• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.7
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• pp.104-114
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• 1995

In this paper, an intermediate representation HSFG(Hanyang Sequential Flow GRaph) and a new scheduling algorithm for the control-dominated ASIC design is presented. The HSFG represents control flow, data dependency and such constraints as resource constraints and timing constraints. The scheduling algorithm minimizes the total operating time by reducing the number of the constraints as maximal as possible, searching a few paths among all the paths produced by conditional branches. The constraints are substitute by subgraphs, and then the number of subgraphs (that is the number kof the constraints) is minimized by using the inclusion and overlap relation among subgraphs. The proposed algorithm has achieved the better results than the previous ones on the benchmark data.

• International Journal of Naval Architecture and Ocean Engineering
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• v.8 no.4
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• pp.398-408
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• 2016

Based on non-completely hybrid flow line scheduling of panel block in shipbuilding, several uncertain factors influencing the problem were analyzed in a real environment, and a nonlinear integer programming model was built for each sub-scheduling problem. To narrow the difference between theory and application, rolling horizon and rescheduling methods are proposed. Moreover, with respect to the uncertainty of processing time, arriving time and due time, we take the minimizing of the early and delayed delivery costs as the objective, and establish an evaluation with a global penalty function. Finally, numerical experiments and a simulation analysis were undertaken to demonstrate the effectiveness of the model and algorithm.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2003.09a
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• pp.187-190
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• 2003

Many manufacturing companies consider the integrated and concurrent scheduling because they need the global optimization technology that could manufacture various products more responsive to customer needs. In this paper, we propose an advanced scheduling model to generate the schedules considering resource constraints and precedence constraints in make-to-order (MTO) manufacturing environments. Precedence of work- in-process(WIP) and resources constraints have recently emerged as one of the main constraints in advanced scheduling problems. The advanced scheduling problems is formulated as a multiobjective mathematical model for generating operation schedules which are obeyed resources constraints, alternative workstations of operations and the precedence constraints of WIP in MTO manufacturing. For effectively solving the advanced scheduling problem, the multi-objective hybrid genetic algorithm (m-hGA) is proposed in this paper. The m-hGA is to minimize the makespan, total flow time of order, and maximum tardiness for each order, simultaneously. The m-hGA approach with local search-based mutation through swap mutation is developed to solve the advanced scheduling problem. Numerical example is tested and presented for advanced scheduling problems with various orders to describe the performance of the proposed m-hGA.

• IE interfaces
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• v.17 no.2
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• pp.242-248
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• 2004

Lot-streaming is the process of splitting a job (lot) into a number of smaller sublots to allow the overlapping of operations between successive machines in a multi-stage production system. A new genetic algorithm (NGA) is proposed for minimizing the mean weighted absolute deviation of job completion times from due dates when jobs are scheduled in a no-wait lot-streaming flow shop. In a no-wait flow shop, each sublot must be processed continuously from its start in the first machine to its completion in the last machine without any interruption on machines and without any waiting in between the machines. NGA replaces selection and mating operators of genetic algorithms (GAs), which often lead to premature convergence, by new operators (marriage and pregnancy operators) and adopts the idea of inter-chromosomal dominance. The performance of NGA is compared with that of GA and the results of computational experiments show that NGA works well for this type of problem.

• Journal of Korea Multimedia Society
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• v.19 no.5
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• pp.924-931
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• 2016

In this paper, Various network adaptive MAC scheduling technique is proposed to effectively overcome limits of narrow bandwidth and low transmission speed in underwater. UPFC(Underwater Packet Flow Control) is a technique to reduce both the number of transmission and transmission time using three types (Normal, Blocked, Parallel) of data transmission. In this technique, the load information, in which a transmission node have, is transmitted to destination node using marginal bit in reserved header. Then the transmitted information is referred to determine weighting factor. According to the weighting factor, scheduling is dynamically changed adaptively. The performance of UPFC is analyzed and flow control technique which can be applied to Cluster Based Network and Ad Hoc network as well.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2006.11a
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• pp.138-141
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• 2006

This paper considers a two-machine flow-shop scheduling problem for minimizing mean flow time. Each job has three non-preemptive operations, where the first and third operations must be Processed on the first and second machines, respectively, but the second operation can be processed on either machine. A lower bound based on SPT rule is derived, which is then used to develop a branch-and-bound algorithm. Also, an efficient simple heuristic algorithm is developed to generate a near-optimal schedule. Numerical experiments are performed to evaluate the performances of the proposed branch-and-bound and the heuristic algorithm

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.4C
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• pp.461-471
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• 2004

Recently, subscribers have strong desire to get QoS based personalized services in high-speed Internet access. Service providers have been rapidly replacing ADSL, cable broadband access networks with Metro-Ethernet based VDSL. But, it is difficult for Motto-Ethernet based broadband access networks to provide QoS based personalized services, because already deployed network elements cannot distinguish subscribers by specific traffic characteristics. In this paper, when the access network has tree topology, we show that it is possible to provide QoS for each downstream flow with only per flow traffic shaping at the edge node without QoS functions in access networks. In order to show that our suggested scheduling algorithm at the edge node can support the assured service in tree topology access networks, we evaluated its performance by simulation. The suggested scheduling algorithm can shape per-flow traffic based on the maximum bandwidth, and guarantees minimum bandwidth per flow by modifying the DRR scheduler. Simulation results show that congestion and loss in the access network elements are greatly reduced, TCP performance is highly enhanced and loss for assured CBR service flows is reduced by only shaping per-flow traffic at the edge node using our proposed scheduling algorithm.

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

• Proceedings of the KIEE Conference
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• 2004.11c
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• pp.215-217
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• 2004

In wireless sensor networks, fair allocation of bandwidth among different nodes is one of the critical problems that effects the serviceability of the entire system. Fair bandwidth allocation mechanisms, like fair queuing, usually need to maintain state, manage buffers, and perform packet scheduling on a per flow basis, and this complexity may prevent them from being cost-effectively implemented and widely deployed. It is a very important and difficult technical issue to provide packet scheduling architecture for fairness in wireless sensor networks. In this paper, we propose an packet scheduling architecture for sensor node, called FISN (Fairness Improvement Sensor Network), that significantly reduces this implementation complexity yet still achieves approximately fair bandwidth allocations. Sensor node for sensing estimate the incoming rate of each sensor device and insert a label into each transmission packet header based on this estimate. Sensor node for forwarding maintain no per flow state; they use FIFO packet scheduling augmented by a probabilistic dropping algorithm that uses the packet labels and an estimate of the aggregate traffic at the gathering node. We present the detailed design, implementation, and evaluation of FISN using simulation. We discuss the fairness improvement and practical engineering challenges of implementing FISN in an experimental sensor network test bed based on ns-2.

• Journal of Korean Institute of Industrial Engineers
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• v.21 no.1
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• pp.85-101
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• 1995

Automated Guided Vehicles(AGVs) are widely used in computer integrated manufacturing(CIM) systems for material handling purposes. Although automated guided vehicles provide higher levels of flexibility and computer integrability, the installations are limited in number and one of the critical reasons lies in the complexity involved in the operation. The main objective of this research is to alleviate this problem by proposing efficient integrated operational control methods for AGV-based CIM systems. Particularly, this research is concerned with the mixed problem of dispatching automated guided vehicles and scheduling machines operation. The proposed dynamic heuristic algorithm uses various priority schemes and relevant information concerning the load of the system, the status of queues, and the position of AGVs in the scheduling process. The scheduling decision process is hierarchical in the sense that different decision criteria are applied sequentially to identify the most appropriate part to be served. This algorithm consists of two sections, the section of part selection by AGVs for the next service whenever an AGV completes the current assignment, and the section of part selection by machines for next service whenever a machine completes the current operation. The proposed algorithm has been compared with other scheduling schemes using the performance measure of mean flow-time and mean tardiness. Simulation results indicate that the proposed algorithm can reduce the mean flow-time and mean tardiness significantly.