• Structural Engineering and Mechanics
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• v.25 no.6
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• pp.733-751
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• 2007

The metis element method (Hung 1978) has been applied to analyse free edge interlaminar stresses and delamination in composite laminates, which are subjected to extension and bending. The paper recalls Lekhnitskii's solution for generalized plane strain state of composite laminate and Wang's singular solution for determination of stress singularity order and of eigen coefficients $C_m$ for delamination problem. Then the formulae of metis displacement finite element in two-dimensional problem are established. Computation of the stress intensity factors and the energy release rates are presented in details. The energy release rate, G, is computed by Irwin's virtual crack technique using metis elements. Finally, results of interlaminar stresses, the three stress intensity factors and the energy release rates for delamination crack in composite laminates under extension and bending are illustrated and compared with the literature to demonstrate the efficiency of the present method.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.42 no.12
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• pp.61-70
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• 2005

In this paper, we propose an efficient global placement algorithm which is an enhanced version of Hybrid Placer$^{[25]}$, a standard cell placement tool, which uses a middle-down approach. Combining techniques used in the well-known partitioner hMETIS and the RBLS(Relaxation Based Local Search) in Hybrid Placer improves the quality of global placements. Partitioning techniques of hMETIS is applied in a top-down manner and RBLS is used in each level of the top-down hierarchy to improve the global placement. The proposed new approach resolves the problem that Hybrid Placer seriously depends on initial placements and it speeds up without deteriorating the placement quality. Experimental results prove that solutions generated by the proposed method on the MCNC benchmarks are comparable to those by FengShui which is a well known placement tool. Compared to the results of the original Hybrid Placer, new method is 5 times faster on average and shows improvement on bigger circuits.

• The Journal of Industrial Distribution & Business
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• v.9 no.5
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• pp.25-35
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• 2018

Purpose - The purpose of this paper is to partition a last-mile delivery network into zones and to determine locations of last mile delivery centers (LMDCs) in Bangkok, Thailand. Research design, data, and methodology - As online shopping has become popular, parcel companies need to improve their delivery services as fast as possible. A network partition has been applied to evaluate suitable service areas by using METIS algorithm to solve this scenario and a facility location problem is used to address LMDC in a partitioned area. Research design, data, and methodology - Clustering and mixed integer programming algorithms are applied to partition the network and to locate facilities in the network. Results - Network partition improves last mile delivery service. METIS algorithm divided the area into 25 partitions by minimizing the inter-network links. To serve short-haul deliveries, this paper located 96 LMDCs in compact partitioning to satisfy customer demands. Conclusions -The computational results from the case study showed that the proposed two-phase algorithm with network partitioning and facility location can efficiently design a last-mile delivery network. It improves parcel delivery services when sending parcels to customers and reduces the overall delivery time. It is expected that the proposed two-phase approach can help parcel delivery companies minimize investment while providing faster delivery services.

• Proceedings of the Korean Information Science Society Conference
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• 2004.04a
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• pp.967-969
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• 2004

본 논문에서는 표준 셀 배치기 Mongrel을 소개하고 두 가지 분할 기법(FM, hMETIS)을 통해 효율적인 초기 배치를 얻음으로써 Mongrel의 성능을 개선한다. Mongrel은 middle-down 방법론을 채택한 전역 배치와 상세 배치의 2단계 표준 셀 배치기이며 전역 배치 단계에서는 RBLS(Relaxation-Based Local Search)를, 그리고 상세 배치 단계에서는 최적 인터리빙(optimal interleaving) 기법을 통해 최적화 알고리즘을 수행한다. MCNC 벤치마크 회로를 이용한 실험을 통해 Mongrel의 성능을 평가하고 효율적인 초기배치가 최종 결과에 미치는 영향을 분석한다.

• Information and Communications Magazine
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• v.32 no.7
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• pp.40-45
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• 2015

네트워크 장비 업체나 통신사뿐만 아니라 여러 국가들에서도 상용화를 목표로 5G 기술 확보를 위한 대규모의 연구 개발 역량을 집결하고 있다. 이 중 대다수의 연구 개발은 SDN(Software Defined Network)과 NFV(Network Function Virtualization)를 기반으로 두고 있다. 이는 5G의 아키텍처가 동적인 네트워크를 생성하는데 초점을 맞추고 있기 때문이다. 이에 본 고에서는 METIS 2020(Mobile and wireless communication Enablers for the Twenty-twenty Information Society)에서 발표한 최종 리포트를 참고하여 5G 이동통신 네트워크에서의 SDN과 NFV의 역할에 대해 알아 보고, 현재 진행 중인 개발 행태를 보기 위해 대표 기업들의 동향을 살펴본다.

• Proceedings of the Korean Information Science Society Conference
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• 2004.10a
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• pp.742-744
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• 2004

본 논문에서는 표준 셀 배치기 Mongrel의 성능을 개선하기 위해 사용된 다양한 기법에 관해 살펴보고 top-down방식의 계층적 분할 기법을 이용한 광역 배치(Hierarchical Global Placement)를 제안한다. 계층적 분할 기법을 이용한 광역 배치는 RBLS(Relaxation Based Local Search) 기법과 더불어 Mongrel의 성능 개선에 결정적인 역할을 하고 있으며 분할 기법으로 hMETIS(클러스터링을 이용한 다단계 분할 기법)를 사용한다. 우리는 표준 벤치마크 회로를 이용한 실험을 통해 계층적 분할 기법을 이용한 광역 배치 기법이 안정적이면서 효율적인 배치 결과를 가져옴을 보인다.

• Korean journal of applied entomology
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• v.54 no.2
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• pp.127-136
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• 2015

We report new host records of four ichneumonids from Korea. They were discovered from the pupae of Apatura metis Frever (Lepidoptera: Nymphalidae), Allotraeus sphaerioninus Bates (Coleoptera: Cerambycidae) and Ivela auripes (Butler) (Lepidoptera: Lymantriidae) respectively. Diagnoses, illustrations, host records of the four species, and a list of ichneumon species parasitizing of I. auripes are provided.

• 한국전산유체공학회:학술대회논문집
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• 2003.10a
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• pp.84-85
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• 2003

A parallelized FEM code based on domain decomposition method has been recently developed for a large scale computational fluid dynamics. A 4-step splitting finite element algorithm is adopted for unsteady computation of the incompressible Navier-Stokes equation, and Smagorinsky LES(Large Eddy Simulation) model is chosen for turbulent flow computation. Both METIS and MPI library are used for domain partitioning and data communication between processors respectively. Tiburon of Hyundai-motor is chosen as the computational model at $Re=7.5{\times}10^{5}$, which is based on the car height. It is confirmed that the drag under road condition is smaller than that of wind tunnel condition.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.8
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• pp.1182-1190
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• 2003

A parallelized FEM code based on domain decomposition method has been recently developed for large-scale computational fluid dynamics. A 4-step splitting finite element algorithm is adopted for unsteady flow computation of the incompressible Navier-Stokes equation, and Smagorinsky LES model is chosen for turbulent flow computation. Both METIS and MPI Libraries are used for domain partitioning and data communication between processors, respectively. Tiburon model of Hyundai Motor Company is chosen as the computational model at Re=7.5 $\times$ 10$^{5}$ , which is based on the car height. The calculation is carried out under both the wind tunnel condition and the road condition using IBM SP parallel architecture at KISTI Super Computing Center. Compared with the existing experimental data, both the velocity and pressure fields are predicted reasonably well and the drag coefficient is in good agreement. Furthermore, it is confirmed that the drag under the road condition is smaller than that under the wind-tunnel condition.

• Proceedings of the KSME Conference
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• 2002.08a
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• pp.55-58
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• 2002

Parallel finite element code has been recently developed for the analysis of the incompressible Wavier-Stokes equations using domain decomposition method. Metis and MPI libraries are used for the domain partitioning of an unstructured mesh and the data communication between sub-domains, respectively. For unsteady computation of the incompressible Navier-Stokes equations, 4-step splitting method is combined with P1P1 finite element formulation. Smagorinsky and dynamic model are implemented for the simulation of turbulent flows. For the validation performance-estimation of the developed parallel code, three-dimensional Laplace equation has been solved. It has been found that the speed-up of 40 has been obtained from the present parallel code fir the bench mark problem. Lastly, the turbulent flows around the MIRA model and Tiburon model have been solved using 32 processors on IBM SMP cluster and unstructured mesh. The computed drag coefficient agrees better with the existing experiment as the mesh resolution of the region increases, where the variation of pressure is severe.