• Proceedings of the Korean Information Science Society Conference
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• 2005.11a
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• pp.934-936
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• 2005

실시간 시스템에서 스케줄링 가능성 여부는 매우 중요하다. 그래서 실시간 시스템이 주어진 시간적 제약 사항을 만족 시킬 수 있도록 스케줄러 등 많은 연구들이 진행되고 있다. 그런데 기존의 스케줄링 방식은 외부 환경이나, 태스크에 대한 정확한 정보를 요구한다. 하지만 이런 정보를 정확히 예측하는 것이 매우 힘들다. 그래서 이런 정보들에 따라 시스템의 성능이 저하 되거나, 아니면 오류를 야기 할 수 있다. 그래서 본 논문에서는 실시간 시스템의 이론에 제어 이론을 접목하여 시스템에 외부 환경에 대해 강인 하면서 높은 효율을 보일 수 있는 스케줄러를 설계하고 제시 한다.

• The KIPS Transactions:PartD
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• v.8D no.1
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• pp.62-70
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• 2001

Correct descriptions for software component functions become a strong requirement in developing critical software especially on the area of real-time applications. In this paper, we introduce both formalization of software design using patterns and verification methods in order for the components to increase their understandability. In particular, the paper investigates into a means of formal description techniques based on VDM++ for the software components, and provides adequacy proof steps for a given functional descriptions.

• Proceedings of the Korean Information Science Society Conference
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• 1999.10a
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• pp.563-565
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• 1999

실시간 시스템은 응용분야의 특성상 높은 신뢰성을 요구하므로 설계시 시스템의 정확성과 안전성을 보장하는 것은 매우 중요하다. 신뢰성 보장을 위한 방법으로 정형기법(formal method)을 이용한 명세 방법이 연구되어 왔다. 정형적인 명세를 사용하는 경우 원하는 시스템의 특성에 대한 검증이 가능하며 자연어로 명세한 경우보다 모호함이 줄어들어 의사소통을 하는데 있어서 명확성을 제공한다. 그러나 이런 장점에도 불구하고 객체 지향 개발 방법론에서의 정형적인 명세에 관한 연구가 미흡하다. 본 논문에서는 객체 지향적 모델을 기반으로 하는 실시간 시스템을 위한 정형명세 언어인 Timed State Chart(TSC)를 제안한다. TSC는 Statecharts와 같은 계층적 상태 기계 모델(state machine model)로서 다양한 시간 제약사항의 명세를 위해 클릭 변수(clock variable)를 도입하여 실시간 객체(Real-Time Object 또는 RTO)를 명세한다. TSC를 이용하여 기존의 연구에서 표현할 수 없었던 주가와 마감시간과 같은 실시간 시스템의 다양한 요구사항을 효과적으로 표현할 수 있다.

• Journal of KIISE:Software and Applications
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• v.29 no.12
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• pp.926-939
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• 2002

The formal specification methods with probability have been demanded in the area of fault real-time systems, in order to specify the uncertainty that the systems can encounter during their execution due to various environmental factors. This paper presents a new formal method with probability. namely Probabilistic Abstract Timed Machine (PATM), in order to analyze and predict system's behavior in dynamical environmental changes, This method classifies the factors into two classes: the variable and the constant. The analysis of system's behavior is performed on the probabilistic reachability graph generated from the ATM specification for the system. The analysis can predict any possibility that the behavior may not satisfy some safety requirements of the system, indicate which variable factors cause such satisfaction, and further recover from this unsatisfying fault state by fixing the variable factors. Consequently the reliability to the fault real-time systems can be improved.

• Journal of KIISE:Computing Practices and Letters
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• v.6 no.2
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• pp.161-172
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• 2000

In this paper, we introduce the development of a LOTOS-based tool, supporting formal methods, called ForTIA (A Formalism for Telecommunication and Information Systems). By using LOTOS, an ISO standard formal specification language, the user requirements and system models can be abstracted and represented formally. Therefore, the system can be validated and verified on the specifications, before implementations. ForTIA supports light-weight formal methods based on validation to be used in real industry. Key functions of ForTIA are simulation and C++ code generation. In simulation, tree based visual validation mechanism is provided and in code generation, the full C++ source code is generated to be used for system implementations.

• KIPS Transactions on Computer and Communication Systems
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• v.10 no.6
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• pp.163-172
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• 2021

To specify a formal semantics for a programming language is to do a significant part for design, standardization and translation of it. The Python is popular and powerful, it is necessary to do research for a formal semantics to specify a static and dynamic semantics for Python clearly in order to design a similar language and do an efficient translation. This paper presents the Action Equation 2.0 that specifies a formal semantics for Python to change and update Action Equation. To measure the execution time for Python programs, we implemented the semantic structure specified in Action Equation 2.0 in Java, and prove through simulation that Action Equation 2.0 is a real semantic structure that can be implemented. The specified Action Equation 2.0 is compared to other descriptions, in terms of readability, modularity, extensibility, and flexibility and then we verified that Action Equation 2.0 is superior to other formal semantics.

• Journal of Computing Science and Engineering
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• v.2 no.1
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• pp.74-97
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• 2008

A scheduling policy or a schedulability test is defined to be sustainable if any task system determined to be schedulable remains so if it behaves "better" than mandated by its system specifications. We provide a formal definition of sustainability, and subject the concept to systematic analysis in the context of the uniprocessor scheduling of periodic and sporadic task systems. We argue that it is, in general, preferable engineering practice to use sustainable tests if possible, and classify common uniprocessor schedulability tests according to whether they are sustainable or not.

• Journal of the Korea Society for Simulation
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• v.21 no.4
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• pp.35-46
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• 2012

As complexity of real-time systems is being increased ad hoc approaches to analysis of such systems would have limitations in completeness and coverability for states space search. Formal means using a model-based approach would solve such limitations. This paper proposes a model-based formal method for logical analysis, such as safety and liveness, of real-time systems at a discrete event system level. A discrete event model for real-time systems to be analyzed is specified by DEVS(Discrete Event Systems Specification) formalism, which specifies a discrete event system in hierarchical, modular manner. Analysis of such DEVS models is performed by Communicating DEVS (C-DEVS) formalism of a timed global state transition specification and an associated analysis algorithm. The C-DEVS formalism and an associated analysis algorithm guarantees that all possible states for a given system are visited in an analysis phase. A case study of a safety analysis for a rail road crossing system illustrates the effectiveness of the proposed method of the model-based approach.

• Journal for History of Mathematics
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• v.32 no.6
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• pp.281-299
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• 2019

Mathematical problem solving has become a major concern in school mathematics, and methods to enhance children's mathematical problem solving abilities have been the main topics in many mathematics education researches. In addition to previous researches about problem solving, the development of a mathematical problem solving method that enables children to establish mathematical concepts through problem solving, to discover formalized principles associated with concepts, and to apply them to real world situations needs. For this purpose, I examined the necessity of problem solving education and reviewed mathematical problem solving researches and problem solving models for giving the theoretical backgrounds. This study suggested the problem solving approach based on the intuitive and the formal inquiry which are the basis of mathematical discovery and inquiry process. And it is developed to keep the balance and complement of the conceptual understanding and the procedural understanding respectively. In addition, it consisted of problem posing to apply the mathematical principles in the application stage.

• Journal of Information Processing Systems
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• v.13 no.5
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• pp.1158-1167
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• 2017

Many real-world applications information are organized and represented with graph structure which is often used for representing various ubiquitous networks, such as World Wide Web, social networks, and protein-protein interactive networks. In particular, similarity evaluation between graphs is a challenging issue in many fields such as graph searching, pattern discovery, neuroscience, chemical compounds exploration and so forth. There exist some algorithms which are based on vertices or edges properties, are proposed for addressing this issue. However, these algorithms do not take both vertices and edges similarities into account. Towards this end, this paper pioneers a novel approach for similarity evaluation between graphs based on formal concept analysis. The feature of this approach is able to characterize the relationships between nodes and further reveal the similarity between graphs. Therefore, the highlight of our approach is to take vertices and edges into account simultaneously. The proposed algorithm is evaluated using a case study for validating the effectiveness of the proposed approach on detecting and measuring the similarity between graphs.