• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.9
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• pp.892-902
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• 2009

An efficient sequential optimization approach for metamodel was presented by Choi et al. This paper describes a new approach of the multilevel optimization method studied in Refs. [2] and [20,21]. The basic idea is concerned with multilevel iterative methods which combine a descent scheme with a hierarchy of auxiliary problems in lower dimensional subspaces. After fitting a metamodel based on an initial space filling design, this model is sequentially refined by the expected improvement criterion. The advantages of the method are that it does not require optimum sensitivities, nonlinear equality constraints are not needed, and the method is relatively easy to understand and use. As a check on effectiveness, the proposed method is applied to an engineering example.

• Proceedings of the Korea Information Assurance Society Conference
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• 2004.05a
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• pp.187-198
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• 2004

Virus protection infrastructure management is network infrastructure management, traffic route management, virus protection zone expansion, and virus protection management for gateway area. This research paper provides a diagnosis of characteristics and weaknesses of the structure of existing virus protection infrastructure, and recommends an improved multi-level virus protection infrastructure as a measure for correcting these weaknesses. Unproved virus protection infrastructure fitters unnecessary mail at the gateway stage to reduce the toad on server. As a result, number of transmission accumulation decreases due to the reduction in the CPU load on the Virus wall and increase in virus treatment rate.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.26 no.1
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• pp.85-94
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• 2003

In this paper, a mathematical model is developed for economic design of multi-stage distribution system that consists of factory, central distribution centers, local distribution centers and retailers. The retailers are supplied products from different stage suppliers according to order size. The retailers are supplied products from factory if demand amount is large, central distribution center if medium, local distribution center if small. The economic design is to determine the economic size of facility factors that consist of distribution system. The cost factors are transportation cost from supply places to demand places, handling cost at distribution centers and inventory holding cost at retailers. It is to determine the transportation route of each retailer, the size and number of the vehicle at factory and distribution centers, the handling amount at distribution centers in order to minimize the total costs. The mathematical model is represented, the solution procedure is developed, and a numerical example is shown.

• Proceedings of the Korea Institutes of Information Security and Cryptology Conference
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• 2003.12a
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• pp.538-542
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• 2003

본 논문에서는 액티브 네트워크 상에서 강력한 자원 관리와 액티브 응용의 제어를 위해 접근제어 메커니즘을 적용한 안전한 리눅스 커널을 분석 설계하였다. 설계된 접근제어 모델은 직무기반 접근제어를 이용하여 권한을 효과적으로 통제하고, 신분 및 규칙 기반 접근제어를 이용하여 정보 및 시스템의 비밀성, 무결성, 가용성의 보장 및 시스템의 불법적인 접근을 방지할 수 있다. 리눅스 마이크로 커널 기반 접근제어 모델을 직무, 보안등급, 무결성 등급 및 소유권의 다단계 보안 정책을 기반으로 시스템의 불법적인 접근, 직무기반, 소유권 등의 다단계 보안 정책을 기반으로 하여 시스템의 불법적인 접근을 통제 할 수 있다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.10
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• pp.696-701
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• 2016

Multi-stage deep drawing is a widely used industrial manufacturing process, and its applications are gradually expanding to both small products and large metallic products. The USB C-type socket used in smart phones, for example, is manufactured using oval multi-stage deep drawing. The socket is very small and slender and it requires precise manufacturing. The thickness distribution of the final product is guaranteed only if it is uniform throughout the overall process. Therefore, minimizing the height difference between long and short sidewalls after the first operation is important for this goal. An initial blank optimization was performed for an oval-type drawing process based on finite element simulations. The goal was to determine an initial blank geometry that can maintain uniform height and thickness after the first draw operation. The initial blank shape of the sheet metal was optimized, and the results show that it satisfied the conditions of minimal thickness reduction and even thickness distribution. The geometry from the optimized simulation was compared with experimental results, which showed good agreement.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.108-113
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• 2002

This paper presents a multi-step structural design optimization method fur machine tool structures using a genetic algorithm with dynamic penalty. The first step is a sectional topology optimization, which is to determine the best sectional construction that minimize the structural weight and the compliance responses subjected to some constraints. The second step is a static design optimization, in which the weight and the static compliance response are minimized under some dimensional and safety constraints. The third step is a dynamic design optimization, where the weight static compliance, and dynamic compliance of the structure are minimized under the same constraints. The proposed design method was examined on the 10-bar truss problem of topology and sizing optimization. And the results showed that our solution is better than or just about the same as the best one of the previous researches. Furthermore, we applied this method to the topology and sizing optimization of a crossbeam slider for a high-speed machining center. The topology optimization result gives the best desirable cross-section shape whose weight was reduced by 38.8% than the original configuration. The subsequent static and dynamic design optimization reduced the weight, static and dynamic compliances by 5.7 %, 2.1% and 19.1% respectively from the topology-optimized model. The examples demonstrated the feasibility of the suggested design optimization method.

• Computational Structural Engineering
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• v.7 no.1
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• pp.117-124
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• 1994

Multi-level Multi-objective optimization(MLMO) for reinforced concrete framed structure is performed, and compared with the results of single-level single-objective optimization. MLMO method allows flexibility to meet the design needs such as deflection and cost of structures using weighting factors. Using Multi-level formulation, the numbers of constraints and variables are reduced at each levels, and the optimization formulation becomes simplified. The force approximation method is used to reflect the variation in design variables between the substructures, and thus coupling is maintained. And the linear approximated constraints and objective function are used to reduce the number of structural analysis in optimization process. It is shown that the developed algorithm with move limit can converge effectively to optimal solution.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.6
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• pp.1137-1147
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• 1997

I propose a RZETA network consisted of switching elements(SEs) that have regular links and alternate links. A modified Zeta nework used for the RZETA network's regular links and a MIN used for its alternate links are generated using the graph theory. The RZETA network is driven from merging the formaer and latter MINs. A necessary and sufficient condition for modified Zeta network to be a nonblocking network is also presented. This condition is a ufficient condition for RZETA network with a faulty link or a faulty SE to be nonblocked. Performance of the RZETA network is analyzed by modification of the model of 2-dilated Banyan network and its performance is compared with existing redundant path networks, when packet arrival rate of each source is 1.

• The Transactions of the Korea Information Processing Society
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• v.4 no.3
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• pp.685-697
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• 1997

A Viedo-on-Demand(VOD) service is a multimedia service that is realized by the rapid advance of computer and data communication techmologies. Basically, a VOD system is composed of a server and a number fo clients.The server stores and manages a large amount of digital moving picture data. Each slient sends an on-line requwet to the server and receives data for real-time displying. Many researches are performed on a VOD server using hard disks for the permanent video fata storage. However, a hard disk is less reliable and requires more storage cost than a massive storage device. Due to these resasons, a multi-level VOD system is proposed for using teh jukeboxes of optical disks as the permanent video storage,device. In this paper, we prpose the necessary software modules and protocols between the server and its clients for the implementation of the multi-level VOD server.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.11a
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• pp.531-532
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• 2008