• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권7호
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• pp.2476-2495
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• 2021

Model-based software architecture verification and test scenarios generation are becoming more and more important in the software industry. Based on the existing temporal graph grammar, this paper proposes a new formalization method of the context-sensitive graph grammar for aiming at UML activity diagrams, which is called the UML Activity Graph Grammar, or UAGG. In the UAGG, there are new definitions and parsing algorithms. The proposed mechanisms are able to not only check the structural correctness of the UML activity diagram but also automatically generate the test scenario according to user constraints. Finally, a case study is discussed to illustrate how the UAGG and its algorithms work.

• The Transactions of The Korean Institute of Electrical Engineers
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• 제57권2호
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• pp.155-163
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• 2008

This paper presents a novel framework for analysis of power system wide-area blackout based on so called fault cascading scenarios. For a given power system operating state, "triggering" faults or a "seed faults" are chosen based on the probabilities estimated from the hazard rates. The fault probabilities reflect both the load and the weather conditions. Effects of hidden failures in protection systems are also reflected in establishing the fault propagation scenarios since they are one of the major causes for the wide-area blackouts. A tree type data structure called a PS-BEST(Power System Blackout Event Scenario Tree) is proposed for construction of the fault cascading scenarios, in which nodes represent various power system operating states and the arcs are the events causing transitions between the states. Arcs can be either probabilistic or deterministic. For a given initial fault, the total probability of leading to wide-area blackout is estimated by aggregating the individual probability of each fault sequence route leading to wide-area blackout. A case study is performed on the IEEE RTS-79(24 bus) system based on the fault data presented by the North American Electrical Reliability Council(NERC). Test results demonstrate the potentials and the effectiveness of the proposed technique for the future wide-area blackout analysis.

• Journal of Korean Dental Science
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• 제12권2호
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• pp.58-65
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• 2019

Purpose: This study was aimed to investigate the possibility of utilizing smart device-based test (SBT) for competency evaluation in dental education and to analyze the student responses on overall competency evaluation using SBT method, in comparison to ubiquitous-based test (UBT). Materials and Methods: Questionnaire surveys have been conducted at Yonsei University College of Dentistry from 2015 to 2018 to obtain students' feedback on the application of SBT to competency evaluation. In addition, in order to supplement the competency evaluation procedure, considerations were explored by comparing the expected and actual difficulty of each item when preparing items for competency evaluation with SBT. Result: According to the survey results, student responses between the initial two years (2015 and 2016) differed from those in next two years (2017 and 2018). Students in 2017 and 2018 had more positive responses on competency evaluation with SBT. To determine the test validity, criterion-referenced evaluation was adopted to compare the data in 2017 and 2018 and slight differences in test difficulty in 2018 between the expected and actual difficulty of items were found. Conclusion: The results indicated that SBT was more appropriate for competency evaluation than UBT, based on four-year period of competency evaluation. The SBT was not affected by either the file size or the number of test-takers. Interestingly, students were not sensitive to test version of competency evaluation (paper-based test and SBT). This study suggests that the quality of the test items should be measured by continuous monitoring of the expected and actual difficulty of items for determining test validity. More detailed results and discussions of the findings are given for the development of test procedure and further potential research directions in dental education.

• Journal of the Korea Safety Management & Science
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• 제17권1호
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• pp.33-43
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• 2015

Modern systems development becomes more and more complicated due to the need on the ever-increasing capability of the systems. In addition to the complexity issue, safety concern is also increasing since the malfunctions of the systems under development may result in the accidents in both the test and evaluation phase and the operation phase. Light rail transit(LRT) with passenger capacity between bus and subway is driven by an unmanned control, so safety issues of LRT in emergency shall be considered more carefully than other rolling stock. Modern railway system is a complex system and many actions in emergency are required. In this view, interoperability approach is effective to identify the related elements in emergency. In this paper, we propose the method to generate the fire response scenario of unmann ed LRT based on the outputs of systems engineering architecture design methodology. The proposed method is could be contributed to establish more reliable and applicable fire response scenario.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권6호
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• pp.2035-2049
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• 2015

Applications deployed in cloud receive a huge volume of requests from geographically distributed users whose satisfaction with the cloud service is directly proportional to the efficiency with which the requests are handled. Assignment of user requests based on appropriate load balancing principles significantly improves the performance of such cloud-based applications. To study the behavior of such systems, there is a need for simulation tools that will help the designer to set a test bed and evaluate the performance of the system by experimenting with different load balancing principles. In this paper, a novel architecture for cloud called Request Assignment Simulator (RAS) is proposed. It is a customizable, visual tool that simulates the request assignment process based on load balancing principles with a set of parameters that impact resource utilization. This simulator will help to ascertain the best possible resource allocation technique by facilitating the designer to apply and test different load balancing principles for a given scenario.

• Journal of Korea Multimedia Society
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• 제24권7호
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• pp.860-867
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• 2021

Lane detection is important technology for implementing ADAS or autonomous driving. Although edge detection has been typically used for the lane detection however, false detections occur frequently. To improve this problem, a deep learning based lane detection algorithm is proposed in this paper. This algorithm is mounted on an ARM-based embedded system to implement a LDW(lane departure warning). Since the embedded environment lacks computing power, the VGG-11, a lightweight model based on VGG-13, has been proposed. In order to evaluate the performance of the LDW, the test was conducted according to the test scenario of NHTSA.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• 제27권3호
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• pp.95-99
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• 2013

The maximum power analysis simulator took advantage of the facilities and power consumption reduction simulator test scenario development and testing of improvement in the scenario. As a maximum demand power controller, Maximum power analysis simulator performs control and disperasion of maximum demand power by calculating base power, load forecast, and present power which are based on signal of watt-hour meter to keep the electricity under the target. In addition, various algorithms to select appropriate control methode on each of the light installations through the peak demand power is configured to management. The simulation shows the success of control power for the specified target controlled by five sequential lighting installations.

• Journal of the Earthquake Engineering Society of Korea
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• 제20권1호
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• pp.1-8
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• 2016

Permanent deformation plays a key role in performance based earthquake resistant design. In order to estimate permanent deformation after earthquake, it is essential to secure reliable response history analysis(RHA) as well as earthquake scenario. This study focuses on permanent deformation of an inverted T-type wall under earthquake. The study is composed of two separate parts. The first one is on the verification of RHA and the second one is on an effect of input earthquake motion. The former is discussed in this paper and the latter in the companion paper. The verification is conducted via geotechnical dynamic centrifuge test in prototype scale. Response of wall stem, ground motions behind the wall obtained from RHA matched pretty well with physical test performed under centrifugal acceleration of 50g. The rigorously verified RHA is used for parametric study to investigate an effect of input earthquake motion selection in the companion paper.

• International conference on construction engineering and project management
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• The 5th International Conference on Construction Engineering and Project Management
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• pp.546-552
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• 2013

The future competitiveness of construction industry is dependent on K-12 students. However, unfavorable images of construction industry have negative influence on K-12 students' decision-making of their career. This negative image makes them not want to find out what actually happens in construction industry. Consequently, it is important to give K-12 students the opportunity to know what construction employees actually do in their job. Studies show that K-12 students who encounter the job early-on are more likely to choose it as their career. In this context, this paper proposes construction educational game in which it can serve as a medium for capturing K-12 students' interest in Construction Management (CM). Based on the literature reviews, challenges of construction educational game for K-12 students which are edutainment, hands-on experience and social interaction, are derived. To address these issues, conceptual model and scenario are designed. Based on designed scenario, prototype of Simulation based Construction Game in Virtual World (SCGVW) is developed in Second Life (SL) and applicability test to K-12 students are implemented. This paper concludes with a discussion of the lessons learned and the future development steps of the construction educational game for K-12 students.

• Composites Research
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• 제21권4호
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• pp.1-6
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• 2008

This paper explains fire safety tests of a hybrid composite train carbody with carbon/epoxy sandwich bodyshell and stainless steel underframe. In this study, a large scale mock-up was used to evaluate the fire safety of the composite train carbody. The test was conducted to the bare composite carbody mock-up without interior facilities and the fully equipped one. Tile fire propagation and temperature distribution of the carbon/epoxy bodyshell and the glass phenol interior panels was evaluated under the real fire accident scenario. The test scenario was based on the DaeGu subway fire accident. From the tests, both the surface temperature of the interiors and the composite bodyshell wore lower than tile ignition temperature. In addition, the fire spread along the surface of the interiors and bodyshell was not occurred.