• Structural Engineering and Mechanics
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• 제7권6호
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• pp.575-588
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• 1999

A boundary element method is applied to the analysis of crack trajectory in materials with complex microstructure, such as discontinuously reinforced composite materials, and systems subjected to complex loading, such as indentation. The path followed by the crack(s) has non-trivial geometry. A study of the stress intensity factors and fracture toughness of such systems must therefore be accompanied by an analysis of crack trajectory. The simulation is achieved using a dual boundary integral method in planar problems, and a single boundary integral method coupled with substructuring in axisymmetric problems. The direction of crack propagation is determined using the maximum mechanical energy release rate criterion. The method is demonstrated by application to (i) a composite material composed of components having the elastic properties of aluminium (matrix) and silicon carbide (reinforcement), and (ii) analysis of contact damage induced by the action of an indenter on brittle materials. The chief advantage of the method is the ease with which problems having complex geometry or loading (giving rise to complex crack trajectories) can be treated.

• 시스템엔지니어링학술지
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• 제11권1호
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• pp.33-39
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• 2015

This paper describes a development of aircraft carrier aviation support system architecture using DoDAF. The aircraft carrier, a warship performing a role of mobile sea air base in offensive and defense mission, is super system that is comprised of carrier itself and carrier-based airwing. Performing critical role in step with aviation operations in carrier-airwing interactions, the aviation support system of aircraft carrier is also system of systems. It requires a complex and integrated approach based on systems engineering in establishing concept of this complex systems. In this view, this study establishes an operational scenario and derives operational requirements by identifying aviation operations environment on deck of aircraft carrier. The study presents the operational architecture of the carrier aviation support system by using DoDAF and CASE tool CORE.

• 시스템엔지니어링학술지
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• 제10권2호
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• pp.81-87
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• 2014

The Korea space launch vehicle-II (KSLV-II) program aims at developing a national launch vehicle system capable of launching 1.5 ton satellite into a sunsynchronous orbit. It is the succeeding program to the Naro launch vehicle program. The KSLV-II is a large-scale complex system which requires a systematic approach to all parts of the program. The KSLV-II program is currently developing a tailored systems engineering process for its need. It references practices and lessons learned from developing Naro launch vehicle. Standardized NASA processes and INCOSE processes were also referenced and compared during development of the process framework. This paper introduces the systems engineering processes developed for the KSLV-II program.

• 제어로봇시스템학회논문지
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• 제15권8호
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• pp.804-811
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• 2009

This paper deals with the relationship between zeros and step response of the second and third order LTI(Linear Time Invariant) SISO(Single-Input and Single-Output) systems. As well known, if a system has a single unstable zero, it shows the step response with undershoot and, on the other hand, a stable zero slower than the dominant pole causes the system to have the step response with overshoot. Generally, in the case of a system with two unstable real zeros, it is known to have B type undershoot[7]. But there are many complex cases of the step response extrema corresponding to zeros location in third order systems. This paper investigates the whole cases depending on DC gains of the additive equivalence systems and they are to be classified by the region of zeros which are related to the shape of the step response. Moreover, monotone nondecreasing conditions are proposed in the case of complex conjugate zeros as well as the case of two stable zeros.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회/대한산업공학회 2003년도 춘계공동학술대회
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• pp.808-813
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• 2003

Maintaining agility and responsiveness m designing and manufacturing activities are the key issues for manufacturing companies to cope with global competition. Distributed design and control systems are regarded as an efficient solution for agility and responsiveness. However, distributed nature of a manufacturing system complicates production activities such as design, simulation, scheduling, and execution control. Especially, existing simulation systems have limited external integration capabilities, which make it difficult to implement complex control mechanisms for the distributed manufacturing systems. Moreover, integration and coupling of heterogeneous components and models are commonly required for the simulation of complex distributed systems. In this paper, a collaborative and adaptive simulation architecture is proposed as an open framework for simulation and analysis of the distributed manufacturing enterprises. By incorporating agents with their distributed characteristics of autonomy, intelligence, and goal-driven behavior, the proposed agent-based simulation architecture can be easily adapted to support the agile and distributed manufacturing systems. The architecture supports the coordination and cooperation relations, and provides a communication middleware among the participants in simulation.

• International Journal of Automotive Technology
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• 제3권2호
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• pp.79-88
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• 2002

Emergent Collision Avoidance Systems (CAS's) are beginning to assist drivers by performing specific tasks and extending the limits of driver's perception. As CAS's evolve from simple systems handling discrete tasks to complex systems managing interrelated driving tasks, the risk of failure from hidden causes greatly increases. The successful implementation of such a complex system depends upon a robust software architecture. Host of the difficulty in implementing system arises from interconnections between the components. The CAS architecture presented in this paper focuses on these interconnections to mitigate this problem. Moreover, by constructing the GAS architecture through the composition of existing architectural styles, the resulting system will exhibit predictable qualities. Some of the qualities represent limitations that translate into constraints on the system. Others are beneficial aspects that satisfy stakeholder requirements .

• 대한전기학회논문지:전력기술부문A
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• 제54권5호
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• pp.205-211
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• 2005

Recently, power system is getting larger and more complex. When the complex power system has a problem, it is very difficult even for the experts to find out where the problem is and to make a timely decision by operators. There have been many studies on these problems but the results are not good enough for applying to real power system. Therefore, power system operators always had to judge the exact state of power system and be preparative for the problems that can occur later. We developed new methods that can be applied to complex power system by dividing the system into small modules. By using 'module', we can combine small modules together to make complex power systems and the knowledge base that is applied to fault diagnosis system. As a result, compared to previously developed diagnosis products, operation time is shortened and the knowledge base is become simpler and clearer, which made online usage capable. This system can be used as a complementary measurement that helps the operator from making any mistakes.

• 대한안전경영과학회지
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• 제15권4호
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• pp.37-47
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• 2013

Due to the evolution of war fields to the net-centric one, weapon systems have become very complex in terms of both mission capability and implementation scales. In particular, the net-centric war field is characterized by a set of interconnected and independently operable weapon systems. As such, the individual weapon systems are required to meet the interoperability and thus, assuring it has been becoming more crucial even in the early stage of development. Furthermore, the ever-growing complexity of the weapon systems has attracted a great deal of attention on the safety issues in the operation and development of weapon systems. The objective of the study is on how to assure the interoperability for safety-critical weapon systems while maintaining system complexity. To do so, the approach taken in the paper is to consider the interoperability from the early stage of the development. Specifically, the required functions to satisfy the interoperability are developed first. The functions are then analyzed in order to link the safety requirements to the reliability evaluation, which results in the study of quantifying the effects of the safety requirements on the system as a whole. As a result, we have developed a methodology and procedure on how to assure interoperability while applying the safety requirements in the weapon systems development.

• BMB Reports
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• 제30권5호
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• pp.362-369
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• 1997

Multiple phosphorylation of the carboxy-terminal domain (CTD) of the largest subunit in RNA polymerase II (RNAP II) is thought to play an important role in the transcription cycle. The preinitiation complex in a partially purified complete transcription system suggested that RNA polymerase IIA containing unphosphorylated CTD is involved in complex assembly, whereas RNA polymerase IIO containing Ser and Thr phosphorylated CTD is not involved in preinitiation complex assembly. Recently a minimal transcription system was developed which requires chemically defined minimal components for its transcription: TBP, TFIIB, TFIIF, RNAP II and a supercoiled adenovirus-2 major late promoter (Ad-2 MLP). It would be using interesting to determine the consequence of CTD phosphorylation on preinitiation complex formation using the minimal transcription system. Contrary to the results from the partially purified complete transcription system, both RNA polymerase IIA and IIO are equally recruited in the preinitiation complex formation. The discrepancy may result from the two different assays used to determine complex formation, the use of chemically undefined complete and defined minimal transcription systems. This implicates that some factors in the complete transcription system are involved in the distinction between RNAP IIA and IIO in complex assembly. In addition multiple tyrosine phosphorylation of the CTD of RNAP II was prepared with c-Abl kinase and its recruiting ability in the preinitiation complex was examined. Compare with Ser and Thr phosphorylated RNAP IIO, Tyr phosphorylated RNAP IlOy forms a stable preinitiation complex in both the minimal and complete transcription systems. Based on these results, it seems that tyrosine phosphorylation of the CTD is important in the transcription cycle on the special subset of class-II promoter or has a different role in the transcription process.

• 대한안전경영과학회지
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• 제14권3호
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• pp.1-10
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• 2012

Recently, we have witnessed the definitely negative impacts of large-scale accidents happened in such areas as atomic power plants and high-speed train systems, which result in increased fear for the potential danger. The problems appear to arise due to the deficiency in the design of large-scale complex systems. One of the causes can be attributed to the design process that does not fully reflect the safety requirements in the early stage of the system development because of the substantially increased complexity. In this paper, to enhance the systems safety an integrated process is studied, which considers simultaneously both the system design process and system safety process from the beginning of the system development. In the conceptual system design phase an integrated process model is constructed by analyzing the activities of both the system design and safety processes. As a case study example, an inner city train system is described with the application of the developed process. The computer simulation of the example case is followed by the result discussed. The results obtained in the paper are expected to be the basis for the future study where a detailed process and its associated activities can be developed.