• Journal of the Korean Society for Railway
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• v.17 no.4
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• pp.313-319
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• 2014

Additional train scheduling is often required to increase the capacity of transporting passengers or freight. In most previous studies on scheduling additional trains, operation time of the added train is designated first; and then the train operation feasibility is examined. However, it is often difficult to apply this approach to domestic trains because the density of the railroad network in Korea is high and various types of trains are in use. Moreover, for freight trains, it is even more challenging because the delay is accumulated due to lower priority whenever a freight train and a passenger train contend for a common segment of rail. In this paper, we address the additional train scheduling problem which entails finding a feasible schedule for an additional train having a fixed departure time or departure time windows. The problem is modeled as a mixed integer programming and a column generation technique is used to solve it.

• Journal of Ship and Ocean Technology
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• v.10 no.2
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• pp.37-44
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• 2006

The erection in shipbuilding is the process to assemble all the blocks one by one in certain order and requires more leveled and efficient schedule than other processes do. However, erection schedule includes too many constraints to be systemized with simple programs and constraints are changed frequently. These difficulties make it rare to find automatic erection schedule generation system with load leveling ability. In this paper, a CSP (Constraint Satisfaction Problem)-based load leveling algorithm using a maximum load diminution technique is proposed and applied to the block erection scheduling of a dock in a shipyard. The result shows that it performs better than currently used scheduling method based on empirical logics. The maximum load of welding length and crane usage are reduced by 31.63% and 30.00% respectively. The deviation of resource usage amount also decreases by 8.93% and 7.51%.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.6
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• pp.71-77
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• 2015

In this paper, we propose a scheduling method for signal measurement and control algorithm execution in a multi-motor drive controller. The multi-motor controller which is used for vehicle control receives position/velocity command and performs position/velocity control and current control. Internal resource allocation and control algorithm execution timing are very important when one microcontroller is used for multi-motor drives. The control performance of the velocity control system is verified by varying ADC(Analog to Digital Converter) conversion timing and algorithm execution timing using real experiments.

• Industrial Engineering and Management Systems
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• v.12 no.1
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• pp.30-35
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• 2013

Motivated by the emergency scheduling in a transportation network, this paper considers a transportation problem, in which, the truck times and transportation costs are assumed as uncertain variables. To meet the demand in the practical applications, two optimization objectives are considered, one is the total costs and another is the completion times. And then, a multi-objective optimization model is developed according to the situation in applications. Because there are commensurability and conflicting between the two objectives commonly, a solution does not necessarily exist that is best with respective to the two objectives. Therefore, the problem is reduced to a single objective model, which is an uncertain programming with a chance-constrain. After some analysis, its equivalent deterministic form is obtained, which is a nonlinear programming. Based on a stepwise optimization strategy, a solution method is developed to solve the problem. Finally, the computational results are provided to demonstrate the effectiveness of our model and algorithm.

• Journal of KIISE:Computing Practices and Letters
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• v.14 no.8
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• pp.753-757
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• 2008

In this paper, we propose a new scheduling strategy for dynamic programming in Grid environment. The key idea of this scheme is to reduce the execution time of a job by dividing the dynamic table based on the locality of table and allocating jobs to nodes which minimize network latency. This scheme obtains optimal concurrency by constructing the dynamic table using a distributed top down method. Through simulation, we show that the proposed Grid strategy improves the performance of Grid environment compared to previous branch-bound strategies.

• International conference on construction engineering and project management
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• 2005.10a
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• pp.1118-1123
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• 2005

This paper proposes the CPM bar chart (CBC), a hybrid of the bar chart and the critical path method (CPM). The CBC overcomes shortages of the fence bar chart, while still retaining its 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.

• Journal of the Institute of Electronics and Information Engineers
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• v.54 no.2
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• pp.16-27
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• 2017

IEEE 802.15.6 standard, a Wireless Body Area Network, aims to transfer not only medical data but also non-medical data, such as physical activity, streaming, multimedia game, living information, and entertainment. Services which transfer those data have very various data rates, intervals and frequencies of continuous access to a medium. Therefore, an efficient anti-collision operations and medium assigning operation have to be carried out when multiple nodes with different data rates are accessing shared medium. IEEE 802.15.6 standard for CSMA/CA medium access control method distributes access to the shared medium, transmits a control packet to avoid collision and checks status of the channel. This method is energy inefficient and causes overhead. These disadvantages conflict with the low power, low cost calculation requirement of wireless body area network, shall minimize such overhead for efficient wireless body area network operations. Therefore, in this paper, we propose a medium access scheduling scheme, which adjusts the time interval for accessing to the shared transmission medium according to the amount of data for generating respective sensor node, and a priority control algorithm, which temporarily adjusts the priority of the sensor node that causes transmission concession due to the data priority until next successful transmission to ensure fairness.

• Journal of KIISE:Computer Systems and Theory
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• v.33 no.3
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• pp.193-204
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• 2006

In most existing distributed Web systems, incoming requests are distributed to servers via Domain Name System (DNS). Although such systems are simple to implement, the address caching mechanism easily results in load unbalancing among servers. Moreover, modification of the DNS is necessary to load considering the server's state. In this paper, we propose a new dynamic load balancing method using dynamic DNS update and round-robin mechanism. The proposed method performs effective load balancing without modification of the DNS. In this method, a server can dynamically be added to or removed from the DNS list according to the server's load. By removing the overloaded server from the DNS list, the response time becomes faster. For dynamic scheduling, we propose a scheduling algorithm that considers the CPU, memory, and network usage. We can select a scheduling policy based on resources usage. The proposed system can easily be managed by a GUI-based management tool. Experiments show that modules implemented in this paper have low impact on the proposed system. Furthermore, experiments show that both the response time and the file transfer rate of the proposed system are faster than those of a pure Round-Robin DNS.

• Proceedings of the Korea Information Processing Society Conference
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• 2008.11a
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• pp.413-416
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• 2008

In the presence of multiple continuous queries, multi-query optimizing is a new challenge to process multiple stream data in real-time. So, in this paper, we proposed an approach to optimize multi-query of sliding window on network traffic data streams and do some comparisons to traditional queries without optimizing. We also detail some method of scheduling on different data streams, while different scheduling made different results. We test the results on variety of multi-query processing schedule, and proofed the proposed method is effectively optimized the data stream similar multi-queries.

• International Journal of Computer Science & Network Security
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• v.24 no.9
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• pp.105-110
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• 2024

Nowadays, permutation problems with large state spaces and the path to solution is irrelevant such as N-Queens problem has the same general property for many important applications such as integrated-circuit design, factory-floor layout, job-shop scheduling, automatic programming, telecommunications network optimization, vehicle routing, and portfolio management. Therefore, methods which are able to find a solution are very important. Genetic algorithm (GA) is one the most well-known methods for solving N-Queens problem and applicable to a wide range of permutation problems. In the absence of specialized solution for a particular problem, genetic algorithm would be efficient. But holism and random choices cause problem for genetic algorithm in searching large state spaces. So, the efficiency of this algorithm would be demoted when the size of state space of the problem grows exponentially. In this paper, the new method presented based on genetic algorithm to cover this weakness. This new method is trying to provide partial view for genetic algorithm by locally searching the state space. This may cause genetic algorithm to take shorter steps toward the solution. To find the first solution and other solutions in N-Queens problem using proposed method: dividing N-Queens problem into subproblems, which configuring initial population of genetic algorithm. The proposed method is evaluated and compares it with two similar methods that indicate the amount of performance improvement.