• 산업공학
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• 제9권2호
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• pp.219-229
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• 1996

Most studies on the operation policy for AS/RS concluded that the class-based storage policy has better performance than random storage policy does. However ASRS performances are examined only with the assumption of fixed production quantity in the studies. It is true that production quantity of each item changes frequently in practice. If an ASRS keeps the current storage policy regardless of production quantity variation, the performance of present storage policy will be worse. The effect of production quantity variation per product between 10 and 80% with random storage policy and class-based storage policy with reassignment and relocation are studied. The results are compared with both of the randomized and class-based storage policies without reassignment nor relocation cases. A typical ASRS system is developed using GPSS/PC for operation policy evaluation purposes.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1992년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 19-21 Oct. 1992
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• pp.303-308
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• 1992

In this study, we propose a shared storage system which is more efficient policy than MIS(Mixed Intermediate Storage) policy for relatively rare storage system and can be called CIS(Common Intermediate Storage) policy. Using this strategy, we develop a new completion time algorithm and apply it to two kinds of optimal or near optimal scheduling method; combinatorial search and simulated annealing method. We also extend this strategy to other storage policy, for example MIS policy, with PLC(Programmable Logic Controller) logic and on/off action of electronic valves. It thus can be accepted as a basic form of FMS(Flexible Manufacturing System) for operating various storage policies. Finally we suggest the interlocking block to compansate for the shortcoming of CIS policy, i.e, complication of operation and safety, resulting in a basic batch process automation mode.

• 한국컴퓨터정보학회논문지
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• 제8권4호
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• pp.159-164
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• 2003

물류창고의 적재위치는 창고를 이동하는 물품의 총 자재취급비용에 의해 직접전인 영향을 받는다. 본 논문의 목적은 물류 창고에서의 총 오더피킹 시간을 감소하기 위한 물품 저장방식인 블록 저장방식을 개발하고자 한다. 블록저장방식은 랙들을 블록으로 분할하고, 각 물품은 회전율과 도크와 블록간의 평균 거리를 기준으로 할당한다. 제시한 저장방식의 수행도를 평가하기 위해 다양한 주문 결합 방법들을 이용하여 기존의 등급별 저장방식과 비교 연구한다.

• 한국경영과학회지
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• 제23권3호
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• pp.91-108
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• 1998

Automated Storage and Retrieval Systems (AS/RSs) are an important facility for modern material management. The expected benefits of these capital-intensive facilities are gained when their control policies and their physical design parameters are determined simultaneously. In this paper we present several analytical models that capture the impact of the storage assignment policy and of the rack design on the expected storage and retrieval times. Sequential and interleaved service modes are considered for sequencing the storage and retrieval requests. We further investigate the impact of the rack structure on the relative performance of the following storage assignment policies : closest open location (random), full turnover-based policy, and class-based. Our analysis clearly indicates that significant savings in crane travel time are realized when implementing full turnover-based policy, rather than random. These savings become more and more pronounced as the profile of the storage racks approaches the square-in-time shape. Furthermore, it is shown that a class-based policy, with a small number of storage classes, will capture most of these savings and be easier to manage in practice.

• 대한산업공학회지
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• 제19권2호
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• pp.95-103
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• 1993

We address a new storage policy, called Skip-k storage, which gives storing priority to the items with relatively higher turnover rates. Applying the policy in storage systems such as AS/RS will reduce expected travel distance considerably. We analyze system behavior and find an appropriate skip size expressed by the system parameters in case arrival rates become larger enough.

• 대한산업공학회지
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• 제25권2호
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• pp.274-281
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• 1999

In this paper, we determine the required storage capacity of a unit-load automated storage/retrieval system(AS/RS) under random storage assignment(RAN) and n-class turnover-based storage assignment(CN) policies. For each of the storage policies, an analytic model to determine the optimal storage capacity of the AS/RS is formulated so that the total cost related to storage space and space shortage is minimized while satisfying a desired service level. A closed form of optimal solutions for the RAN policy is derived from the model. For the CN policy, an optimal storage capacity is shown to be determined by applying the existing iterative search algorithm developed for the full turnover-based storage(FULL) policy. Finally, an application of the approach to the standard economic-order-quantity inventory model is provided.

• 대한산업공학회지
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• 제30권4호
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• pp.294-300
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• 2004

This paper considers a trade-off effect between in-house storage space and leased storage space in generic warehouses operated under a randomized storage assignment policy. The amount of in-house storage space is determined based on the law of large numbers satisfying a given service level of protection against space shortages. Excess space requirement is assumed to be met via leased storage space. A new analytic model is formulated for determining the excess space such that the total cost of storage space is minimized. Finally, computational results are provided for the systems where the standard economic-order-quantity inventory model is used for all items.

• 한국경영과학회지
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• 제24권3호
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• pp.39-47
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• 1999

It has been concluded that the performance of class-based storage policy is better than the performance of random storage policy in the literature. However, the rack shortage problem assigned to the 1st class items makes the decision hard to apply the class-based storage policy in practice. In this paper, a new common zone concept is introduced between two classes to resolve the problem with class-based storage policy. The common zone is the area to accept items from both classes. An AS/RS model is developed for computer simulation study and the effect of common area sizes with various AS/RS operation conditions is analyzed.

• 대한산업공학회지
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• 제20권2호
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• pp.39-50
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• 1994

Most research results on the throughput of unit-load automated storage retrieval (AS/R) systems assume the randomized storage; that is, all slots In the entire rack are equally likely to be selected for the storage location. However, for the most existing AS/R systems which use Closest Open location storage policy, Park[6] mathematically showed that this assumption results in a significant difference from the actual performance of AS/R systems. In this study, we present more details about the performance of the unit-load AS/R systems by considering the rack utilization and rack density; and examine their impact on the throughput of AS/R systems by using computer simulation. A new storage policy named Shortest Cycle Location(SCL) is proposed. Simulation results indicate that the performance of SCL policy consistently outperforms the Closest Open location storage policy. We also define the "Extra-Cost Zone" compared to the "No-Cost Zone"[3] and explore its geometric and practical meaning.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권1호
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• pp.340-367
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• 2018

Storage services integration can be done for achieving high availability, improving data access performance and scalability while preventing vendor lock-in. However, multiple services environment management and interoperability have become a critical issue as a result of service architectures and communication interfaces heterogeneity. Storage federation model provides the integration of multiple heterogeneous and self-sufficient storage systems with a single control point and automated decision making about data distribution. In order to integrate diverse heterogeneous storage services into a single storage pool, we are proposing a storage service federation framework named BoxBroker. Moreover, an automated decision model based on a policy-driven data distribution algorithm and a service evaluation method is proposed enabling BoxBroker to make optimal decisions. Finally, a demonstration of our proposal capabilities is presented and discussed.