• Proceedings of the Korean Information Science Society Conference
• /
• 2012.06d
• /
• pp.300-302
• /
• 2012

In this paper, we investigate the performance of multi-channel cognitive radio networks (CRNs) by taking into consideration the problem of channel assignment and link scheduling. We assume that secondary nodes are equipped with multiple radios and can switch among multiple channels. How to allocate channels to links and how much power used on each channel to avoid mutual interference among secondary links are the key problem for such CRNs. We formulate the problem of channel assignment and link scheduling as a combinatorial optimization problem. Then, we propose a the optimal solution and show that it converges to maximum optimum in some iterations by using numerical results.

• Proceedings of the KIEE Conference
• /
• 2006.07a
• /
• pp.216-217
• /
• 2006

This paper presents development of program for generator maintenance scheduling. The maintenance scheduling of generating units is a dynamic discrete combinatorial optimization problem with constraints to determine the optimal maintenance periods of each generating units for a given planning periods. The developed program is designed so as to provide the maintenance schedule satisfying the operating reserve margin levelization and the procurement of proper reliability. In order to verify the effectiveness of the developed program, the numerical study has been performed with the practical data in 2005.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.31 no.3
• /
• pp.17-23
• /
• 2008

In this research article, scheduling a casting sequence in a job-shop type foundry involving a variety of casts made of an identical alloy but with different shapes and II weights, has been investigated. The objective is to produce the assigned mixed orders satisfying due dates and obtaining the highest ingot efficiency simultaneously. Implementing simple integer programming instead of complicated genetic algorithms accompanying rigorous calculations proves that it can provide a feasible solution with a high accuracy for a complex, multi-variable and multi-constraint optimization problem. Enhancing the ingot efficiency under the constraint of discrete ingot sizes is accomplished by using a simple and intelligible algorithm in a standard integer programming. Employing this simple methodology, a job-shop type foundry is able to maximize the furnace utilization and minimize ingot waste.

• Proceedings of the KSR Conference
• /
• 2000.11a
• /
• pp.86-92
• /
• 2000

The crew operation scheduling problem is divided into duty generation and duty allocation. The railway crew roster scheduling(duty allocation) is developed monthly for each crew's office, considering the car types and crew's driving ability. However, it is very difficult to make schedules which assign monthly working hours to each crew evenly. The purpose of this thesis is to minimize the differences between each crew's total duty times and make a rostering table. To minimize the differences among monthly working hours of each crews are grouped according to car type and crew's driving ability and a rostering table which could be shared by the group members is developed. Our approach is to apply the techniques of Constraint Programming in order to solve such problems efficiently. This algorithm is suitable to solve optimization problems which involve many complicated constraints. And including the concept of cost, we suggested the model which enable to make the rostering table with a minimum personnel.

• Proceedings of the KIEE Conference
• /
• 1995.11a
• /
• pp.513-515
• /
• 1995

A computer aided process is inevitable for the optimization of train operation planning. Developing of train diagrams is very important for the train operation planning. In this paper, the user friendly program related to the train scheduling that can be used for the basic data on developing of train diagram is introduced. It can also provide basic data for other train operation plannings, such as Timetabling, Crew Operation Scheduling, etc. It provides the planner with data moving, data changing and zooming functions, and it can assist the user easily produces their optimal solution. All this operations are performed interactively through graphic windows.

• Journal of Information Processing Systems
• /
• v.11 no.1
• /
• pp.116-124
• /
• 2015

Smart grids propose new solutions for electricity consumers as a means to help them use energy in an efficient way. In this paper, we consider the demand-side management issue that exists for a group of consumers (houses) that are equipped with renewable energy (wind turbines) and storage units (battery), and we try to find the optimal scheduling for their home appliances, in order to reduce their electricity bills. Our simulation results prove the effectiveness of our approach, as they show a significant reduction in electricity costs when using renewable energy and battery storage.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2018.05a
• /
• pp.41-42
• /
• 2018

Various methods that crash the project completion time have been studied. Line-of-Balance (LOB) is well accepted as a useful method that enables steady resource utilization without frequent hire-and-fire of resources for a project having repetitive units. Existing studies involved in LOB-CPM focuses on thesis such as resource leveling and optimization in construction scheduling community. However, crashing methods are not arrived at a full maturity in LOB scheduling, because no one handles steady resource utilization while keeping activity-relationships. This paper proposes a method that crashes project completion time by hybridizing concurrent engineering and LOB scheduling without using additional resources.

• Journal of the Korea Society of Computer and Information
• /
• v.7 no.2
• /
• pp.40-45
• /
• 2002

In this paper, we deals with scheduling problem for data-path synthesis in high-level synthesis. We proposed a new method to optimize interconnection cost for operator allocation. Especially, we focus to optimize for buses to transfer data channel and register to restore operation result. Also we take account ILP formulation in order to get optimal scheduling result. To verify the effectiveness of this study, we select 5th Digital Wave Filter. The experimental result show that purposed method was better then the general methods.

• ETRI Journal
• /
• v.36 no.6
• /
• pp.960-967
• /
• 2014

In this paper, an analytical framework is proposed for the optimization of network performance through joint congestion control, channel allocation, rate allocation, power control, scheduling, and routing with the consideration of fairness in multi-channel wireless multihop networks. More specifically, the framework models the network by a generalized network utility maximization (NUM) problem under an elastic link data rate and power constraints. Using the dual decomposition technique, the NUM problem is decomposed into four subproblems - flow control; next-hop routing; rate allocation and scheduling; power control; and channel allocation - and finally solved by a low-complexity distributed method. Simulation results show that the proposed distributed algorithm significantly improves the network throughput and energy efficiency compared with previous algorithms.

• Proceedings of the KSR Conference
• /
• 2000.05a
• /
• pp.324-329
• /
• 2000

Object of a real-time system, that performs exact information based on the real-time constraint. is required for an improvement of high reliability. The fault-tolerant task scheduling strategy of multiprocessor as using a distributed memory based on a hardware redundancy can be improved into a high reliability of the real-time system. Therefore, this paper is shown to analyze the reliability of the system by using the transfer parameter and make the modeling in reference to a minimization of the fault-tolerant task scheduling strategy which uses a percentage of task missing and deadline parameter based on optimization task size.