• Industrial Engineering and Management Systems
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• 제12권1호
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• pp.2-8
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• 2013

Uncertainty theory is a branch of mathematics based on normolity, duality, subadditivity and product axioms. Uncertain process is a sequence of uncertain variables indexed by time. Canonical Liu process is an uncertain process with stationary and independent increments. And the increments follow normal uncertainty distributions. Uncertain differential equation is a type of differential equation driven by the canonical Liu process. Stability analysis on uncertain differential equation is to investigate the qualitative properties, which is significant both in theory and application for uncertain differential equations. This paper aims to study stability properties of linear uncertain differential equations. First, the stability concepts are introduced. And then, several sufficient and necessary conditions of stability for linear uncertain differential equations are proposed. Besides, some examples are discussed.

• Industrial Engineering and Management Systems
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• 제15권2호
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• pp.143-147
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• 2016

Uncertainty appears not only in real quantities but also in complex quantities. Complex uncertain process is essentially a sequence of complex uncertain variables indexed by time. In order to describe complex uncertain process, a formal definition of complex uncertain distribution is given in this paper, as well as the concepts of independence and variance. In addition, some properties of complex uncertain integral are presented.

• Journal of the Korean Data and Information Science Society
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• 제8권1호
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• pp.1-7
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• 1997

전문가 시스템에서의 추론은 주로 IF-THEN 형태의 규칙을 기반으로 하는 지식베이스에 기초한다. 그러나, 한의 전문가 시스템의 지식은 불확실한 지식 특히 애매한 개념의 지식을 많이 포함하고 있으므로 이에 대한 처리가 요구된다. 본 논문에서는 한의 진단 과정을 추론에 기준하여 분석하고 한의 진단 과정에서 발생하는 불확실한 진단 지식을 제약 조건 논리 프로그래밍언어의 일종인 CLP( R ) 언어를 이용하여 표현하고 처리하는 방법을 제안하였다.

• Industrial Engineering and Management Systems
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• 제12권1호
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• pp.41-45
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• 2013

Age replacement policy is a commonly policy in maintenance management of spare part. It means that a spare part is always replaced at failure or fixed time after its installation, whichever occurs first. An optimal age replacement policy of spare parts concerns with finding the optimal replacement time determined by minimizing the expected cost per unit time. The age of the part was generally assumed to be a random variable in the past literatures, but in many situations, there are few or even no observed data to estimate the probability distribution of part's lifetime. In order to solve this phenomenon, a new uncertain age replacement policy has been proposed recently, in which the age of the part was assumed to be an uncertain variable. This paper discusses the optimal age replacement policies by dealing with the parts' lifetimes as different distributed uncertain variables. Several results on the optimal age replacement time are provided when the lifetimes are described by the uncertain linear, zigzag and lognormal distributions.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2002년도 ICCAS
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• pp.118.2-118
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• 2002

Uncertain time delay happens when the process reads the sensor data and sends the control input to the plant located at a remote site in distributed control system. As in the case of data network using TCP/IP, VDN that integrates both device network and data network has uncertain tim e delay. Uncertain time delay can cause degradation in stability of distributed control system based on VDN. This paper investigates the transmission characteristic of VDN and suggests a control scheme based on the Smith's predictor to minimize the effect of uncertain time delay. The validity of the proposed control scheme is demonstrated with tracking position control of experiments.

• International Journal of Computer Science & Network Security
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• 제24권10호
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• pp.147-153
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• 2024

The problem of handling uncertain data has been attracting the attention of researchers. This paper mainly focuses on uncertain data clustering and noise data streams. Therefore, we will provide a framework to realize the effect of uncertainty. Nowadays, a large number of tenders are present which measure the data roughly. As, sensors normally have distortion in their results cause of the imprecisions transmission in data and retrieval. Mostly these errors are identified. This information is used for minimizing process to advance results according to quality. In this paper, we compare general methods of monitor uncertainty, which have described in the different research papers.

• 한국경영과학회지
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• 제8권1호
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• pp.31-40
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• 1983

An uncertain dynamic evolving process has been a continuing challenge to decision problems. The dynamic random variable (drv) changes which characterize such a process are very important for the decision-maker in selecting a course of action in a world that is perceived as uncertain, complex, and dynamic. Using this subjective point prediction algorithm based on a modified recursive filter, the decision-maker becomes to have periodically changing plausible points with the passage of time.

• 한국정밀공학회지
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• 제15권2호
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• pp.75-80
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• 1998

Process information is known to have the continuous distribution in many manufacturing processes. Generalized p-chart has been developed for controlling processes by classifying the information characteristics into several groups. But it is improper to describe continuous processes with the classified process informal ion, which is based on the classical set concept. Fuzzy control chart, has been developed for the control of linguistic data, but it is also based on the dichotomous notion of classical set theory. In this paper, fuzzy sampling method is studied in order to process the uncertain data properly. The method is incorporated with the fuzzy control chart. Statistical characteristics of the fuzzy representative value are utilized to device the fuzzy-statistical control chart. The fuzzy-statistical control chart is compared with the generalized p-chart and both the sensitivity to the process information distribution change pared robustiness against the noise on the process information of the fuzzy-statistical control chart are shown to be superior.

• 대한산업공학회지
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• 제24권4호
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• pp.559-569
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• 1998

Cellular manufacturing system (CMS) has been recognized as an alternative to improve manufacturing productivity in conventional batch-type manufacturing systems through reducing set-up times, work-in-process inventories and throughput times by means of group technology. Most of the studies on the design of CMS assumed that each part has a unique process plan, and that its demand is known as a deterministic value despite of the probabilistic nature of the real world problems. This study suggests an approach for designing CMS, considering both alternative process plans and uncertain demand. A mathematical model is presented to show how to minimize the expected amortized and operating costs satisfying these two relaxations. Four heuristic algorithms are developed based on tabu search which is well suited for getting an optimal or near-optimal solution. Example problems are carried out to illustrate the heuristic algorithms and each of them is compared with the deterministic counterpart.

• 한국경영과학회지
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• 제25권2호
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• pp.23-31
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• 2000

Many studies in marketing and economics have attempted to model price and sales path under the dynamic diffusion process. Most of these models have been based on a fixed product lifetime. The current business climate requiring intensive development of new products however affects the diffusion of new products and their lifetime. Many products have not enjoyed the expected life cycle at the launching stage due to intense technical development competitive reactions, and financial problems. Most diffusion models however have not taken account of the lifetime uncertainty of new product. If the products do not last over the planning horizon set by those models. the optimal price derived from them could be futile. Therefore we had better take such lifetime uncertainty into consideration when developing diffusion models, In this paper we study the impact of uncertain product lifetime on its optimal pricing path in non-competitive market. We develop an optimal pricing model under uncertain product lifetimes and conduct a simulation study to investigate their effects on the optimal pricing and corresponding sales paths. The simulation study provides some interesting findings on optimal pricing policy under uncertain product lifetime. This study could be a stepping stone for the further extended study of optimal pricing strategy with uncertain product lifetime.