relations: 11 1 1, 1 1, 1 1 : :1n n n n w w w w         (13) 11 2 1, 2 1, 2 2 : :1n n n n w w w w         (14) Then, it is calculated: 11 1, 1 k n n w w     (15) 12 1, 2 k n n w w     (16) where 1 k nw  and 2 k nw  are the control weight coefficients of the criterion Cn-1 respectively, Cn-2. Finally, the value is obtained: 1 1 1 1 nn k n w d w      (17) 2 2 2 1 nn k n w d w      (18) Here, dn-1 and dn-2 are the values of deviation of the weight coefficients of the criteria Cn-1 and Cn-2, respectively. If the conditions  1 0, 0.1nd   and  2 0, 0.1nd   are met, it can be concluded that there was an error in defining the relations of significance between the most and the least significant criterion (η1,n). In that case, the existing results can be accepted or the values can be defined again (η1,n) and quality checked again as well. Briefly said, if  1 0, 0.1nd   or  2 0, 0.1nd   , the complete procedure of defining the relations of significance and calculation of the weight coefficients must be repeated. Step 8. Aggregation of weight coefficients of criteria for each expert. The previous seven steps refer to the definition of weight coefficients when decisions are made by a single decision maker, i.e. an expert. In situations where the decision is made by several people, it is necessary to aggregate their opinions. For the purposes of this model, the weigh coefficients of the criteria were aggregated, which were obtained for each expert separately, using the Bonferroni aggregator: Application of the DIBR II – rough MABAC Decision-Making Model for Ranking... 9 , 1 1 ( ) ( ) ( 1) l a e p u q i i i e u e u w w w l l                (19) where l is the number of experts, a iw are the aggregated values obtained by applying the Bonferroni aggregator, p,q ≥ 0 are the stabilization parameters of Bonferroni aggregator, e and u are the e-th or u-th expert, where 1 ≤ e, u ≤ l. 2.2 Rough MABAC method The MABAC (Multi-Attributive Border Approximation area Comparison) method belongs to the group of newer and frequently applied methods. This method was developed by Pamučar i Ćirović [37]. In this paper, the method is improved by applying rough numbers. In the next part of the paper, the basic assumptions about rough numbers and the presentation of the steps of the MABAC method in rough environment are given. In the 1990s, Pawlak [38,39], developed rough sets. Some twenty years later, inspired by the idea of rough sets, Zhai et al. [40], developed rough numbers. Rough numbers prove to be very useful in considering uncertainty. A brief description of rough numbers is given below. Definition 1 [40]. Let’s assume that there is a set F consisting of (K1, K2, K3,…, Kt), which represents all the objects in a particular universe U. At the same time, there is Y presenting boundary objects of the universe U. If all the elements form part of the sequence K1