• Journal of computational fluids engineering
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• v.7 no.2
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• pp.8-16
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• 2002

A numerical study on the use of the momentum interpolation method for flows with a large body force is presented. The inherent problems of the momentum interpolation method are discussed first. The origins of problems of the momentum interpolation methods are the validity of linear assumptions employed for the evaluation of the cell-face velocities, the enforcement of mass conservation for the cell-centered velocities and the specification of pressure and pressure correction at the boundary. Numerical experiments are performed for a typical flow involving a large body force. The numerical results are compared with those by the staggered grid method. The fact that the momentum interpolation method may result in physically unrealistic solutions is demonstrated. Numerical experiments changing the numerical grid have shown that a simple way of removing the physically unrealistic solution is a proper grid refinement where there is a large pressure gradient. An effective way of specifying the pressure and pressure correction at the boundary by a local mass conservation near the boundary is proposed, and it is shown that this method can effectively remove the inherent problem of the specification of pressure and pressure correction at the boundary when one uses the momentum interpolation method.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.76.1-76.1
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• 2011

With the growing penetration of distributed generation including from renewable sources, smart grid power system is needed to address the reliability problem. One important feature of smart grid is demand response. In order to design a demand response program, it is indispensable to understand how consumer reacts upon the change of electricity price. In this paper, we construct an econometrics model to estimate the hourly price elasticity of demand. This panel model utilizes the hourly load data obtained from KEPCO for the period from year 2005 to 2009. The hourly price elasticity of demand is found to be statistically significant for all the sample under investigation. The samples used for this analysis is from the past historical data under the price structure of three different time zones for each season. The result of the analysis of this time of use pricing structure would allow the policy maker design an appropriate incentive program. This study is important in the sense that it provides a basic research information for designing future demand response programs.

• Korean Journal of Digital Imaging in Medicine
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• v.7 no.1
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• pp.33-38
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• 2005

Modern hospitals have been greatly facilitated with information technology (IT) such as hospital information system (HIS). One of the most prominent achievements is medical imaging and image data management so-called Picture Archiving and Communication Systems (PACS). Due to inevitable use of diagnostic images (such as X-ray, CT, MRI), PACS made tremendous impact not only on radiology department but also nearly all clinical departments for exchange and sharing image related clinical information. There is no doubt that better use of PACS leads to highly efficient clinical administration and hospital management. However, due to rapid and widespread acceptance of PACS storage and management of digitized image data in hospital introduces overhead and bottleneck when transferring images among clinical departments within and/or across hospitals. Despite numerous technical difficulties, financing for installing PACS is a major hindrance to overcome. In addition, a mirroring or a clustering backup can be used to maximize security and efficiency, which may not be considered as cost-effective approach because of extra hardware expenses. In this study therefore we have developed a new based on grid of distributed PACS in order to balance between the cost and network performance among multiple hospitals.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.1673-1677
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• 2008

A method of construction with a basis treatment that uses a latticed bamboo mat puts bamboo's peculiarity and bamboo mat's bending substance to use, and a latticed bamboo mat equally distributes to embankment loading in a basis ground. Therefore it prevents ground destruction by an ill-balanced load and an irregular ground subsidence, and it makes safety system. This investigation make progress a soil box model by a dredged reclamation ground of west and south sea at domestic area, and make a comparative study and analyze the strengthening effect based on a grid size of a bamboo-mat and ground failure that it will use in the field.

• Journal of Electrical Engineering and Technology
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• v.13 no.5
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• pp.1821-1830
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• 2018

With the wide application of intelligent household appliances, the optimization of electricity behavior has become an important component of home-based intelligent electricity. In this study, a multi-objective optimization model in an intelligent electricity environment is proposed based on economy and comfort. Firstly, the domestic consumer's load characteristics are analyzed, and the operating constraints of interruptible and transferable electrical appliances are defined. Then, constraints such as household electrical load, electricity habits, the correlation minimization electricity expenditure model of household appliances, and the comfort model of electricity use are integrated into multi-objective optimization. Finally, a continuous search multi-objective particle swarm algorithm is proposed to solve the optimization problem. The analysis of the corresponding example shows that the multi-objective optimization model can effectively reduce electricity costs and improve electricity use comfort.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.2
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• pp.309-315
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• 2007

It is X.509 certificate that use to offer authentication and delegation service in grid. Authentication service offers by X.509 user certificate, and delegation service offers by X.509 proxy certificate. However, in case of provide delegation service using X.509 poxy certificate, can not fulfill complicated delegation requirement of grid. In this paper, proposed delegation mechanism that is done restricted delegation, multiple delegation and light weight that delegation service that use existent X.509 proxy certificate does not have. In this paper, delegation service that proposed used SPKI certificate.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.2
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• pp.617-636
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• 2021

This paper presents a privacy-preserving data aggregation scheme deals with the multidimensional data. It is essential that the multidimensional data is rarely mentioned in all researches on smart grid. We use the Paillier Cryptosystem and blinding factor technique to encrypt the multidimensional data as a whole and take advantage of the homomorphic property of the Paillier Cryptosystem to achieve data aggregation. Signature and efficient batch verification have also been applied into our scheme for data integrity and quick verification. And the efficient batch verification only requires 2 pairing operations. Our scheme also supports fault tolerance which means that even some smart meters don't work, our scheme can still work well. In addition, we give two extensions of our scheme. One is that our scheme can be used to compute a fixed user's time-of-use electricity bill. The other is that our scheme is able to effectively and quickly deal with the dynamic user situation. In security analysis, we prove the detailed unforgeability and security of batch verification, and briefly introduce other security features. Performance analysis shows that our scheme has lower computational complexity and communication overhead than existing schemes.

• Archives of design research
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• v.15 no.2
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• pp.125-136
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• 2002

The purpose of this study is to investigate the editorial design of the advertising brochure in relation to the promotion of entering college freshmen. The role and function of the brochure promoting universities have been explained in terms of the editorial design. The special regard is paid to the Grid-system that must be handled with the greatest possible care in editorial design of brochures. In this study, it has not only divided into the three categories (Single Grid-system, Multiple Grid-system and Non-Grid-system) according to the Grid-system, and but also analyzed each case of the modeled college brochure. In the analyses, it is found that the using Grid-system brochures are much more effective than that of the lesser using Grid-system, especia1ly in the communication and design. Therefore, the Grid-system is shown to be crucial tool in the current design process of the college brochures. The suggestion of the using criterion of the Grid-system has also been made for the unity as well as diversity of layout in the editorial design. The study then extends this core object principle with the possible development of the Grid-system that includes the balance of the expression of the contents and the artistic structure of design. Additionally, the relationship between the Grid-system and the visual materials for the creative application to the brochure promoting the universities is presented as the final result of this study.

• Journal of Korean Society of Disaster and Security
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• v.13 no.1
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• pp.25-39
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• 2020

Despite the global promotion of Smart City, there is currently no standard for smart water grid development, and it is not possible to judge the success of Smart City. There is a clear need to establish the requirements and goals of the Smart Water Grid and accurately diagnose and improve the limitations and problems of the existing Smart Water Grid. For this purpose, it is very important to use the index suitable for Smart Water Grid goals. In this study, we developed Smart Water Grid Index which can be used to evaluate the target measurement and attainment of Smart Water Grid and can be utilized based on the implementation plan for Smart Water Grid in the future. Through the development of the Smart Water Grid Key Performance Index (SWG KPI), we will lay the groundwork for continuous capacity evaluation of the Smart Water Grid and improve the reliability of the Index. It is expected that it will be possible to prepare and evaluate a Challenge Evaluation Card for the planned Smart Water Grid by providing an evaluation table for grid competency evaluation.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.12
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• pp.2221-2224
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• 2011

During an emergency due to a shortage of power, a load aggregator (LA) can use the demand response operation system to deploy demand response resources (DRRs) through various demand response (DR) programs. This paper introduces the demand response operation system for a load aggregator to manage various demand response resources in a smart grid environment.