• The Journal of Korean Association of Computer Education
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• v.7 no.6
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• pp.129-139
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• 2004

In developing highly reliable systems such as C4I systems formal methods provide both developers and clients with assurance that they are in the right development processes. This paper investigates into techniques for formal specifications and tests for software components where rigorous verification is required. In particular, the paper suggests decomposition techniques for state-model based specifications using the weakest precondition, and suggests test methods for the specification by generating black box test-cases.

• Nuclear Engineering and Technology
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• v.54 no.5
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• pp.1635-1643
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• 2022

STPA (System-Theoretic Process Analysis) is a widely used safety analysis technique to identify UCAs (Unsafe Control Actions) resulting in potential losses. It is totally dependent on the experience and ability of analysts to construct an information model called Control Structures, upon which analysts try to identify unsafe controls between system components. This paper proposes a formal approach to support the manual identification of UCAs, effectively and systematically. It allows analysts to mechanically extract Process Model, an important element that makes up the Control Structures, from a formal requirements specification for a software controller. It then concisely constructs the contents of Context Tables, from which analysts can identify all relevant UCAs effectively, using a software fault tree analysis technique. The case study with a preliminary version of a Korean nuclear reactor protections system shows the proposed approach's effectiveness and applicability.

• Journal of KIISE:Software and Applications
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• v.33 no.12
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• pp.1008-1021
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• 2006

Product line engineering(PLE) is one of the recent and effective reuse approaches that enables developing a number of applications by instantiating a core asset. Elements of a core asset are product line architecture(PLA), component, and decision model. Among these elements, PLA is the key element since it defines the overall structure of the core asset. Although numerous PLE methodologies have been introduced, it is still unclear what should be the elements of a PLA and how to systematically instantiate it for specific applications. Formal specifications can play a key role in defining detailed and precise instantiation process. In this paper, we first present a meta model of PLA and show how to specify PLA in a formal language, Object-Z. Then, we propose instantiation rules using formal specification and those rules precisely define constraints for instantiating PLA. By applying the proposed formal specification, we believe PLA instantiation can be carried out precisely and correctly, yielding high quality software development.

• Journal of Distribution Science
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• v.16 no.3
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• pp.23-32
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• 2018

Purpose - This study aims to investigate whether the buyer's participation in CSR activities can affect the informal cooperation and relationship beyond formal cooperation and relationship. Research design, data, and methodology - We defined the research model and selected variables(monitoring and contracts by the buyer, formal cooperation & relationship, and informal cooperation & relationship). After completing the questionnaire, we analyzed 319 manufacturing companies. Prior to the hypothesis testing, Exploratory factor analysis(EFA) and confirmatory factor analysis(CFA) were conducted to check for discriminant validity and convergent validity. Results - The stronger the buyer monitoring on the company's CSR activities, the more positive it affects the formal business cooperation. On the other hand, strong buyer monitoring did not affect formal business relationships. Therefore, even if buyers' monitoring of CSR activities is strong, it does not mean that the formal business relationship is improved, but it means that it is possible to improve the formal business cooperation. Conclusions - This study shows that the stronger the buyer monitoring on the supplier's CSR activities, the more positive it affects formal cooperation. It also demonstrates that formal business cooperation between the supplier and the buyer, that is, sharing goals and works for CSR activities, has a positive effect on relationships based on emotional exchange and commitment.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.10
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• pp.2310-2316
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• 2010

This paper presents an application of retiming to model checking, a branch of formal verification. Retiming can change the transition relation of a circuit without changing its input-output behaviour by relocating its registers. With the retiming, a given circuit can have a different structure more adequate for model checking. This paper proposes a cost function to reflect the number of registers and the characteristic of its transition relation and develops a heuristic annealing algorithm to search efficiently the circuit structures obtained by retiming. Experimental results show that the proposed method can improve the model checking performance.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.8
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• pp.1435-1442
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• 2006

The ideal method of safety evaluation is to verify results of execution against all possible operations within operating system, but it is impossible. However, the formal method can theoretically prove the safety on actual logic of operating system. Therefore we explain the contents of the art of the safety verification of security kernel, and make a comparative study of various standardized formal verification tools. And then we assigned PVS(Prototype Verification system) of SRI(Stanford Research Institute) to verify the safety of a modified BLP(Bell & LaPadula) model, the core access control model of multi-lavel based security kernel. Finally, we describe formal specification of the revised BLP model using the PVS, and evaluate the safety of the model by inspecting the specification of the PVS.

• Journal of KIISE:Computing Practices and Letters
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• v.12 no.2
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• pp.141-148
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• 2006

This paper suggests method of safe security S/W by verifying and its result of formal verification tool. We will survey many formal verification tools and compare features of these tools. And we will suggest what tool is appropriate and methodogoly of developing safe security S/W. The Z/EVES is the most appropriate tool. This paper proposes formal verification of ACS by using RoZ tool which is formal verification tool to create UML model. The specification and verification are executed using Z/EVES tool. These procedures can find weak or wrong point of developed S/W.

• Journal of the Korean Society of Mechanical Technology
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• v.13 no.2
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• pp.21-29
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• 2011

This paper examines the applicability of formal safety assessment to the passenger ships. This is followed by an analysis of passenger ship characteristics and a proposed formal safety assessment methodology. Five interlocking steps are described to construct a safety model including novel risk assessment, cost-benefit analysis and decision-making approaches. A case study is carried out in order to demonstrate the proposed methodology. Further development in formal safety assessment in the context of passenger ship safety is finally discussed in detail.

• Journal of Digital Convergence
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• v.11 no.6
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• pp.103-112
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• 2013

Traditional method of establishing prediction model is usually using formal data stored in Data Base. However, nowadays advent of "smart" era brought by ground-breaking development of communication system makes informal data to dominate overall data, such 80% in total. Therefore, conventional method using formal data as establishing predicting model would be untrustworthy means in present. In other words, it is indispensible to make prediction model credible including informal data(SNS, image, video) and semi-formal data(log data). In this study, we increase credibility of predicting model adapting Bigdata method and comparing reliability of conventional measurement to real-data.

• Journal of Internet Computing and Services
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• v.22 no.4
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• pp.13-28
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• 2021

Reinforcement Learning (RL) is a machine learning algorithm that repeat the closed-loop process that agents perform actions specified by the policy, the action is evaluated with a reward function, and the policy gets updated accordingly. The key benefit of RL is the ability to optimze the policy with action evaluation. Hence, it can effectively be applied to developing advanced intelligent systems and autonomous systems. Conventional RL incoporates a single policy, a reward function, and relatively simple policy update, and hence its utilization was limited. In this paper, we propose an extended RL model that considers multiple instances of RL elements. We define a formal model of the key elements and their computing model of the extended RL. Then, we propose design methods for applying to system development. As a case stud of applying the proposed formal model and the design methods, we present the design and implementation of an advanced car navigator system that guides multiple cars to reaching their destinations efficiently.