• Journal of Korean Society of Industrial and Systems Engineering
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• v.34 no.4
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• pp.189-196
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• 2011

In this paper, we propose a logical control-based actor-critic algorithm as an efficient approach for the approximation of the capacitated fab scheduling problem. We apply the average reward temporal-difference learning method for estimating the relative value functions of system states, while avoiding deadlock situation by Banker's algorithm. We consider the Intel mini-fab re-entrant line for the evaluation of the suggested algorithm and perform a numerical experiment by generating some sample system configurations randomly. We show that the suggested method has a prominent performance compared to other well-known heuristics.

• Journal of the Korea Computer Industry Society
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• v.7 no.4
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• pp.309-320
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• 2006

The imprecise real-time system provides flexibility in scheduling time-critical tasks. Most scheduling problems of satisfying both 0/1 constraint and timing constraints, while the total error is minimized, are NP-complete when the optional tasks have arbitrary processing times. Liu suggested a reasonable strategy of scheduling tasks with the 0/1 constraint on uniprocessors for minimizing the total error. Song et al suggested a reasonable strategy of scheduling tasks with the 0/1 constraint on multiprocessors for minimizing the total error. But, these algorithms are all off-line algorithms. In the online scheduling, NORA algorithm can find a schedule with the minimum total error for the imprecise online task system. In the NORA algorithm, the EDF strategy is adopted in the optional scheduling.<중략> The algorithm, proposed in this paper, can be applied to some applications efficiently such as radar tracking, image processing, missile control and so on.

• Proceedings of the Safety Management and Science Conference
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• 2005.11a
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• pp.30-39
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• 2005

Line capacity calculation has been used to determine optimum efficiency and safe train service for train scheduling plan and investment priority order throughout detecting bottleneck section. Because of some problems of Yamagisi and UIC methods for line capacity calculation, developing of the method of line capacity calculation and evaluation for the Korea circumstance is important. This paper deals with the integrated system of TPS(Train Performance Simulator), PES(Parameter Evaluation Simulator), LCS (Line Capacity Simulator) and sensitivity analysis for line capacity calculation model.

• The KIPS Transactions:PartA
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• v.18A no.4
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• pp.143-150
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• 2011

This paper presents an EDF based scheduling algorithm for scheduling imprecise computation model where each task consists of mandatory part and optional part. Imprecise computation is useful to manage overload condition. In overload situation, some optional parts should be removed. The proposed DOP algorithm removes optional parts of earlier deadline tasks to enhance flexibly for newly arriving tasks. A simulation result shows that DOP has better performance than other algorithms.

• Journal of the Society of Naval Architects of Korea
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• v.43 no.2 s.146
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• pp.228-235
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• 2006

Nowadays, digital manufacturing has been known to be very effective method in manufacturing fields. It is aimed to estimate process time, to improve operation efficiency, and to prevent bottleneck processes in advance of real manufacturing. This paper addresses a scheduling support system for panel hues in a shipyard through digital manufacturing simulation. The proposed system supports operators to make better decisions on the shop-floor scheduling in panel lines. It ,would provide a complete schedule that is at least as good as any schedule currently obtained. Furthermore, it can evaluate the operator's schedule by simulating it with 3-dimensional models before the work orders and schedules are released.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.7
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• pp.1309-1313
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• 2010

In this paper, we propose a novel guidance law for controlling an UAV(Unmanned Air-Vehicle) to follow a reference line in vertical plane. A kinematics model representing the relative motion of the UAV to the reference line is derived. And then LQR(Linear Quadratic Regulator) theory is applied to the model to derive the VLFG(Vertical Line Following Guidance) law. The resultant guidance law forms a gain-scheduling controller scheduled by a simple parameter $\sigma$ which is a function of the UAV's velocity, axial acceleration, gravity, and the slope of the reference line. Also derived is a stability condition for the $\sigma$ variation based on Lyapunov theory. Simulation results show that the proposed guidance law can be applied effectively to UAV guidance algorithm design.

• Journal of KIISE:Computer Systems and Theory
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• v.31 no.7
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• pp.387-396
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• 2004

In this paper, we propose an algorithm that distributes processor time to the tasks decoding encoded frames with a goal maximizing total QoS (quality of services) of video conference system. An encoded frame has such a characteristic that the QoS of recovered frame image also increases as the processor time given for decoding the frame gets to increase. Thus, the quality of decoded image for each frame can be represented as a QoS function of the amount of service time given to decode. In addition, every stream of video conference has close time-dependency between continuous frames belonging to the same stream. Based on the time-dependency and QoS functions, we propose an on-line frame scheduling algorithm which does not schedule all frames in the system but just a few frames while maximizing total QoS of video streams in the conference. The simulation results show that, as the system load gets to increase, the proposed algorithm compared to the existing EDF algorithm can reduce the quality of decoded frame images more smoothly and show the movements of conference attendees more naturally without short cutting.

• 제어로봇시스템학회:학술대회논문집
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• 1994.10a
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• pp.449-454
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• 1994

This paper describes new PID control methods based on the fuzzy logic. PID gains are retuned after evaluating control performances of transient responses in terms of performance features. The retuning procedure is based on fuzzy rules and reasoning accumulated from the knowledge of experts on PID gain scheduling. For the case that the retuned PID gains result in worse CLDR (characteristics of load disturbance rejection) than the initial gains, an on-line tuning scheme of the set-point weighting parameter is, proposed. This is based on the fact that the set-point weighting method efficiently reduce either overshoot or undershoot without any degradation of CLDR. The set-point weighting parameter is adjusted at each sampling instant by the fuzzy rules and reasoning. As a result, better control performances were achived in comparison with die controllers tuned by the Z-N (Ziegler-Nichols) parameter tuning formula or by the fixed set-point weighting parameter.

• Journal of the Society of Naval Architects of Korea
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• v.53 no.1
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• pp.18-28
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• 2016

In shipbuilding, the scheduling system is susceptible to sudden changes and thus it turns to be difficult to predict the differences between schedule and production records in advance. A computer-based simulation is commonly utilized to overcome the discrepancies occurred in estimating workloads and resulting processing times. The main drawback of this simulation-based solution is its limited applicability because, in most cases, each shipyard requires specific and customized simulation environment. By standardizing the planning data of the midterm scheduling system, as proposed in this paper, the efficiency of the current simulation model can be enhanced. To present an alternative approach, this paper begins with the analysis of the complex planning data structure of several shipyards and then proceeds to construct a standard data structure based on the neutral format. An interface application is developed for the data transaction and simulation in on-line environment. As a result, a simulation-based production management of shipyards can be achieved by the efficient prediction of planning and scheduling.

• Journal of Information Technology Applications and Management
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• v.14 no.3
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• pp.227-236
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• 2007

Students in cyber universities can take every course because there are no physical constraints such as class rooms. On the other hand. cyber universities should take a heavy burden to schedule real-time exams in a designated time period. Any two courses a student takes must not be simultaneously allocated to a time slot in such a schedule. It is well known that the complexity of this kind of scheduling problem increases exponentially as the number of courses does. This research provides a heuristic method to make on-line real-time exam timetables with minimal exam time span. It considers the constraint of not allocating courses a student takes to simultaneous exam time and prioritizes courses by the number of students.