• 전기학회논문지
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• 제61권1호
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• pp.148-154
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• 2012

For a successful checkpointing strategy, we should place checkpoints so as to optimize fault-tolerance capability of real-time systems. This paper presents a novel scheme of checkpoint placement for real-time systems with periodic multi-tasks. Under the influence of transient faults, multi-tasks are scheduled by the Rate Monotonic (RM) algorithm. The optimal checkpoint intervals are derived to maximize the probability of task completion. In particular, this paper is concerned about the general case that the deadline of a task is longer than the period. Compared with the special condition that the deadline is equal to or less than the period, this general case causes a more complicate test procedure for schedulability of the RM algorithm with respect to a given set of checkpoint re-execution vectors. The probability of task completion is also derived in a more complex form. A case study is given to show the applicability of the proposed scheme.

• 대한음성학회:학술대회논문집
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• 대한음성학회 2005년도 추계 학술대회 발표논문집
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• pp.117-120
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• 2005

This paper suggests an algorithm that can estimate the direction of the sound source in realtime. Our intelligent service robot, WEVER, is used to implement the proposed method at the home environment. The algorithm uses the time difference and sound intensity information among the recorded sound source by four microphones. Also, to deal with noise of robot itself, the kalman filter is implemented. The proposed method takes shorter execution time than that of an existing algorithm to fit the real-time service robot. The result shows relatively small error within the range of ${\pm}$ 7 degree.

• 한국정보과학회논문지:시스템및이론
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• 제29권4호
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• pp.176-184
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• 2002

본 논문은 고신뢰 실시간 시스템에 체크포인팅을 적용할 수 있도록 실시간성과 신뢰성을 모두 고려하는 체크포인팅 프레임워크를 제공한다. 실시간 태스크의 시간 예측성은 할당된 체크포인트의 수와 태스크가 실행 중에 감내 해야하는 고장의 수를 기반으로 태스크의 최악 실행 시간(WCET: Worst Case Execution Time)을 산출함으로써 보장된다. 태스크가 실행 중에 극복해야하는 고장의 수는 태스크의 신뢰성 요구조건을 기반으로 산출됨으로써 태스크의 신뢰성이 보장되도록 한다. 이렇게 얻어진 태스크들의 WCET와 태스크가 극복해야 하는 고장의 수를 이용하여, 각 태스크의 스케줄 가능성을 보장하기 위해 요구되는 최소의 체크포인트 수를 유도하는 알고리즘을 제안한다. 본 논문에서 제안하는 프레임워크는 체크포인팅의 시간 중복량을 기반으로 하므로, 다른 시간 중복 기법에 대해서도 확장이 용이하다.

• 한국통신학회논문지
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• 제14권4호
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• pp.388-397
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• 1989

본 논문에서는 불규칙하게 분포된 non-zero 원소를 가진 대형 space 행렬로서 표시되는 선형시스템의 해를 능률적으로 얻기 위한 반복 병렬 알고리즘에 대하여 기술하고, 이 알고리즘을 수행하는데 적절한 컴퓨터로서 dataflow컴퓨터 구조를 제안하였다. 이 알고리즘에서는 Jacobi 반복법을 사용하였으며 행렬의 내적을 구하는데 소요되는 시간을 단축함으로서 병렬 수행시간을 단축시켰다.

• 산업경영시스템학회지
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• 제21권45호
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• pp.101-112
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• 1998

Data mining, which is also referred to as knowledge discovery in database, means a process of nontrivial extraction of implicit, previously unknown and potentially useful information (such as knowledge rules, constraints, regularities) from data in databases. The discovered knowledge can be applied to information management, decision making, and many other applications. In this paper, a new data mining problem, discovering sequential patterns, is proposed which is to find all sequential patterns using sampling method. Recognizing that the quantity of database is growing exponentially and transaction database is frequently updated, sampling method is a fast algorithm reducing time and cost while extracting the trend of customer behavior. This method analyzes the fraction of database but can in general lead to results of a very high degree of accuracy. The relaxation factor, as well as the sample size, can be properly adjusted so as to improve the result accuracy while minimizing the corresponding execution time. The superiority of the proposed algorithm will be shown through analyzing accuracy and efficiency by comparing with Apriori All algorithm.

• 한국산업융합학회 논문집
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• 제20권1호
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• pp.1-7
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• 2017

Most conventional processors execute program instructions in a sequential manner. On the other hand, VLIW processor can execute multiple instructions at the same time. It exploits instruction level parallelism to improve system performance. To that end, program code should be rearranged to VLIW instruction format by a compiler. The compiler determine an optimal execution order of instructions of a program code. This instruction ordering is also called instruction scheduling. The scheduling is an algorithm that decides the execution order for instruction codes in loop parts of a program so that the instruction level parallelism can be maximized. In this research, we apply an existing scheduling algorithm to a VLIW FCC and describe analysis results to further improve its performance. And, we present a solution to solve some limitation of the existing scheduling technique. By using our solution, FCC's performance can be improved upto 32% compared to the existing scheduling only setting.

• 전기학회논문지
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• 제58권9호
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• pp.1658-1666
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• 2009

This paper proposes an approach of Mult_HPSO based on the PC cluster system to reduce or remove the stagnation on an early convergence effect of PSO, reduce an execution time and improve a search ability on an optimal solution. Hybrid PSO(HPSO) is combines the PSO(Particle Swarm Optimization) with the mutation of conventional GA(Genetic Algorithm). The conventional PSO has operated a search process in a single swarm. However, Multi_PSO operates a search process through multiple swarms, which increments diversity of expected solutions and reduces the execution time. Multiple Swarms are composed of unsynchronized PC clusters. We apply to SCED(security constrained economic dispatch) problem, a nonlinear optimization problem, which considers line flow constraints and N-1 line contingency constraints. To consider N-1 line contingency in power system, we have chosen critical line contingency through a process of Screening and Selection based on PI(performace Index). We have applied to IEEE 118 bus system for verifying a usefulness of the proposed approaches.

• Management Science and Financial Engineering
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• 제12권1호
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• pp.79-94
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• 2006

In this paper, we readdress a layout design problem, PTL[3], for determining an optimal 3-class-based dedicated linear storage layout in a class of unit load storage systems. Based on some fundamental properties derived, we provide a converging exact algorithm with O(n[logn]), which is more efficient than that of Yang and Kim [8] and can be applied to PTL[K] with $K{\ge}4$ in order to reduce computational execution time. In addition, we prove that the necessary condition suggested by them is also a sufficient condition to PTL[3].

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1993년도 한국자동제어학술회의논문집(국내학술편); Seoul National University, Seoul; 20-22 Oct. 1993
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• pp.417-422
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• 1993

Robots working in the multiple robot system can perform the variety of tasks compared to the single robot system, while they are subject to the various tight constraints such as the precise coordination and the mutual collision avoidance during the task execution. In this paper, we provide an algorithm and graphical verification for collision avoidance between two robots working together. The algorithm calculates the minimum time delay for collision avoidance and the graphical verification is performed through the 3-D graphic simulator.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1999년도 하계종합학술대회 논문집
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• pp.555-558
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• 1999

In this paper, Ire present the result of feature points recognition and classification of radial pulse by the shape of pulse wave. The recognition algorithm use the method which runs in parallel with both the data of ECG and differential pulse simultaneously to recognize the feature points. Also we specified 3-time elements of pulse wave as main parameters for diagnosis and measured them by execution of algorithm. then we classify the shape of radial pulse by existence and position of feature points.