• IE interfaces
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• v.15 no.1
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• pp.49-54
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• 2002

A bus scheduling problem with multiple objective functions and travel time constraint is to determine the allocation of buses to customer service requests minimizing the number of buses and travel costs under the travel time restriction for each bus. For the scheduling, we first represent the scheduling problem using a graph and develop a hierarchical approach. Second, we develop a mathematical model based algorithm for the scheduling problem including heuristic methods. We tested the performance of the algorithm on instances with real data. As a result, the total number of buses and travel costs are reduced over about 10% comparing with that of current practice at the company.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2000.10a
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• pp.149-152
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• 2000

The chartered bus scheduling is to determine the allocation of buses to customer service requests. For the scheduling, we first represent the scheduling problem using a graph and develop a mathematical model. Second, we develop an algorithm for the scheduling problem including heuristic methods. We tested the performance of the algorithm on instances with real data. As a result, the total empty load driving time is reduced over 10% comparing with that of current practice at the company

• Journal of Korean Society of Transportation
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• v.17 no.4
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• pp.47-58
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• 1999

The Purpose of this Paper is to develop a multi-period bus scheduling model, in which a decomposition technique is applied. In general a bus scheduling requires a vast amount of calculation. Thus, a bus scheduling is a very complicated problem even with a single depot and is almost unable to obtain the optimal solution theoretically with many depots. In this paper in order to simplify the problem, the whole operating hours of a day are partitioned into several time periods. In one period, the same headways are maintained. For one period, the bus scheduling is simple and the solution applying the FIFO(First-In, First-Out) Principle is the optimal. However, connection between Periods remains as another scheduling Problem with a reduced problem size. This paper suggests how to connect bus schedules of consecutive periods efficiently, minimizing the operating cost. Through case studies for multiple routes with a single depot, this decomposition technique is proved to be effective practically.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.6 no.3
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• pp.12-23
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• 2007

The purpose of this studγ if to understand problem of present bus scheduling system and to develop optimal bus scheduling model which improve bus passenger's degree of satisfaction(DOS) and bus company's operation efficiency at the same time. This study developed optimal bus scheduling model, which reflected bus passenger's degree of satisfaction(DOS), applied to existing model that summery of bus operation cost($C_o$), passenger queuing time cost($C_{pw}$) and passenger travel time cost($C_{pl}$). And optimal bus scheduling model which developed in this study is optimized that using LINGO program based on linear program. Also by using the general case in Busan, compare total cost of present bus scheduling system and existing scheduling model with total cost of optimal bus scheduling model which reflected bus passenger's degree of satisfaction(DOS).

• The Transactions of the Korea Information Processing Society
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• v.6 no.8
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• pp.2196-2203
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• 1999

This paper describes the bus scheduling problem and register optimization method in datapath synthesis. Scheduling is process of operation allocation to control steps in order to minimize the cost function under the given circumstances. For that purpose, we propose some formulations to minimize the cost function for bus assignment to get an optimal and minimal cost function in hardware allocations. Especially, bus and register minimization technique are fully considered which are the essential topics in hardware allocation. Register scheduling is done after the operation and bus scheduling. Experiments are done with the DFG model of fifth-order digital ware filter to show its effectiveness. Structural integer programming formulations are used to solve the scheduling problems in order to get the optimal scheduling results in the integer linear programming environment.

• Journal of the military operations research society of Korea
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• v.13 no.1
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• pp.101-115
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• 1987

This paper presents an optimization based heuristic algorithm for a tour bus scheduling problem where buses consist of various kinds of sightseeing and commutation services. First, this algorithm transforms the prolem into a vehicle routing problem on whose nodes denote trips and arcs denote connections between trips. Second, a greedy heuritic routing technique is applied to find a good feasible bus-route set. Then the greedy feasible solution is improved by the simplex method using column generation technique. The algorithm provides a better near-optimal solution which gives much reductions in the total tour distance and the number of tour buses.

• IE interfaces
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• v.23 no.2
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• pp.139-146
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• 2010

In this paper, we present the study of a real passenger transportation system. Passenger transportation problem aims to transport passengers from bus stops to their destinations by a fleet of vehicles while satisfying various constraints such as vehicle capacity, maximum allowable riding time in a bus, and time windows at destinations. Our problem also has special issues such as mixed loading, consideration of afternoon problem together with morning problem, and transferring passengers between vehicles. Our solution approach consists of three serial procedures: bus route generation, bus scheduling, and post optimization. Efficient heuristic algorithms were developed and implemented for the procedures. The proposed solution approach has been successfully applied to several real world problem instances and could reduce about 10% to 15% of buses.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.34C no.3
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• pp.1-10
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• 1997

We present an approach to high-level synthesis for a specific target architecture-partitioned bus architecture. In this approach, we have specific goals of minimizing data transfer length and number of buses in addition to common synthesis goals such as minimizing number of control steps and satisfying given resource constraint. Minimizing data transfer length and number of buses can be very important design goals in the era of deep submicron technology in which interconnection delay and area dominate total delay and area of the chip to be designed. in partitioned bus architecture, to get optimal solution satisfying all the goals, partitioning of operation nodes among segments and ordering of segments as well as scheduling and allocation/binding must be considered concurrently. Those additional goals may impose much more complexity on the existing high-level synthesis problem. To cope with this increased complexity and get reasonable results, we have employed two ideas in ur synthesis approach-extension of the target architecture to alleviate bus requirement for data transfer and adoption of genetic algorithm as a principal methodology for design space exploration. Experimental results show that our approach is a promising high-level synthesis mehtodology for partitioned bus architecture.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.4
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• pp.457-466
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• 2013

Wind energy is rapidly becoming significant generating technologies in electricity markets. As probabilistic nature of wind energy creates many uncertainties in the short-term scheduling, additional actions for reliable market operation should be taken. This paper presents a novel approach to evaluate ramping capability requirement for changes in imbalance energy between day-ahead market and real-time market due to uncertainty of wind generation as well as system load. Dynamic ramp rate model has been applied for realistic solution in unit commitment problem, which is implemented in day-ahead market. Probabilistic optimal power flow has been used to verify ramping capability determined by the proposed method is reasonable in economic and reliable aspects. This approach was tested on six-bus system and IEEE 118-bus system with a wind farm. The results show that the proposed approach provides ramping capability information to meet both forecasted variability and desired confidence level of anticipated uncertainty.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.7
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• pp.1441-1449
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• 2015

Wireless universal serial bus (WUSB) is the USB technology merged with WiMedia PHY/MAC. WUSB can be applied to wireless persanal area network (WPAN) applications as well as PAN applications like wired USB. Because numerous WUSB networks operate independently for each application, data conflict can occur between adjacent networks. To avoid data conflict, the resource in a different time zone can be utilized. However, if devices in a network increase, available resources in the network decrease, and then the lack of resources necessary to provide service can occur. To solve this problem, we propose interference avoidance scheme for WUSB systems.