• Journal of Navigation and Port Research
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• v.31 no.7
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• pp.605-611
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• 2007

In order to become a mega hub port, major ports all over the world are making every effort to enhance their productivity through efficiency of internal operation. Accordingly, in order to enhance the competitiveness of a container terminal, an automated container terminal is considered as the best alternative. An automated container terminal is using such automated handling equipment as AGV(Automated Guided Vehicles) and ATC(Automated Transfer Crane). The efficient equipment operation plays a critical role in enhancing the productivity of an automated container terminal. In an automated container terminal, the most important equipments are AGV and ATC. Each block of containers with a vertical layout is generally operating two ATCs. The two ATCs can be crossed or not at each block. In the case of operating crossover ATC, it has an advantage of high flexibility that ATC work is possible at both TP(Transfer Point) of each block. But it has also a disadvantage that the yard has to be operated at a low storage level of containers in the terminal yard. Recently, for automated container terminals, which are being prepared for opening in Korea, they plan to use uncrossed twin ATC in order to make the storage level of their yards high at a low cost. Therefore, studies have to be made in order to increase the efficiency of twin ATC system based on the flexibility that the crossover ATC system has. This research aims to suggest an operation strategy to improve efficiency of twin ATC at each storage block in a yard.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.10
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• pp.1718-1726
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• 2010

Utilization of renewable energy is becoming increaingly important from the viewpoints of environmental protection and conservation of fossil fuel. However, the generating power of renewable energy is always fluctuating due to the environmental status. This paper presents a scheme for supervisory control of wind generation system with the energy storage and STATCOM to reduce the power variation. In this paper, we especially concentrate on constant power output control of wind generation system. In order to achieve this purpose, the coordinated control strategy between different types of energy storage system and reactive power compensation device. The proposed control scheme has been validated by PSCAD/EMTDC simulation. As a result, the proposed scheme can handle the power output of wind generation system with a constant value.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.321-322
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• 2015

An area of severity (AOS) assessment is defined as a set of the fault positions that can result in the voltage sag bigger than certain level for sensitive buses simultaneously. Using the AOS assessment, the location of devices for compensating voltage sag can be determined as the site expected to less voltage sag at the sensitive bus. The energy storage system based on the control strategy emulating the traditional synchronous generator can contribute the fault current with fast response. Therefor are of venerability (AOV) can be reduced. The energy storage system installed by the AOS assessment has function which can experience relatively less voltage sag in addition to the conventional role of energy storage.

• Journal of Industrial Technology
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• v.14
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• pp.49-61
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• 1994

This study deals with the automated storage/retrieval systems (AS/RS) where the rack is discrete and the random storage assignment rule is adopted. New storage policies named FNSC (first no-cost zone, second closest-open location) and FNSH (first no-cost zone, second a half side closest-open location) are proposed. Simulation results indicate that performance of FNSH is slightly lower than that of the SCL but it does not need much time to perform. The "stay" strategy of S/R machine is examined as a means of increasing the frequency of dual command.

• Journal of Power Electronics
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• v.10 no.6
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• pp.733-738
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• 2010

This paper deals with a ride-through technique for permanent-magnet synchronous generator (PMSG) wind turbine systems using energy storage systems (ESS). A control strategy which consists of current and power control loops for the energy storage systems is proposed. By increasing the generator speed, some portion of the turbine power can be stored in the system inertia. Therefore, the required energy capacity of the ESS can be decreased, which results in a low-cost system. In addition, the power fluctuations due to wind speed variations can be smoothened by controlling the ESS appropriately. The effectiveness of the proposed method is verified not only by the simulation results for a 2[MW] PMSG wind turbine system, but also by the experiment results for a reduced-scale turbine simulator.

• Journal of Industrial and Engineering Chemistry
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• v.68
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• pp.140-145
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• 2018

Bulky carbon layer uniformly distributed with nanoscale $Fe_2O_3$ was prepared via a direct carbonation of $Fe^{3+}$-polyacrylonitrile complexes at $700^{\circ}C$ under $N_2$ flow. The iron oxide carbon composites exhibited an excellent cycling performance for lithium storage with a reversible capacity of ${\sim}810mAh\;g^{-1}$ after 250 cycles at a current rate of $100mA\;g^{-1}$. The enhancement was mainly attributed to dual functions of bulky carbon layer which facilitated the lithium-ion diffusion and accommodated the volume changes of active $Fe_2O_3$ during charge/discharge process. Our novel chemical strategy is quite effective for scalable fabrication of high capacity lithium-storage materials.

• Journal of Korean Institute of Industrial Engineers
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• v.19 no.1
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• pp.19-29
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• 1993

The problem of clustering stock-keeping-units to assign storage locations is treated. Firstly, a construction heuristic algorithm is developed to cluster items considering demand dependencies(correlated assignment) for the case that the maximum number or the maximum volume(weight) of items per tray is constrained by the capacity of tray. Secondly, inventory-related cost as well as material handling cost is considered to determine the space requirement and the storage location of each item simultaneously.

• The Journal of Information Technology and Database
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• v.1 no.2
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• pp.103-125
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• 1994

In this paper, we introduce a new main memory storage system called FLASH that is designed for real-time applications. The FLASH system is characterized by the memory residency of data and a new fast and dynamic hashing scheme called extendible chained bucket hashing. We compared the performance of the new hashing algorithm with other well-known ones. Also, we carried out an experiment to compare the overall performance of the FLASH system with a commercial one. Both comparison results show that the new hashing scheme and the FLASH system outperforms other competitives.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.163.3-163
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• 2001

This paper presents the two-step strategy method of performing optimal scheduling of paper mill processes using MINLP (Mixed-Integer Non-Linear Programming) considering the trim loss problem in sheet cutting processes. The mathematical model for a sheet cutting process in the form of MINLP is developed in this study, and minimizing total cost is performed considering the cost of raw paper roll, :hanging cutting patterns, storage of over-product and recycling/burning trim. The paper has been used to deliver and conserve information for a long time, and it is needed to have various sizes and weights ...

• Journal of the Korea Society of Computer and Information
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• v.22 no.4
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• pp.17-24
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• 2017

In this paper, we propose an efficient dynamic workload balancing strategy which improves the performance of high-performance computing system. The key idea of this dynamic workload balancing strategy is to minimize execution time of each job and to maximize the system throughput by effectively using system resource such as CPU, memory. Also, this strategy dynamically allocates job by considering demanded memory size of executing job and workload status of each node. If an overload node occurs due to allocated job, the proposed scheme migrates job, executing in overload nodes, to another free nodes and reduces the waiting time and execution time of job by balancing workload of each node. Through simulation, we show that the proposed dynamic workload balancing strategy based on CPU, memory improves the performance of high-performance computing system compared to previous strategies.