• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제9권5호
• /
• pp.1752-1767
• /
• 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
• /
• 제8권4호
• /
• pp.331-344
• /
• 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
• /
• 제11권3호
• /
• pp.209-215
• /
• 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.

• 한국안전학회지
• /
• 제38권6호
• /
• pp.36-49
• /
• 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.

• 한국항해항만학회지
• /
• 제28권3호
• /
• pp.161-167
• /
• 2004

지금까지(1988∼2000년) 국내 해양안전심판원에서 재결한 선박충돌사고의 원인분류 통계데이터를 살펴보면 전체 2,290건의 인적과실(Human Error) 중에서 상대선박에 대한 경계의무소홀이 929건으로 약 40.6％나 되는 가장 많은 비중을 차지하고 있는 것으로 파악되고 있다. 선박충돌사고는 좌초사고와 더불어 인적과실로 기인한 수많은 인명피해와 재산피해 및 해양환경오염을 유발하는 심각한 해양사고로서 이에 대한 사고원인을 철저히 분석하고 그 예방대책 마련이 무엇보다 중요한 과제가 되고 있다. 따라서, 본 연구에서는 선박충돌사고의 인적과실을 분석하기 위한 목적으로 목포해양안전심판원에서 재결한 선박충돌사고(1990∼2002, 65건)에 대하여 상대선 경계의무소홀이나 동정감시 불충분으로 기인하여 발생한 충돌사고를 조사항목별로 분석하고, GEMS 동적모델을 이용하여 선박충돌사고의 인적과실 유형을 체계적으로 분류하였다.

• International Journal of Automotive Technology
• /
• 제7권7호
• /
• pp.785-793
• /
• 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.

• 한국정밀공학회지
• /
• 제17권12호
• /
• pp.76-81
• /
• 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
• /
• 제8권1호
• /
• pp.23-41
• /
• 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.

• 융합경영연구
• /
• 제11권4호
• /
• pp.53-63
• /
• 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.

• 디지털콘텐츠학회 논문지
• /
• 제19권2호
• /
• pp.363-370
• /
• 2018

최근 랜섬웨어 탐지는 디지털 콘텐츠 보호를 위한 컴퓨터 보안 분야에서 중요한 주요한 이슈가 되고 있다. 그러나 불행하게도 현재 시그니쳐 기반이나 정적 탐지 모델의 경우 압축 및 암호화 등의 기법을 이용하여 탐지를 피해갈 수 있다. 이를 극복하기 위해 본 논문에서는 RF, SVM, SL, NB 알고리즘 같은 데이터 마이닝 기법을 이용한 다이나믹 랜섬웨어 탐지 시스템을 제안하였다. 이 기법은 실제 소프트웨어를 구동 시켜 동작 행위를 추출해 API 호출 흐름 그래프를 만들고 그 특징을 분석에 이용하였다. 그 후 데이터 정규화, 특징 선택 작업을 진행하였다. 우리는 이러한 분석과정을 더욱더 개선 시켰다. 마지막으로 데이터 마이닝 알고리즘을 적용시켜 랜섬웨어인지를 판별하였다. 제안한 알고리즘의 성능 측정을 위해 더 적합한 추가 샘플 랜섬웨어 데이터를 수집하여 실험하였고 탐지성능이 향상되었음을 보여주었다.