점용접 위치의 최적화를 위한 CAD Tool 개발

류시욱,이종찬,이태수,Ryu, Si-Uk,Lee, Jong-Chan,Lee, Tae-Soo 대한기계학회 1998 大韓機械學會論文集A Vol.22 No.1

Spot welding palys a key role in increasing productivity and weight reduction of the final products. This paper proposes a systematic approach on the design of spot weld configuration, dealing with the requried number and location of spot weld joints under the given design parameters, such as the applied loads, lap area, and individual spot weld strength. The optimal design of a spot-welded joint is postulated as a state when the safety factors of all spot weld points (i) are evenly distributed and (ii) reach maximum value. A CAD program is developed to arrange the optimal location of each spot weld based on the derived objective function and constraints. The CAD tool integrates the optimization procedure with Finite Element Analysis (FEA) code through an interface. The interface automatically provides geometrical data and mesh configuration for different spot weld locations to FEA model. It also extracts the transmitted load of each spot weld from the FEA code, and allows the optimization code predict an improved arrangement of spot weld locations. The feasibility of the developed approach is demonstrated by the selected examples.

AHP를 이용한 불안전행동 배경요인 평가에 대한 연구

류시욱,허덕규 대한안전경영과학회 2009 대한안전경영과학회 학술대회논문집 Vol.2009 No.11

Most industrial accidents occur when the workers' unsafe behavior and the unsafe situation of workplace take place at the same time. Although human's unsafe behavior is indispensable to work field, the evaluation scheme to detect the causes for the accident resulted from human's unsafe behavior and counterplan should be prepared to prevent and reduce accident. To do this, we first classify the specific background factors in terms of human inner factor and environment factor and then develop the AHP (Analytic Hierarchy Process) model to analyze the background factors that affect the worker's unsafe behavior. We also develop a checklist to be able to evaluate the occurrence possibility of individual worker's unsafe behavior.

AHP를 이용한 불안전행동 배경요인 평가에 대한 연구

류시욱,허덕규 대한안전경영과학회 2009 대한안전경영과학회 학술대회논문집 Vol.2009 No.1

엔트로피법과 Fuzzy ELECTRE III를 이용한 고장모드영향분석

류시욱 대한안전경영과학회 2014 대한안전경영과학회지 Vol.16 No.4

Failure modes and effects analysis (FMEA) is a widely used engineering tool in the fields of the design of a product or a process to improve its quality or performance by prioritizing potential failure modes in terms of three risk factors―severity, occurrence, and detection. In a classical FMEA, the risk priority number is obtained by multiplying the three values in 10 score scales which are evaluated for the three risk factors. However, the drawbacks of the classical FMEA have been mentioned by many previous researchers. As a way to overcome these difficulties, this paper suggests the ELECTRE III that is a representative technique among outranking models. Furthermore, fuzzy linguistic variables are included to deal with ambiguous and imperfect evaluation process. In addition, when the importances for the three risk factors are obtained, the entropy method is applied. The numerical example which was previously studied by Kutlu and Ekmek‡ioğlu(2012), who suggested the fuzzy TOPSIS method along with fuzzy AHP, is also adopted so as to be compared with the results of their research. Finally, after comparing the results of this study with that of Kutlu and Ekmek‡ioğlu(2012), further possible researches are mentioned.

공급자 선정을 위한 주관적 가중치를 갖는 퍼지 ELECTRE-III 다기준 의사결정 기법의 개발

류시욱 대한설비관리학회 2019 대한설비관리학회지 Vol.24 No.2

In this paper, among multi-criteria decision making (MCDM) procedures, the ELECTRE(Elimination and (Et) Choice Translating Reality)-III is revised to solve the supplier selection problem where both a criteria evaluation matrix and a decision matrix are linguistically evaluated by a group of decision makers. Final weights are obtained through subjective weights from criteria matrix and weights of the entropy from decision matrix. In addition, the fuzzy theory for dealing with ambiguity of linguistic variables is incorporated to develop the new procedure of the ELECTRE-III. The proposed procedure is tested through the numerical example which was used in the previous research with the fuzzy TOPSIS (technique for order preference by similarity to ideal solution). The results of the proposed procedure are compared to validate the outranking orders of suppliers. On the other hand, sensitivity analyses for the five cases with different subjective weights are carried to investigate the changes in the outranking orders of suppliers. In conclusion, the fuzzy ELECTRE-III procedure with entropy weights considering subjective judgement seems to be useful in the supplier selection problem.

AHP를 이용한 철도종사자의 안전업무 수행도 평가에 관한 연구

류시욱 대한안전경영과학회 2007 대한안전경영과학회지 Vol.9 No.4

It is known that human factors account for 80 percent of all railway accidents. To reduce human errors must be the most efficient shortcut to railway safety. For public transportation employees like railway, the more delicate safety management should be executed in individual level. However, there are rarely efforts to improve safety performance of workers who are the subject operating the railway system. This paper develops a hierarchy model to evaluate the human safety performance in railway industry. To evaluate the model, AHP (Analytic Hierarchy Process) methodology is adopted. The hierarchy model is composed of four levels which are objective, two criteria, specific factors of criteria, and rating scales. In addition, since employees for evaluation are over 10, the pairwise comparisons for rating scales are carried out by the absolute measurement. We explore the applicability of AHP to the performance evaluation of railway safety workers by an example and also investigate the changes of alternatives that are railway employees according to the changes of human characteristic which is one of criteria.

정보보안 예산 수립에서 퍼지 AHP의 적용을 통한 위험 비용 분석

류시욱,허덕규 대한안전경영과학회 2012 대한안전경영과학회지 Vol.14 No.3

정보의 부재를 고려하는 다기준 의사결정 모형의 개발과 공급자 선정에의 적용

류시욱 ( Si-wook Ryu ) 대한설비관리학회 2016 대한설비관리학회지 Vol.21 No.4

Supplier selection, which is substantial to make a successful supply chain relationship, is the complex decision making problem with both conflicting multiple criteria and usually several decision makers. This paper extends the existing MCDM (multi-criteria decision making) method to the situation considering lack of information caused by ignorance of knowledge, especially when lack of information happens at all levels including criteria in the hierarchical decision structure. To hurdle the ambiguity and incompleteness of evaluation process, fuzzy linguistic variables are used when the matrices for criteria and alternatives are built. In addition, to deal with lack of information, Demspter-Shafer (DS) evidential theory is applied to the MCDM evaluation scheme. Belief intervals composed of belief function and plausible function are converted to crisp values through the PPT (pignistic probability transformation) method and the quadratic programming with weighted loss objective function. All of the procedures are implemented in detail for a supplier selection example, which shows the newly proposed MCDM evaluation scheme to be applicable and effective.

서로 다른 Fuzzy AHP 방법의 혼합 적용과 FMEA 평가에의 응용

류시욱 ( Si Wook Ryu ) 대한설비관리학회 2013 대한설비관리학회지 Vol.18 No.4

Failure mode and effects analysis (FMEA) provides an effective way for improving product design and process planning by prioritizing potential product and process failures so that preventive measures can be taken in early stages. However, one of the drawbacks of the FMEA is especially the risk priority number (RPN) as determined by multiplying the converted scores of the three predefined factors without considering their relative importance. This paper addresses a compromising measure to mix the existing two fuzzy AHP methods when the three factors with their relative importance should be considered and there are over 10 potential failure odes to be evaluated. A numerical example is shown to explain the procedures and to testify the applicability of the proposal.

퍼지 AHP와 퍼지 TOPSIS의 통합과 공급자 선정문제에의 적용

류시욱 ( Si Wook Ryu ) 대한설비관리학회 2012 대한설비관리학회지 Vol.17 No.3

Under many conditions, exact data are inadequate to model real-life situation and fuzzy logic can be incorporated to handle the vagueness of the decision makers. Fuzzy analytic hierarchy process (fuzzy AHP) and fuzzy technique for order performance by similarity to ideal solution (fuzzy TOPSIS) are widely used for tackling multi-criteria decision making (MCDM) problems in real situations for these reasons. Some researches that incorporate the different decision making methods have been introduced in order to compensate the weights among criterion. This paper first presents a hybrid multi-criteria decision making procedure using fuzzy AHP and fuzzy TOPSIS. This proposed procedure is used to solve the supplier selection problem to investigate the applicability of procedure. More specifically, the fuzzy decision matrix is identified by fuzzy TOPSIS and then fuzzy AHP is employed to obtain the crisp values for each alternative to make the final decision. To demonstrate the applicability of the proposed approach, an illustrative example for supplier selection problem is presented and the results are analyzed by comparison of the proposed approach and fuzzy TOPSIS.