• Journal of Korean Society of Industrial and Systems Engineering
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• v.22 no.50
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• pp.351-362
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• 1999

버퍼는 생산시스템에서 시스템내의 기계고장, 프로세스시간의 변화, 그리고 부품들의 이동경로의 복잡성 등과 같은 요인들로 인해 발생 가능한 blocking현상과 starving현상을 감소시키는데 사용되고 있다. 유연 생산시스템(Flexible Manufacturing System)에서는 버퍼의 단위당 비용이 높아 시스템내의 총 버퍼 크기는 제한적이어서, 적절한 버퍼 관리를 통해 시스템 효율성을 향상시킬 수 있다. 본 연구는 이러한 버퍼의 특성을 분석하고 AGVS(Automated Guided Vehicle System)을 사용하는 다중셀방식의 FMS(multi-cell Flexible Manufacturing Systems) 환경에서의 버퍼관리와 관련된 기존 연구들을 검토하고, 새로운 개념의 가상시스템버퍼를 소개한다.

• Journal of Institute of Control, Robotics and Systems
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• v.15 no.5
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• pp.473-479
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• 2009

This paper proposes an efficient method to locate the automated guided vehicle (AGV) into a specific parking position using artificial visual landmark and vision-based algorithm. The landmark has comer features and a HSI color arrangement for robustness against illuminant variation. The landmark is attached to left of a parking spot under a crane. For parking, an AGV detects the landmark with CCD camera fixed to the AGV using Harris comer detector and matching descriptors of the comer features. After detecting the landmark, the AGV tracks the landmark using pyramidal Lucas-Kanade feature tracker and a refinement process. Then, the AGV decreases its speed and aligns its longitudinal position with the center of the landmark. The experiments showed the AGV parked accurately at the parking spot with small standard deviation of error under bright illumination and dark illumination.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.20 no.43
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• pp.249-263
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• 1997

This paper addresses the parts route selection and economic design in flexible manufactuirng system (FMS). Parts are processed through several stage workstations according to operation sequences. The machine of each workstation can do multiple operation functions. And the operation stage of a part can be processed in several workstations, which are non-identical in functional performance. The objective of this paper is to determine the processing routes of parts, number of machine at each workstation, number of vehicle and makespan time. Two models are suggested. One is assumed that the operation stage of parts can be processed at the only one among several available workstations. Other is assumed that the operation stage of parts is allowed to be processed at several workstations. Parts are transported by automated guided vehicles (AGVs). The decision criteria is to minimize the sum of processing cost, travel cost, setup cost and overhead cost. The formulation of models is represented. A solution algorithm is suggested, and a numerical example is shown.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.21 no.46
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• pp.19-32
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• 1998

This paper addresses the processing route of parts and economic design in flexible manufacturing systems (FMSs) employing AGVs for Transport. Parts are processed through several workstations according to operation sequences. The machine of each workstation can do multiple operation functions. The operation stage of a part can be processed in several workstations, which are non-identical in functional performance. The objective of this paper is to determine the processing route of parts, number of machines at each workstation, number of vehicles. The model is assumed that the operation stage of parts can be processed at the only one among several available workstations. Parts are transported by automated guided vehicle system(AGVS). The decision criteria is to minimize the sum of processing cost, travel cost, operating cost. A model formulation is represented. A solution algorithm is suggested by using mathematical programming and simulation technique, and a numerical example is shown.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 1998.10a
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• pp.330-340
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• 1998

자율주행 반송차가 주어진 경로를 따라 주행 할 때 주행면의 불균일성과 같은 외란요인과 자율반송차 시스템 자체의 비선형성 등으로 인하여 원치 않는 경로추종오차가 발생하게 되는데 본 연구에서는 이러한 경로추종오차를 최소화하기 위해서 신경회로망을 이용한 경로추종 오차 보상방법을 제안한다. 본 방법에서는 신경회로망을 통하여 조향각 보상량을 제공하므로써 경로추종오차를 보상한다. 신경망은 다층 퍼셉트론을 채용하였으며 역전파 알고리즘의 최급강하규칙(Gradient descent rule)을 이용하여 학습을 수행하였다. 본 제안에서는 학습오차를 경로추종오차로부터 정의하므로써 경로추종오차가 최소화되록 신경회로망을 학습시켰다. 제안된 방법의 타당성은 다양한 경로에 대한 모의실험 및 실제 실험을 통하여 검증하였다.

• Journal of Korean Port Research
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• v.12 no.2
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• pp.195-206
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• 1998

By the rapid expansion of containerization and intermodal transportation in international shipping since the 1970's, the larger containerships have emerged and concentrated their calls at a limited number of ports. Moreover, large-scale container terminals have been built to accommodate the ever-larger containerships, and the mordernization of terminal facilities and many developments in information technology etc. have been brought out. Thus, unlimited competition has been imposed on every terminal with neighbouring ports in Japan, Singapore, Hongkong and Taiwan etc. The purpose of this study is to suggest how the container terminal operators cope with unlimited competition between local or foreign terminals. The results are suggested as follows: First, transshipment cargoes, which the added value is high, is to be induced. Second, the function of storage is given on On-Dock Yard. Third, Berth Pool Operation System is to be introduced, especially in Gamman Container Terminal and Kwangyang Container Terminal. Fourth, the cargo handling charges is to be decided by terminal operator.

• Journal of Korean Institute of Industrial Engineers
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• v.26 no.4
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• pp.392-401
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• 2000

In this work, a deadlock avoidance strategy is proposed in order to effectively handle conflicts and deadlocks occurring in zone-control AGV (Automated Guided Vehicle) systems. The basic idea is based on Capacity-designated Directed Graph (CDG) theory that was developed to avoid from deadlocks in manufacturing systems. However, to enforce the effectiveness of detecting impending and restricted deadlocks, AGV routings are explicitly described in Extended Directed Graph (EDG). From EDG, a non-conservative deadlock-avoidance strategy is derived. The superiority of the proposed strategy lies on the applicability to diverse AGV path configurations using zone control. Also, because of its insensibility and robustness, it can be effectively used when the system has randomness and stochastic nature.

• Journal of Navigation and Port Research
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• v.35 no.2
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• pp.167-172
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• 2011

The motivation of this study is the recent advancement of the Straddle Carrier (S/C). Previously Straddle Carrier (S/C) system was used focusing on container lift on/off due to its lower driving speed than that of (Y/T). Shuttle Carrier is evaluated as an upgraded Straddle Carrier. Recently, however, the driving speed of (S/C) has been improved to the level of Yard Tractor and Trailer systems (Y/T), which is 30Km per hour which makes (S/C) qualified as terminal in-yard transportation equipment. This paper, therefore, aims to evaluate three types of terminal in-yard transportation equipments such as (Y/T), (AGV) and the advanced (S/C) from economic perspective. The results revealed that by observing the total costs of equipment, (S/C) is a cheaper option than (Y/T) over 20 years, and than (AGV) over 6 years.

• Proceedings of the Korea Inteligent Information System Society Conference
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• 2007.11a
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• pp.564-569
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• 2007

자동화 컨테이너 터미널에서 안벽크레인, AGV(Automated Guided Vehicle)와 같은 하역장비의 작업은 수 많은 요인에 영향을 받으며, 이로 인해 각 장비의 작업시간을 정확하게 추정하는 것은 거의 불가능하다. 작업시간의 불확실성은 AGV 배차를 어렵게 만들고 작업효율을 떨어뜨리는 주요 원인이다. 본 논문에서는 이러한 불확실성에 대처하기 위하여 확률적 시뮬레이션 기반 AGV 배차 알고리즘을 제안한다. 제안 방안은 AGV를 배차할 때, 이후 일정 기간 동안의 AGV작업에 대해 확률적 시뮬레이션을 여러번 반복하여 수행하고 평가 값을 평균함으로써 불확실성의 영향을 줄인다. 확률적 시뮬레이션을 위해 크레인 작업시간의 불확실성을 간단한 확률함수로 모델링하고 그에 따라 크레인 작업시간을 결정한다. 또한 AGV 작업시간을 가감속, 간섭을 고려하여 추정한다. 시뮬레이션 실험을 통해 제안방안을 검증한 결과 안벽크레인의 지연이 감소함을 확인하였다.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.18 no.35
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• pp.139-155
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• 1995

This study is concerned with the economic analysis of implementing a material handling system using automated guided vehicle(AGV)s in order to improve the productivity of the production process of chinawares. Analytic hierarchy process(AHP) method for selecting the facilities of material handling systems is presented. Subsequently, as an example, a chinaware production line is analyzed for the economic analysis. The result shows that seven manpowers can be reduced. However the introduction of the new material handling system is turn out to be undesirable due to high initial cost of AGV system, Nevertheless, in the long term, automatic material handling system such as AGV system are expected to play major roles in the modern manufacturing area.