• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2015년도 춘계학술대회
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• pp.105-107
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• 2015

본 논문에서는 네트워크의 유동확률밀도를 이용하여 분산적인 라우팅 경로를 분석하는 LTD(Load Tolerance Density-distribution) 알고리즘을 제안한다. 모바일 애드 혹 네트워크(Mobile Ad-hoc Networks)는 유동성을 가진 노드들로 구성된 네트워크로서, 토폴로지의 변화가 빈번하다. 토폴로지의 변화를 줄이기 위해 계층적 네트워크가 연구되었으나, 특정 클러스터 헤드노드에게 부하가 집중되어 통신이 단절된다. 본 논문에서 제안하는 알고리즘은 포아송 분포를 이용한 노드의 유동확률밀도를 계산하여, 분산적인 라우팅 경로를 제공하는 알고리즘이다. 모의실험에서, 본 논문에서 제안한 알고리즘의 패킷 전송률은 비교 알고리즘에 비해 향상된 결과를 보여주었다.

• 대한전자공학회논문지TC
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• 제44권10호
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• pp.76-82
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• 2007

노드들의 이동성을 보장하고, 별도의 인프라가 필요하지 않다는 점에서 최근에 MANET에 대한 관심이 커지고 연구가 활발히 진행되고 있다. 최근 들어 노드들이 이동한다는 개념이 단순이 걸어 다니는 것이 아니라 GPS를 기반으로 빠른 속도로 움직이는 자동차에 대한 Ad hoc 망의 이용에 많은 관심을 가지게 됨에 따라 MANET에서의 이동성이 과거에 비해 중요시되고 있다. 노드들이 빠르게 이동하는 경우 각 노드들이 목적지를 탐색하고 라우팅 하는 것은 많은 비용을 비롯하여 여러 문제가 발생한다. 이러한 문제를 해결하기 위하여 No path-Location Aided Routing (N-LAR) 란 새로운 라우팅 프로토콜을 제안한다. 제안하는 방법은 이동성이 큰 MANET에서 좀 더 짧은 응답속도와 높은 전송성공률을 갖는다.

• 식물조직배양학회지
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• 제22권6호
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• pp.335-337
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• 1995

주목의 줄기절간 조직배양에 의한 다경줄기 유도를 위해 식물생장조절물질 중 4가지 형태의 싸이토키닌 효과를 조사 한 바, BAP, kinetin 및 thidiazuron의 경우 거의 반응을 보이지 않았으나, zeatin을 5 $\times$ $10^{-5}$M 처리하였을 경우 평균 6 개 이상의 다경줄기를 얻을 수 있었으며, 배양시료에 따라서 는 12개 이상의 다경을 형성하는 경우도 관찰되었다. 유도된 다경줄기를 지속적으로 계대배양하여 줄기를 신장시킨 후 이로부터 2 cm 크기의 기내삽목도 가능하였다. 기내발근율은 LP기본배지를 이용하는 것이 비교적 양호하였으나 효율은 3%에 지나지 않았다. 기외발근의 경우, 약 34%까지 발근율을 올릴 수 있었으며 포지에 이식시킨 조직배양묘는 1년이상 정상적인 생육을 보이고 있음이 관찰되었다.

• Journal of information and communication convergence engineering
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• 제8권6호
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• pp.655-659
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• 2010

In the conventional PNC scheme, the relay node requires simultaneous transmission of two source nodes with strict power control and carrier-phase matching between two received symbols. However, this pre-equalization process at source nodes is not practical in fading channels. In this letter, we propose a novel physical-layer network coding (PNC) scheme with log-likelihood ratio (LLR) conversion for fading channels, which utilizes not pre-equalizer at transmitters (source nodes) but joint detector at receiver (relay node). The proposed PNC requires only channel side information at the receiver (CSIR), which is far more practical assumption in fading channels. In addition, the proposed PNC scheme can use the conventional modulation scheme like M-QAM regardless of modulation order, while the conventional PNC scheme requires reconfiguration of modulation scheme at the source nodes for detection of the received signal at relay node. We consider the combination of the proposed PNC and channel coding, and find that the proposed PNC scheme is easily combined the linear channel codes such as turbo codes, LDPC, and convolutional codes.

• 전자공학회논문지S
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• 제35S권7호
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• pp.53-61
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• 1998

In this paper, we propose an efficient multi-view images coding algorithm to find the optimal depth and texture from the set of multi-view images. The proposed algorithm consists of two consecutive steps, i) the depth estraction step, and ii) the texture extraction step, comparedwith the traditional algorithem which finds the depth and texture concurrently. The X-Y plane of the normalized object space is divided into traingular paatches and the Z value of the node is determined in the first step and then the texture of the each patch is extracted in the second step. In the depth extraction step, the depth of the node is determined by applying the block based disparity compensation method to the windowed area centered at the node. In the second step, the texture of the traingular patches is extracted from the multi-view images by applying the affine transformation based disparity compensation method to the traingular pateches with the depth extracted from the first step. Experimental results show that the SNR(Singnal-to- Noise Ratio) of images enconded by our algorithm is better than that of images encoded by the traditional algorithm by the amount about 4dB for for the test sets of multi-view images called dragon, kid, city and santa.

• 전산구조공학
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• 제10권2호
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• pp.179-188
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• 1997

본 논문에서는 평판 구조물의 효율적인 해석을 위한 4절점 평판휨 요소를 개발하였다. 이 요소는 전단변형을 고려하기 위해 Mindlin평판이론에 의하여 유도하였다. 평판휨 문제에서 4절점요소와 같은 저차의 등매개변수 Mindlin평판요소는 전단강성을 실제보다 강하게 평가하기 때문에 얇은 평판에서는 요소의 기능을 발휘하지 못한다. 이러한 문제점을 극복하기 위해 4절점 요소에 5개의 비적합변위모드를 추가함으로써 개선된 결과를 얻을 수 있었으며, 개발된 요소는 유사영에너지모드를 발생시키지 않는다. 아주 얇은 평판에서도 요소의 형상과 무관하게 전단구속현상을 극복하였으며, 예제 해석으로부터 변위의 신속한 수렴성과 단면력의 분포가 양호한 결과를 얻을 수 있었다. 또한 요소형상비가 매우 큰 경우에도 좋은 결과를 얻을 수 있었다.

• Steel and Composite Structures
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• 제39권2호
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• pp.149-158
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• 2021

In this research paper, the free vibrational response of laminated composite plates is investigated using a non-polynomial refined shear deformation theory (NP-RSDT). The most interesting feature of this theory is the parabolic distribution of transverse shear deformations while ensuring the conditions of nullity of shear stresses at the free surfaces of the plate without requiring the Shear correction factor "Ks". A fourth-nodded isoparametric element with four degrees of freedom per node is employed for laminated composite plates. The numerical analysis of simply supported square anti-symmetric cross-ply and angle-ply laminated plate is carried out using a special discretization based on four-node finite element method which four degrees of freedom per node. Several numerical results are presented to show the effect of the coupling parameters of the plate such as the modulus ratios, the thickness ratio and the plate layers number on adimensional eigen frequencies. All numerical results presented using the current finite element method (FEM) is presented in 3D curve form.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권7호
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• pp.3386-3411
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• 2019

Secured and reliable routing is a crucial factor for improving the performance of Wireless Mesh Networks (WMN) since these networks are susceptible to many types of attacks. The existing assumption about the internal nodes in wireless mesh networks is that they cooperate well during the forwarding of packets all the time. However, it is not always true due to the presence of malicious and mistrustful nodes. Hence, it is essential to establish a secure, reliable and stable route between a source node and a destination node in WMN. In this paper, a trust based secure routing algorithm is proposed for enhancing security and reliability of WMN, which contains cross layer and subject logic based reliable reputation scheme with security tag model for providing effective secured routing. This model uses only the trusted nodes with the forwarding reliability of data transmission and it isolates the malicious nodes from the providing path. Moreover, every node in this model is assigned with a security tag that is used for efficient authentication. Thus, by combining authentication, trust and subject logic, the proposed approach is capable of choosing the trusted nodes effectively to participate in forwarding the packets of trustful peer nodes successfully. The simulation results obtained from this work show that the proposed routing protocol provides optimal network performance in terms of security and packet delivery ratio.

• 디지털산업정보학회논문지
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• 제18권4호
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• pp.13-21
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• 2022

Recently, in wireless video sensor networks(WVSN), various schemes for efficient video data transmission have been studied. In this paper, a layer based cooperative relaying(LCR) algorithm is proposed for minimizing scalable video transmission distortion from packet loss in WVSN. The proposed LCR algorithm consists of two modules. In the first step, a parameter based error propagation metric is proposed to predict the effect of each scalable layer on video quality degradation at low complexity. In the second step, a layer-based cooperative relay algorithm is proposed to minimize distortion due to packet loss using the proposed error propagation metric and channel information of the video sensor node and relay node. In the experiment, the proposed algorithm showed that the improvement of peak signal-to-noise ratio (PSNR) in various channel environments, compared to the previous algorithm(Energy based Cooperative Relaying, ECR) without considering the metric of error propagation.The proposed LCR algorithm minimizes video quality degradation from packet loss using both the channel information of relaying node and the amount of layer based error propagation in scalable video.

• Journal of information and communication convergence engineering
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• 제14권1호
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• pp.14-20
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• 2016

The AODV protocol uses many RREQ messages and one RREP message in the path-discovery process. This protocol has only one metric, the number of hops. Although it is simple, this protocol is not efficient. To avoid this problem, we propose a new AODV with two auxiliary metrics (AuM-2-AODV). The AuM-2-AODV protocol tries multiple route replies, which reduces the chance of path failure and helps the network obtain a better data rate. It has two auxiliary metrics, the remaining energy of its nodes and the number of HELLO messages received at the nodes. With these two metrics, the reliable path from the source node to the destination node will be chosen. In this paper, the performance of the AuM-2-AODV is evaluated using the NS-3 simulator. The performance results show that AuM-2-AODV provides greater throughput and packet delivery ratio by 20% and up to 50% and about 100% in some cases, respectively, than previous protocols.