• Proceedings of the Korea Information Processing Society Conference
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• 2003.05a
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• pp.173-176
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• 2003

최근 분산 컴퓨팅 환경에서 데이터와 서비스의 복제는 통신비용의 감소, 데이터 가용성 증가, 그리고 단일 서버의 병목현상을 피하기 위해 필수적이다. 기존의 대표적인 복제 프로토콜로 네트워크를 논리적으로 구성하는 Tree quorum 프로토콜이 있다 Tree quorum프로토콜은 최선의 경우 가장 우수한 읽기 성능을 보이는 반면 트리의 높이가 증가할수록 노드의 수가 기하급수적으로 증가한다는 단점을 가지고 있다. 따라서 본 논문에서는 Tree quorum 프로토콜의 장점을 가지며, 급격한 노드 증가에 따른 성능 저하 문제를 해결하기 위한 가상 트리 프로토콜을 제안한다. 제안된 가상 트리 프로토콜은 안정된 삼각형 구조의 노드 구성과 가상 구조를 통한 Quorum 프로토콜의 사용으로 Tree quorum 프로토콜에 비해 적은 읽기 비용을 가지며, 적은 수의 노드 구성에서도 높은 읽기 가용성을 갖는다.

• Proceedings of the Korea Inteligent Information System Society Conference
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• 2001.06a
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• pp.359-368
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• 2001

본 연구에서는 부도예측용 인공신경망의 입력노드 선정을 위한 휴리스틱으로 연결강도분석 접근법을 제안한다. 연결강도분석은 학습이 끝난 인공신경망에서 입력노드와 은닉노드와 연결된 가중치의 절대값 즉, 연결강도를 분석하여 입력변수를 선정하는 접근법으로, 본 연구에서는 약체연결뉴론제거법, 강체연결뉴론선택법 그리고 이 두 기법을 통합한 통합 연결강도 모형을 제안하여 각각 의사결정 트리 및 다변량판별분석에 의해 선정된 입력변수를 이용한 인공신경망 모형과 예측율을 비교한다. 실험 결과 본 연구에서 제안하고 있는 방법론이 의사결정트리나 다다변량판별분석 기법 보다 높은 예측율을 보여 주었다. 특히 두 기법의 통합연결강도 모형의 경우에는 다른 단일 기법보다 높은 예측율을 보이고 있다.

• Proceedings of the Korea Information Processing Society Conference
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• 2015.10a
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• pp.56-58
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• 2015

버스 시스템은 단일 시스템 내부의 디바이스들을 물리적으로 연결하는데 사용되던 연결망으로 최근에는 PCI-Express(PCIe)방식의 버스가 주로 사용되고 있다. PCIe 스위칭 기술은 단순히 노드내의 디바이스들만을 연결하는데 그치지 않고 더 나아가 노드간 통신을 가능하게 하는 기능을 제공한다. 본 연구에서는 PCIe 스위칭 기술의 특징과 노드간 통신에 사용될 수 있는 다양한 PCIe 스위치 활용 기법을 살펴보았다.

• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
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• v.8 no.8
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• pp.825-834
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• 2018

Broadcasting is a basic data communication method for interconnection networks. There are two types of broadcasting. One-to-all broadcasting is to transmit a message from one node to all other nodes and all-to-all broadcasting is to transmit a message from all the nodes that have messages to other nodes. And by the using way of the transmission port per unit time, there are two schemes of broadcasting. Single port telecommunication(SLA) is to transmit messages from one node that contains the messages to one adjacent node only and all port telecommunication(MLA) is to transmit messages from one node to all adjacent nodes within a time of unit. Matrix hypercube is that an interconnection network has improved network cost than that of hypercube with the same number of nodes. In this paper, we analyze broadcasting scheme of matirx hypercube. First, we propose one-to-all and all-to-all broadcasting algorithms of matrix hypercube. And we prove that one-to-all broadcasting times are 2n+1 and $2{\lceil}{\frac{n}{2}}{\rceil}+1$ based on the SLA and MLA models, respectively. Also, we show all-to-all broadcasting time using SLA model is $5{\times}2^{\frac{n}{2}}-2$ when n=even, and is $5{\times}2^{\frac{n-1}{2}}+2$ when n=odd.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.7C
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• pp.1015-1023
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• 2004

In order to protect an exchanged data, it is indispensable to establish a peer-to-peer key between the two communicating nodes. Pre-distributing keys among the nodes is unrealistic in Ad-Hoc network environment because of the dynamic nature of its network topology and the equal authority of its nodes. This paper presents a peer-to-peer key establishment scheme without pre-distributing keys in Ad-Hoc networks. The proposed scheme is based on the Diffie-Hellman key exchange protocol. Main idea is to prevent the falsification of Diffe-Hellman values using some elements of a hash chain. As a result, it is as safe as the underlying hash function against a man-in-the-middle attack. Simulation results have shown that the proposed scheme dramatically reduces the number of messages, and has relatively higher scalability, as compared with the key pre-distribution based scheme.

• The Journal of the Korea Contents Association
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• v.6 no.2
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• pp.117-126
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• 2006

Although the Java bytecode has numerous advantages, there are also shortcomings such as slow execution speed and difficulty in analysis. In order to overcome such disadvantages, bytecode analysis and optimization must be performed. First control flow of the bytecode should be analyzed, after which information is required regarding where the variables are defined and used to conduct data flow analysis and optimization. There may be cases where variables with an identical name contain different values at a different location during the execution according to the value assigned to a variable in each location. Therefore, in order to statically determine the value and type, the variables must be separated according to allocation. In order to do so, the variables can be expressed using a static single assignment form. After the transformation into a static single assignment form, the type information of each node expressed by each variable and expression must be configured to perform static analysis and optimization. Based on the basic type information, this paper proposes a method for finding related equivalent nodes, setting the nodes with strongly connection components and efficiently assigning each node the type.

• Proceedings of the Korea Information Processing Society Conference
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• 2009.11a
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• pp.539-540
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• 2009

본 논문에서는 무선 메쉬 네트워크에 기반한 공정제어 시스템에서의 노드 고장에 따르는 통신 시스템의 특성을 파악하기 위하여 시뮬레이션 환경을 설정하고 노드의 고장 수와 그리드의 차원에 따르는 고립노드의 수를 측정하였다. 실험 환경에서 좌상단의 노드를 제어포인트로 설정하고 각 무선링크의 오류율이 주어졌을 때 노드들에 고장을 발생시켜 제어포인트로부터의 도달가능성을 측정하였다. 실험 결과는 25 % 보다 많은 노드들의 고장은 정상적인 노드를 고립시키기 시작하며 그리드의 차원이 클수록 동일한 비율의 노드 고장에도 더 영향을 받음을 보이고 있다. 이는 노드들의 고장율이 높은 시스템인 경우 노드 수리의 시간과 비용의 요구사항을 추정할 수 있도록 하며 그리드의 차원이 8 이상인 경우 또다른 제어포인트, 즉 싱크노드 도입의 필요성을 나타낸다.

• The Journal of the Korea Contents Association
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• v.16 no.8
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• pp.706-716
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• 2016

Because of efficient space utilization and fast key search times, B-trees have been widely accepted for the use of indexes in HDD-based DBMSs. However, when the B-ree is stored in flash memory, its costly operations of node updates may impair the performance of a DBMS. This is because the random updates in B-tree's leaf nodes could tremendously enlarge I/O costs for the garbage collecting actions of flash storage. To solve the problem, we make all the parents of leaf nodes the virtual nodes, which are not stored physically. Rather than, those nodes are dynamically generated and buffered by referring to their child nodes, at their access times during key searching. By performing node updates and tree reconstruction within a single flash block, our proposed B-tree can reduce the I/O costs for garbage collection and update operations in flash. Moreover, our scheme provides the better performance of key searches, compared with earlier flash-based B-trees. Through a mathematical performance model, we verify the performance advantages of the proposed flash B-tree.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.5
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• pp.921-928
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• 2017

Unlike wired networks, broadcasting in wireless networks can transmit data to several nodes at a time in a single transmission. The omnidirectional broadcasting of node in wireless networks simultaneously reaches all neighboring nodes. In this paper, we propose a greedy algorithm to solve the minimum power broadcasting problem that minimizes the total transmission power when broadcasting in wireless networks. The proposed algorithm uses a neighborhood list which is a set of nodes that can transmit messages within the maximum transmission range of each node, and among the transmitting nodes that have received the data, the node having the largest number of the neighboring nodes firstly transmits the data to neighboring node. The performance of the proposed algorithm was evaluated by computer simulation, and was compared with existing algorithms in terms of total transmission power and broadcasting frequency for broadcasting to all nodes. Experiment results show that the proposed algorithm outperforms the conventional algorithms.

• Journal of KIISE:Computing Practices and Letters
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• v.16 no.4
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• pp.487-491
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• 2010

In this paper we propose a new single-query path planning algorithm for working well in high-dimensional configuration space. With the notice of the similarity between single-query algorithms with exploration algorithms, we propose a new path planning algorithm, which applies the Remembering Exploration method, which is one of exploration algorithms, to a path-planning problem by selecting a node from a roadmap, finding out the neighbor nodes from the node, and then inserting the neighbor nodes into the roadmap, recursively. For the performance comparison, we had experiments in 2D and 3D environments and compared the time to find out the path. In the results our algorithm shows the superior performance than other path planning algorithms.