• 대한조선학회논문집
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• 제47권1호
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• pp.76-87
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• 2010

According to the new rules and regulations (New SOLAS), major safety critical systems are to be designed to be redundant, which is called 'Redundancy Design'. This paper was to quantitatively analyze the degree of influence of the redundancy design applied to major safety critical systems using IMO's FSA(formal Safety Assessment) method. For the purpose of this study, the diesel engine system, which is actually one of major safety critical systems, was dealt with FMEA, FTA and ETA technique. In addition, whether the redundancy was met or not was verified and the degree of safety, or redundancy, was represented in terms of reliability. In conclusion, the safety of propulsion systems is possibly assessed systematically by estimating the risk level in terms of frequency and fatality.

• 한국정보통신학회논문지
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• 제18권12호
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• pp.2864-2870
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• 2014

시스템 및 네트워크의 끊김 없는 안정적인 서비스를 위해 다양한 서비스 지원방안이 제안되었다. 대표적으로 복수의 서비스 시스템으로 안정적인 서비스를 지원하는 이중화가 있다. 다양한 이중화 시스템이 제안되었고 이러한 이중화 시스템은 서비스 지원 시스템의 개수에 따라 다양한 형태를 가진다. 본 논문에서는 복수의 이중화 시스템에 대하여 다양한 이중화 모델의 가용도를 분석하고자 한다. 가용도분석도구로는 복잡한 이중화 시스템을 비교적 간단히 분석 가능한 SRN기반의 SPNP를 이용한다. 본 논문은 다양한 이중화 모델을 설명하고 서비스 지원 시스템의 개수에 따른 이중화 모델의 가용도를 SPNP를 이용하여 비교 분석한다.

• 로봇학회논문지
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• 제3권4호
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• pp.338-344
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• 2008

Most omni-directional mobile robots have to change their trajectory for avoiding obstacles regardless of the size of the obstacles. However, an omni-directional mobile robot having kinematic redundancy can maintain the trajectory while the robot avoids small obstacles. This works deals with the kinematic modeling and motion planning of an omni-directional mobile robot with kinematic redundancy. This robot consists of three wheel mechanisms. Each wheel mechanism is modeled as having four joints, while only three joints are necessary for creating the omni-directional motion. Thus, each chain has one kinematic redundancy. Two types of wheel mechanisms are compared and its kinematic modeling is introduced. Finally, several motion planning algorithms using the kinematic redundancy are investigated. The usefulness of this robot is shown through experiment.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.3104-3110
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• 2011

This paper describes how to ensure safety of train by guaranteeing stable and continuous communication in RF-CBTC. CBTC System uses the wireless communication between onboard and wayside so that safety of wireless communication is the most important. Losing the position of train causes vital problem of train service. By losing the position of train, the other trains are blocked in the block and the train move by emergency mode so headway and safety cannot guaranteed. Therefore, safety is ensured by redundancy of wireless equipment. One of the ways to make redundancy is redundancy of equipment. However, the redundancy of equipment spends a lot of money to avoid interference in limited place like underground. Continuous communication is guaranteed by means of redundancy of wireless communication coverage to solve the problems even though one of the equipment is broken.

• 로봇학회논문지
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• 제6권4호
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• pp.308-316
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• 2011

This work deals with development of effective redundancy resolution algorithms for the motion control of manipulator. Differently from the typical kinematically redundant robots that are attached to the fixed ground, the ZMP condition should be taken into account in the manipulator motion in order to guarantee the system stability. In this paper, a new motion planning algorithm for redundant manipulator not fixed to the ground is introduced. A sequential redundancy resolution algorithm is proposed, which ensures the ZMP (Zero Moment Point) stability, the planned operational motion, and additional sub-criteria such as joint limit index. A geometric constraint equation derived by reshaping the existing ZMP equation enables one to employ the sequential redundancy algorithm. The feasibility of the proposed algorithm is verified by simulating a redundant manipulator model.

• 한국정보컨버전스학회:학술대회논문집
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• 한국정보컨버전스학회 2008년도 International conference on information convergence
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• pp.157-160
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• 2008

The pursuit of efficiency is taken for granted in today's public administration, and the limit of this study exists in the point that we should carefully deal with combining the redundancy scheme to the public administration. Accordingly, although this study should suggest the specific plans and backgrounds of the needs for the redundancy, it will only find out the applicability of the redundancy to the public administration for its purpose. Redundancy means the excess or superfluity in something, which means the surplusage status ranging from the wasteful and excessive supplies, insignificant additions, to the surplusage in a legal pleading. The emphasis of this study is placed on the changes in the rigidity in believing that the removal of the redundancy from the public administration is the best option in any case of the efficiency. In addition, the necessity of the overlapped organization should not be neglected by the concept of the efficiency. Indeed, it is necessary to correct the overlapped function of superfluity and ambiguity public administration, in order to remove the neglect conflicts between the organizations, to guarantee the inconsistency in the public administration and to ensure the efficiency in the public administration volunteering.

• 한국신뢰성학회지:신뢰성응용연구
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• 제1권1호
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• pp.1-8
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• 2001

Redundancy allocation problems have been considered at single-level systems and it may be the best policy in some specific situations, but not in general. With regards to reliability, it is most effective to allocate the lowest objects, because parallel-series systems are more reliable than series-parallel systems. However, the smaller and lower in the system an object is, the more time and accuracy are needed for duplicating it, and so, the cost can be decreased by using modular redundancy Therefore, providing redundancy at high levels like as modules or subsystems, can be more economical than providing redundancy at low levels or duplicating components. In this paper, the problem in which redundancy is allocated at all level in a series system is addressed, a mixed integer nonlinear programming model is presented and a genetic algorithm is proposed. An example illustrates the procedure.

• Structural Engineering and Mechanics
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• 제59권5호
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• pp.821-840
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• 2016

A simple design process is proposed for supplemental viscous dampers based on structural safety redundancy. In this process, the safety redundancy of the primary structure without a damper is assessed by the capacity and response spectra. The required damping ratio that should be provided by the supplemental dampers is estimated by taking the structural safety redundancy as a design target. The arrangement of dampers is determined according to the drift distribution obtained by performing pushover analysis. A benchmark model is used to illustrate and verify the validity of this design process. The results show that the structural safety redundancy of the structure provided by the viscous dampers increases to approximately twice that of the structure without a damper and is close to the design target. Compared with the existing design methods, the proposed process can estimate the elastic-plastic response of a structure more easily by using static calculation, and determine the required damping ratio more directly without iterative calculation or graphical process. It can be concluded that the proposed process is simple and effective.

• Computational Structural Engineering : An International Journal
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• 제1권2호
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• pp.137-137
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• 2001

The reliability/redundancy of structural system has become a serious concern among engineers and researchers after structural failures in Northridge and Kobe earthquakes. The reliability/redundancy factor, ρ, in current codes considers only member force and floor area and has received much criticism from dissatisfied engineers. Within a reliability framework. the redundancy is investigated for dual systems of primary shear walls and secondary moment frames and steel moment frame systems. Probabilistic performance analyses are carried out baled on nonlinear responses under SAC ground motion. The effects of structural configuration, ductilily capacity, 3-D motion, and uncertainty of demand verses capacity are investigated. Important redundancy-contributing factors are identified and a uniform-risk redundancy factor is developed for design. The result are compared with the p factor and its inconsistency is pointed out.

• 한국항공우주학회지
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• 제32권10호
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• pp.46-52
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• 2004

본 논문은 2중으로 다중화된 무인 비행체의 다중화 관리 설계 방법에 대하여 논의한다. CCM(Cross Channel Monitor) 기법의 두 주요 인자, 즉 두 채널간의 편차 허용한도인 문 턱값(threshold) 및 지속시간(persistence count)을 어떻게 설계하여야 하는 가에 관한 문제를 통계학적인 해석을 사용하여 그 해결법을 제시하였다. 또한, 무인 비행체의 생존확률을 증대시킬 수 있는 해석적 다중화 가법에 대한 문제를 칼만 필터링 (Kalman filtering)을 적용하여 접근하였다. 여기서 제시된 방법으로 설계된 CCM 및 칼만 필터링을 이용한 해석적 다중화의 설계 결과들은 XV-15 틸트 로터 비행체에 적용되어, 그 설계의 타당성이 시뮬레이션을 통하여 검증되었다.