• Korean Management Science Review
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• v.29 no.1
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• pp.1-14
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• 2012

The goal of the multi-reservoir operation planning is to provide an optimal release plan that maximize the reservoir storage and hydropower generation while minimizing the spillages. However, the reservoir operation is difficult due to the uncertainty associated with inflows. In order to consider the uncertain inflows in the reservoir operating problem, we present a Stochastic Dynamic Programming (SDP) model based on the markov decision process (MDP). The objective of the model is to maximize the expected value of the system performance that is the weighted sum of all expected objective values. With the SDP model, multi-reservoir operating rule can be derived, and it also generates the steady state probabilities of reservoir storage and inflow as output. We applied the model to the Geum-river basin in Korea and could generate a multi-reservoir monthly operating plan that can consider the uncertainty of inflow.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.32 no.3
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• pp.71-77
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• 2009

Using the results of the expected busy periods for the dyadic Min(N, D) and Max(N, D) operating policies in a controllable M/G/1 queueing model, an important relation between them is derived. The derived relation represents the complementary property between two operating policies. This implies that it could be possible to obtained desired system characteristics for one of the two operating policies from the corresponding known system characteristics for the other policy. Then, upper and lower bounds of expected busy periods for both dyadic operating policies are also derived.

• Journal of the Korea Safety Management & Science
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• v.23 no.4
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• pp.105-112
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• 2021

This paper presents a periodic replacement policy for a system subject to shocks when the system is operating for a finite random horizon. The system is subject to shocks during operation, and each shock causes downgrading of the system performance and makes it more expensive to run by the additional running cost. Shocks arrive according to a nonhomogeneous or a renewal process, and we develop periodic replacement policies under a finite random operating horizon. The optimum periodic replacement interval which minimizes the total operating cost during the horizon is found. Numerical examples are presented to demonstrate the results.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.2097-2100
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• 2003

Many studies have been done on secure operating system using secure kernel that has various access control policies for system security. Secure kernel can protect user or system data from unauthorized and/or illegal accesses by applying various access control policies like DAC(Discretionary Access Control), MAC(Mandatory Access Control), RBAC(Role Based Access Control), and so on. But, even if secure operating system is running under various access control policies, network traffic among these secure operating systems can be captured and exposed easily by network monitoring tools like packet sniffer if there is no protection policy for network traffic among secure operating systems. For this reason, protection for data within network traffic is as important as protection for data within local system. In this paper, we propose a secure operating system trusted channel, SOSTC, as a prototype of a simple secure network protocol that can protect network traffic among secure operating systems and can transfer security information of the subject. It is significant that SOSTC can be used to extend a security range of secure operating system to the network environment.

• Food Science and Industry
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• v.53 no.3
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• pp.307-315
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• 2020

The food R&D operating system needs to be changed according to the changes in the food industry as well as the domestic and overseas environments. In this aspect, a future-oriented food R&D operating strategy linked with the governmental policy are proposed to foster the promising food industry. The strategic R&D approaches are summarized on the basis of global mega-trends and food industry trend analysis, and current R&D status and issues are also reviewed to set the R&D operating direction for future food industry. To advance the R&D operating system of the food industry, some practical suggestions are given as follows: strengthening the research planning system for efficient R&D program operation, enhancing the role assignment and collaboration among the R&D organizations, reinforcing the support system tailored to industrial sites and securing the future technology bases as well as resolving present issues, and linking R&D programs with policies and improving the food R&D management system.

• Journal of the Korean Institute of Telematics and Electronics
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• v.27 no.4
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• pp.571-579
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• 1990

A dynamic relocation algorithm for non-deterministic process graph in distributed computer systems is proposed. A method is represented for determining the optimal policy for processing a process tree. A general database query request is modelled by a process tree which represent a set of subprocesses together with their precedence relationship. The process allocation model is based on operating cost which is a function fo selection of site for processing operation, data reduction function and file size. By using expected values of parameters for non-deterministic process tree, the process graph and optimal policy that yield minimum operating cost are determined. As process is relocated according to threshold value and new information of parameters after the execution of low level process for non-deterministic process graph, the assigned state that approximate to optiaml solution is obtained. The proposed algorihtm is heuristic By performing algorithm for sample problems, it is shown that the proposed algorithm is good in obtaining optimal solution.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.14 no.24
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• pp.7-13
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• 1991

Recently, in FMS composing of various automatic equipments, the machines with lower operating costs, and with higher operating costs and replacement costs resulting from deterioration have been appearing successively as a result of rapidly advances in technology. "Control Limit Policy" [1] by using Markov decision policy, a kind of optimal economic replacement decision, well reflects and represents this environment. In this paper, it is reviewed that the decision method of the forecasted replacement alternatives in planning horizon under technological advances is derived. The proposed method is applied to a numerical example and some characteristics are examined by sensitivity. It is clarified that the method is relatively insensitive to changes of parameters at the present decision. decision.

• Journal of Appropriate Technology
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• v.7 no.2
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• pp.172-187
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• 2021

In remote villages without access to modern IT technology, simple devices such as smartcards can be used to carry out business transactions. These devices typically store multiple business applications from multiple vendors. Although devices must prevent malicious or accidental security breaches among the applications, a secure communication channel between two applications from different vendors is often required. In this paper, first, we propose a method of establishing secure communication channels between applications in embedded operating systems that run on multi-applet smart cards. Second, we enforce the high assurance using an intransitive noninterference security policy. Thirdly, we formalize the method through the Z language and create the formal specification of the proposed secure system. Finally, we verify its correctness using Rushby's unwinding theorem.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2020.11a
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• pp.151-152
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• 2020

There is a possibility of failure as a result of field application in the planning and execution process to change the operating policy for operating terminals, so a lot of time and effort are required to reduce trial and error. In the planning stage to change the terminal operation policy, simulation technology can be used to support decision making. This study introduces a case of using a virtual terminal system among simulation technologies.

• Informatization Policy
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• v.23 no.1
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• pp.38-55
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• 2016

This study discusses the operating systems upgrade to motivation of windows users. To discuss this issues, research hypotheses were set based on Unified Theory of Acceptance Use of Technology(UTAUT) and Theory of Reasoned Action(TRA). The data were collected from undergraduate students. Total of 199 data were used for the analysis. The results of the analysis were summarized into two ways. first, performance expectancy and effort expectancy has a positive influence on attitude towards upgrade the operating systems. Second, social influence, facilitating conditions, and attitude had a positive influence on intention towards upgrade the operating systems. Thus, when users perceived a high degree of performance expectancy, effort expectancy, social influence, and facilitating conditions towards upgrade the operating systems, they evaluated more positively the upgrade the operating systems.