• 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 Journal of The Korea Institute of Intelligent Transport Systems
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• v.8 no.1
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• pp.1-8
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• 2009

This paper aims mainly to reinterpretate Optimal Bus Scheduling Model by applying System Dynamics Perspective. Traditionally, the study regarding Optimal Bus Scheduling Model stems on the linear relationshp. However, this paper attempted to convert linear relationship based Optimal Bus Scheduling Model to causal loop perspective based Model. In result, the paper present Casual Loop Diagram for Optimal Bus Scheduling Model. Furthermore, the paper also ran a simulation based on Stock & Flow Diagram for Optimal Bus Scheduling Model. The outcome was not much different from the linear relationship based Model due to the similarity of the equation applied on two models.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.5D
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• pp.587-595
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• 2008

Many studies on bus scheduling optimization have been done from the 1960s to recent years for establishing rational bus schedule plan that can improve convenience of bus passengers and minimize unnecessary runs. After 2000, as part of the Intelligent Transport Systems (ITS), the importance of the schedule management and providing schedule information through bus schedule optimization has become a big issue, and much research is being done to develop optimization models that will increase bus passenger convenience and, on the side of bus management, minimize unnecessary bus operation. The purpose of this study is to calculate the optimal bus frequency and create a timetable for each bus stop by applying DTR or DTRC model that use data for each bus stop and route segment. Model verification process was implemented using data collected from bus management system (BMS) and integrated transit-fare card system for bus route of Seoul's No. 472 line. In order to evaluate the reliability and uncertainty of optimal solution, sensitivity analysis was implemented for the various parameters and assumptions used in the bus scheduling model.

• 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 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 Korean Society of Transportation
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• v.24 no.7 s.93
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• pp.129-138
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• 2006

After Seoul has introduced semi-public bus management system(public management-private operation), the Seoul Metro Government needs a scientific management tool for optimal scheduling for bus routes, to reduce unnecessary operations and provide demand responsive service. As a product of this effort, this paper proposes a heuristic model that could minimize total passenger waiting time under the constraints, such as number of vehicles, working conditions, max load point, minimax headway. etc. For verifying the validity of the proposed model, it is applied to an existing bus route. It results that headways in rush hours become decreased and the passenger waiting time could be decreased. In conclusion. it is thought that the Proposed model contributes to efficiency of bus operation.

• Journal of KIISE:Computer Systems and Theory
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• v.27 no.4
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• pp.401-407
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• 2000

Modern microprocessors exploit instruction-level parallel processing to increase the performance. Especially VLIW processors supported by the parallelizing compiler are used more and more in specific applications such as high-end DSP and graphic processing. Bus-based VLIW architecture was proposed for these specific applications and it was designed to reduce the overhead of forwarding unit and the instruction width. In this paper, a optimizing scheduling compiler developed for the proposed bus-based VLIW processor is introduced. First, the method to model interconnections between buses and resource usage patterns is described. Then, on the basis of the modeling, machine-dependent optimization techniques such as bus-to-register promotion, copy coalescing and operand substitution were implemented. Optimization techniques for general-purpose VLIW microprocessors such as selective scheduling and enhanced pipelining scheduling(EPS) were also implemented. The experiment result shows about 20% performance gain for multimedia application benchmarks.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.140.3-140
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• 2001

This paper analyzes a blocking that is due to shared resource in multiprocessor system. A proposed analysis for shared resource suggests a scalable and amendable scheduling method about task allocation. An equation of shared resource blocking is proposed by a throughput at common bus and a ratio of throughput during time period, it is included a parameter of tasks scheduling. Using this equation, a new guideline for task allocation of multiprocessor is presented. Finally, in proposed system a model simulations for the proposed blocking model is given by a deterministic ratio of shared resource.