• The Transactions of the Korean Institute of Electrical Engineers P
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• v.59 no.3
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• pp.245-252
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• 2010

This paper proposes a constrained multi-area dispatch scheduling algorithm applicable to interconnected power system operations. The dispatch scheduling formulated as an MIP problem can be efficiently computed by GBD algorithm. GBD guarantees adequate computation speed and solution convergence by reducing the dimension of the dispatch scheduling problem. In addition, the regional decomposition technique based on ADM is introduced to obtain efficient inter-temporal OPF solution. It can find the most economic dispatch schedule incorporating power transactions without each regional utility's private information open.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.05a
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• pp.401-402
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• 2012

• Journal of Information Technology Applications and Management
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• v.19 no.1
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• pp.37-46
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• 2012

The scheduling problem of large products like ships, airplanes, space shuttles, assembled constructions, and automobiles is very complex in nature. To reduce inherent computational complexity, we often design scheduling systems that the original problem is decomposed into small sub-problems, which are scheduled independently and integrated into the original one. Moreover, the steep growth of communication technology and logistics makes it possible to produce a lot of multi-nation corporation by which products are produced across more than one plant. Therefore vertical and lateral coordination among decomposed scheduling systems is necessary. In this research, we suggest an agent-based coordinating mechanism for multi-level scheduling systems in supply chain. For design of a general coordination mechanism, at first, we propose a grammar to define individual scheduling agents which are responsible to their own plants, and a meta-level coordination agent which is engaged to supervise individual scheduling agents. Second, we suggest scheduling agent communication protocols for each scheduling agent topology which is classified according to the system architecture, existence of coordinator, and direction of coordination. We also suggest a scheduling agent communication language which consists of three layers : Agent Communication Layer, Scheduling Coordination Layer, Industry-specific Layer. Finally, in order to improve the efficiency of communication among scheduling agents we suggest a rough capacity coordination model which supports to monitor participating agents and analyze the status of them. With this coordination mechanism, we can easily model coordination processes of multiple scheduling systems. In the future, we will apply this mechanism to shipbuilding domain and develop a prototype system which consists of a dock-scheduling agent, four assembly-plant-scheduling agents, and a meta-level coordination agent. A series of experiment using the real-world data will be performed to examine this mechanism.

• Industrial Engineering and Management Systems
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• v.7 no.2
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• pp.84-92
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• 2008

Scheduling is one of the most important issues in the planning and operation of production systems. This paper investigates a general job shop scheduling problem with reentrant work flows and sequence dependent setup times. The disjunctive graph representation is used to capture the interactions between machines in job shop. Based on this representation, four two-phase heuristic procedures are proposed to obtain near optimal solutions for this problem. The obtained solutions in the first phase are substantially improved by reversing the direction of some critical disjunctive arcs of the graph in the second phase. A comparative study is conducted to examine the performance of these proposed algorithms.

• Journal of Korean Institute of Industrial Engineers
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• v.40 no.1
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• pp.135-139
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• 2014

In a connection-oriented packet switching network, the data communication starts after a virtual circuit is established between source and destination. The virtual circuit establishment time includes the queue waiting times in the direction from source to destination and the other way around. We use this two-way queueing delay to evaluate scheduling policies of a packet switching processor through simulation studies. In this letter, we also suggest user testing functions for the packet switching processor to manage virtual circuits. By detecting error causes, the user testing helps the packet switching processor provide reliable connection-oriented services.

• Journal of Korea Society of Industrial Information Systems
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• v.8 no.4
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• pp.64-72
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• 2003

A Web crawler is an important Internet software technology used in a variety of Internet application software which includes search engines. As Internet continues to grow, implementations of high performance web crawlers are urgently demanded. In this paper, we study how to support dynamic scheduling for a multiprocess-based web crawler. For high peformance, web crawlers are usually based on multiprocess in their implementations. In these systems, crawl scheduling which manages the allocation of web pages to each process for loading is one of the important issues. In this paper, we identify issues which are important and challenging in the crawl scheduling. To address the issue, we propose a dynamic crawl scheduling framework and subsequently a system architecture for a web crawler with dynamic crawl scheduling support. And we analysed the behaviors of Web crawler. Based on the analysis result, we suggest the direction for the design of high performance Web crawler.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.6B
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• pp.377-386
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• 2005

Recently, to increase throughput per hour on real-time disk scheduling, a lot of algorithms that apply SCAN technique to EDF(Earliest Deadline First) that is representative real-time disk scheduling algorithm are studied. However, existing disk scheduling algorithms have several limitations because they consider continuous I/O requests when create SCAN group. Also, because SCAN technique was fixed direction, the existing algorithms have shortcoming that there are a lot of time damages. This paper proposes a new real-time disk scheduling algorithm based on the insertion technique and the two-way SCAN technique to solve the problems of the exiting real-time disk scheduling algorithms in hard real-time system. The simulation result shows that, when using our techniques, the disk throughput and the number of serviceable I/O requests are enhanced.

• Korean Journal of Construction Engineering and Management
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• v.5 no.5 s.21
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• pp.135-142
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• 2004

This paper proposes the CPM bar chart (CBC), a hybrid of the bar chart and the critical pad method (CPM). The CBC overcomes shortages of the fenced bar chart, while still keeping advantages. The fence with direction is applied instead of the broken fence, which triggers considerable problems to identify and apply in the fenced bar chart. In addition, the notorious task to find dummy activities is no longer required. Upon the benefits of simplicity in the bar chart and logical work sequence in the CPM network. the CBC provides a relatively easy way to create and understand a schedule, thus improving communication quality between project participants. With the advantages, the CBC can also be effectively applied to various scheduling techniques such as resource constrained scheduling, resource leveling, scheduling with activity split, delay impact analysis, etc.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.42 no.4 s.334
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• pp.19-28
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• 2005

In this paper, we proposed a parallel fast 2-D discrete wavelet transform hardware architecture based on lifting scheme. The proposed architecture improved the 2-D processing speed, and reduced internal memory buffer size. The previous lifting scheme based parallel 2-D wavelet transform architectures were consisted with row direction and column direction modules, which were pair of prediction and update filter module. In 2-D wavelet transform, column direction processing used the row direction results, which were not generated in column direction order but in row direction order, so most hardware architecture need internal buffer memory. The proposed architecture focused on the reducing of the internal memory buffer size and the total calculation time. Reducing the total calculation time, we proposed a 4-way data flow scheduling and memory based parallel hardware architecture. The 4-way data flow scheduling can increase the row direction parallel performance, and reduced the initial latency of starting of the row direction calculation. In this hardware architecture, the internal buffer memory didn't used to store the results of the row direction calculation, while it contained intermediate values of column direction calculation. This method is very effective in column direction processing, because the input data of column direction were not generated in column direction order The proposed architecture was implemented with VHDL and Altera Stratix device. The implementation results showed overall calculation time reduced from $N^2/2+\alpha$ to $N^2/4+\beta$, and internal buffer memory size reduced by around $50\%$ of previous works.

• Journal of KIISE:Computing Practices and Letters
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• v.5 no.6
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• pp.738-747
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• 1999

본 논문에서는 분산 실시간 시스템의 특징인 분산 처리 과정의 신뢰성을 지원하기 위한 동적 트랜잭션 처리 구조를 연구하였다. 실시간 분산 처리 환경에서 동적으로 발생하는 실시간 분산 트랜잭션 처리를 위하여 트랜잭션 내에 필수적인 3가지 언어적 특성들을 제시하였다. 첫째는 트랜잭션 내에 실시간 시스템의 가장 중요한 특징인 시간적인 제약 조건들을 정의 할 수 있는 방안을 제시하고, 둘째는 비동기적인 처리 성격을 지닌 실시간 특성을 고려한 비동기적 트랜잭션 처리 방법을 제시한다. 또한, 분산 처리 과정에서 발생되는 예외 사항들을 처리하기 위하여 긴급성을 고려한 다중레벨 우선순위 스케줄링 (Multi-Level Priotiry Scheduling)이라 부르는 트랜잭션 스케줄링 방안을 제시한다. 그리고, 제시한 실시간 분산 트랜잭션 처리 구조의 타당성 및 가능성을 입증하기 위한 실시간 트랜잭션 처리 과정을 시물레이션을 통하여 제시한 언어적 특성에 대한 고려 사항들을 보여준다.Abstract We propose a dynamic transaction processing model that supports a reliability for distributed real-time processing. For the dynamic processing in distributed real-time transaction systems, we suggest three features that are defined in programming language. First, we propose a specification model to explicitly define the time constraints, needs in real-time distributed processing. Second, we describe an asynchronous transaction processing mechanism based on the real-time characteristics. So, we suggest three communication primitives to support asynchronous transaction processing. Lastly, a scheduling policy based on urgent transaction is suggested to manage the exception occurred during the distributed processing. This scheduling policy is called multi-level priotiry scheduling (MPLS). Based on three features and scheduling policy, we describe a direction to manage a dynamic transaction processing in distributed real-time systems.