• 한국인터넷방송통신학회논문지
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• 제10권6호
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• pp.215-223
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• 2010

새로운 정보기술의 발전으로 인해 정보 접근과 획득 방식이 훨씬 다양하고 용이해지고 있는 반면 다양하고 성능 좋은 도구를 이용한 불법적인 접근이 가능하도록 하는 부작용이 초래되고 있다. 이러한 위협에 대응하는 데이터베이스 기술로는 접근제어가 있고 현재 새로운 컴퓨팅 환경에 대응하기 위해 전통적인 접근제어를 확장한 다양한 연구들이 수행되고 있다. 본 연구에서는 상황정보의 시멘틱 정보를 기반으로 보안정책에 의해 명시된 상황제약조건이 질의에 수반되는 상황제약조건의 구문과 일치하지 않는 경우에도 적절한 보안정책 집행이 가능하도록 하는 접근제어 방식을 제안한다. 상황에 대한 의미적 정책집행을 위해 시멘틱 트리계층구조 상에서 이들 간의 의미적 함의관계를 이용하고 함의관계에 의해 초래될 수 있는 과도한 권한부여를 방지하기 위해 의미 차를 정량적으로 측정할 수 있는 인수를 정의하여 설정된 시스템 정의 임계치 범위 내에서만 의미적 함의에 의한 권한부여가 이루어지도록 한다.

• 제어로봇시스템학회논문지
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• 제7권10호
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• pp.799-805
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• 2001

In this paper, we propose eigenstructure assigned sliding mode control for mismatched uncertain system. Variable structure control has the sliding mode in which the system is robust against the uncertainty and the sliding motion depends upon the sliding surface. Therefore, the surface design is one of the important problems. Also in mismatched cases, the uncertainty may affect on the sliding motion and may cause unexpected instability of the system. Thus, that should be considered, too. For robust sliding mode against the mismatched uncertainty, we suggest the design method of the sliding surface using the eigenstructure assignment, define an index as the measure of the robustness which shows the size of affordable unstructured uncertainty, and present the computation method. And also we propose the controller which can ensure the sliding mode and prove the robust stability of the proposed controller by using Lyapunov method. Finally we show the appropriateness of the proposed scheme for the mismatched uncertainty via the example.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1991년도 하계학술대회 논문집
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• pp.670-677
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• 1991

All models of dynamical systems invariably have some measure of uncertainties associated with some of their dynamics. The recent approaches to establish robustness of stabilizing feedback control against the possible uncertainties have a serious limitation, that is, their applicability only to the systems that satisfy the matching conditions. Such conditions are rarely met in general applications. If a particular system satisfies the matching conditions, the addition of an actuator will destroy the satisfaction of such conditions. In this paper, we develop robust control algorithm for uncertain multivariable systems in which the matching conditions are not necessarily met. In order to eliminate an influence over partial state variables due to unknown constant disturbances we perform the appropriate block-decomposition for a given system. Functional observers are introduced to estimate the unknown constant disturbances. The sliding mode controller is designed in such a way that the partial state variables in the state-space are directed towards switching surfaces and regulated to the origin asymptotically. Numerical examples are discussed as illustrations.

• 전자공학회논문지SC
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• 제39권5호
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• pp.8-17
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• 2002

본 논문에서는, 섭동과 제어기 이득 섭동을 갖는 이산 대규모 시간지연 시스템의 강인 비약성 제어기 설계에 관하여 논한다. 리아프보프 해석법을 의거하여 선형행렬 부등식으로 표현되는 주어진 시스템의 강인 안정화를 꾀하는 상태 궤환 제어기의 존재를 보장하는 조건 식을 구한다. 이 조건 식의 해로부터 각 부 시스템에서의 제어기의 이득 및 제어기의 비약성 지수도 얻을 수 있다. 제시된 선형행렬 부등식은 잘 알려진 최적화 기법으로 쉽게 풀 수 있으며, 예제를 통하여 제어기 설계 방법을 보인다.

• Nuclear Engineering and Technology
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• 제50권6호
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• pp.829-841
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• 2018

An experiment was conducted for the OECD/NEA ROSA-2 Project using the large-scale test facility (LSTF), which simulated a 17% hot leg intermediate-break loss-of-coolant accident in a pressurized water reactor (PWR). In the LSTF test, core uncovery started simultaneously with liquid level drop in crossover leg downflow-side before loop seal clearing, and water remaining occurred on the upper core plate in the upper plenum. Results of the uncertainty analysis with RELAP5/MOD3.3 code clarified the influences of the combination of multiple uncertain parameters on peak cladding temperature within the defined uncertain ranges. For studying the scaling problems to extrapolate thermal-hydraulic phenomena observed in scaled-down facilities, an experiment was performed for the OECD/NEA PKL-3 Project with the Primarkreislaufe Versuchsanlage (PKL), as a counterpart to a previous LSTF test. The LSTF test simulated a PWR 1% hot leg small-break loss-of-coolant accident with steam generator secondary-side depressurization as an accident management measure and nitrogen gas inflow. Some discrepancies appeared between the LSTF and PKL test results for the primary pressure, the core collapsed liquid level, and the cladding surface temperature probably due to effects of differences between the LSTF and the PKL in configuration, geometry, and volumetric size.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 2003년도 ISIS 2003
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• pp.28-31
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• 2003

In the present work, a main purpose is to propose a fuzzy integral-based aggregation framework to complementarily combine partial information due to lack of completeness. Based on Choquet integral (CI) viewed as monotone expectation, we take into account complementary, non-interactive, and substitutive aggregations of different sources of defective information. A CI-based system representing upper, conventional, and lower expectations is designed far handling three aggregation attitudes towards uncertain information. In particular, based on Choquet integrals for belief measure, probability measure, and plausibility measure, CI$\_$bi/-, CI$\_$pr/ and CI$\_$pl/-aggregator are constructed, respectively. To illustrate a validity of proposed aggregation framework, multiple matching systems are developed by combining three simple individual template-matching systems and tested under various image variations. Finally, compared to individual matchers as well as other traditional multiple matchers in terms of an accuracy rate, it is shown that a proposed CI-aggregator system, {CI$\_$bl/-aggregator, CI$\_$pl/-aggregator, Cl$\_$pl/-aggregator}, is likely to offer a potential framework for either enhancing completeness or for resolving conflict or for reducing uncertainty of partial information.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제49권4호
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• pp.249-257
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• 2000

In this paper, we propose the use of stochastic finite element method, that is popularly employed in mechanical structure analysis, for more practical designing purpose of RF device. The proposed method is formulated based on the vector finite element method cooperated by pertubation analysis. The method utilizes sensitivity analysis algorithm with covariance matrix of the random variables that represent for uncertain physical quantities such as length or various electrical constants to compute the probabilities of the measure of performance of the structure. For this computation one need to know the variance and covariance of the random variables that might be determined by practical experiences. The presenting algorithm has been verified by analyzing several device with different be determined by practical experiences. The presenting algorithm has been verified by analysis several device with different measure of performanes. For the convenience of formulation, two dimensional analysis has been performed to apply it into waveguide with dielectric slab. In the problem the dielectric constant of the dielectric slab is considered as random variable. Another example is matched waveguide and cavity problem. In the problem, the dimension of them are assumed to be as random variables and the expectations and variances of quality factor have been computed.

• 한국생산제조학회지
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• 제19권5호
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• pp.637-644
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• 2010

This paper presents a reliability-based shape optimization (RBSO) using the growth-strain method. An actual design involves uncertain conditions such as material property, operational load, Poisson's ratio and dimensional variation. The purpose of the RBSO is to consider the variations of probabilistic constraint and performances caused by uncertainties. In this study, the growth-strain method was applied to shape optimization of reliability analysis. Even though many papers for reliability-based shape optimization in mathematical programming method and ESO (Evolutionary Structural Optimization) were published, the paper for the reliability-based shape optimization using the growth-strain method has not been applied yet. Growth-strain method is applied to performance measure approach (PMA), which has probabilistic constraints that are formulated in terms of the reliability index, is adopted to evaluate the probabilistic constraints in the change of average mises stress. Numerical examples are presented to compare the DO with the RBSO. The results of design example show that the RBSO model is more reliable than deterministic optimization. It was verified that the reliability-based shape optimization using growth-strain method are very effective for general structure. The purpose of this study is to improve structure's safety considering probabilistic variable.

• 생물정신의학
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• 제21권3호
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• pp.87-92
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• 2014

Objectives Risk taking has been implicated in the development of various psychiatric disorders. Previous studies have indicated that risk taking behavior is associated with high levels of impulsiveness. Risk taking entail uncertain situation that outcome probability is unknown. This study tested impulsivity, intolerance of uncertainty and risk taking behavior. Methods A total of 73 participants completed a test battery comprised of the UPPS-P scale as a psychometric measurement of five dimensions of impulsivity, Intolerance of Uncertainty Scale, and Balloon Analog Risk Task (BART) as a behavioral measure of risk taking. The Pearson correlation analysis was used. Results The sensation seeking factor was positively correlated with BART measure (r = 0.27, p = 0.02). Specifically, the relationship between sensation seeking and BART was significant in females. Conclusions Among the five factors of UPPS-P, only the sensation seeking factor predicts risk taking propensity.

• 한국건설관리학회논문집
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• 제14권4호
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• pp.15-23
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• 2013

건설프로젝트는 현장여건의 변화와 불확실성으로 신뢰성 높은 계획을 수립하기 힘들고 따라서 건축시공시뮬레이션 시스템의 도입으로 그러한 문제점을 해결하고 신뢰성 높은 계획을 수립하려는 노력을 보이고 있다. 그러나 현시점의 시뮬레이션 시스템은 단순 애니메이션 용도로만 사용되고 실제 엔지니어링 업무를 지원하는 경우도 드물다. 최근 들어 이러한 한계점을 탈피하고 보다 시뮬레이션 시스템을 보다 적극적으로 사용하기 위한 연구와 개발이 이루어지고 있다. 하지만 BIM의 가장 핵심이 업무 효율성이라는 점에서 이러한 BIM기반 건축시공시뮬레이션시스템 등의 BIM기반 시스템은 성능 분석이 매우 필요한 요소라고 판단된다. 본 연구에서는 이를 위하여 시뮬레이션의 핵심 업무 프로세스를 정의하고 표준 시나리오를 정의하여 이를 기준으로 성능을 분석하는 방법론을 제시함으로써 좀 더 효율적이고 적극성을 갖춘 시뮬레이션 시스템 개발을 가능하게 하고자 한다.