• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.5
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• pp.1752-1767
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• 2015

As a special type of mobile ad-hoc network, Vehicular Ad-hoc Network (VANET) is considered as an attractive topic by many researchers. In VANETs, vehicles act as routers and clients, which are connected with each other through unreliable wireless links. Due to the dynamic nature of vehicles, developing communication protocols for VANETs is a challenging task. In this paper, we tackle the problem of real-world VANET operations and propose a new dual-level communication scheme through the combination of power and rate control algorithms. Based on the game theoretic approach, the proposed scheme effectively formulates the interactive situation among several vehicles. With a simulation study, it is confirmed that the proposed scheme can achieve better performance than other existing schemes under widely diverse VANET environments.

• Advances in aircraft and spacecraft science
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• v.8 no.4
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• pp.331-344
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• 2021

Airframe internal and external specifications are the product of intensive intellectual efforts and technological breakthroughs distinguishing each aircraft manufacturer. Therefore, geometrical information characterizing aircraft primary aerodynamic surfaces remain classified. When attempting to model real aircraft, many members of the aeronautical community depend on their personal expertise and generic design principles to bypass the confidentiality obstacles and sketch real aircraft airfoils, which therefore vary for the same aircraft due to the different designers' initial assumptions. This paper presents a photogrammetric shape prediction method for deriving geometrical properties of real aircraft airframe by utilizing their publicly accessible static and dynamic visual content. The method is based on extracting the visually distinguishable curves at the fairing regions between aerodynamic surfaces and fuselage. Two case studies on B-29 and B-737 are presented showing how to approximate the sectional coordinates of their wing inboard airfoils and proving the good agreement between the geometrical and aerodynamic properties of the replicated airfoils to their original versions. Therefore, the paper provides a systematic reverse engineering approach that will enhance aircraft conceptual design and flight performance optimization studies.

• Journal of Positioning, Navigation, and Timing
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• v.11 no.3
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• pp.209-215
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• 2022

As intelligent autonomous driving vehicle development has become a big topic around the world, accurate reference dynamics estimation has been more important than before. Current systems generally use speed and heading information sensed from a distant point as a vehicle reference dynamic, however, the dynamics between different points are not same especially during rotating motions. In order to estimate properly estimate the reference dynamics from the information such as velocity and heading sensed at a point distant from the reference point such as center of gravity, this study proposes estimating reference dynamics from any location in the vehicle by combining the Bicycle and Ackermann models. A test system was constructed by implementing multiple GNSS/INS equipment on an Robot Operating System (ROS) and an actual car. Angle and speed errors of 10° and 0.2 m/s have been reduced to 0.2° and 0.06 m/s after applying the suggested method.

• Journal of the Korean Society of Safety
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• v.38 no.6
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• pp.36-49
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• 2023

Since the recently established obligation to implement safety and health measures for specialized workers as outlined in the Occupational Safety and Health Act (OSHA) for nine occupations in January 2020 and five occupations in November 2021, there is a need to verify and inspect the on-site operation of related systems. After a comprehensive fact-finding survey and risk factor analysis, it is necessary to examine the responsibility for on-site safety and preventive measures, along with the roles and responsibilities of specialized workers. Stakeholder analysis is essential to identify the fundamental problems related to the responsibility stipulated in the purpose of OSHA and to explore the entity responsible for implementing safety measures. Therefore, in this paper, we discuss the topic of implementation based on legal standards for on-site safety and preventive measures. Additionally, we develop a role model for appropriate safety measures, outlining the dynamic relationship between those who provide labor and those who provide labor in the context of specialized workers.

• Journal of Navigation and Port Research
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• v.28 no.3
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• pp.161-167
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• 2004

Maritime safety and marine environmental protection are the most important topic in marine society. But, so many marine accidents have been occurred with the development of marine transportation industry. On the other side, ship is being operated under a highly dynamic environment and many factors are related with ship's collision Nowadays, the increasing tendency to the human errors of ship's collision is remarkable, and the investigation of the human errors has been heavily concentrated. This study analysed on the human errors of ship's collision related to the negligence of lookout and classified basic error type using GEMS(Generic Error Modeling System) dynamic model.

• International Journal of Automotive Technology
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• v.7 no.7
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• pp.785-793
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• 2006

The topic of this study is the control strategy of a mild hybrid electric vehicle (HEV) equipped with a continuously variable transmission (CVT). A brief powertrain and vehicle configuration is introduced followed by the control strategy of the HEV with emphasis on two key parts. One of them is an ideal operating surface (IOS) that operates the CVT powertrain optimally from the viewpoint of the tank-to-wheel efficiency. The other is a charge sustaining energy management to maintain the battery state of charge (SOC) within an appropriate level. The fuel economy simulation results of the HEV over standard driving cycles were compared with those of the baseline vehicle. Depending on the driving cycle, 1.3-20% fuel saving potential is predicted by the mild hybridisation using an integrated starter alternator (ISA). The detailed energy flow analysis shows that the majority of the improvement comes from the idle stop function and the benefits for electrical accessories. Additionally, the differences between the initial and the final SOC are in the range $-1.0{\sim}+3.8%$ in the examined cycle.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.12
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• pp.76-81
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• 2000

Analysis on failure of the panel glass under mechanical shock is the main topic of this study. Since the glass for the LCD panel is thin, it needs to be designed to have enough toughness against mechanical shock. In this paper, a process of estimating fracture of the panel glass is proposed to guarantee reliability of the product. The fracture toughness of the panel glass is used as a criterion of the fracture based on an experimental approach. The stress intensity factor was calculated considering a model with the largest initial crack size on a cut surface and with the boundary force obtained from a dynamic finite element analysis. Critical surface roughness on the cut surface of a typical glass panel, to prevent fracture in case of bending mode, is obtained.

• Computers and Concrete
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• v.8 no.1
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• pp.23-41
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• 2011

The behaviour of concrete confined by transverse reinforcement is a classical topic. Numerous studies have been conducted to establish the stress-strain relationships for concrete under various confining reinforcement arrangements. Many empirical and semi-empirical formulas exist. Simplified analytical models have also been proposed to evaluate the increase in the strength and ductility of confined concrete. However, relatively few studies have been conducted to utilise advanced computational models for a realistic simulation of the behaviour of concrete confined by transverse reinforcement. As a matter of fact, high fidelity simulations using the latest numerical solvers in conjunction with advanced material constitutive models can be a powerful means to investigating the mechanisms underlying the confining effects of different reinforcement schemes. This paper presents a study on the use of high fidelity finite element models for the investigation of the behaviour of concrete confined by stirrups, as well as the interpretation of the numerical results. The development of the models is described in detail, and the essential modelling considerations are discussed. The models are then validated by simulating representative experimental studies on short columns with different confining reinforcement schemes. The development and distribution of the confining stress and the subsequent increase in the axial strength are examined. The models are shown to be capable of reproducing the behaviour of the confined concrete realistically, paving a way for systematic parametric studies and investigation into complicated confinement, load combination, and dynamic loading situations.

• The Journal of Economics, Marketing and Management
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• v.11 no.4
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• pp.53-63
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• 2023

Purpose: The purpose of this study is to examine the research trends in the papers published by Korean researchers related to traditional markets, to check what topics have been studied, and to make various suggestions for research directions and effective ways to revitalize traditional markets. Research design, data and methodology: To this end, this study conducted word frequency analysis, co-occurrence frequency analysis, BERTopic, LDA, dynamic topic modeling and OLS regression analysis using Python 3.7 on the English abstracts of a total of 502 papers extracted through ScienceON. Results: As a result of word frequency analysis and co-occurrence frequency analysis, it was found that studies related to traditional markets have been conducted not only on factors related to customers, but also on traditional market merchants and government policies, and the degree of service, quality, and satisfaction perceived by customers using traditional markets. Through BERTopic and LDA, three topics such as 'Traditional market safety management' were identified, and among them, it was found that 'Traditional market safety management' is relatively less attention by researchers. Conclusions: The results of this study suggest that future research on the revitalization of traditional markets should be conducted from a specific consulting perspective along with the establishment of various data, a causal model study from various perspectives such as the characteristics of merchants as well as consumers, and an integrated and convergent approach to policy formulation by the government and local governments.

• Journal of Digital Contents Society
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• v.19 no.2
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• pp.363-370
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• 2018

Ransomware detection has become a hot topic in computer security for protecting digital contents. Unfortunately, current signature-based and static detection models are often easily evadable by compress, and encryption. For overcoming the lack of these detection approach, we have proposed the dynamic ransomware detection system using data mining techniques such as RF, SVM, SL and NB algorithms. We monitor the actual behaviors of software to generate API calls flow graphs. Thereafter, data normalization and feature selection were applied to select informative features. We improved this analysis process. Finally, the data mining algorithms were used for building the detection model for judging whether the software is benign software or ransomware. We conduct our experiment using more suitable real ransomware samples. and it's results show that our proposed system can be more effective to improve the performance for ransomware detection.