• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1993년도 가을 학술발표회논문집
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• pp.216-223
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• 1993

The safety factors of current standard code are considered to be not appropriate compared to design and construction practices, even this safety factors are not determined from probabilistic study but merely from experiences and practices. This study pripose the optimum safety indices based on expected total cost minimization using only three parameters, which are the level of the failure cost to the initial cost by improvement in safety, and the order of the initial cost function.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1994년도 가을 학술발표회 논문집
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• pp.152-159
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• 1994

One of the main objectives of the study is to propose a pratical and realistic reliability analysis by ETCM(Expected Total Cost Minimization). This study is intended to propose the safety assesment and capacity rating of existing reinforced concrete members by evaluating the safety evaluation index, that is RF(Rating Factor) from the results of the field test and inspection for 5 reinforced concrete bridges. ETCM method is used for the reliability analysis of the proposed models. The proposed reliability model and method are applied the safety assesment and system factors of reinforced concrete members.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1998년도 가을 학술발표회 논문집
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• pp.151-158
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• 1998

This paper presents an optimal decision model for minimizing the life-cycle cost of steel box girder bridges. The point is that it takes into account service life process as a whole, and the life-cycle costs include initial (design, testing, and construction) costs, maintenance costs and expected failure costs. The problem is formulated as that of minimization of expected total life-cycle cost with respect to the design variables. The optimal solution identifies those values of the decision variables that result in minimum expected total cost. The performance constraints in the form of flexural failure and shear failure are those specified in the design code. Based on extensive numerical investigations, it may be positively stated that the optimum design of steel box girder bridges based on life-cycle cost approach proposed in this study provides a lot more rational and economical design, and thus the proposed approach will propose the development of new concepts and design methodologies that may have important implications in the next generation performance-based design codes and standards.

• 산업경영시스템학회지
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• 제46권4호
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• pp.93-100
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• 2023

In this paper, an alternative inventory policy that trades off the bullwhip effect at an upstream facility with cost minimization at a current facility, with the goal of reducing system wide total expected inventory costs, when external demand distributjon is autocorrelated, is considered. The alternative inventory policy has a form that is somewhere between one that completely neglects the autocorrleation and one that actively utilizes the autocorrelation. For this purpose, a mathematical model that allows us to evaluate system wide total expected inventory costs for a periodic review system is developed. This model enables us to identify an optimal inventory policy at a current facility that minimizes system wide total expected inventory costs by the best tradeoff of the bullwhip effect at an upstream facility with cost minimization at a current facility. From numerical experiments, it has been found that (i) when the autocorrelation is negative, the optimal policy is one that actively utilizes the autocorrelation, (ii) when the autocorrelation is small and positive, the optimal policy is one that neglects the autocorrelation, and (iii) when the autocorrelation is large and positive, the optimal policy is somewhere between one that actively utilizes the autocorrelation and one that neglect the autocorrelation.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2000년도 가을 학술발표회논문집
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• pp.109-114
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• 2000

In this paper, an optimum design model for minimizing the life-cycle cost (LCC) of high-speed railway steel bridges is proposed The point is that it takes into account service life process as a whole, and thus the life-cycle costs include initial (design, testing, and construction) costs, maintenance costs, expected strength failure costs and expected serviceability failure costs. The problem is formulated as that of minimization of expected total life-cycle cost with respect to the design variables. By processing the optimum LCC design the effective and rational basis is proposed for calculating the total LCC and the sensitivity analysis of LCC is peformed. Based on a numerical example, it may be positively stated that the optimum LCC design of high-speed railway steel bridges proposed in this study provides a lot more rational and economical design, and thus the proposed approach will expedite the development of new concepts and design methodologies that may have important implications in the next generation performance-based design codes and standards.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2001년도 가을 학술발표회 논문집
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• pp.201-210
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• 2001

In this study, large-scale distributed design approach for a life cycle cost (LCC) optimization of steel box girder bridges was implemented. A collaborative optimization approach is one of the multidisciplinary design optimization approaches and it has been proven to be best suited for distributed design environment. The problem of optimum LCC design of steel box girder bridges is formulated as that of minimization of the expected total LCC that consists of initial cost maintenance cost expected retrofit costs for strength, deflection and crack. To discuss the possibility of the application for the collaborative optimization of steel box girder bridges, the results of this algorithm are compared with those of single level algorithm. From the numerical investigations, the collaborative optimization approach proposed in this study may be expected to be new concepts and design methodologies associated with the LCC approach.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 추계 학술발표회
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• pp.1090-1097
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• 2008

This study conducted the decision method of lateral flow in abutment structures founded on the soft soils and the reliability analysis on the foundation pile for abutment. On the basis of the results, this study proposed the reliability design model. Reliability analysis was conducted by applying second moment method, point estimation method, and expected total cost minimization to lateral movement index, lateral movement decision index, modified lateral movement decision index, and circular failure safety factor for the decision criteria of lateral flow. The reliability index by analysis method had a similar tendency each other. Point estimation method was found as a practical method in the aspect of convenience because it could conduct the analysis only by mean and standard deviation as well as the partial derivative on random variables was not necessary. Optimum reliability index and optimum safety according to increasing in failure factors and load ratio were analyzed and loads and resistance factors of the design criteria of optimum reliability were estimated. It presented rational design model which can consider construction level and stability and economical efficiency overall.

• 한국구조물진단유지관리공학회 논문집
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• 제6권4호
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• pp.189-199
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• 2002

This study is intended to propose a systematic procedure for the development of the conditional assessment based on the safety of structures and the cost effective performance criteria for designing and upgrading of bridge structures. As a result, a set of cost function models for a life cycle cost analysis of bridge structures is proposed and thus the expected total life cycle costs (ETLCC) including initial (design, testing and construction) costs and direct/indirect damage costs considering repair and replacement costs, human losses and property damage costs, road user costs, and indirect regional economic losses costs. Also, the optimum safety indices are presented based on the expected total cost minimization function using only three parameters of the failure cost to the initial cost (${\tau}$), the extent of increased initial cost by improvement of safety (${\nu}$) and the order of an initial cost function (n). Through the enough numerical invetigations, we can positively conclude that the proposed optimum design procedure for bridge structures based on the ETLCC will lead to more rational, economical and safer design.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2001년도 봄 학술발표회 논문집
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• pp.128-136
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• 2001

This paper presents an optimum deck and girder system design for minimizing the life-cycle cost (LU) of steel box girder bridges. The problem of optimum LCC design of steel box girder bridges is formulated as that of minimization of the expected total LCC that consists of initial cost, maintenance cost, expected retrofit costs for strength, deflection, and crack. To demonstrate the effect of LCC optimum design of steel box girder bridges, the LCC optimum design is compared with conventional design method for steel box girder bridges design. From the numerical investigations, it may be positively stated that the optimum design of steel box girder bridges based on LCC will lead to more rational, economical and safer design.

• 한국전산구조공학회논문집
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• 제15권4호
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• pp.557-566
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• 2002

본 논문에서는 강상자형교의 바닥판과 주형에 대한 생애주기비용(Life-Cycle Cost : LCC)를 고려한 최적설계 방법을 제안하였다. 생애주기비용의 최적설계 문제는 초기비용, 유지관리비용 그리고 강도와 처짐 그리고 균열에 대한 파손 기대비용의 최소화 문제로 정식화할 수 있다. 기존의 재래적인 설계방법과의 비교를 동해서 강상자형교의 생애주기비용 최적설계의 우수성을 입증하였다. 또한 수치적인 결과의 고찰을 통하여 LCC에 근거한 최적설계가 여타의 설계방법들보다 좀 더 합리적이고 경제적이며 안전한 설계를 유도하는 것으로 분석되었다.