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Safety Requirement Elicitation for Small Aircraft Collision Avoidance Software using STPA, FTA and FMEA
Jongwon Lee, Uicheon Lee, Taehwan Kim, Seonah Lee
http://doi.org/10.5626/JOK.2024.51.8.706
With the growing trend of urban air traffic, aircraft are becoming smaller and more reliant on software. As a result, safety analysis techniques and standards, which have traditionally focused on ARP4761, the aircraft safety evaluation process, must evolve to incorporate a software-centered approach. In this paper, we propose how to link STPA method to FTA and FMEA for safety analysis in air mobility, which is a software-intensive system. To assess the feasibility and effectiveness of this approach, we conducted a safety analysis case study focusing on the collision avoidance software of a small aircraft. The results of the study confirmed the effectiveness of linking STPA, FTA, and FMEA methods and enabled the derivation of safety requirements.
Ray Tracing-based Real-time Collision Detection Using Bounding Mesh of Polygonal Model
Seokyoung Koh, Youngwook Kim, Insung Ihm
http://doi.org/10.5626/JOK.2024.51.2.173
For accurate real-time collision detection between two polygonal meshes, it is essential to check if each triangle of one polygonal mesh is intersected with the other polygonal mesh. However, because the number of triangles of large-size meshes easily increases, such a simple method often cannot achieve real-time detection. In this paper, we propose a GPU-assisted real-time collision detection technique where both a bounding mesh approximating a given large-size mesh and the GPU-assisted ray-tracing hardware are effectively exploited. In this method, the bounding mesh that intends to reduce the number of triangles participating in the triangle-object intersection is first intersected with the other mesh. In this way, it was possible to perform the collision detection operation within the reduced region with decreased numbers of triangles. In addition, we improved the performance of the collision detection process by exploiting the GPU-supported ray-tracing engine for accelerating the triangle-object intersection operation.
Ontology-based Approach to Determine the Conflicts between Security and Usability Requirements in the Requirements Engineering Process
http://doi.org/10.5626/JOK.2018.45.11.1142
Considering the trade-offs or conflicts between security and usability during the requirements engineering (RE) process is a complicated task. This is due to the contrary characteristics of security and usability as well as a lack of research on finding a consensus on the semantics of quality attributes, especially for security and usability. Furthermore, the number of security experts available is decreasing, while a methodology to determine the conflicts between security and usability during the RE process has not yet been developed. We, therefore, propose a novel approach to construct a three-layer ontological knowledge base by linking the keywords from definitions, criteria, and metrics of security and usability. In addition, we discuss the applicability of this knowledge base by examining two case studies with software engineering (SE) students. These case studies show that the participants using the proposed approach (Team A) can derive conflicts that are more precise compared to the participants who did not use the knowledge base (Team B). Moreover, the number of conflicts derived by Team A is half that by Team B. Regardless of the knowledge level, the proposed approach can determine the conflicts between security and usability during the RE process. Also, while practical RE studies have often been considered difficult to handle, the proposed approach can show the applicability of RE research.
Case Study for Collecting Policy Evaluation Factors upon Request when Creating XACML Policy
http://doi.org/10.5626/JOK.2018.45.9.975
As the Internet of Things environment continues to expand, access control issues continue to emerge. OneM2M, one of the standards of the IOT platform, allows access control using XACML. In the arena of access control, conflicts must be solved. Because of this, various solutions are being investigated in order to solve these problems. Currently, however, the policy editor must solve policy conflicts by themselves. So, the policy editor needs to be able to effectively collect information about policies and conditions that affect their policy evaluation decisions in order to resolve policy conflicts. In this paper, we analyze policy and express policy evaluation methods in terms of Truth Table. In addition, we present a tree-based policy evaluation factor collection method through a case study on a policy evaluation factor collection method according to requests using Truth Table.
Using Cache Access History for Reducing False Conflicts in Signature-Based Eager Hardware Transactional Memory
This paper proposes a method for reducing false conflicts in signature-based eager hardware transactional memory (HTM). The method tracks the information on all cache blocks that are accessed by a transaction. If the information provides evidence that there are no conflicts for a given transactional request from another core, the method prevents the occurrence of a false conflict by forcing the HTM to ignore the decision based on the signature. The method is very effective in reducing false conflicts and the associated unnecessary transaction stalls and aborts, and can be used to improve the performance of the multicore processor that implements the signature-based eager HTM. When running the STAMP benchmark on a 16-core processor that implements the LogTM-SE, the increased speed (decrease in execution time) achieved with the use of the method is 20.6% on average.
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