• 제목/요약/키워드: Roll out Algorithm

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Roll out 알고리듬을 이용한 반복 작업을 하는 안전병렬기계 알고리듬 개발 (- Development of an Algorithm for a Re-entrant Safety Parallel Machine Problem Using Roll out Algorithm -)

  • 백종관;김형준
    • 대한안전경영과학회지
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    • 제6권4호
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    • pp.155-170
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    • 2004
  • Among the semiconductor If-chips, unlike memory chips, a majority of Application Specific IC(ASIC) products are produced by customer orders, and meeting the customer specified due date is a critical issue for the case. However, to the one who understands the nature of semiconductor manufacturing, it does not take much effort to realize the difficulty of meeting the given specific production due dates. Due to its multi-layered feature of products, to be completed, a semiconductor product(called device) enters into the fabrication manufacturing process(FAB) repeatedly as many times as the number of the product specified layers, and fabrication processes of individual layers are composed with similar but not identical unit processes. The unit process called photo-lithography is the only process where every layer must pass through. This re-entrant feature of FAB makes predicting and planning of due date of an ordered batch of devices difficult. Parallel machines problem in the photo process, which is bottleneck process, is solved with restricted roll out algorithm. Roll out algorithm is a method of solving the problem by embedding it within a dynamic programming framework. Restricted roll out algorithm Is roll out algorithm that restricted alternative states to decrease the solving time and improve the result. Results of simulation test in condition as same as real FAB facilities show the effectiveness of the developed algorithm.

대단위 부품-기계 군집 문제를 위한 Look-ahead 휴리스틱 알고리듬 (A Look-ahead Heuristic Algorithm for Large-scale Part-Machine Grouping Problems)

  • 백종관;백준걸;김창욱
    • 한국경영과학회지
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    • 제30권3호
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    • pp.41-54
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    • 2005
  • In this paper, we consider a multi-objective machine cell formation problem. This problem Is characterized as determining part route families and machine cells such that total sum of inter-ceil part movements and maximum machine workload imbalance are simultaneously minimized. Together with the objective function, alternative part routes and the machine sequences of part routes are considered In grouping Part route families. Due to the complexity of the problem, a two-phase heuristic algorithm is proposed. And we developed an n-stage look-ahead heuristic algorithm that generalizes the roll-out algorithm. Computational experiments were conducted to verify the performance of the algorithm.

실시간 차량 동역학 해석을 위한 안티 롤 바 힘 계산 알고리듬 (Anti Roll Bar Force Computation Algorithm for Real Time Multibody Vehicle Dynamics)

  • 김성수;정완희;하경남
    • 대한기계학회논문집A
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    • 제32권2호
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    • pp.170-176
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    • 2008
  • Anti roll bar model for real time multibody vehicle dynamics model has been proposed using kinematic constraint. Anti roll bar have been modeled by kinematic relationship, and mass properties are neglected. Relative angle of torsion bar spring is computed by constraint about drop-link using Newton-Raphson iteration, and then the torque of torsion bar spring can be computed with the angle and torsion spring stiffness. Finally anti roll bar force acting on both knuckle can be calculated. To validate the proposed method, half car simulations of McPherson strut suspension and full car simulations are also carried out comparing with the ADAMS vehicle model with anti roll bar. CPU times are also measured to see the real-time capabilities of the proposed method.

On the Passive type Anti-Rolling Tank and its Activation by Air Blower

  • Lew, Jae-Moon;Park, Bong-Joon;Kim, Hyo-Chul
    • Journal of Ship and Ocean Technology
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    • 제7권1호
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    • pp.19-28
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    • 2003
  • The systematic results of anti-rolling tanks tests obtained by bench tester and roll test in towing tank have been examined. The effects on the oscillating period of fluid transfer through the duct of U-tube tank due to damper plates and the effects on roll damping moment of the tank due to swash plates are alto evaluated from the results. A simple control algorithm for a forced fluid transfer in U-tube tanks if devised to active operation of the tank by air blower. The active performances of the tank are confirmed very effective through the tank tests carried out in the irregular waves.

피드포워드 제어를 이용한 위상차 보정 속도리플 제어기의 설계 (Design of Velocity Ripple Controller using Phase Compensation Feedforward Control)

  • 태원형;김정한;심종엽;오정석;송준엽
    • 한국정밀공학회지
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    • 제31권8호
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    • pp.705-713
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    • 2014
  • In this paper, we propose a novel velocity ripple controller using phase compensation feedforward control. Velocity ripples result in many kinds of performance degradations in manufacturing machines, especially such as ultra-precision roll lathes. The generation of velocity ripple in constant velocity control comes from various causes, such as electrical torque ripples, mechanical worn out, inconsistent mass center, etc. Conventional researches about ripple is mainly for reducing torque ripple in actuator level, which is only one of reasons for velocity ripples, so in this study, we focus on eliminating velocity ripples in upper level controller using phase compensation feedforward controller. The proposed algorithm is composed of several modules, such as ripple extractor, phase adjuster and phase follower etc. The suggested algorithm can be easily extended, and it shows a superior performance in the experiments of ultra-precision roll lathes.

고정형 블레이드가 있는 터빈의 블레이드 균형화 문제 (A Turbine-Blade-Balancing Problem with Some Locking Blades)

  • 최원준
    • 산업공학
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    • 제14권2호
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    • pp.140-147
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    • 2001
  • In the turbine-blade manufacturing industry, turbine-blades are machined and then are assembled to form a circular roll of blades. The roll of blades should be balanced as much as possible, since otherwise the efficiency of the turbine generator might be damaged. A locking blade is a blade whose location is fixed and a non-locking blade is a blade whose location can be freely changed. In this paper, we study methods for balancing the weights of the rotating blades for a turbine where some blades are locking blades. The turbine-blade balancing problem is formulated into a mixed-integer programming problem, which turns out to be NP-hard. A heuristic method based on the number partitioning algorithm is developed and the computational experiments show very promising results.

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3-Axis Gyro Sensor based on Servo Motion Control 시스템 개발 (3-Axis Gyro Sensor based on Servo Motion Control System)

  • ;이원부;박수홍
    • 한국정보통신학회:학술대회논문집
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    • 한국해양정보통신학회 2010년도 춘계학술대회
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    • pp.725-727
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    • 2010
  • 선박의 운동을 시뮬레이터 하기 위해서는 Pitch, Roll, Yaw의 세가지 선박 운동 요소를 시뮬레이터 할 수 있어야 한다. 이를 위해 선박의 운동을 시뮬레이터 할 수 있는 6축의 자유도를 가지는 모션 시뮬레이터를 설계 개발 하였다. Gyro Sensor based Servo Motion Control 알고리즘은 선박의 6자유도운동을 분석하여 그에 대응 할 수 있는 Motion Control 동요안정화 제어장치를 개발하였다.

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사각형 블랭킹을 통한 리드프레임의 블랭킹 특성에 관한 기초연구 (A Study on the Characteristics for the Blanking of Lead Frame with the Rectangular Shape Blanking)

  • 임상헌;서의권;심현보
    • 한국정밀공학회지
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    • 제18권3호
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    • pp.182-188
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    • 2001
  • An experiment is carried out to investigate the characteristics of blanking for copper alloy C194 (t=0.254mm), a kind of IC lead frame material. By varying clearance between die and punch, the shapes of shear profile are examined. Finite element analysis with element deletion algorithm for ductile fracture mode is also carried out to study the effect of clearance theoretically and to compare with experimental results. The rectangular shape specimen with four different corner radius is used to study the characteristics of blanking for straight side and corner region simultaneously. As the result, the ratios measured from the experiment of roll over, burnish, and fracture zone based on intial blank thickness are compared with those of FE analysis. Both experiment and FE analysis show that the amount of roll over and fracture is increased as the clearance increases. It has been found that larger clearance is required than that of straight region when the radius of corner is less than thickness of blank, in order to maintain same quality of shear profile at the corner region.

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Design of Induction Heating Coil for Automatic Hull Forming System

  • Ryu, Hyun-su
    • 해양환경안전학회지
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    • 제24권3호
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    • pp.360-366
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    • 2018
  • In shipyards hull forming is performed by the line heating method using a gas torch and by cold treatment using a roll-press. However, this forming process has some issues, such as difficulties in controlling and accurately estimating the amount of the heat input, as well as a harsh working environment due to exposure to loud noises and air pollution. The induction heating method, which is introduced in this paper, exhibits good control and allows for the estimation of precise heat input. Also, workers can carry out the induction heating in a comfortable working environment. In this research, the induction heating simulation, which consists of electro-magnetic, heat transfer and thermal elasto-plastic analysis, was developed and modified through induction heating experiments. Finally, the effective heating coil was designed for the automatic hull forming system based on the results of induction heating simulation. For the purposes of a future study, if an algorithm to obtain optimal working conditions is developed, automatic systems for hull forming can then be constructed.

조종자 입력패턴을 활용한 RIB형 무인선의 침로제어기 설계 (Design of Course Keeping Controller for RIB-type USV Using a Pilot's Steering Pattern)

  • 윤근항;여동진;윤현규
    • 대한조선학회논문집
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    • 제47권3호
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    • pp.462-468
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    • 2010
  • A new course keeping controller for RIB(Rigid Inflatable Boat)-type USV(Unmanned Surface Vehicle) is developed using pilot's steering pattern. A pilot's simple steering pattern is found out from various course change tests. It is used to course keeping algorithm, suitable for large course change more than 60 degrees. To validate the course keeping controller, sea trial tests are conducted. From sea trial test, new course keeping controller shows good performance with less overshoot, maximum roll angle less than $20^{\circ}$, which makes it possible that fast course changes without slip motion of USV.