• 산업경영시스템학회지
• /
• 제38권3호
• /
• pp.169-180
• /
• 2015

Recently, scheduling problems with position-dependent processing times have received considerable attention in the literature, where the processing times of jobs are dependent on the processing sequences. However, they did not consider cases in which each processed job has different learning or aging ratios. This means that the actual processing time for a job can be determined not only by the processing sequence, but also by the learning/aging ratio, which can reflect the degree of processing difficulties in subsequent jobs. Motivated by these remarks, in this paper, we consider a two-agent single-machine scheduling problem with linear job-dependent position-based learning effects, where two agents compete to use a common single machine and each job has a different learning ratio. Specifically, we take into account two different objective functions for two agents: one agent minimizes the total weighted completion time, and the other restricts the makespan to less than an upper bound. After formally defining the problem by developing a mixed integer non-linear programming formulation, we devise a branch-and-bound (B&B) algorithm to give optimal solutions by developing four dominance properties based on a pairwise interchange comparison and four properties regarding the feasibility of a considered sequence. We suggest a lower bound to speed up the search procedure in the B&B algorithm by fathoming any non-prominent nodes. As this problem is at least NP-hard, we suggest efficient genetic algorithms using different methods to generate the initial population and two crossover operations. Computational results show that the proposed algorithms are efficient to obtain near-optimal solutions.

• 한국컴퓨터정보학회논문지
• /
• 제13권3호
• /
• pp.85-90
• /
• 2008

본 논문에서는 가장 덜 복잡한 공간부터 청소하는 공간 효율적인 새로운 로봇 청소 알고리즘인 SetClean 알고리즘을 제안한다. 청소 완료 시간이 길어지거나, 예측하기 어려운 경우에는 전체 청소 완료시간을 최적화하기보다는 가능한 빠른 시간에 가장 넓은 공간을 최대한 청소하는 것이 유리한 경우가 있다. 이를 위해 SetClean 알고리즘에서는 전체 공간을 셋 커버 알고리즘을 이용하여 청소 가능한 공간으로 구분하고, 단위 시간 당 청소 효율이 가장 높은 공간부터 청소를 진행하게 된다. SetClean 알고리즘은 해당 청소 가능 구역의 면적뿐만 아니라 로봇의 현재위치로부터 해당 청소 구역까지의 이동 거리, 청소 구역 내에서의 로봇의 회전으로 인한 지연 시간 등을 고려하여 최적의 청소 순서를 결정한다. 실험을 통해 SetClean 알고리즘의 동작 과정 및 성능을 보여준다.

• 경영과학
• /
• 제25권3호
• /
• pp.45-57
• /
• 2008

This paper considers a genetic algorithm for sequencing activities and allocating resources to reduce the over all completion time of workflow in the presence resource constraints. The algorithm provides an integrated solution for two sub-problems. The first is to decide the priority for the activities which require the same resource. The other problem is to select one among available resources for each activity by considering the incurred setup time and the performance factor of each resource. We evaluate the algorithm performance for three different kinds of workflows including parallel structures. Computational results show that the proposed algorithm is more effective than a previous work.

• 한국경영과학회:학술대회논문집
• /
• 대한산업공학회/한국경영과학회 1993년도 춘계공동학술대회 발표논문 및 초록집; 계명대학교, 대구; 30 Apr.-1 May 1993
• /
• pp.6-15
• /
• 1993

A generalization of one machine maximum lateness minimization problem is considered. There are one achine with controllable speed and n weighting jobs $J_{j}$, j=1, 2, ..., n with ambiguous duedates. Introducing fuzzy formulation, a membership function of the duedate associated with each job $J_{j}$, which describes the satisfaction level with respect to completion time of $J_{j}$. Thus the duedates are not constants as in conventional scheduling problems but decision variables reflecting the fuzzy circumstance of the job completing. We develop the polynomial time algorithm to find an optimal schedule and jobwise machine speeds, and to minimize the total sum of costs associated with jobwise machine speeds and dissatisfaction with respect to completion times of weighting jobs. jobs.

• 산업경영시스템학회지
• /
• 제20권44호
• /
• pp.1-12
• /
• 1997

In this paper a new heuristic algorithm has been developed and presented for minimizing the total completion time of a scheduling problem in a multi stage automated machining and assembly systems. The proposed Higher Ratio First(HRF) algorithm is based on the idea that jobs with higher processing time ratio should be a higher priority. The heuristic algorithm is implemented on the various problem cases by number of jobs and machines. The proposed algorithm provided smaller makespan than the makespan applied by three previously documented heuristics. The results obtained show a superior solution by the new heuristic over previous heuristics on all problem sizes.

• 한국전산구조공학회:학술대회논문집
• /
• 한국전산구조공학회 2007년도 정기 학술대회 논문집
• /
• pp.327-332
• /
• 2007

An engineering design problem involving Multi-Disciplinary Analysis(MDA) generally requires a large amounts of CPU time for the entire design process, and therefore Multiple Processing System (MPS) are essential to reduce the completion time. However, when applying conventional parallel processing techniques, all of the CAE S/W required for the MDA should be installed on all the servers making up NIPS because of characteristic of MDA and it would be a great expense in CAE S/W licenses. To solve this problem, we propose a Weight-based Multiqueue Load Balancing algorithm for a heterogeneous MPS where performance of servers and CAE S/W installed on each server are different of each other. To validate the performance, a computational experiments comparing the First Come First Serve algorithm and our proposed algorithm was accomplished.

• 대한안전경영과학회지
• /
• 제13권4호
• /
• pp.125-137
• /
• 2011

Customers are generally requiring a variety of products, earlier due date, and lower price. A manufacturing process needs the efficient scheduling to meet those customer's requirements. This study proposes the novel algorithm named MJA(Minimum Job completion time and AGV time) that increases the performance of machines and AGV(Automated Guided Vehicles) in many kinds of job types. MJA optimizes the bottleneck of machines and efficiency of AGV with considering two types of dispatching at the same time. Suggested algorithm was compared with existing heuristic methods by several simulations, it performed better for reducing the time of tardiness.

• 국제학술발표논문집
• /
• The 5th International Conference on Construction Engineering and Project Management
• /
• pp.243-251
• /
• 2013

Cash management is a major concern for all contractors in the construction industry. It is arguable that cash is the most critical resource of all. A contractor needs to secure sufficient funds to navigate the project to the end, while keeping an eye on maximizing profits along the way. Past research attempted to address such topic via developing models to tackle the time-cost tradeoff problem, cash flow forecasting, and cash flow management. Yet, little was done to integrate the three aspects of cash management together. This paper, as such, presents a comprehensive model that integrates the time-cost tradeoff problem, cash flow management, and cash flow forecasting. First, the model determines the project optimal completion time by considering the different alternative construction methods available for executing project activities. Second, it investigates different funding alternatives and proposes a project-level cash management plan. Two funding alternatives are considered; they are borrowing and company own financing. The model was built as a combinatorial optimization model that utilizes ant colony search capabilities. The model also utilizes Microsoft Project software and spreadsheets to maintain an environment that incorporates activities, their durations, and other project data, in order to estimate project completion time and cost. Ant Colony Optimization algorithm was coded as a Macro program using VBA. Finally, an example project was used to test the developed model, where it acted reliably in maximizing the contractor's profit in the test project.

• 정보처리학회논문지A
• /
• 제16A권1호
• /
• pp.35-42
• /
• 2009

이 논문은 지능형 로봇을 위한 새로운 커버리지 알고리즘을 제안한다. 커버리지 알고리즘의 성능을 향상하기 위한 많은 연구들은 전체 커버리지 완료 시간을 최소화하는데 초점을 맞추어왔다. 그러나, 만일 전체 커버리지를 완료하기에 충분한 시간이 없다면, 최적의 경로는 달라질 수 있다. 이러한 문제를 해결하기 위하여 본 논문에서는 MaxCoverage라고 하는 데드라인이 있을 경우에 가능한 많은 면적을 커버하기 위한 새로운 커버리지 알고리즘을 제안한다. MaxCoverage 알고리즘은 이동 경로를 셋 커버 문제를 위한 그리디 알고리즘을 이용하여 결정한다. 실험 결과에 의하면 MaxCoverage 알고리즘은 임의의 데드라인에 대하여 다른 알고리즘들에 비해 향상된 성능을 보여준다.

• 한국시뮬레이션학회논문지
• /
• 제24권4호
• /
• pp.77-88
• /
• 2015

본 논문은 작업별 위치기반 지수학습 효과를 갖는 2-에이전트 단일기계 스케줄링 문제를 고려한다. 에이전트 A는 가중 완료 시간의 합을 최소화하며, 에이전트 B는 총소요시간에 대한 상한 값을 만족하는 조건을 갖는다. 본 연구에서는 먼저 우수해/가능해에 대한 특성을 개발하고, 이를 이용하여 최적 해를 찾기 위한 분지한계 알고리즘을 설계한다. 또한 근사 최적 해를 구하기 위해 6가지 다른 초기해 생성 방법을 이용한 시뮬레이티드 어닐링 알고리즘을 제안한다. 수치 실험을 통해 제안된 알고리즘의 우수한 성능을 검증한다. 실험 결과, 다른 초기해 생성 방법들 간에는 %errors 차이가 유의하게 발생하지 않았으며, 에이전트 A의 작업 순서를 무작위로 생성할 때 성능이 좋아짐을 발견하였다. 반면에, 에이전트 B의 초기해 생성 방법은 성능에 영향을 미치지 않았다.