• Title/Summary/Keyword: Constraint Satisfaction Technique

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A Job Sequencing Model for Cold Coil Production Processes (냉연 공정에서의 작업단위 편성)

  • Jun, C.H.;Lee, S.M.;Park, C.S.;Kang, S.Y.;Chang, S.Y.;Choi, I.J.;Kang, J.T.
    • IE interfaces
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    • v.6 no.2
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    • pp.117-131
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    • 1993
  • A job sequencing model is developed and its computer system is tested for processing cold-rolled coils in Tandem Cold Mills(TCM) at the Pohang Iron and Steel Company. Given coils waiting to be processed, this system generates a sequence of jobs satisfying operational constraints for the TCM process. We formulate the problem as a constraint satisfaction problem and employ the backtracking technique combined with looking ahead features in order to generate a feasible solution within a reasonable time. Our system is implemented in C language on 80486-based IBM PC. Some tests based on the real data show that our system is adequate with respect to search time and that it consistantly generates a good feasible solution.

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Procedural Animation Method for Realistic Behavior Control of Artificial Fish (절차적 애니메이션 방법을 이용한 인공물고기의 사실적 행동제어)

  • Kim, Chong Han;Youn, Jae Hong;Kim, Byung Ki
    • KIPS Transactions on Software and Data Engineering
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    • v.2 no.11
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    • pp.801-808
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    • 2013
  • In the virtual space with the interactive 3D contents, the degree of mental satisfaction is determined by how fully it reflect the real world. There are a few factors for getting the high completeness of virtual space. The first is the modeling technique with high-polygons and high-resolution textures which can heighten an visual effect. The second is the functionality. It is about how realistic represents dynamic actions between the virtual space and the user or the system. Although the studies on the techniques for animating and controlling the virtual characters have been continued, there are problems such that the long production time, the high cost, and the animation without expected behaviors. This paper suggest a method of behavior control of animation by designing the optimized skeleton which produces the movement of character and applying the procedural technique using physical law and mathematical analysis. The proposed method is free from the constraint on one-to-one correspondence rules, and reduce the production time by controlling the simple parameters, and to increase the degree of visual satisfaction.

Study on Hull Form Variation of Fore Body Based on Multiple Parametric Modification Curves (다중 파라메트릭 변환곡선 기반 선수 선형 변환기법 연구)

  • Park, Sung-Woo;Kim, Seung-Hyeon;Lee, Inwon
    • Journal of the Society of Naval Architects of Korea
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    • v.59 no.2
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    • pp.96-108
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    • 2022
  • In this paper, we propose a systematic hull form variation technique which automatically satisfies the displacement constraint and guarantees a high level of fairness. This method is possible through multiple parameter correction curves. The present method is to improve the hull form variation method based on parametric modification function and consists of two sub-categories: SAC variation and section lines modification. For SAC variation, the utilization of two B-Spline curves satisfying GC1 condition led to the satisfaction of displacement constraint and high level of fairness at the same time. Section lines modification methods involves in using two fuctions: the first is the waterplane modification function combining two cubic splines. the other function is the sectional area modification function consisting of 2nd order polynomial over the DLWL(Design Load Waterline) and 3rd order polynomial below the DLWL, This function enables not only the fundamental U-V section shape variation but also systematically modified section lines. The present method is expected to be more useful in the hull form optimization process using CFD compared to the existing method.

UAV-MEC Offloading and Migration Decision Algorithm for Load Balancing in Vehicular Edge Computing Network (차량 엣지 컴퓨팅 네트워크에서 로드 밸런싱을 위한 UAV-MEC 오프로딩 및 마이그레이션 결정 알고리즘)

  • A Young, Shin;Yujin, Lim
    • KIPS Transactions on Computer and Communication Systems
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    • v.11 no.12
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    • pp.437-444
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    • 2022
  • Recently, research on mobile edge services has been conducted to handle computationally intensive and latency-sensitive tasks occurring in wireless networks. However, MEC, which is fixed on the ground, cannot flexibly cope with situations where task processing requests increase sharply, such as commuting time. To solve this problem, a technology that provides edge services using UAVs (Unmanned Aerial Vehicles) has emerged. Unlike ground MEC servers, UAVs have limited battery capacity, so it is necessary to optimize energy efficiency through load balancing between UAV MEC servers. Therefore, in this paper, we propose a load balancing technique with consideration of the energy state of UAVs and the mobility of vehicles. The proposed technique is composed of task offloading scheme using genetic algorithm and task migration scheme using Q-learning. To evaluate the performance of the proposed technique, experiments were conducted with varying mobility speed and number of vehicles, and performance was analyzed in terms of load variance, energy consumption, communication overhead, and delay constraint satisfaction rate.

An Efficient Lot Grouping Algorithm for Steel Making in Mini Mill (철강 Mini Mill 에서의 효율적인 작업 단위 편성)

  • Park, Hyung-Woo;Hong, Yu-Shin;Chang, Soo-Young;Hwang, Sam-Sung
    • Journal of Korean Institute of Industrial Engineers
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    • v.24 no.4
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    • pp.649-660
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    • 1998
  • Steel making in Mini Mill consists of three major processing stages: molten steel making in an electric arc fuenace, slab casting in a continuous caster, and hot rolling in a finishing mill. Each processing stage has its own lot grouping criterion. However, these criteria in three stages are conflicting with each other. Therefore, delveloping on efficient lot grouping algorithm to enhance the overall productivity of the Mini Mill is an extremely difficult task. The algorithm proposed in this paper is divided into three steps hierarchically: change grouping, cast grouping, and roll grouping. An efficient charge grouping heuristic is developed by exploiting the characteristics of the orders, the processing constraints and the requirements for the downstream stages. In order to maximaize the productivity of the continuous casters, each cast must contain as many charges as possible. Based on the constraint satisfaction problem technique, an efficient cast grouping heuristic is developed. Each roll consists of two casts satisfying the constraints for rolling. The roll grouping problem is formulated as a weighted non-bipartite matching problem, and an optimal roll grouping algorithm is developed. The proposed algorithm is programmed with C language and tested on a SUN Workstation with real data obtained from the H steel works. Through the computational experiment, the algorithm is verified to yield quite satisfactory solutions within a few minutes.

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Optimization and Evaluation of Flight Control Laws to Satisfy Longitudinal Handling Quality and Stability Margin Requirements (종축 비행성 요구도 및 안정성 여유 만족을 위한 비행제어법칙 최적화 및 평가)

  • Kim, Seong Hyeon;Ko, Deuk Won;Lee, Tae Hyun;Kim, Dong Hwan;Kim, Byoung Soo
    • Journal of Aerospace System Engineering
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    • v.15 no.5
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    • pp.8-15
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    • 2021
  • This paper describes a design method using an optimization technique to satisfy the longitudinal handling quality of high maneuverable jet aircraft. The dynamic inversion technique was applied to the target aircraft, and the control gain optimization satisfied the longitudinal short-period handling quality, however, the stability margin was not considered. If the stability margin is not satisfied, it is necessary to directly readjust the gains through trial and error methods for improvement. To improve this, an additional compensator and an optimization constraint were added to the control gain optimization procedure. In addition, the degree of handling quality satisfaction with the optimization result was reevaluated, and additional control evaluation criteria for the convergence of the time response and the steady state error that the flight performance requirement set as the optimization constraint cannot be reflected, and the results are described.

Performance Analysis of Adaptive Bandwidth and Subcarrier Allocation Scheme for a Multi-user OFDM System (다중 사용자 OFDM 시스템을 위한 적응적 대역폭 및 부반송파 할당 기법의 성능 분석)

  • Lim, Yeon-Ju;Park, Sang-Kyu
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.31 no.11A
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    • pp.1113-1119
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    • 2006
  • For a multi-user OFDM system in mobile channels which requires low-complexity in adaptive resource allocations, resource allocation algorithm using multi-threshold is proposed. The allocation scheme, which is performed by the multi-threshold values in descending order, considers only subcarriers over each threshold level. Moreover, some subcarriers with the lowest channel gain can be· removed in the present threshold level within the constraint of satisfaction of the required data rate, in order to allocate them to the other users when the allocation process of next threshold is executed. As a result, the proposed bandwidth and subcarrier algorithm has better system performances than the conventional allocation schemes in terms of required power and processing time, which is expected as a technique that improves the spectral efficiency of OFDM systems in a mobile environment.