• 인터넷정보학회논문지
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• 제12권3호
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• pp.27-36
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• 2011

센서 네트워크 시스템의 센서 노드들은 싱크 노드와 무선으로 송수신하며 사람이 일일이 접근하기 힘든 방대한 지역의 센서 데이터를 획득 및 전송한다. 하지만 센서 노드들의 중복 센서 데이터의 비효율적인 반복 전송은 전체 시스템의 수명을 짧게 하고, 이때 발생하는 많은 양의 데이터들은 사용할 때 다시 선별해야 하는 번거로움이 있다. 본 논문에서는 네이밍 에이전트의 네임 스페이스의 메타 테이블로부터 제공되는 이주 대상 노드들을 차례로 방문하여, 사용자 조건에 따라 중복 센서 데이터를 제거하고, 용도 및 필요에 따라 센서 데이터를 수집 및 전송함으로써 센서 데이터의 과잉 송수신을 막고 전체 시스템의 수명을 늘릴 수 있는 이동 에이전트 미들웨어를 설계 및 구현한다. 또한, 실제 환경에서 발생할 수 있는 상황을 고려한 조건 및 제한들을 적용한 이동 에이전트를 이용한 실험을 통하여 중복 센서 데이터의 제거 및 데이터 수집의 효율성을 보이고, 향후 제안된 이동 에이전트 미들웨어에 능동 규칙을 탑재하거나 능동 규칙 시스템과의 연계를 통하여 다양한 능동적 센서 네트워크 응용에의 적용 가능성을 보인다.

• 전력전자학회논문지
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• 제7권5호
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• pp.499-508
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• 2002

본 논문에서는 N.1 모듈형 UPS 시스템의 병렬운전을 위해 기존에 사용된 부하분담용 신호선을 제거하고 독립적인 운전을 수행하는 새로운 형태의 wirelss 병렬제어 알고리즘을 제안하고자 한다. 제안된 제어시스템은 기존 방식이 갖는 센싱 노이즈나 상호간섭에 의한 문제를 제거할 수 있다. 또한 wireless방식의 단점을 보완하기 위해 인버터간 불평형요소 제거 알고리즘을 적용하여 무효전력편차의 발생을 최소화하는 구조를 가지며, 시스템의 불안정한과도특성을 완충하는 가상의 임피던스를 삽입하여 과도순환전류를 저감하는 방식이 적용되었다. 제안된 알고리즘의 타당성을 검증하기 위해 시뮬레이션 결과를 제시하였다.

• Nuclear Engineering and Technology
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• 제15권4호
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• pp.229-235
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• 1983

원자력발전소에서 Common Mode Failures (CMFs)가 상당한 관심을 모으고 있다. 이 논문에서는 중복 시스템의 비가용도(Unavailability)에 있어서의 전체 CMFs를 잠재적 CMFs(Potential CMFs)와 의존성 인간 실수에 의한 CMFs (CMFs of dependent human error)로 나누어 이론적으로 고찰하였다. 결론적으로, 인간 실수의 의존성이 높아질수록 전체 CMFs는 의존성 인간실수에 의해서 주로 영향을 받는다고 할 수 있다. 역으로, 인간 실수의 의존성이 낮아질수록, 전체 시스템의 비가용도는 기계적 고장이나 의존성 인간실수보다 잠재적 CMFs에 의해 지배된다고 할 수 있다. 그리고, 중복 시스템의 비가용도에 있어서 전체 CMFs가 기계적 고장보다 주된 요소임도 알 수 있었다.

• KIEAE Journal
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• 제16권6호
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• pp.57-67
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• 2016

Purpose: Laws and regulations of land use are enormous, and the appliance of regulations is overlapped redundantly. Therefore, there are many problems such as time consuming in the process, limiting individual property rights, and interrupting enterprises' economic activities. This study will discuss problems of redundant regulations of land use and its improvement by figuring out current regulations of land use in Gyeonggi-do, one of provinces which applies the most various regulations of land use. Method: This study reviews laws on national land-use planning system and characteristics of land-use regulation in Korea. The extent of the review is limited to "framework act on the regulation of land use" with categories of national land, urban planing, architecture, etc. Through case studies in Gyeonggi-do, the status and problems of redundant regulations of land use are defined. For example, it is overlapped in "Seoul Metropolitan Area Readjustment Planning Act", Development Restriction Zone, Paldang Special District, and so on. It is mainly referred to 2015 Gyeonggi-do land-use restriction map. Result: First, Gyeonggi-do confronts many problems related to the development restrictions and the financial increasement for environmental management by redundant regulations. The development restrictions include supplying additional land for industrial use, relocating colleges, and height limitation relating to military facilities. Second, in order to organize redundant regulations, it is required to combine similar regulations and adjust through communication system among other departments. Third, regulations should consider unique local condition of each district. Lastly, efficient application of regulations is necessary so as to maximize the function of land, protect individual property rights, and stimulate local development.

• 한국신뢰성학회:학술대회논문집
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• 한국신뢰성학회 2000년도 춘계학술대회 발표논문집
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• pp.231-238
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• 2000

The distributed digital control system has many shared common components, and a single fault in the system may have effects on not a single function. Not as in an analog system, the faults in a digital system usually make discrete and abrupt changes in its output, which are hard to be expected. To cope with these situations, the fault-tolerance is an inevitable property of a distributed control system. A distributed digital control system consists of many equipments, and each equipment can be implemented by many different technologies. The fault-tolerance has to be implemented depend-ing on the overall architecture and how each equipment is implemented. The paper analyzes and compares the strategies and tactics to add the fault-tolerances in a distributed digital control system, and studies how they can be combined appropriately.

• 전자통신동향분석
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• 제8권3호
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• pp.39-52
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• 1993

This study involves a Common Cause Failure (CCF) problem on the ultra-high reliability required system development such as war game operations, nuclear power control, air traffic control, space shuttle missions, and large scale network communication system. The system situation problems are defined according to CCF, reliability and system fault identifications for the development cast verifications in the multi-version redundant software system. Then, CCF analysis of redundant system, system principles and statistical dependence are also described. This validation oh the CCF in the human software interaction system will notify software engineers to conceive what really is CCF contribution factor, not only the internal but the external ones.

• 제어로봇시스템학회논문지
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• 제7권5호
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• pp.384-392
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• 2001

In this paper, we propose a novel robust fault isolation filter design method using the left eigenstructure assignment scheme proposed by the authors. The proposed method guarantees that the ${\gamma}$ simultaneous faults can be isolated when the number of available outpur measurements is ${\gamma}$. Moreover, if there exist redundant output measurements, the eigenvaluses of te filter system can be assigned to the desired position or the filter can be designed robustly to, the system parameter variation. Liu & Si developed a filter design method which has the same purpose, fault isolation. However their method cannot use the redundant freedom of the output matrix C. The proposed filter can use the redundant freedom of the matrix C effectively. Beside this in this paper, an eigenstructure assignment methodology that satisfies the required fault isolation conditions is also proposed. The proposed fault isolation filter was applied for isolating the simultaneous faults to a VTOL aircraft in order to verify the fault isolation performance.

• 대한전기학회논문지:시스템및제어부문D
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• 제53권4호
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• pp.235-245
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• 2004

In this paper, fault tolerant mechanisms are presented for a servo manipulator system designed to operate in a hot cell. A hot cell is a sealed and shielded room to handle radioactive materials, and it is dangerous for people to work in the hot cell. So, remote operations are necessary to handle the radioactive materials in the hot cell. KAERI has developed a servo manipulator system to perform such remote operations. However, since electric components such as servo motors may fail by radiation, fault tolerant mechanisms have to be considered. For fault tolerance of the servo manipulator system, duplication mechanism increasing the reliability of the transport's driving motors and reconfiguration algorithm accommodating the slave's motor failure have been presented. The reconfiguration algorithm recovering the end effector's motion in spite of one motor's failure is based on control allocation redistributing redundant axes. The constrained optimization method and pseudo inverse method have been adopted for control allocation. Simulation examples and real test results have been presented to verify the Proposed methods.

• 한국항공우주학회지
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• 제37권6호
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• pp.595-601
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• 2009

높은 신뢰도를 요구하는 비행제어 시스템은 복잡한 중복구조로 구성된다. 이러한 중복 구조는 시스템의 내고장성(fault tolerant)을 향상시킬 수 있다. 따라서 시스템 설계자는 다양하게 구성될 수 있는 중복구조의 정량적 데이터를 바탕으로 적절한 구조를 선택할 수 있다. 본 논문에서는 중복구조의 특징을 분석하고 신뢰도 해석을 위해 필요한 수학적 모델을 정의하였다. 이렇게 정의된 해석 모델을 적용하여 Simulink 블록 기반의 Reliability Block Diagram 해석 도구를 구성하고, 상용으로 사용되고 있는 도구를 이용하여 분석도구의 타당성을 검증하였다.

• Structural Engineering and Mechanics
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• 제63권6호
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• pp.799-808
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• 2017

Failure of a redundant long-span bridge is often described by innumerable failure modes, which make the structural system reliability analysis become a computationally intractable work. In this paper, an innovative procedure is proposed to efficiently identify the dominant failure modes and quantify the structural reliability for a long-span bridge system. The procedure is programmed by ANSYS and MATLAB. Considering the correlation between failure paths, a new branch and bound operation criteria is applied to the traditional stage critical strength branch and bound algorithm. Computational effort can be saved by ignoring the redundant failure paths as early as possible. The reliability of dominant failure mode is computed by FORM, since the limit state function of failure mode can be expressed by the final stage critical strength. PNET method and FORM for system are suggested to be the suitable calculation method for the bridge system reliability. By applying the procedure to a CFST arch bridge, the proposed method is demonstrated suitable to the system reliability analysis for long-span bridge structure.