• 대한전자공학회논문지TC
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• 제47권5호
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• pp.9-17
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• 2010

본 논문에서는 이동 Ad-hoc 네트워크를 지원하여 확장성과 광대역의 무선 환경을 제공하는 무선 메쉬 네트워크인 무선 하이브리드 메쉬 구조를 고려하여, 이에 효율적으로 적용될 수 있는 무선 하이브리드 메쉬 네트워크를 위한 계층구조의 라우팅 기법을 제안하였다. 무선 하이브리드 메쉬 네트워크상에서 효율적인 토폴로지 관리와 소스노드에서 목적노드로 라우팅 패스를 설정할 시에 발생하는 트래픽을 감소시키고 노드간 링크 안정성을 고려하고, 노드의 문제 또는 링크간 장애로 인한 잦은 라우팅 재설정 문제를 해결하는 계층구조의 라우팅 기법을 제안하였다. 또한 case study를 통하여 본 논문에서 제안된 계층구조의 라우팅 기법을 이용하여 네트워크 클러스터링 및 토폴로지 관리의 효율성을 인지할 수 있었으며, 성능분석 결과에서는 제안된 방법을 적용하였을 때, 링크의 상태가 좋지 않을 경우 기존 HOLSR (hierarchical optimized link state routing) 방법보다 데이터 전송에 따른 종단간 지연시간이 감소되고 aggregate goodput과 packet delivery ratio가 향상됨을 알 수 있었다.

• 반도체디스플레이기술학회지
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• 제14권1호
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• pp.55-59
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• 2015

This study demonstrates hybrid-type transparent electrodes for touch screen panels. The hybrid-type electrodes were fabricated by coating carbon nanotubes (CNTs) on metal meshes. To form the metal-meshes, thin films of silver (Ag) were deposited on glass substrates using the sputtering method and then patterned via photolithography to obtain mesh structures whose line width was $10{\mu}m$ and line-to-line spacing was $300{\mu}m$. CNTs were coated on Ag-meshes by using two different methods, such as spray coating and electrophoretic deposition (EPD). For the samples of a Ag-meshes and CNTs-coated Ag-meshes, their surface morphologies, electrical sheet resistances, and visible-range transmittances and reflectances were characterized and compared. The experimental results indicated that the reflectance of Ag-mesh electrodes was substantially reduced by coating of CNTs. Especially, the hybrid electrodes of Ag-meshes with EPD-coated CNTs showed excellent properties such as sheet resistance lower than $20{\Omega}/{\Box}$, transmittance higher than 90 %, and reflectance lower than 8%.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제5권11호
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• pp.1909-1928
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• 2011

Node cooperation during packet forwarding operations is critically important for fair resource utilization in Community Wireless Mesh Networks (CoWMNs). In a CoWMN, node cooperation is achieved by using fairness protocols specifically designed to detect and isolate malicious nodes, discourage unfair behavior, and encourage node participation in forwarding packets. In general, these protocols can be split into two groups: Incentive-based ones, which are managed centrally, and use credit allocation schemes. In contrast, reputation-based protocols that are decentralized, and rely on information exchange among neighboring nodes. Centrally managed protocols inevitably suffer from scalability problems. The decentralized, reputation-based protocols lacks in detection capability, suffer from false detections and error propagation compared to the centralized, incentive-based protocols. In this study, we present a new fairness protocol management scheme, called Hybrid FPMS that captures the superior detection capability of incentive-based fairness protocols without the scalability problems inherently expected from a centralized management scheme as a network's size and density grows. Simulation results show that Hybrid FPMS is more efficient than the current centralized approach and significantly reduces the network delays and overhead.

• Steel and Composite Structures
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• 제18권6호
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• pp.1391-1404
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• 2015

A radially retractable roof structure based on the concept of the hybrid grid shell is proposed in this paper. The single-layer steel trusses of the radially foldable bar structure are diagonally stiffened by cables, which leads to a single-layer lattice shell with triangular mesh. Then comparison between the static behavior between the retractable hybrid grid shell and the corresponding foldable bar shell with quadrangular mesh is discussed. Moreover, the effects of different structural parameters, such as the rise-to-span ratio, the bar cross section area and the pre-stress of the cables, on the structural behaviors are investigated. The results show that prestressed cables can strengthen the foldable bar shell with quadrangular mesh. Higher structural stiffness is anticipated by introducing cables into the hybrid system. When the rise-span ratio is equal to 0.2, where the joint displacement reaches the minimal value, the structure shape of the hyrbid grid shell approaches the reasonable arch axis. The increase of the section of steel bars contributes a lot to the integrity stiffness of the structure. Increasing cable sections would enhance the structure stiffness, but it contributes little to axial forces in structural members. And the level of cable prestress has slight influence on the joint displacements and member forces.

• Journal of applied mathematics & informatics
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• 제27권5_6호
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• pp.1001-1015
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• 2009

In this paper, two hybrid difference schemes on the Shishkin mesh are constructed for solving a weakly coupled system of two singularly perturbed convection-diffusion second order ordinary differential equations with a small parameter multiplying the highest derivative. We prove that the schemes are almost second order convergence in the supremum norm independent of the diffusion parameter. Error bounds for the numerical solution and its derivative are established. Numerical results are provided to illustrate the theoretical results.

• Journal of Computational Design and Engineering
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• 제3권2호
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• pp.121-131
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• 2016

Organic modeling of 3D characters is a challenging task when it comes to correctly modeling the anatomy of the human body. Most sketch based modeling tools available today for modeling organic models (humans, animals, creatures etc) are focused towards modeling base mesh models only and provide little or no support to add details to the base mesh. We propose a hybrid approach which combines geometrical primitives such as generalized cylinders and cube with Shape-from-Shading (SFS) algorithms to create plausible human character models from sketches. The results show that an artist can quickly create detailed character models from sketches by using this hybrid approach.

• Journal of applied mathematics & informatics
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• 제28권5_6호
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• pp.1035-1054
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• 2010

We consider a mixed type singularly perturbed one dimensional elliptic problem with discontinuous source term. The domain under consideration is partitioned into two subdomains. A convection-diffusion and a reaction-diffusion type equations are posed on the first and second subdomains respectively. Two hybrid difference schemes on Shishkin mesh are constructed and we prove that the schemes are almost second order convergence in the maximum norm independent of the diffusion parameter. Error bounds for the numerical solution and its numerical derivative are established. Numerical results are presented which support the theoretical results.

• Macromolecular Research
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• 제8권1호
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• pp.6-11
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• 2000

In this study, we examined the charging behavior of chopped carbon fibers during electro-flocking process, which is one of the key processes of the novel technique for fabricating conductive polymer composite films. Short carbon fibers (CF) during electroflocking were electrically charged by the combined effect of contact charging, corona charging and tribocharging. The specific charge built on CF surface was measured by using Faraday cup method. Specific charge increased not only with increasing electric field strength and potential impressed to mesh electrode as expected from theoretical considerations in literature, but with decreasing mesh opening size due to the improved contact charging condition. However, CF length was found unexpectedly to influence the amount of CF specific charge due to the agglomerated nature of CF flocks leading to the change in charging conditions.

• Ocean Systems Engineering
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• 제1권4호
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• pp.317-336
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• 2011

A time domain finite element based method is employed to analyze wave radiation by multiple cylinders. The nonlinear free surface and body surface boundary conditions are satisfied based on the perturbation method up to the second order. The first- and second-order velocity potential problems at each time step are solved through a finite element method (FEM). The matrix equation of the FEM is solved through an iteration and the initial solution is obtained from the result at the previous time step. The three-dimensional (3D) mesh required is generated based on a two-dimensional (2D) hybrid mesh on a horizontal plane and its extension in the vertical direction. The hybrid mesh is generated by combining an unstructured grid away from cylinders and two structured grids near the cylinder and the artificial boundary, respectively. The fluid velocity on the free surface and the cylinder surface are calculated by using a differential method. Results for various configurations including two-cylinder and four-cylinder cases are provided to show the mutual influence due to cylinders on the first and second waves and forces.

• 한국통신학회논문지
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• 제34권8B호
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• pp.812-821
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• 2009

본 논문은 다양한 멀티미디어 어플리케이션을 수행하는 hybrid NoC 시스템을 위한 새로운 동적 재구성 가능한 스위치를 제안한다. 기존의 고정된 스위치와 job 분배 알고리듬을 사용하는 hybrid NoC 구조는 효과적인 동작을 위하여 해당 NoC 시스템에서 수행될 어플리케이션을 정확히 예측해야 한다. 본 논문은 NoC 시스템에서 수행되는 다양한 멀티미디어 어플리케이션에 대하여 버퍼 오버플로우를 최소화할 수 있는 재구성 가능한 스위치 구조를 제안한다. 제안된 시스템의 검증을 위하여 임베디드 시스템에서 사용되는 다양한 멀티미디어 어플리케이션 중 MPEG4 동영상 재생, MP3재생, GPS 위치 계산, OFDM 복조를 대상으로 실험하였다. 버퍼 오버플로우는 단일구조의 서브 클러스터로 mesh 토폴로지와 star 토폴로지를 갖는 NoC와 비교하여 각각 평균 41.8%와 29.0%의 감소를 보인다. 전력 소모에서는 고정된 스위치를 사용한 hybrid NoC 구조와 비교하여 평균 2.3%의 증가를 보인다. 면적에서는 서브 클러스터의 구조에 따라 -0.6% ${\sim}$ 5.7% 의 증가를 보인다.