• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.11 no.9
• /
• pp.3232-3238
• /
• 2010

As flexible manufacturing systems (FMSs) are highly automated and required flexibility to satisfy market need, dispatching rules are constrained by specific environments of manufacturing systems such as mechanical failures, absence of employees, and lack of spare parts. In this paper, an ontology-based knowledge approach is proposed to improve efficiency of system through adapting suitable dispatching rules, considering context in a FMS shop floor, which consists multiple manufacturing cells. the multi-agents monitor manufacturing system status and job so that it figures out a dispatching rule considering context. To demonstrate the proposed approach, a proof-of-concept prototype system has been implemented in the $JADE^{TM}$ platform and Protege to make OWL DL ontology.

• Journal of Information Technology Applications and Management
• /
• v.11 no.1
• /
• pp.53-67
• /
• 2004

We propose an advanced transaction scheduling protocol to improve the concurrency and to guarantee the mobility for the mobile database management systems. Mobility, portability, and wireless link In mobile computing environment can cause certain drawbacks, and thus it is more difficult to solve the concurrency control problems. However, a locking scheme should be used to guarantee the data consistency and to prevent the data conflicts. It is well known that data consistency is guaranteed by standard transaction scheduling schemes like two-phase locking (2PL). It has two of operation, lock and unlock. But 2PL does not give solution for mobile system. Altruistic Locking (AL) and classifying transactions, we adapt, can give solution for the previous problems. AL, as an advanced protocol, has attempted to reduce delay effects associated with lock release moment by the use of donation. In this paper, we extend those approaches and classify the transactions to reduce delay effects of short-lived transaction caused by long-lived transaction. In addition, we show efficient solution for the case of disconnection occurrence. Our protocol, namely, Mobile Altruistic Locking (MAL) is shown to be efficiently used in order to reduce delay effects and to guarantee database consistency in a state of the slippery connection in mobile database systems.

• Journal of IKEEE
• /
• v.6 no.1 s.10
• /
• pp.1-9
• /
• 2002

Converged LAN accepts diverse traffics so that performance analysis is very important for successful development of converged LAN. In this paper, we develop simulation program using SALM II and simulate queue management scheme and scheduling algorithm for converged LAN. The result of simulation shows the effect of performance for cyclic service algorithm larger than priority algorithm using weight. And queue management can be easy by implementation of Back Pressure scheme.

• Journal of Construction Engineering and Project Management
• /
• v.3 no.1
• /
• pp.1-9
• /
• 2013

Construction is a competitive industry and successful contractors must be able to win bids to obtain projects. Cash flow analysis not only determines actual profit at the end of the project, but also estimates required cash resources or cash ballances at the end of every month. Cash flow analysis is important in managing a construction project; however, it requires extensive information that is not immediately available to the general contractor. Before contractors can perform cash flow analysis, they must first complete a series of pre-requisites such as the quantity take off, scheduling, and cost estimating, followed by accurate assessments of project costs incurred and billable progress made. Consequently, cash flow analysis is currently a lengthy, uncertain process. This paper suggests improved cash flow analysis can be developed using data extraction in Building Information Modeling (BIM). BIM models contain a wealth of information and tools have been developed to automate a series of process such as quantity takeoff, scheduling, and estimating. This paper describes a prototype tool to support BIM-based, automated cash flow analysis.

• Industrial Engineering and Management Systems
• /
• v.11 no.3
• /
• pp.288-298
• /
• 2012

Lot sizing and shipment scheduling are two interrelated decisions made by a manufacturing plant and a third-party logistics distribution center. This paper analyzes a dynamic inbound ordering problem and shipment problem with a freight container cost, in which the order size of multiple products and single container type are simultaneously considered. In the problem, each ordered product placed in a period is immediately shipped by some freight containers in the period, and the total freight cost is proportional to the number of containers employed. It is assumed that the load size of each product is equal and backlogging is not allowed. The objective of this study is to simultaneously determine the lot-sizes and the shipment schedule that minimize the total costs, which consist of production cost, inventory holding cost, and freight cost. Because the problem is NP-hard, we propose three meta-heuristic algorithms: a simulated annealing algorithm, a genetic algorithm, and a new population-based evolutionary meta-heuristic called self-evolution algorithm. The performance of the meta-heuristic algorithms is compared with a local search heuristic proposed by the previous paper in terms of the average deviation from the optimal solution in small size problems and the average deviation from the best one among the replications of the meta-heuristic algorithms in large size problems.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2022.05a
• /
• pp.126-126
• /
• 2022

Climate change has continued to impact meteorological factors like rainfall in many countries including Nigeria. Thus, altering the rainfall patterns which subsequently affect the crop yield. Maize is an important cereal grown in northern Nigeria, along with sorghum, rice, and millet. Due to the challenge of water scarcity during the dry season, it has become critical to design appropriate strategies for planning, developing, and management of the limited available water resources to increase the maize yield. This study, therefore, determines the quantity of water required to produce maize from planting to harvesting and the impact of drought on maize during different growth stages in the region. Rainfall data from six rain gauge stations for a period of 36 years (1979-2014) was considered for the analysis. The standardized precipitation and evapotranspiration index (SPEI) is used to evaluate the severity of drought. Using the CROPWAT model, the evapotranspiration was calculated using the Penman-Monteith method, while the crop water requirements (CWRs) and irrigation scheduling for the maize crop was also determined. Irrigation was considered for 100% of critical soil moisture loss. At different phases of maize crop growth, the model predicted daily and monthly crop water requirements. The crop water requirement was found to be 319.0 mm and the irrigation requirement was 15.5 mm. The CROPWAT 8.0 model adequately estimated the yield reduction caused by water stress and climatic impacts, which makes this model appropriate for determining the crop water requirements, irrigation planning, and management.

• International conference on construction engineering and project management
• /
• 2013.01a
• /
• pp.141-144
• /
• 2013

This paper presents a system called a Cash-flow based Construction Schedule Optimization system(CfSO). The existing CPM effectively handles schedule and cost management. However, funding strategy should be considered to obtain maximum profit and to progress a project favorably. One of measures is to coordinate the contract terms between owner and subcontractors (or suppliers). Contractor may decrease the interest cost attributed to project financing by adjusting the timing of cash-inflows and cash-outflows. It is an excellent method maximizing profits. This paper presents a method to estimate the amount of a cash-flow occurred periodically by integrating the terms of contract into scheduling. The proposed method is implemented as a system prototype in Microsoft Excel. This system provides a user an automated tool that identifies an optimal schedule that secures maximum profit by adjusting start and finish times of non-critical activities' free-floats without affecting on the project completion time. This system supports a project manager to establish an optimum project schedule and identifies profitable contractual conditions against to a construction owner.

• Journal of KIISE:Computer Systems and Theory
• /
• v.30 no.5_6
• /
• pp.307-318
• /
• 2003

In this paper, we design and construct a TMO object group that provides the guaranteed real-time services in the distributed object computing environments, and verify execution power of its model for the correct distributed real-time services. The TMO object group we suggested is based on TINA's object group concept. This model consists of TMO objects having real-time properties and some components that support the object management service and the real-time scheduling service in the TMO object group. Also TMO objects can be duplicated or non-duplicated on distributed systems. Our model can execute the guaranteed distributed real-time service on COTS middlewares without restricting the specially ORB or the of operating system. For achieving goals of our model. we defined the concepts of the TMO object and the structure of the TMO object group. Also we designed and implemented the functions and interactions of components in the object group. The TMO object group includes the Dynamic Binder object and the Scheduler object for supporting the object management service and the real-time scheduling service, respectively The Dynamic Binder object supports the dynamic binding service that selects the appropriate one out of the duplicated TMO objects for the clients'request. And the Scheduler object supports the real-time scheduling service that determines the priority of tasks executed by an arbitrary TMO object for the clients'service requests. And then, in order to verify the executions of our model, we implemented the Dynamic Binder object and the Scheduler object adopting the binding priority algorithm for the dynamic binding service and the EDF algorithm for the real-time scheduling service from extending the existing known algorithms. Finally, from the numerical analyzed results we are shown, we verified whether our TMO object group model could support dynamic binding service for duplicated or non-duplicated TMO objects, also real-time scheduling service for an arbitrary TMO object requested from clients.

• Proceedings of the Korean Operations and Management Science Society Conference
• /
• 1992.04b
• /
• pp.332-341
• /
• 1992

본 연구에서는 가동준비 비용과 시간의 특수구조를 갖는 다품종 제품군이 있을때의 생산일정계획을 고려하며, 제품군 가동준비에 있어서의 작업순서간 상호의존성에 따라 일정계획 문제를 분류하고, 그 문제들을 정형화시킨다. 특히, 하나의 제품군만이 생산되어지는 작업환경에 대하여 발견적 기법을 개발하여 이를 적용한 생산계획을 마련한다. 또한, 그 결과를 정수선형 계획에 의한 최적해와 비교.분석한다.

• Proceedings of the Korean Operations and Management Science Society Conference
• /
• 2000.04a
• /
• pp.111-117
• /
• 2000

경제적 로트 일정계획 문제(Economic Lot Scheduling Problem : ELSP)는 지난 수십 여 년간 많은 연구가 이루어진 생산일정계획 문제 중의 한 분야이다. 이 문제는 NP-hard 문제이기 때문에 수많은 발견적 기법이 제안되고, 사용되어져 왔다. 그 중에서도 Dobson［1］의 발견적 기법이 그 수행도의 우수성으로 보아 최고의 기법으로 여겨지고 있는데, 본 연구에서는 Dobson［1］의 시변 로트 크기(time varying lot size) 접근방법에 유전자 알고리즘을 이용한 새로운 발견적 기법을 제안하고, 수치실험을 통해서 새로운 기법이 기존의 Dobson［1］의 기법보다 더 우수하다는 것을 보이고자 한다.