• Journal of the Korea Society for Simulation
• /
• v.15 no.3
• /
• pp.103-114
• /
• 2006

Now distribution centers include an ASRS (Automated Storage and Retrieving System) and automated transfer systems such as conveyors and AGV (Automated Guided Vehicle). These automated distribution centers have lots of parameters to be considered fur operating performance. The general basic parameters in the distribution centers are specifications of storage equipment, system operating rules, configuration of storage area and unit load features. In this paper, an approach using simulation and metamodeling with response Surface method to optimize the design parameters of an automated distribution center model is presented. The simulation based metamodel will constitute an efficient approximation of the system function, and the approximate function will be used to design rapid optimal parameters of the distribution center model. This paper provides a comprehensive framework for economical material flow system design using the simulation and metamodeling.

• Journal of KIISE:Computing Practices and Letters
• /
• v.16 no.12
• /
• pp.1204-1208
• /
• 2010

In this paper, we propose a flash memory wear-leveling scheme that makes use of meta-data storage region as a regulation pool. By concentrating program and erase operations on the blocks with lower erase counts in the regulation pool, the proposed scheme achieve an even wear-leveling in a simple and efficient way. Experiments with an implementation of the proposed scheme in RS-FTL showed that the erase count deviation is reduced by around 40% through the erase count regulation.

• IEMEK Journal of Embedded Systems and Applications
• /
• v.2 no.1
• /
• pp.1-8
• /
• 2007

In this paper, we developed a file system architecture for portable multimedia devices. To enhance user convenience, the information about the stored files should be easily retrieved and organized. We defined NMD (Networked MetaData), which can organize the files in networked fashion by attaching user-defined attributes and relation between files. The NMD is stored in flash memory to utilize its nonvolatile property and low-power consumption, while multimedia files are stored in hard disk, an inexpensive mass storage. The experimental implementation showed that this architecture was able to save about 10% power compared to the hard disk NMD-store.

• Journal of Information Technology Applications and Management
• /
• v.12 no.1
• /
• pp.125-140
• /
• 2005

Nowadays, we have many embedded systems which store and process multimedia data. For multimedia systems using hard disks as storage media such as DVR, existing file systems are not the right choice to store multimedia data in terms of cost. performance and reliability. In this study we designed a reliable file system with very high performance for embedded multimedia applications. The proposed file system runs with quite simple disk layout to reduce time to initialize and to recover after power failures, uses a large data block to speed up the sequential accesses, incorporates a time-based indexing scheme to improve the time-based random accesses and boosts reliability by backing up the important meta data on a small NVRAM. We implemented the file system on a Linux-based DVR and verified the performance by comparing with existing file systems.

• Journal of the Korea Society for Simulation
• /
• v.14 no.3
• /
• pp.43-54
• /
• 2005

For the effective design of automated distribution center composed of Automated Storage/Retrieval System, Automated Guided Vehicle System, and Conveyor System, we proposed an analysis method to determining. design and control parameters with multiple performance objectives using Compromise Programming, which can resolve the dilemma of conflicting objectives. The Evolution Strategy generates the optimal solutions for each objectives. The Analytic Hierarchy Process selects the best solution among the alternatives generated from Evolution Strategy. The Regression Analysis formulates the objective functions for each objectives. By reducing deviations between goal values and target values generated from Analytic Hierarchy Process, Compromise Programming determines design and control parameters by compromising the multiple objectives formulated using Regression Analysis. When the parameters of system are changed, this proposed analysis method has a benefit of reducing costs and time without repeating whole simulation run.

• ETRI Journal
• /
• v.41 no.1
• /
• pp.10-22
• /
• 2019

Since Leith and Upatnieks demonstrated the first optical hologram in 1964, hologram technology has attracted a great deal of interest in a wide range of optical fields owing to its potential use in future optical applications such as holographic imaging and optical data storage. Although there have been considerable efforts to develop holographic technologies using conventional optics, critical issues still hinder future development. Recently, metasurfaces composed of artificially fabricated subwavelength structures have been considered as novel holographic devices that show an unprecedented ability to control electromagnetic waves. In this review, we outline the recent progress in metasurface holography. A general introduction to several types of metasurface holography categorized based on their physics and application is provided. Then, our personal perspective on the future of this field is discussed.

• Advances in Energy Research
• /
• v.7 no.1
• /
• pp.67-84
• /
• 2020

Given the recent surge of interest towards utilization of renewable distributed energy resources (DER), in particular in remote areas, this paper aims at designing an optimal hybrid system in order to supply loads of a village located in Esfarayen, North Khorasan, Iran. This paper illustrates the optimal design procedure of a standalone hybrid system which consists of Wind Turbine Generator (WTG), Photo Voltaic (PV), Diesel-generator, and Battery denoting as the Energy Storage System (ESS). The WTGs and PVs are considered as the main producers since the site's ambient conditions are suitable for such producers. Moreover, batteries are employed to smooth out the variable outputs of these renewable resources. To this end, whenever the available power generation is higher than the demanded amount, the excess energy will be stored in ESS to be injected into the system in the time of insufficient power generation. Since the standalone system is assumed to have no connection to the upstream network, it must be able to supply the loads without any load curtailment. In this regard, a Diesel-Generator can also be integrated to achieve zero loss of load. The optimal hybrid system design problem is a discrete optimization problem that is solved, here, by means of a recently-introduced meta-heuristic optimization algorithm known as Lightning Attachment Procedure Optimization (LAPO). The results are compared to those of some other methods and discussed in detail. The results also show that the total cost of the designed stand-alone system in 25 years is around 92M€ which is much less than the grid-connected system with the total cost of 205M€. In summary, the obtained simulation results demonstrate the effectiveness of the utilized optimization algorithm in finding the best results, and the designed hybrid system in serving the remote loads.

• The Journal of Korean Academy of Prosthodontics
• /
• v.39 no.4
• /
• pp.417-432
• /
• 2001

The pcf metal primers on the bond strength and durability of 4-META/MMA-TBB resins adhered to an Au-Ag-Pd alloy. For this study, the specimens were divided into 8 groups as follows: Thermocyle 0 : (1) control group : sandblast, (2) Group I : sandblast + Cesead Opaque Primer; (3) Group II : sandblast + Metal Primer; (4) Group III : sandblast + V-Primer; Thermocyle 10,000 (5) control sandblast: (6) Group I : sandblast + Cesead Opaque Primer: (7) Group II : sandblast + Metal Primer; (8) Group III sandblast + V-Primer. The shear bond strength was determined using an Instron were observed with the use of scanning electron microscope. Finally, the strengths of bonded joints were evaluated with regard to their adherence energy using a wedge test. The results obtained were as follows ; (1) The shear bond strength of 4-META/MMA-TBB resin to the Au-Ag-Pd alloy was significantly improved in all the groups treated with the primers (p<0.05). (2) Regardless of the adhesive primers used, a significant difference was observed in the bond strength of the thermocycle 0 groups and 10,000 groups (p<0.05). (3) Both before and after thermocycling, the strongest bond strength between the resin an the alloy was obtained after treatment with a metal primer containing MEPS (p<0.05). (4) In the wedge test, the adherence energies of the control group and Group III decreased more rapidly than those of Group I and II during the 2nd day of storage in water.

• The KIPS Transactions:PartD
• /
• v.13D no.7 s.110
• /
• pp.931-938
• /
• 2006

It is important to operate an education resources which could be integrated to an system. But most of existing education information system was not developed with standardization. It is need the core education asset and reusable education service to make a good education system. Consequently, it is needed to use Sharable Content Object Reference Model(SCORM) based contents managing in order to reuse the contents of education. And it needs assembling and producing method with reusable core asset of education system to develop the application program for education. In this thesis, we study the Teaching-Learning supporting system to support systematic education resources. Teaching-Learning support system is developed of educational domain assess through development process based on Model Driven Architecture(MDA) and core asset on each stage. Application program of education is developed using MDA automatic tool through analyzing and designing for contents storage which is based on contents meta model. We finally can develop the application software of education with low cost and high productivity by raising the reusability of education contents and by using the core asset to the whole development process.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.20 no.2
• /
• pp.26-35
• /
• 2019

By operating servers, storage, and networking devices, Data centers consume a lot of power such as cooling facilities, air conditioning facilities, and emergency power facilities. In the United States, The power consumed by data centers accounted for 1.8% of total power consumption in 2004. The data center industry has evolved to a large scale, and the number of large hyper scale data centers is expected to grow in the future. However, as a result of examining the server share of the data center, There is a problem where the server is not used effectively such that the average occupancy rate is only about 15% to 20%. To solve this problem, we propose a Virtual Machine Reallocation research using virtual machine migration function. In this paper, we use meta-heuristic for effective virtual machine reallocation. The virtual machine reallocation problem with the goal of maximizing the idle server was designed and solved through experiments. This study aims to reducing the idle rate of data center servers and reducing power consumption simultaneously by solving problems.