• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 2004년도 춘계공동학술대회 논문집
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• pp.102-106
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• 2004

The purpose of this paper is to develope a large-scale mixed integer program MIPBB. In this paper, the various issues such as branching strategies, searching and bounding strategies, storing basis information, handling numerical instability, that are important for developing a large-scale mixed integer programming program, are considered. And the experimental results of MIPBB are presented and compared to those of GLPK.

• 산업경영시스템학회지
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• 제44권1호
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• pp.26-36
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• 2021

The topic of this study is the field of humanitarian logistics for disaster response. Many existing studies have revealed that compliance with the golden time in response to a disaster determines the success or failure of relief activities, and logistics costs account for 80% of the disaster response cost. Besides, the agility, responsiveness, and effectiveness of the humanitarian logistics system are emphasized in consideration of the disaster situation's characteristics, such as the urgency of life-saving and rapid environmental changes. In other words, they emphasize the importance of logistics activities in disaster response, which includes the effective and efficient distribution of relief supplies. This study proposes a mathematical model for establishing a transport plan to distribute relief supplies in a disaster situation. To determine vehicles' route and the amount of relief for cities suffering a disaster, it mainly considers the urgency, effectiveness (restoration rate), and uncertainty in the logistics system. The model is initially developed as a mixed-integer nonlinear programming (MINLP) model containing some nonlinear functions and transform into a Mixed-integer linear programming (MILP) model using a logarithmic transformation and piecewise linear approximation method. Furthermore, a minimax problem is suggested to search for breakpoints and slopes to define a piecewise linear function that minimizes the linear approximation error. A numerical experiment is performed to verify the MILP model, and linear approximation error is also analyzed in the experiment.

• 전기학회논문지
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• 제67권7호
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• pp.833-839
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• 2018

This paper presents an analysis and the methodology of optimal operation strategy of the ESS(Energy Storage System) for reduce electricity charges. Electricity charges consist of a basic charge based on the contract capacity and energy charge according to the power usage. In order to use electrical energy at minimal charge, these two factors are required to be reduced at the same time. QP(Quadratic Programming) is appropriate for minimization of the basic charge and LP(Linear Programmin) is adequate to minimize the energy charge. However, the integer variable have to be introduced for modelling of different charge and discharge efficiency of ESS PCS(Power Conversion System), where MILP(Mixed Integer Linear Programming) can be used. In this case, the extent to which the peak load savings is accomplished should be assumed before the energy charge is minimized. So, to minimize the electricity charge exactly, optimization is sequentially performed in this paper, so-called the Two Stage Hybird optimization, where the extent to which the peak load savings is firstly accomplished through optimization of basic charge and then the optimization of energy charge is performed with different charge and discharge efficiency of ESS PCS. Finally, the proposed method is analyzed quantitatively with other optimization methods.

• 경영과학
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• 제33권2호
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• pp.75-87
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• 2016

Quality function deployment (QFD) is a widely adopted customer-oriented product development methodology by analyzing customer requirements. It is a main activity in QFD planning process to determine the optimal values of the technical attributes (TAs) so as to achieve the customer requirements (CRs) from the House of Quality (HoQ). In most of the previous research, all the TAs in QFD are assumed to have either continuous or discrete values. In the real world applications, the continuous TAs and the discrete TAs are often mixed in QFD. In this paper, a mixed integer linear programming model is formulated to obtain the optimal values for the continuous TAs and the discrete TAs in QFD planning as well as Branch and Bound (B and B) algorithm is proposed as the solution approach. Finally, the proposed model and solution approach are illustrated with an office chair under multi-segment market, and the sensitivity analysis is performed to study how the proposed model and its solutions respond to the variation for the two elements which are budget and CRs' weights.

• 한국컴퓨터정보학회논문지
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• 제26권12호
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• pp.255-264
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• 2021

본 연구에서는 부유식 해상풍력발전의 운영 및 유지보수에 필요한 체계적인 정비계획 수립을 위해 최적화기법을 활용한 수리 모형을 제안하고자 한다. 주간 단위로 선박과 기술자를 운용하는 계획정비와 고장정비 작업의 배정에 혼합정수계획법(Mixed Integer Linear Programming, MILP)을 도입하였다. 본 연구의 최적화 모델을 활용한 사례연구에서는 선박과 기술자의 투입 규모가 유지정비 비용에 미치는 영향을 확인하였으며 1년간 정비계획 수립에서 더 나아가 정비작업별 상세 스케줄링까지 연계되는 단계적 최적화 방법론을 함께 제시하였다. 세부적으로는 기상 데이터와 정비 데이터를 활용한 발전량 손실을 비가동 비용으로 반영하여 정비 우선순위를 선정하였으며, 이를 통해 국내 실정에 맞는 해상풍력단지의 유지보수 전략을 제시할 수 있을 것으로 기대한다.

• 한국경영과학회지
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• 제10권2호
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• pp.24-27
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• 1985

This paper presents sufficient conditions for zero duality gap of Lagrangean relaxation in mixed integer programming problems and discusses about an algorithm which updates multipiers using the dual varibles of the linear programming constructed by fixing integer variables.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.392-392
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• 2000

This study performs optimization of paper mill scheduling using MINLP(Mixed-Integer Non-Linear Programming) method and 2-step decomposing strategy. Paper mill process is normally composed of five units: paper machine, coater, rewinder, sheet cutter and roll wrapper/ream wrapper. Various kinds of papers are produced through these units. The bottleneck of this process is how to cut product papers efficiently from raw paper reel and this is called trim loss problem or cutting stock problem. As the trim must be burned or recycled through energy consumption, minimizing quantity of the trim is important. To minimize it, the trim loss problem is mathematically formulated in MINLP form of minimizing cutting patterns and trim as well as satisfying customer's elder. The MINLP form of the problem includes bilinearity causing non-linearity and non-convexity. Bilinearity is eliminated by parameterization of one variable and the MINLP form is decomposed to MILP(Mixed-Integer Linear programming) form. And the MILP problem is optimized by means of the optimization package. Thus trim loss problem is efficiently minimized by this 2-step optimization method.

• 전기학회논문지
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• 제68권4호
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• pp.513-522
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• 2019

We calculate the benefit of distributed combined heat power generators from avoiding a transmission expansion cost by building distributed generators near electricity demand centers. We determine a transmission expansion plan by solving a mixed integer linear problem, where we modify capacities of existing transmission lines and build new transmission lines. We calculate the benefit by comparing the sum of generation and transmission expansion costs with or without distributed generators through two simulation frames. In the first frame, for the current demand, we substitute existing distributed generators for non-distributed generators and measure an additional cost to balance the generation and demand. In the second frame, for increased future demand, we compare the cost to invest only in distributed generators to the cost to invest only in non-distributed generators. As a result, we show that the distributed generators have at least 5.8 won/kWh of the benefit from avoiding the transmission expansion cost.

• 무역학회지
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• 제46권2호
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• pp.213-228
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• 2021

In recent year, US government requires local investment ,unlike in the past, when import restrictions and tariff were imposed. In this situation, many companies are considering new investment in the US and entering the local market. However, research on the optimal investment plan along with the case analysis on trade regulation is extremely limited and more research needs to be conducted. Accordingly, this study aims to suggest the implications and countermeasure of the SCM and logistical perspective by studying the optimal measures for the new investment of each company due to trade regulation. As a research method, the gravity location model, Mixed Integer Linear Programming Model were used to select the optimal automobile manufacturing factory considering each state's population. This study will be implication of SCM and logistics perspective not only for companies considering new investment in the US but also for the government to conduct trade negotiations. In the future, it is expected that the US trade pressure will increase and affect Korea in many ways. Therefore, in order to cope with such difficult situation in a timely manner, continuous research considering various possibilities is needed in the future.

• 산업공학
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• 제7권2호
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• pp.75-85
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• 1994

This paper presents a production scheduling model in a block assembly shop in shipbuilding industry. In a block assembly shop, the most important performance criterion is load leveling, which balances manpower and work area utilization through the planning horizon. The problem is formulated as a mixed-integer nonlinear programming(MINLP) problem of which objective function is to optimize load leveling. The developed MINLP problem can not be solvable due to computational complexity. The MINLP problem is decomposed into two stage mixed-integer linear programming (MILP) problems to obtain a good solution, but the decomposed MILP problems are still computationally intractable because of combinatorial complexity. Therfore, a heuristic method using linear programming is proposed to solve two stage MILP problems sequentially. The proposed heuristic generates a good production schedule within a reasonable computation time, and it is easily applicable for establishing the production schedule in a block assembly shop in shipbuilding industry.