• The Journal of the Korea Contents Association
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• v.8 no.8
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• pp.37-46
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• 2008

Launch control system controls the sequence for launching missile in weapon systems. This system have to generate the engagement plan, input information and launch the missile in timeliness requirement. Such a system may fail to operate correctly either due to errors in hardware and software or due to violation of timing constraints. We presented fault-tolerant ethernet for embedded real-time system like launch control system. This approach is designed to handle network faults using dual commercial-off-the-shelf(COTS) network devices. To support fault-tolerant ethernet each node is composed dual channel ethernet and designed the communication middleware for network fault detect and recovery. Especially for time-critical system, the middleware is being developed to achieve that no point of network failure shall take down or cause loss of communication to network nodes.

• The KIPS Transactions:PartA
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• v.10A no.3
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• pp.215-224
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• 2003

Since there are various networks and heterogeneity of nodes in Internet, the existing load-sharing algorithms are hardly adapted for use in Internet-based clustering systems. Therefore, in Internet-based clustering systems, a load-sharing algorithm must consider various conditions such as heterogeneity of nodes, characteristics of a network and imbalance of load, and so on. This paper has proposed an expanded-WF algorithm which is based on a WF (Weighted Factoring) algorithm for load-sharing in Internet-based clustering systems. The proposed algorithm uses an adaptive granularity strategy for load-sharing and duplicate execution of partial job for fault-tolerance. For the simulation, the to matrix multiplication using PVM is performed on the heterogeneous clustering environment which consists of two different networks. Compared to other algorithms such as Send, GSS and Weighted Factoring, the proposed algorithm results in an improvement of performance by 55%, 63% and 20%, respectively. Also, this paper shows that It can process the fault-tolerance.

• Journal of Korea Multimedia Society
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• v.10 no.1
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• pp.94-101
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• 2007

Partial dominant pruning(PDP) is regarded as the most practical scheme, reducing redundant messages arisen in broadcasting over ad hoc networks, in such a way that only part of nodes are allowed to forward the received broadcast message. In this paper we propose an extend PDP version called DPDP(directional PDP) such that it reduces not only the number of selected forward nodes, but also the number of antenna elements deployed by the forward nodes. It turns out through simulation that as the number of antenna elements increases, the number of selected forward nodes by DPDP slightly outnumbers that obtained using PDP but both the number of antenna elements deployed by the forward nodes and the redundancy ratio of the received message per node always outperform respectively those given by PDP.

• Journal of KIISE:Computer Systems and Theory
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• v.29 no.4
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• pp.176-184
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• 2002

We provide a checkpointing framework reflecting both the timeliness and the dependability in order to make checkpointing applicable to dependable real-time systems. The predictability of real-time tasks with checkpointing is guaranteed by the worst case execution time (WCET) based on the allocated number of checkpoints and the permissible number of failures. The permissible number of failures is derived from fault tolerance requirements, thus guaranteeing the dependability of tasks. Using the WCET and the permissible number of failures of tasks, we develop an algorithm that determines the minimum number of checkpoints allocated to each task in order to guarantee the schedulability of a task set. Since the framework is based on the amount of time redundancy caused by checkpointing, it can be extended to other time redundancy techniques.

• Journal of the Korea Society of Computer and Information
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• v.13 no.6
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• pp.13-24
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• 2008

The multi robot operation technique has emerged as one of the most important research subjects that focus on minimizing redundancy in space exploration and maximizing the efficiency of operation. For an efficient operation of the multi robot systems, the movement of each Single robot in the multi robot systems should be properly observed and controlled. This paper suggests Multi Robot Management System to minimize redundancy in space exploration by assigning exploration space to each robot efficiently to take advantage of the RFID. Also, this paper has suggested fault tolerance technique that detects disable Single robot and substitute it by activated Single robot in order to ensure overall exploration and improve efficiency of exploration. Proposed system overcomes previous fault that it is difficult for central server to detect exact position of robot by using RFID system and Home Robot. Designated Home robot manages each Single robot efficiently and assigns the best suited space to Single robot by using RFID Tag Information. Proposed multi robot management system uses RFID for space assignment, Localization and Mapping efficiently and not only maximizes the efficiency of operation, but also ensures reliability by supporting fault-tolerance, compared with Single robot system. Also, through simulation, this paper proves efficiency of spending time and redundancy rates between multi robot management applied by proposed system and not applied by proposed system.

• Journal of Intelligence and Information Systems
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• v.17 no.1
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• pp.111-125
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• 2011

Clustering is a process of grouping similar or relevant documents into a cluster and assigning a meaningful concept to the cluster. By this process, clustering facilitates fast and correct search for the relevant documents by narrowing down the range of searching only to the collection of documents belonging to related clusters. For effective clustering, techniques are required for identifying similar documents and grouping them into a cluster, and discovering a concept that is most relevant to the cluster. One of the problems often appearing in this context is the detection of a complex concept that overlaps with several simple concepts at the same hierarchical level. Previous clustering methods were unable to identify and represent a complex concept that belongs to several different clusters at the same level in the concept hierarchy, and also could not validate the semantic hierarchical relationship between a complex concept and each of simple concepts. In order to solve these problems, this paper proposes a new clustering method that identifies and represents complex concepts efficiently. We developed the Hierarchical Overlapping Clustering (HOC) algorithm that modified the traditional Agglomerative Hierarchical Clustering algorithm to allow overlapped clusters at the same level in the concept hierarchy. The HOC algorithm represents the clustering result not by a tree but by a lattice to detect complex concepts. We developed a system that employs the HOC algorithm to carry out the goal of complex concept detection. This system operates in three phases; 1) the preprocessing of documents, 2) the clustering using the HOC algorithm, and 3) the validation of semantic hierarchical relationships among the concepts in the lattice obtained as a result of clustering. The preprocessing phase represents the documents as x-y coordinate values in a 2-dimensional space by considering the weights of terms appearing in the documents. First, it goes through some refinement process by applying stopwords removal and stemming to extract index terms. Then, each index term is assigned a TF-IDF weight value and the x-y coordinate value for each document is determined by combining the TF-IDF values of the terms in it. The clustering phase uses the HOC algorithm in which the similarity between the documents is calculated by applying the Euclidean distance method. Initially, a cluster is generated for each document by grouping those documents that are closest to it. Then, the distance between any two clusters is measured, grouping the closest clusters as a new cluster. This process is repeated until the root cluster is generated. In the validation phase, the feature selection method is applied to validate the appropriateness of the cluster concepts built by the HOC algorithm to see if they have meaningful hierarchical relationships. Feature selection is a method of extracting key features from a document by identifying and assigning weight values to important and representative terms in the document. In order to correctly select key features, a method is needed to determine how each term contributes to the class of the document. Among several methods achieving this goal, this paper adopted the $x^2$�� statistics, which measures the dependency degree of a term t to a class c, and represents the relationship between t and c by a numerical value. To demonstrate the effectiveness of the HOC algorithm, a series of performance evaluation is carried out by using a well-known Reuter-21578 news collection. The result of performance evaluation showed that the HOC algorithm greatly contributes to detecting and producing complex concepts by generating the concept hierarchy in a lattice structure.

• Proceedings of the Korea Information Processing Society Conference
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• 2002.11c
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• pp.1871-1874
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• 2002

최근 인터넷 환경에서 지리 정보 서비스를 제공받으려는 사용자들의 지속적인 증가로 인해 저비용의 여러 개의 단일 노드를 고속의 네트워크로 연결하여 고성능을 제공하는 클러스터 기반의 공간 데이터베이스에 대한 연구가 활발하게 진행되고 있다. 이러한 공간 데이터베이스 클러스터에서 사용자가 요구한 공간 질의를 빠르게 처리하기 위해서는 고비용의 공간 조인 연산을 효율적으로 처리하기 위한 기법이 요구된다. 본 논문에서는 비공유 공간 데이터베이스 클러스터 환경하에서 공간 조인 연산 수행 시 효율적인 병렬 처리를 위한 영역 분할 기법 및 병렬 공간 조인 기법을 제안한다. 기존의 병렬 공간 데이터베이스 시스템에서의 분할 기반 병렬 공간 조인 기법들은 병렬로 수행할 작업 분배 및 할당과 분할 경계선 상에 존재하는 공간 객체들에 대한 중복 조인 연산 및 중복 결과 제거 등의 추가적인 연산을 해야 한다는 문제점들이 있다. 제안된 기법은 공간 릴레이션들을 일정 영역들로 분할하여 비공유 공간 데이터베이스 클러스터의 각 노드에서 중복없이 저장, 관리하도록 하며 분할 영역의 경계선 상에 위치하는 공간 데이터에 대해서만 중복 저장을 허용하여 병렬 공간 조인 연산 시 누락되는 공간 데이터가 없도록 한다. 본 기법은 공간 조인 연산 시 병렬 처리를 위한 별도의 작업 할당 과정을 거치지 않고 각 노드에서 병렬적으로 공간 조인 연산을 수행하며, 분할 경계선 상에 존재하는 공간 객체들은 여과 과정을 거쳐 한번만 공간 조인이 수행되므로 중복 결과들을 제거하기 위한 별도의 연산이 필요없는 특징을 갖는다. Ad Hoc망의 위상변화에 대한 적응성을 높일 수 있도록 한다. SQL Server 2000 그리고 LSF를 이용하였다. 그리고 구현 환경과 구성요소에 대한 수행 화면을 보였다.ool)을 사용하더라도 단순 다중 쓰레드 모델보다 더 많은 수의 클라이언트를 수용할 수 있는 장점이 있다. 이러한 결과를 바탕으로 본 연구팀에서 수행중인 MoIM-Messge서버의 네트워크 모듈로 다중 쓰레드 소켓폴링 모델을 적용하였다.n rate compared with conventional face recognition algorithms. 아니라 실내에서도 발생하고 있었다. 정량한 8개 화합물 각각과 총 휘발성 유기화합물의 스피어만 상관계수는 벤젠을 제외하고는 모두 유의하였다. 이중 톨루엔과 크실렌은 총 휘발성 유기화합물과 좋은 상관성 (톨루엔 0.76, 크실렌, 0.87)을 나타내었다. 이 연구는 톨루엔과 크실렌이 총 휘발성 유기화합물의 좋은 지표를 사용될 있고, 톨루엔, 에틸벤젠, 크실렌 등 많은 휘발성 유기화합물의 발생원은 실외뿐 아니라 실내에도 있음을 나타내고 있다.>10)의 $[^{18}F]F_2$를 얻었다. 결론: $^{18}O(p,n)^{18}F$ 핵반응을 이용하여 친전자성 방사성동위원소 $[^{18}F]F_2$를 생산하였다. 표적 챔버는 알루미늄으로 제작하였으며 본 연구에서 연구된 $[^{18}F]F_2$가스는 친핵성 치환반응으로 방사성동위원소를 도입하기 어려운 다양한 방사성의 약품개발에 유용하게 이

• Journal of the Korea Institute of Information Security & Cryptology
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• v.30 no.6
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• pp.1013-1021
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• 2020

Malware Authorship Attribution is a research field for identifying malware by comparing the author characteristics of unknown malware with the characteristics of known malware authors. The authorship attribution method using binaries has the advantage that it is easy to collect and analyze targeted malicious codes, but the scope of using features is limited compared to the method using source code. This limitation has the disadvantage that accuracy decreases for a large number of authors. This study proposes a method of 'Defining semantic features from binaries' and 'Defining allowable ranges for redundant features using the concept of survival network' to complement the limitations in the identification of binary authors. The proposed method defines Opcode-based graph features from binary information, and defines the allowable range for selecting unique features for each author using the concept of a survival network. Through this, it was possible to define the feature definition and feature selection method for each author as a single technology, and through the experiment, it was confirmed that it was possible to derive the same level of accuracy as the source code-based analysis with an improvement of 5.0% accuracy compared to the previous study.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 2010.09a
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• pp.95-98
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• 2010

수질오염총량제가 도입되면서 각 지방자치단체는 허용배출량을 산정하기 위하여 QUAL2E 수질모델을 이용한 수질모의를 적극적으로 활용하고 있다. 그러나 수질모의 수행에 필요한 입력 자료를 작성하기 위하여 많은 시간이 소요되기 때문에 시간 및 경제적 손실을 가져오고 있다. 따라서 본 연구에서는 수질모의 입력 자료를 자동으로 작성하기 위하여 오염원 DB와 수리계수 DB 및 한국형 리치파일을 연계할 수 있는 데이터모델을 수립하였다. 모델을 이용하여 수질모의 대상하천의 기본 정보를 한국형 리치파일에서 얻은 후 오염원 DB와 표준유역명으로 연계하여 오염원 정보를 추출토록 하였다. 아울러 수리계수 DB에서 하천코드와 상류지점으로부터 누적거리를 이용하여 대상 하천의 수리계수를 추출하였다. 이는 모의대상하천을 선택하였을 때 자동으로 수질모의 입력 자료를 작성할 수 있는 모듈을 개발할 수 있도록 지원이 가능하다. 이러한 모델의 개발을 통하여 다양한 기관에서 중복 구축하던 수질모의 자료의 통합관리가 가능하며, 나아가 수질모의 입력 자료의 작성을 자동화함으로써 시간 및 비용 절감에 기여가 클 것으로 사료된다.

• The Journal of Information Technology and Database
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• v.6 no.2
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• pp.71-86
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• 1999

The performance of relational database is measured by the number of disk accesses necessary to transfer data from disk to main memory. The paper proposes to vertically partition relations into fragments and to allow attribute replication to reduce the number of disk accesses. To reduce the computational time, heuristic search method using genetic algorithm is used. Genetic algorithm used employs a rank-based-sharing fitness function and elitism. Desirable parameters of genetic algorithm are obtained through experiments and used to find the solutions. Solutions of attribute replication and attribute non-replication problems are compared. Optimal solutions obtained by branch and bound method and by heuristic solutions(genetic algorithm) are also discussed. The solution method proposed is able to solve large-sized problems within acceptable time limit and shows solutions near the optimal value.